Recently purchased a 1969 Grand Prix with 428 AT (non-HO engine). Can someone tell me if this is correct: from what I can gather, the 1969 428's in the Grand Prix were either the 066 grind (370 HP version) and the 068 grind in the HO version? I want to do a basic rebuild, and some restoration of the car - it is all there, pretty solid, no rust except for a small area on driver door. Main thing is it is all there, and in pretty good shape. The engine, I was told has not been apart - and that appears to be true - numbers matching. I don't care about date coded wires and clamps and assembly line markings - but do want to keep close to original, except where it makes sense to upgrade (thinking of upgrading the brakes - larger calipers on front, stock rebuild back, new springs and shocks front and back - maybe lowering springs?, new basic front end and steering components, mostly stock but maybe upgraded sway bar - and want to add boxed trailing arms in back and add sway bar - and upgraded bushings, etc.).Will have more specific questions as I go, but just getting ideas of how to proceed. Any thoughts on basic engine rebuild will be appreciated. For example, I imagine stock rebuild on bottom end - but maybe forged? balanced, etc., maybe stock heads, but new valves, valve job, guides, etc., maybe change to long branch cast headers (or RAIV?). I am trying to figure out the differences between the 370 and 390 HP engines - I think cam (068 vs 066?), maybe exhaust manifolds? I do know the HO version had an extra 0.25 compression ratio (10.75 vs. 10.50). I don't want this to turn into a 5 year, nut and bolt experience that would mean I would go way over budget, and not enjoy the car for far too long - but I do want to take it a step at a time, and learn, and enjoy - and share this experience with my son. THANKS if you have any input!Oh yeah, it has #62 heads (xxx968 casting, XF code block - 428) - and I am confused by the lists I find online regarding head codes for various engines - it shows #62 heads for the 1969 428 (370 horse) and shows 16/62 heads for the HO version - what the heck does that mean? Sorry for the length, and thanks again!
69GP, welcome to the forum!For your build goals, I don't feel that you need to go to forged internals. Good prep on factory rods (re-sizing, magnafluxing and casting flash stress relieving w/application of ARP rod bolts) would certainly meet your goals. I would definitely have the internals balanced, heads cleaned up with a fresh 3 angle valve job and gasket/port matched to the intake. The long branch (RAIV style) would be a good up grade.Given the state of todays gasoline, you'll want to lower your CR to <=9.5:1 for Pontiac iron heads unless you have access to 98+ octane gas. This is best done with dish pistons. Speaking of which, a good set of hypereutectic pistons would work well for your application.For your camshaft selection, you can go with the 068 which i believe is still available through Melling tool, aftermarket grinds are probably a better choice given the enhancements with computer design. The 041 cam is the only cam that used the 1.65 rocker arm ratio versus the standard 1.5 from Pontiac which would necessitate careful measurements around installed spring height/compression and clearence to valve spring retainer.Lunati and Crower are two good companies that can make a pontiac motor sing.. I'm running a Crower roller in my 428.HP #'s were a game the manufacturers played to sell thier cars and while I don't know where the .25 increase came from between the 370 and 390HP versions, my guess would be something to do with a deck height change between the two t oraise the CR since the heads are the same.this is just my 2 cents here..
