I recently picked up a 428 block bored .030 over the deck was also zeroed. I have a pair of 6x-8 heads, and a 455 crank. Basically what I'm wanting is to get into the 450 to 500 hp range on pump gas. Im new to pontiac engines so if you guys could give me a good combination of pistons, heads,cam, exc. my budget is 5,500 Thanks Mike
hi;welcome to the forum.hey, you have money, ok we can spend that. do you have money for gears and a stall conv.do you want.mild, moderate or nasty idle?vacuum for power brakes?fwy flier, drag car or in between?what are your gears and are you willing to change them?what trans?
I would like a moderate idle. I do have extra money for brakes and gears, not sure what gears are in the car my dad and I are building it together and he is the one that just acquired the car. As far as tranny we will be converting to a manual haven't picked one yet. The car will mainly be a weekend head turner not a daily driver.
First thing I would want to know is, What body you'll be using? And has the crank been ground for the 428?Weight transfer has a huge effect on drive train. My experience with old Pontiacs, the GTO has more than early Firebirds. Getting 500 HP from the 428 won't take all that money. I'm a 4 speed guy so I like that idea.GTO guy
The car is a 69 firebird and the crank has not been ground.
ok well 500 hp is WAY more than a mild idle weekend cruiser car imo. so i'm cluless as to what you want.
okHEADS - Your heads suck with those big 101 cc chambers. Get the block decked to .005” then mill the heads until the total milled between the two is .025” or buy used heads, new aluminum heads or pop up pistons to get your compression up to around 9.3 - .9.5. If you deck your block and heads, your compression with those heads will be 8.6 which kinda low for a high perf build.PORTING - I would also get any oem heads pocket ported and have the intake valves back cut.PISTONS - Buy forged from summit or flatanderracing.com. buy custom pop ups to use with those heads. I hate hypers but I suppose they are ok. Keith black has those. Don’t get the 8 valve relief ones, lol. flatlanderracing.com has the beat deal on customs i have found.COMPRESSION - Your low compression limits your hp. if you deck the block to .005 and the heads so that the total amount of material removed between the two is around .028" you will have around 8.5 static compression. CAM - the biggest cam i would run with this compression would be a lunati 60903. 268 duration and 1600 - 5800 rpm range. it will have a mild/moderate lope with a nice mild performance sound and good power from around 2000 - 5000. i would also buy an adjustable timing gear set [65.00] and advance it 2 degrees. this will increase compression slightly and lower operating range slightly. http://www.lunatipower.com/Product.aspx?id=1776INTAKE - I might use a std non rpm eddy intake with a 1 inch spacer. CARB – Holley 770 street avenger annular venturi type vacuum secondary. GEARS - Around 3.43 with around a 2200 rpm stall converter.BALANCE - Get this done.IGNITION - Buy a rebuilt hei from autozone or at least a high voltage coil and an msd box. the cheap ones are aruund 110.00This should roast the tires until the cows come half way home. If you want it to roast the tires till the cows come all the way home, get your compression up to 9.5 - 9.7, get a lunati 60904 cam, eddy rpm intake, port the bejesus out of your heads if they are oem and 2600 rpm stall.
Mike, welcome to the forum.It's not too hard to get your HP (and commensurate torque) figures from a 428. Mine is developing well over 500 HP but it takes some careful thought and $.First off, your 455 crank as a 4.210" stroke and the 428 crank has a 4.0" stroke so you'll have to get pistons with the correct compression height. This is critical. Can you tell us what engine code is on your 428? it should be a two letter or letter number stamp along the front of the block. (WB, XD, Y2, etc..)Also the year casting along the top rear of the block. Should be a letter number combo.The 6x-8 heads you have will hurt your goal. You can mill them, but you'll never get enough off of them toreally get you where you want to be. And any amount over.020" taken from the head, you'll have to take that much again off of the intake.For pump gas, you'll want to shoot for around 9.5:1 CR which will let you use premium pump gas w/Iron Pontiac heads. For your set up, you're looking for somthing around 87-90 (90 being ideal) CC heads w/your zerop decked block. Of the cams mentioned previously, Lunati is a favorite. Currently I'm running a Crower in mine and have nothing but praise for its performance. To take advantage of which ever cam you choose, pocket porting and gasket matching is a must for your head/intake combo as well as balancing the bottom end.
Going along with what My71 said, 6X-4 heads have a factory volume of about 93cc's. I found a pair on my local craigslist for $50. So, they are relatively cheap. Having them milled to bring the chambers down to about 90cc would be much easier. Jim Hand wrote an excellent book on this entire process and really recommends a zero deck height with about .040" quench area to help the flame turbulence and to prevent detonation. Good luck and keep us posted.
factory iron heads are not a good choice for a 500 HP build imo.I would start off with a pair of Edelbrock aluminum heads.
Engine builder,self taught auto body guy.Horsepower sells engines and torque wins races
"6X-4 heads have a factory volume of about 93cc's."101 cc's but all head cc's should be verified.
Ok if I go with the 87cc edelbrock heads would it be better to run the 455 crank or have it ground to a 428. Should I get the heads pre assembled or bare casting.
Actually, there are 6X-4 and 6X-8 and maybe 6X-11 heads. The 6X-4 are 93cc from factory, the 6X-8 are 101cc. FWIW.Tony