Rebuild or Replace 350?

I am restoring a 1976 Firebird Formula exactly like the one I drove in High School many years ago.  It is almost down to the unibody, and I will soon be restoring the front end, rear end, and having the body shop prep the unibody.

The engine and tranny are original with numbers matching the body VIN.  I am skeptical about the horsepower rating for this 1976 Pontiac 350 engine (160 hp), but reluctant to buy a crate engine due to the matching numbers.

Should I have the original 350 rebuilt, and maybe upgrade the CAM, carb and exhaust to add horsepower, which would keep all matching numbers? Or, should I just go ahead and buy a crate engine with more horsepower?  I appreciate any advice that I can get.  Thanks.  

i'm no pro but i would go with a the rebuild. holla at pontiacman8 he has good info bout the engine world  

Bird76,
Definitely go with a good quality rebuild and upgrade of your original 350. I have a 1975 160hp 350 in my 79 Formula with only basic upgrades and it works beautifully. My 350 came with 5C-4 heads (2.11" intake and 1.66" exhausts), 066 cam, 7.6:1 compression ratio and the 2bbl carb and intake. The only difference to the 76 350 was a change to 6X-4 heads which were basically identical to the 5C-4 and a 555 camshaft. When we start to look at the other available 350's of the that time period, the 75/76 350 4bbl was rated at 170hp with no changes except the carb and intake, the 74 GTO 350 had only slightly higher compression ratio and dual exhaust but used the same mild cam and smaller valves yet was rated at 200hp.
I based my 350 on a fairly low mileage all original block from a 75 Esprit. All the pistons, rings and bearings are 100% original and compression tested at 120psi and had 25psi oil pressure while cranking. All I did was change all the 30-plus year old gaskets and frost plugs, replaced the cam/lifters with a Crane 272 kit and added an Edelbrock Performer timing set, factory 4bbl carb and manifold and true 2 1/4" dual exhaust after the stock log manifolds. The car weighs 3960lbs with me and a half tank of gas(87 octane is all it needs) and has a TH400 automatic with stock converter and a mild shift kit. The rear end is a 3.42:1 Saf-T-Track (posi) from a 77TA which of course bolts right in. Currently this combo will run mid to high 14's in the high 90 mph range any day of the week, with a best time on a G-Tech Pro of 14.45@99mph.
If I were to recommend a build up recipe, I would say to spend the money on good quality basic machine work. Have the block properly bored and decked, make sure the crank is straight and round, resize the rods and add ARP bolts and have the heads rebuilt with new 1 piece valves and good valve springs to match the camshaft. Go with a cam similar to mine (around 218 degrees@.050" lift and .450" lift at the valve, COMP 268H is close to my cam) and add the 4bbl.
Any mid 70's stock intake and carb will work fine or if you prefer an aftermarket aluminum manifold, you can't go wrong with an Edelbrock Performer (not RPM) and a 600cfm carb. Headers will add 10-15hp but manifolds will give you less hassle and they are free since you already have them! This combo will work with any of the factory gears your car might have, but will benefit from lower gears although I don't recommend anything deeper than 3.42.
An upgrade for the th350 trans that you likely have is a shift kit and maybe a mild, no more than 2000rpm stall speed converter or change it out for a 200-4r overdrive, especially if using gears deeper than 3.08 and if you are going to do any highway cruising.
Hope all this helps, but by all means stay with the 350 instead of the crate motors (assuming that you meant Chevy crate motors, of course).
Steve  
Trying to help... 'cause we don't all have to learn the hard way!

Most definitely go back with the original 350 do not judge it by the factory horse power because it is capable of a lot more.
What heads are on the 350.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Steve, thanks for the reply and the very helpful information.  Your quarter mile time is great, and if I can get my 350 to that level I would be totally satisfied.  I like your recipe suggestions, and with all the combined input from this forum I am convinced that I should build the original 350. Finding a quality engine builder in my area (East Tennessee) may be tough, but I will do the research and find the right shop.  I think this engine has good rebuild potential, since the car shows only 75k miles which the seller said was accurate, although the speedometer could have rolled over since it only has 5 digits.  My son drove the car from Florida where we bought it, and it performed well at high speeds, but did not have much takeoff power.  I pulled the engine and tranny last week, and I can't wait to feel the torque after the rebuild.  By the way, on the crate motor option, I was assuming I could find a Pontiac crate motor, but I have not done any research.  I take it from your message that Chevy is the only crate option, which convinces me even more to build the original Pontiac engine!  Thanks again.
Robert  

Thanks for the advice, Pontiacman8.  I have read some of your other postings -- very impressive knowledge.  Everyone on this board says rebuild, and I am convinced.  Good question about the heads.  Now that I intend to rebuild, I will need to figure out what specs I have and what all should be changed.  I will most likely do about the same thing that barneyformula did with his 350, which gave him great results.  I will post the engine data when I find it.  Unfortunately, there is no build sheet.  Thanks,
Robert  

Hello Pontiacman8.  It has the 6x heads.  That's all I know at this point.  I'm a novice and still learning how everything works.  Picked up a Pontiac engine book today and quickly found out how much I need to learn.  Thanks for your help.  