+1 my71I’m missing 2 of the following. Code yr ci hp trans carb eng cast # main boltsXF B-body 69 428 370 Turbo 400 1x4 9792968 4 XG B-body 69 428 390 Turbo 400 1x4 9792968 4 CAMS370 hp auto used 66 cam 10.50390 hp auto used 68 cam 10.75370 hp man used 67 10.50390 hp man used 68 10.75HEADSI have seen 16, 16/62 and 62 numbers for 69. I bekieve the 16 are small valve 360 hp heads.Both the 16/62 and 62 show the same large valve size and 72 cc so I jhave no clue what the difference is but might guess that it is head flow and/or screw in studs vs non screw in studs. Rowsley or another member will know.As far as engine builds go it would help to get more info so here’s a brief inbterrogation.Do you want a mild moderate or rough idle?Do you need vacuum for power brake?Are you willing to run optional vacuum can for 40.00 for your brakes if need be?Do you want a tire roaster or tire warmer?Are you willing to change rear end gears if yours sare not suitable?What are your gears?Overdrive trans?Auto or manual?Mostly fwy, street or inbetween driving?For a basic build i
+1 my71I’m missing 2 of the following. Code yr ci hp trans carb eng cast # main boltsXF B-body 69 428 370 Turbo 400 1x4 9792968 4 XG B-body 69 428 390 Turbo 400 1x4 9792968 4 CAMS370 hp auto used 066 cam, 10.50390 hp auto used 068 cam, 10.75370 hp man used 067 cam, 10.50390 hp man used 068 cam, 10.75HEADSI have seen 16, 16/62 and 62 numbers for 69 428's. I believe the 16 are small valve 360 hp heads.Both the 16/62 and 62 show the same large valve size and 72 cc so I have no clue what the difference is but might guess that it is head flow and/or screw in studs vs non screw in studs. Rowsley or another member might know.As far as engine builds go it would help to get more info so here’s a brief interrogation.Do you want a mild moderate or rough idle?Do you need vacuum for power brake?Are you willing to run optional vacuum can for 40.00 for your brakes if need be?Do you want a tire roaster or tire warmer?Are you willing to change rear end gears if yours sare not suitable?What are your gears?Overdrive trans?Auto or manual?Mostly fwy, street or inbetween driving?For a basic build I would follow my71's suggestions and add the following.Damper - ATIINTAKE - Eddey RPM.CARB - Holley street avenger 750 vacuum secondary. this carb has annular boost venturies. this type of boost venturi has been proven in different dyno tests to provide noticeably more hp and tq than the same size and brand non annular type from idle to around 5800 rpm. quick fuel also makes an annular 750 but i have heard they have some probs. i would not use one.EXHAUST - Yes, some nice ra manifolds, 2 1/4" - 2/3/4" tubes with crossover or X pipe.HEADS - Screw in studs, pocket port and back cut intake valves, stainless valves.ROCKER ARMS - I like rollers, i would buy Scorpion "race" models from summit.PUSH RODS - US made like Manley etc.CAMS265DEH 1200 - 5500 - kinda mild, torquey, use non rpm intake, 3.00 - 3.23 gears, stock converter.275DEH 1500 - 5800 slight lope, 3.23 - 3.43 gears 2000 rpm stallXE268H 1600 - 5800 slight lope, 3.23 - 3.43 gears 2000 rpm stallXE274H 1800 - 6000 - i would not go bigger than this for moderate street eng, might need vacuum can for brakes. 3.43 - 3.50 gears and 2400 stall.See all cam specs in link below.http://www.compcams.com/Company/CC/cam-specs/cam-search-results.aspx?sc=70&sm=By%20Engine%20Family
Thanks very much for the reply. Not sure what you are looking for with info at beginning (maybe that was just for me?). The car has a TH400 trans, and I believe the rear end is a 3:55 - I had a GP back in the day, and I think it was a 3:07 or so, I can live with the 3:55 - I won't drive enough to worry about as mileage, and driving will be mostly around town, country roads, pleasure driving. Unfortunately it is an open rear - I am thinking about upgrading to a posi unit (and that alone causes me to ponder many variables - for example, with a posi, and modern tires, I have heard that I could easily damage something with much flogging - the other issue is cost - I can afford it, but think I'd rather put that money into things that make more of a difference to me - upgraded steering, suspension, brakes, etc.).It is a 69 block, can't remember the date code, but it checks out - number matching. I think all 69 428 blocks were 4 bolt blocks, but I think you are right in that the 16 heads were small valve and used on B body cars - I think they also had a milder cam, small valve, low compression heads, single exhaust, etc. Thanks for the cam info, sometimes it is hard to find details online - I obviously would have the 066 grind, and I figured the HO used the 068 (as did RA I, 68 HO, RA III etc., and I assumed that the RA IV grind and the 68 RA II grind were hotter and only used on a few engines). Also, I was assuming I'd go with an 068 or RA IV grind - but as you point out, modern technology, computer modeling has likely come up with superior alternatives - so, I will check out your cam info - I don't mind a mildly rough or rough idle, so long as it is not a pain in the but for street - I will not race the car ever, and will mostly cruise, but want to be able to play a little bit. I have not driven a radically cammed car - I assume with my TH400, it would be more "livable" to have a hotter cam, compared to a manual trans car.I think I have addressed your points and questions - regarding the vacuum, I guess to radical a cam would screw with vacuum operated stuff - uh, haven't given it a lot of thought - I wouldn't have a problem adding vacuum assist - haven't done that before, but seems pretty straightforward. Regarding vacuum, I had planned, initially, on rebuilding the Q-jet - I think an under-appreciated carb. I think thy are complex, but if set up properly, work brilliantly - my dad, who helped me build my first car (a 70 GP, back in the late 70's), and I know that all we did was basic rebuild, with good valve job, 068 cam, and he rebuilt the carb - I know he made mods, but don't know - and he recently passed away, so.. - anyway, that car would simply fly. I remember my dad always told me that these cars could easily go from 200 to about 400 HP (and vice versa) with fairly minor changes in the carb settings. I wouldn't mind changing to a modern setup - a lot of people seem to go with the Edelbrock intake and carb combo - and obviously bolting on a set of round port, or D-port aluminum Edelbrock heads could help me solve some of the issues - compression ratio, and bolt on parts - but, again, for the money, I think I could get just about as much out of stock parts, and retain the feel, look, etc. and put money in other areas - I don't know, it seems like a part of the fun, to me, is having, maintaining, and driving a real Pontiac - I have NO problem with bolt-ons - for upgrades, or replacing broken or missing parts, but my car is complete, and I don't want or need much more than the original performance specs. Thanks again for the response and info. If you have further comments, I happily welcome them.Oh yeah, just re-read post - regarding tire warmer vs. roaster - I have no desire to sit and destroy a pair of tires in one sitting - too wasteful, expensive, etc., but would like to be able to get them going - and unless I am way off here, I think a stock rebuild of this engine would/should be able to fry the tires. In fact, that is why I mentioned the possible upgrade to posi - the idea being that I could launch better - but, that could, I have heard, with this amount of torque, and with a good, modern set of tires, break something fairly easily - maybe an upgrade to a 12 bolt? Anyway, thanks again.
ok, thanks fir the info.yes the 4 bolt info at the beginning of my post was for you.actually my71 suggested a "modern" grind cam so to speak but that is what i use anyway.DIFF - yes with 355 and a non posi it should roast the tires anyway.i would not worry about breaking anything unless you have a "bop" diff but others here will know better about that. i only know about 12 bolts. POWER - even if you have so much power it easily roasts tires on a posi it is still not a waste because you can simply use less throttle off the line but the you will have very strong acceleration with no tire spin if yiu get on it from 30 mph on up which satisfies your desire for good power there. this gives you something to think about.HEADS - Yes i am sensing that you might have all the power you want with mildly ported stock heads.INTAKE - The 274 and 268 cams really might work better with an eddy intake, but you can get away with a non rpm with the others if you want to keep the orig look.CARB - Yes the q's are good when set up properly however you will get more hp and tq with an annular type as i mentioned.also find out what cfm yours is, obviously if it is like 600 it might not be sufficient for your app.if you are consideringCAMS - Comps xe series cams tend to hit just a little harder than their deh series.
Thanks very much for the reply and info. I hope I am posting correctly - to reply to someone's post, do we simply hit reply on that post? I guess I will figure that out pretty quick.OK, I am thinking you are correct regarding the forged - seeing that I only want a modest upgrade of performance (I really want longevity more than ridiculous power). I also assumed that balancing was a pretty important aspect of the build - that scares me a little, since I am pretty much a novice - I can figure this stuff out, and I understand that most have to turn to a shop that has the equipment and expertise to do much of the initial build - but 1) I want to share as much of this process with my son (maybe some day he will look back and have good memories, as I have of my father when he helped me build my first car - and although my son is only 12, hopefully he can appreciate some of it, and learn some things, and enjoy the experience - and if I am still around (God willing), I assume that some day, I will give this car to my son, and hopefully he will keep it and appreciate it.I haven't picked up any literature yet, but I am sure there are good sources out there (if you have a suggestion, let me know). My plan is to put together the basics of the build (like stick with stock rotating assembly, but plan to balance, cam choice, piston, intake, carb, etc.), and then make a task list - from disassembly to re-installation - and then make it happen - I am in the process of trying to gain enough knowledge to get the basics of the build ready to go. I understand there are just about infinite choices here - and like everyone else, even with an unlimited budget I'd have a hard time building my ideal engine - it's like a lot of things, there are no ideal engines, just engines that are more ideal for a given application. Since I only want modest upgrades in performance (I think much more power would/should be accompanied by lots of other high dollar upgrades - to be safe as well as to make sense), I think mostly stock makes sense. I only see changing when it makes sense - areas where modern technology gives a new part a real advantage, and since I don't care about keeping 100% authentic - but want as stock as possible. I will make a list of my current thoughts - feel free if you get a chance to point out any errors in