Robert, you are welcome. We are here to help and pass on the knowledge we've learned the hard way. I would check the gear ratio in the rearend, Pontiac was notorious (as were most automakers of the 70's) for putting very low, numerically, gears in the rear for economy purposes. We of course refer to these as higher or highway gears as opposed to low, performance oriented gearing. I would not be surprised to find 2.41, 2.56 or 2.73 gears back there, which gives excellent cruising and decent mileage but less than stellar acceleration.
You might try removing the fuel tank to find a build sheet, I have found them on top of the tank several times especially in cars built at the Norwood Ohio plant. Generally these build sheets are not in great shape because they are exposed to the weather. You could also contact Pontiac Historical Services to find out how they record the car as built and shipped.
My comments concerning crate engine centered on the common Chevy crates available thru the dealer because they are the ones that get all the press. There are Pontiac crate engines available from several engine builders, just do your research to be sure you are getting what you want/need. Same goes for a machine shop, ask around and find the ones who have a solid reputation for reliable quality work. When building your 350, you don't need anything trick, just solid workmanship and an honest guarantee.
By the way, be sure to convert the rockers to adjustable posi-locks to avoid valvetrain issues.
Steve  
Trying to help... 'cause we don't all have to learn the hard way!

No problem bird76 we all had to start some were I was fortunate enough to have a neighbor now a buddy of mine that worked on cars and engines that helped me learn alot and some I learned on my own.
Barney is right you need to make sure you are dealing with a repetable machine shop that does quality work and that has experience with pontiac engines.
THe only thing I would do different is use a lunati .458 cam instead of the crane it will perform  better then the crane.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Steve, thanks for the further information.  I will be removing the gas tank soon and will be sure to look for the build sheet.  I will also be checking into Pontiac Historical Services.  Great tip about the rearend.  I read somewhere that the Firebird rearends were very durable, but did not focus on gear ratios.  Now that you mention it, the car did perform much better at high speeds and had sloppy acceleration at low speeds.  Probably has the highway gears.  Its good to know that a Pontiac crate engine is available.  I plan to have the original rebuilt, but if the machine shop tells me it is cracked or otherwise not rebuildable, then I am definitely going with the Pontiac crate engine.  I have no problem with the Chevy product, but would like to keep the car a true Pontiac as much as possible.  Plus the Pontiac engines are iconic, and their reputation is unbeatable.  I am keeping these posts in my research notebook, which I will use when I begin working with the engine builder.  My son and nephew are helping me on the restoration, but I am doing most of the research, and of course, writing the checks.  This is a long-term project for us, and we have already had many hours of shop-time, which we all enjoy very much. Thanks again,
Robert  

Thanks Pontiacman8.  It is comforting to know that you and Barney agree on the recipe.  By the time this is done, I should know much more about how engines operate, and how performance is affected by the CAM, intake, carb, exhaust, etc.  I fear that finding a machine shop will be very difficult.  I plan to stop by a couple of performance parts houses tomorrow and see if I can get a recommendation.  My internet search for area engine builders came up empty.  The good news is that I have a lot of work to do on the car, so plenty of time to find the right builder.  Thank you,
Robert  

I picked up a 350 off of Craigslist cheap- tore it down to inspect it and found the crank and bearings were clean, so I decided to overhaul it. I ball honed the cylinders, put new rings on the pistons, Crane 272H cam, lifters, pushrods, timing chain, water pump, oil pump, rear main seal. The 4c's that came with the motor turned out to be cracked, so I sent a set of ported no.13's into the shop for a rebuild.

I'm using this engine to sub for a 406 w/ no.48's which needs to come out for an overhaul and upgrades- I'll put the same Holley 750 v/s and e-performer on it, and run the same Hooker comps and 2 1/2" duals in the car. I expect this engine to run mid-13's easy w/ the same 3.08 posi. I'll take it easy with this 350 since it still has the cast rods in it, but it will fill in nicely while my 406 is down, since a 350 with these heads and cam should put out around 325-340 hp. I've had 400's and 455's in my 'Bird for most of the 21 years I've owned it, but it will be nice to run a 350 in it again.

Geno  

Your welcome Robert.
Anything else just ask.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Iam enjoying this site more and more Pontiacman8 Barneyformula are the fellows who will help-I am new to the site and somewhat cautious-My Father and I raced in the mid to late 60's with his 389 3x2 Bonneville heavy cars hook hard 4.30 Deroit Locker
4-speed hydramatic a hole shot monster
Remember for every fast Poniac there are a dozen fast Chevys   Like Pop said when you leave the drive way be ready to do battle Back in the street racing (dumb)days.
1977 T/A  1969 GTO Judge RA IV motor 9.75 to 1 comp.ported by Dad Round ports yes and super strong on bottom and mid range A best of 12.20  drove to the track and drove home 90 miles each way  

inthewoods,
Thanks for the kind words and for sharing your Dad's wise words. How true!
Steve  
Trying to help... 'cause we don't all have to learn the hard way!