my thinking - and thanks very much for the response.1) 1969 XF code 428 block, casting number XXX968, 4 bolt mains2) clean engine - check for cracks, etc. and if it checks out,3) deck - only if it needs it4) align bore - only if needed (if these two things are within specs, is it OK to skip?)5) stock crank, stock rods, dished pistons to deal with CR - balanced internals6) advice on bearings - clevite? etc., rings?7) engine bore - stock OK with me, but I assume it might need bored - if so, have professional do it - I assume there are many pistons available.8) heads, stainless valves, three angle grind, I guess there are valve guides or something that needs to be changed for modern gas? but, port matched to intake? I know - I can bolt on Edel's round port or D-port and deal with CR, and basically have a modern version of the RA IV head - maybe this is a good investment - I haven't decided 100%, but I think for the money, and given that I only desire modest performance upgrade, Pontiac steel heads will do.9) exhaust manifolds - long branch or RA IV upgrade - over whatever cast set came stock - seems to me that the cost and maintenance of headers would not be worth it - but with upgraded head (rockers, etc.) I assume these would look great, look stock and improve performance.10) Carb - thinking stick with Q-jet - rebuilt. I can bolt on an Edel carb or cab and intake combo - and get moderate improvement - but is it worth the money? Is it a pain to deal with choke, vacuum issues - trans kickdown, etc.?11) cam - I was thinking 068 grind - upgrade from the 066 grind in the 370 HP version. I understand I could also go to RA II or RA IV (same thing, different number, right) grind - and get even better performance - would I curse myself after - trying to enjoy cruising around town and back country roads - given that I have TH 400 trans? But, as you point out, there likely are modern alternatives that give even better performance, and I am not terribly concerned with stock - like I sad, I don't care about date coded clamps and inspection marks, etc., but want to look and feel as stock as possible - except where modern technology makes sense to change - better disc brakes up front, etc.12) timing chain - I assume a good double roller setup will suffice? I assume I don't want pure stock here - and a good roller setup seems to be not that much more expensive - and assume I don't need the expensive, exotic new stuff.13) oh yeah, rockers - I hadn't give this much thought - but I guess stamped steel stock makes no sense - but roller rockers seem to be ubiquitous in most engines built by competent builders. Seems to me that the moderately upgraded steel/roller sets, like those of comp cams would suffice?14) oil - OK to stay stock? Go with RA IV version, which I think is simply a higher pressure unit? Along with this, stock pan? Is it worth adding a larger oil capacity pan - is it worth moving the oil filter - maybe worth it if I upgrade to long branch headers, since they don't fit well on the GP.15) decent exhaust - 2..5 inch? I assume x-pipe setup is worth it. Actually, would love to have cut-outs, just for fun - but don't know if it is worth it - that is a lot of bucks for a minimal amount of fun - but it'd be damn cool.16) Stock TH400 - maybe a shift kit? I really don't know if it is worth the money and effort to upgrade the trans, etc.17) now it is a 3:55 open unit -would like to have posi - a new Auburn unit seems like the most economical way to get there? But, it's my understanding that there are a lot of better posi units out there these days. Posi would give better launch - but I will never really race - and this could cause too much traction - and with modern tires and even a slightly upgraded engine, could cause much grief when I snap something in the rear.18) I assume I will do basic, common sense stuff like new engine and trans mounts, u-joints - is it worth worrying about or upgrading the drive shaft?19) cooling system - is stock OK, or should I upgrade - are there better water pumps out there? Will it be necessary or advisable to upgrade the radiator - seems like a big chunk of bucks?20) oh yeah, I forgot about intake - as mentioned, I could bolt on Edel stuff - or I could stay with bone stock - or I could upgrade to ???? There are RA IV, aluminum repros out there - are they good? IF I do go with an aftermarket intake, should I upgrade the carb, as a package?I guess that takes care of most of the basic engine stuff. I want to start buying and collecting this stuff - and hopefully get going on it this winter. I don't want this to be a multi-year project - I want to drive and enjoy. I enjoy turning wrenches - but I don't want to dedicate too much time to it. Hopefully I can find happy medium - I'd like to upgrade the car with small (or large) projects and upgrades - but drive and enjoy the car as I go. I really want this to be a car I can drive and enjoy - don't care about shows, and don't care about nut and bolt - I am looking for that happy balance between pure stock and all out restomod - well, I guess once we upgrade the first thing with modern parts (even a better sway bar, brakes, etc.) we enter the realm of restomod - but I can't afford a 100 point show car - and don't care about that kind of thing - but want to stay stock looking - where possible.Thanks so much for your response and input - I didn't mean to write a book here sorry - but it helps me to get it down - and in print - I am learning as I go here. And any and all advice is very much appreciated. I simply LOVE that people are not only here to help, but also seem happy to help - GOOD PEOPLE!
hi, ok, click post reply anywhere, if you want to quote the post click the box in the lower right above post box.this is what i would most likely do, others might not. this is what i think you are looking for not including the info i already posted.block/pistons -line bore only if needed,deck block to .005" from 0.get kb hyper dished pistons or flatlander racing, use the online calculators at wallaceracing.com to determine what you need based on your cam but we can do that for you also. if they do not make the dish you need then surfsace the block as little as possible and buy dished pistons. i think you need around 17cc.if block is rusty heavily rusted in water jackets get it acid or caustic soda dipped.get cylinders sonic checked for thickness.bore to .030" if it will clean up there.balance - yes balance.rockers - do not use the stamped steel comp rollers buy the scorpions and be done with it. the most friction is at the stud not the tip.cam - forget about the origs buy a comp or lunati 60903 1600 - 5800.carb - you could not pay me to use a q jet or eddy, others love them, yes i can easily tune them i just don't like the way they look. timing chain - yes us made roller like edelbrock or cloyes.oil pan - stockoil filter - leave it where it istrans - a shift kit is nice, a trans guy can make his own for you.ra intake - yes you can use it and it will not work as well for your app but you might not notice a big difference so if you like the look then use it.radiator - depends on what you have but a 3 row high efficiency orig looking rad from us radiator sold by coolcraft.com is what i would do if yours is a 3 row or smaller. of course you can try yours to see if it runs hot first then change it later if need be.heads - use ported cast iron for your app. break in - this process requires a certain technique and use of non synthetic oil with high levels of zddp in it. we'll help you when you are ready.book - rocky rotella, look up jim hand in google search, smokey yunick, how to build a big block chev.yes we enjoy spending other peoples money and making their car way faster than they really want it to be.
Thanks again for the replies.shyrgfuh3 - thanks - at first I missed the extra info at the end of your post. I will do some more research on the intakes and other stuff you suggested. I understand that stock Pontiac intake on my car is pretty useless at the RPM range that the other mods will allow - actually, that is one thing I was contemplating in my fist response to your post - I know there are repro Pontiac intakes - like the RA IV - and obviously there are many other aftermarket choices. I have problem with aftermarket - I am just trying to maximize my return on investment - and trying to end up with a "balanced" car - not too much money in engine and none in suspension/brakes, and so on. There are a lot of possibilities - some people want 100% stock (too expensive and impractical for me), some want restomod - improved performance - with performance being more important than stock looks - and there are people out there using modern equipment - and go out of the way to make it appear stock - like grinding off the Edelbrock script on the intake - and painting it to make it look like stock Pontiac. And some people like the look of what most modified cars actually looked like back in the day - after all, a lot of people added aluminum intakes, headers, air cleaners, etc., as soon as they got their hands on a new car. I will think about these suggestions - intake, carb, etc. I can see going either way - and actually, I don't think there is a right way and wrong way - just the way we choose.Anyway, thanks again - I appreciate it.Regarding my goal for upgrades in power - while I think it'd be fun to have a 600 HP car, I think it'd be lost on me, with respect to what I will realistically do with the car - and as I said, I want it to make sense - kinda doesn't make sense to have 700 HP and zero upgrades to suspension/steering/brakes - at least to me. So, in all honesty, an honest 400 HP (and hopefully a little over 500 TQ) will do everything I want and need it to do (I'm 51 - too old and lazy - and honest - when I was 30, I would have demanded more HP, and wanted 4 speed - now, I can admit that I'd rather have auto, in this car, and 400 HP will do me fine. The extra HP it takes to affect performance is non-linear with respect to increasing top end speed and reducing quarter mile times - and the extra money just doesn't make sense to me (at this time, for this car and application).Thanks again - I gotta get back to some real work - PEACE!
wow, you must type 2000 words a minute, that was fast.you will have 400 hp with our suggestions we already made if you want it.you will not have 500 tq, that is a tall order but can be done.i'm really thinking the comp xe274h might be a hair much for you, hard to say yet but we'll figure it out.does your car roast the tires now?do you want more hp than you already have?confirm your exact specs again and we can go from there also.the more hp you have the less bottom end power you will have.other than installing a 12 bolt suspension upgradres are not too expensive. in other words you do not need to spend 2500.00 on suspension just because you have 400 hp. buy stiffer front and rear springsslightly larger front sway bar.kyb white gas shockstraction barschain your engine down on the driver sideyou're done.
i would only replace seats if yours are not useable, your engine will go 80k with orig seats.your heads might be 700.00 - 850.00 with valve job, guides if needed, surface if needed, new valves and mild porting.alum eddy heads 2000.00
shyrgfuh3 - thanks again for the info - I am definitely getting closer to a real build plan. sorry for delay, had to take a quick break. Regarding typing speed - yeah, that's funny, my kids, 11 and 13, always comment about my speed when I am helping them with homework, etc. I sit at a computer, and have done so for much of the last 25 years or so - can type really fast.Anyway, with a starting (stock) HP of 370, I just assumed I'd be up around 400 with a few mods (and if I do as you suggest, balance bottom end, new valves, roller rockers and porting mods to head, etc., new intake capable of higher RPM's, and a cam that I assume is much better than the 066 stock grind, and other mods should easily give me a robust engine with 400+ HP). And that should do just fine. Regarding torque, I think the engine's stock rating is around 450. Hadn't really thought about it, but I guess it is easier to get more HP, especially with higher RPM's and the mods we discussed, than torque. But, to be honest, if I got the engine back to stock specs (should be really, really easy), it should be enough to do everything I want. Sounds like the XW268H should do fine - if going to the hotter cam you mentioned requires vacuum mods, etc. Everything else being the same, do you have an idea of how much more I could expect if I went to the 274 cam. Also, do you have an idea how this cam compares to the 068 or other stock Pontiac cams?The car will currently light up the tires - with a bit of power braking. The engine has 92k miles, and has not been apart (at least from what I was told, and how it appears, and how it runs). So, I am sure I am far, far below the stock value of 370 hp. So, it's hard to say how much I have or want. Obviously much more than it currently has, but how much beyond stock, I don't know. I am sure an honest 370 would be OK, but if I am going to spend the money to rebuild the engine - and seeing that most of these upgrades are not that much compared to stock rebuild, it seems to me that the 400 figure is realistic and doable.IF I am going to spend 800 on head work, what are your thoughts on the added value of aftermarket heads - eddy, etc. I could see adding a grand or so - IF it made sense. Regarding top end HP v. low end torque - I think realistically, since I am not concerned with telling people how much my engine made on a dyno, and will not race it - seems to me that a nice broad torque curve would be more important than and engine with a narrow RPM range of high HP. But, as I said, IF I am going to spend the bucks to rebuild the engine, I want to make sensible changes that leave me with a drivable, long lasting engine. I will have to give this some more thought - but the changes we have discussed seem to make sense.Regarding suspension mods - I understand that a 400 hp car won't need serious mods to suspension, steering, braking - on the other hand, these cars were ahead of their time with torque and horsepower, but lacked in suspension, steering braking. And, the car is currently far from stock specs - I am sure that little, if anything has been rebuilt - so a purely stock rebuild of suspension, steering would yield fantastic results. But, as with the engine, if I am going to dedicate this amount of time and money - it seems like a few upgrades make sense.With braking, someone told me to upgrade the front discs and simply rebuild the drum rears - more bang for the buck. I'd like to upgrade to discs on rear, but think the money is better spent elsewhere. Anyway, I was told that I'd notice MUCH more difference in upgrading the front discs than I would adding discs to the rear and leaving front stock - that is, more stopping power per dollar spent.With steering, I plan to simply rebuild the stock setup. I have driven these cars before and after steering rebuild, and the difference is remarkable. Only thing I planned to change was going to better bushings. I might switch steering to a faster ratio? But, this car has 90k miles and the steering is simply shot, as is suspension.Regarding suspension - front - was going to replace springs -was thinking of lowering the car - either with springs or drop spindles - any thoughts? I also identified exactly what you suggested - KYB gas shocks. new springs and these shocks should greatly improve things. These things, and a larger anti-sway bar for the front with better bushings. On the rear, I want to add a sway bar - and that requires boxed lower trailing arms. I understand their are very expensive, adjustable upper and lower arms, etc., but seems to me to be too much to spend for what I am doing to the car. So, boxed lower arms, new bushings for upper and lower, and added sway bar - and their is a brace that you can buy that is supposed to beef up this system - apparently Pontiac realized by 69 that the torque, especially with posi, was breaking things, and they made a bolt on brace - I think I will add that. And of course, new springs and KYB gas shocks for rear also.So, upgraded front discs. Larger anti-sway bar in front, and new steering components (tie rods, ball joints, bushings, etc.). New springs and shocks front and back, and added sway bar in back, with boxed trailing arms and new bushings - and these things together should give me a car that is night and day better than it currently is. Hadn't thought about traction bars - do you think they will be necessary - or yield a better launch?Anyway, OK, thanks again for the info. Usually I am very busy - not a lot of time to play - so I might think about this car and plan for 12 hours in a row -and then have to deal with kids, job, etc., and it may be a week or more before I get back to it.Thanks again!
WGF, Hi. I am not an engine builder. I do restore cars for a living though. Having driven my '69 GP as long as I have, I think I can maybe help you with some general suggestions / observations. I get that you're not looking to re-invent the wheel with this thing, just needing guidance to find the common path to overall satisfaction. Glad to see you getting a variety of input here.I have read your other threads. This seems to be the one you'd like to discuss the overall plan on so here I am. My advice is with good intent but its free and should be treated as such.To me, it sounds like the car you want is almost 100% stock. Now theres a big difference between "stock" and "correct", or "concours". Correct or concours being the date coded hoses, chalk marks and what-not like they care about at the Pebble Beach event. Stock means replacement parts, not correct just serviceable as original equipment like rebuilt or foreign - made items in the original style. But stock would also include improvements that have been made in replacement OE- type parts since 1969. It also means adding optional equipment or upgrades from other years of the same car, or using common modifications for factory issues.So- would the same car but brand new and stock except with posi, nicely tired 15-17" wheels, a great sounding set of pipes, and lightly upgraded cornering capability work?If so, heres my plan for you- Search the world over if you have to, but find an engine builder you can use that has plenty of Pontiac V8 builds under his belt. Lots of kiddos fresh from school can run machinery but their knowledge (not smarts but familiarity) is dated wrong and important things can be missed. You will be shocked by the price of the engine rebuild, it takes probably twice what one might think just to go through the whole engine, whether performance modifications are involved or not. Your engine has to be all the way apart and measured before you or your builder will have any idea whats going to be involved in bringing all the parts into spec. Any proper build done today should have performance exceeding original, simply due to improved techniques and materials. But configuring it for today's fuel does lose a certain amount of power. A mild camshaft change that requires few other modifications should be sufficient, if chosen to suit the piston and head choice. Use the stock heads if you can't afford aluminum, simple as that. With the lack of desire for hairy upgrades later, I'd probably stick with what I had as long as the castings are in fair condition. If using small valve heads, I'd go to the large exhaust valve only and pass on hardened seat inserts but I would want fat screw-in studs topped with quality full or partial roller rockers. It kind of sounds like using a stock intake and paying for port matching and maybe mild head porting with back-cut valves might be your style. The stock intake is close to a regular Performer and will work fine with a mild cam but the main thing is weight difference, iron vs alum. Using your existing Q-Jet is a fine plan, as is switching to an Edelbrock. I like both. Keep the redline below 5,500 and do pay for careful rod resizing and bearing fitting. Leave the parts selection to your trusted builder and answer his questions, don't bring him a cam choice. Let the builder make the engine plan.On chassis- check me on this but I believe since ours is the early type disc brakes, the steering arm is bolted to the knuckle rather than cast as one piece. If its two-piece, you have the option to mount a caliper bracket there and put bigger brakes on the existing spindles. Stock ride height is quite cool to me, as long as theres plenty of tire. Stock 14" pizza-cutters are clownish-looking to me. If you choose to lower, I suggest drop spindles up front and a set of springs designed to drop the rear to match the modified front height.Box the stock rear lower control arms with a welder or grab the whole control arm and sway bar set from another car (like GTO). A stocker will do out back, but you could get a pair of aftermarket bars instead. Get those braces you mentioned, they prevent cracking at the crossmember. Consider non-stock rear upper control arms IF you have wheel hop with the new all-around setup. I used Moog springs all around with polyurethane control arm and sway bar bushings, Monroe gas shocks. I would go rubber bushings if I had it to do again, after putting about 100K miles on the polys. Your steering box is probably beginning to affect the feel of your handling at this point, and I am like you- love the stock steering.I have an el Camino 12-bolt in mine. Your B-O-P 10 bolt will do everything you want. Here again, find the trusted shop thats going to do the work then let them be your guide to which actual unit to install. You may not need a traction aid, but theres adjustable rear upper control arms if you do. You can always lift your foot off the gas! Mine has 3.31s behind a 455 and loves to be two lanes wide.The stock transmission will be great if freshened and the right converter is chosen. I like the stock TH400 shift fine, but a mild-level reprogramming does produce a more exciting tire chirping shift around town. Mine has a B&M Torkmaster 2000 converter, TCI Trans-Scat kit, heavy duty sprag, deep pan with washable filter. It has run forever. Here again, find the trusted shop who is going to build the trans and answer their questions then let them choose mods for you. Most shops have forgotten TurboHydramatics by now, so again be sure that the technicians are sufficiently familiar with what you have.What did I miss? Let me know if I skipped something. On my way out the tail pipe, I'll leave on an exhaust note by saying- I like full length headers, theres no reason not to use them. Bending a couple existing brake lines to relocate the brake proportioning valve is all thats needed and your car takes all the GTO stuff. An X-pipe would kinda be like brightly painted sway bars to me, just for looks from underneath. A 2.5" custom bent setup will serve you fine, but the bend over the axle is so tight that your guy may want to do down to 2.25" for tailpipes. And thats fine, really. Add 3" tips. Its what I have, with 2.5 x 30" glass packs and a 2" H pipe near the front U-joint. maybe just order some 2.5" mandrel-bent pipes and preferred mufflers then go to the exhaust shop and spend a couple hundred more.Hope theres some input of value there for you, enjoy the project and feel free to explore all the different areas of the website for relevant technical info. Just about anything that applies to a 69 GTO applies to the Grand Prix.
Hello again,More good info from idj.DISC UPGRADE - I'm pretty useless here so use others suggestions, i'm not too concerned about stopping. maybe call, the usual suspects like baer, sbc etc. i agree leave the rears drum.DROP SPINDLES - I do know a little about this which is:If you want a slightly firmer, less boat like ride i am not aware of any stock length front springs that are significantly stiffer than stock. check out year one, ames, opg and eibach if no one here knows. if you can not get stiffer stock length springs then you might consider dropping the front with shorter high perf springs instead of drop spindles. the lowering springs will do both things you want. the spindles will only lower it. you also have the option of using spindles and lowering springs and adding optional spacers to the lowering springs which will raise the front back to oem travel amount but the spindkles still lower it. if you use lowering springs only you loose travel equal to the amount you lower it. this is not terrible though because it is a very common thing to do. even though you have less travel lowering it with springs it really won't bettom out much motre than it did before simply because you are using stiffer shocks and springs, confused yet?SHOCKS - I am referring to the white kyb's not the grey ones, grey is for grandma. You can also get adjustable bilsteins or konis for around 125.00 ea.HEADS - Your heads purportedly flow 200 on intake and 154 on ex at .500 lift. this makes them one of the better flowing stock pontiac heads. my guess which is all it is, is that you could easily get another 30 intake and 20 ex or more with just the basic pocket porting and valve job alone. I love aluminum heads, you can run a bit higher compression with them which gives more hp and tq throughout the entire rpm range. they will also.The flow on std eddy heads is 250 in and 150 ex, on the rpm's it is 265 in and 175 ex so both flow more than yours but with mild porting you will be close to the non rpm numbers.If it were me i would use the rpm heads and xe274h cam or comperable lunati or possible even 1 a bit bigger bit this is not what i think you want.You got some things to think about now regarding heads.CAMS - As idj suggested a competent engine builder can help you with your cam choice or grind a custom one for you however competent engine builders might be hard to find. custom can grinders are not and it might be worth the few extra dollars to get bone done but someone that specializes in pontiacs is who you want to see. butler performance is one of them. there are so many choices for off the shelf cams that you might not notice much difference between the two. more confusion, lol.RINGS - Plasma moly is a common choice, good quality cast iron will also work.TRACTION BARS - Leave them off add if you think you need them. hopedully yoi have enough power that you will.CURRENT TIRE SPIN - I think your tired engine should still roast your single drive tire on your heavy old car with ease without power braking if you really have 355 gears. i would check to confirm, might be 3.23.500 TORQUE - I did not know your engine had 450 stock, that's a ton for a stocker. the higher you spin an engine the more tq it will have. you can get more tq without increasing rpm simply by increasing compression but due to the crummy gas you can't do much about that.COMPRESSION/0 DECK BLOCK - I suggested earlier to deck your block close to 0. this will increase compression which is not what you want but you can lower it with dished pistons. what this does is reduce the potential for detonation. this means if you have two engines with the same compression, but one has the piston .030" below the top of the block and the other has it even, the one that is even is less likely to detonate. its a complicated physics thing.I know this is how it works with flat top pistons BUT the fact that you are running dished pistons might negate this benefit, i really have no clue. more confusion for ya.