68 GTO 400 Engine Build Feedback
 

I'm finally getting the correct engine into my 68 convert. Since i haven't been up on the latest, I'd like to hear your experiences. I want to keep it basically stock appearing, with correct date codes, but warm it up a bit. Car is original. Might be driven ~1000 miles/yr and might see a quick run at the strip, but not often. Thanks!
68 GTO convert, stock AT, 3:55 rear
400 SR block with #16 heads, regular valve job
Stock intake and probably stock Quadrajet (any tips on rebuild?)
~30 over, forged pistons, stock replacements, Stock rods. Compression will likely be close to 10:1 and I'm told that shouldn't be problem with the amount I'll drive it.
Debating between the RAIII or 068 cam.
Distributor (worth converting the stock body to electronic with kit from PY?)
Add HO/RA exhaust manifolds. OK to use stock exhaust or is it worth increasing the size?
RA oil pump?
Stock fuel pump? Fuel line? The 350 block in the car seemed to starve for fuel on hard accel, so wondered if the fuel system is worth improving.

Thanks for the info and hope this isn't too basic. It will be great having a real motor again!

Any other worthwhile upgrades? Any recommendations on the TH400 if I have it rebuilt?

I'm thinking about going a similar route with the rebuild of my stock YS-code so I'm anxious to hear feedback from others. I've been told anything over about 9.5:1 compression will not run well on modern pump gas, but I'm by no means an expert on this subject. You might consider having the pistons dished to get the compression down from the stock 10.75:1.

couple 5 cents worth
 

Stock intake will work fine, maybe massage the divder a'la Jim hands book, which if you haven't picked up you should. The Q jet will work great if rebuilt well. If you're willing and have some experience you can do a pretty god job following Cliff Ruggles tips in his book- yeah this is the other "if you haven't picked up you should" tip.
16 heads are good, simple porting and gasket match will help a bit. RA manifolds beat out the stock Logs and may fit easier than headers. More stock looking too.
I just looked into a cam for my new motor build and Butlers suggested a XE268 for my "stock" 428 rebuild. Specs are a cross between the RA III and IV.
But your situation maybe different than mine, I've got a M20 tranny which is more forgiving then a AT

Have you or are you joinign the Rochester POCI group?

I'm in the Syracuse Six Nations POCI club and theres usually good people there and lots of advice/ experience. Pontiac Jack on here (PY) is out your way (Phelps).

Several guys from Roch came to Syr for our Spring show and several guys from here when to Webster for the Roch show. I hope to do that to this year.

My motor should be done this week but not sure when it will get installed. Sometime before the first ESTA test and tune in April I hope :D

Howard

Is the block fresh and 30 over or will it need bored to that? If it needs bored I would go with a stroker crank kit for more cubes and it will look stock. You can drop the compression so its more drive able also. Definately get the Qjet calibrated for your combination. Bigger exhaust like 2.5" mandrel bent pipes with RA manifolds will help a bunch. Get some new rods too as the old ones are 40 years old. Cam selection is a personal choice but bigger isnt always better here. Cam depends on compression, cubes, rear gear, and tire size to really figure out a good choice. More cubes can tolerate a bigger cam. Put a shift kit in your trans and get a good converter if budget allows. The 3.55 gear is a good all around gear. Stock fuel pump should be fine. Problem may be pickup tube in tank as well as fuel lines. Could have dirt and crap clogging things up. A lot of choices to make before you spend the cash. Good luck. Jim

Thanks for the info, keep it coming!
 

Thanks for the feedback! I'll be getting Jim Hand's book, that should help.

I think the car has always had shift kit in it, but I never really cared for it, due to the drawn out shifts. Maybe it was just poor tuning or vacuum. Any recommendations on a shift kit and set up, for a mild cruising ride, but still have firm shifts? Any torque converter worth considering over stock?

I'll go with the 2.5" exhaust and RA manifolds. Rather do it now than later.

I purchased the engine and the rebuild was already started, so it is already 30 over. I was going to stick with the original crank. My shop is checking everything over first, so I'll see what they think of the rods.

Once I get the info back, I'll let you guys know how it is progressing. Keep the info coming, it is a great help after being away from my GTOs for awhile

I'm not in the Rochester POCI but knew some of the members from the 80's when I was banging around in my 67. I may just join once the 68 is running decent again. I'll be up at the Nationals (with or without the 68).

Good advice in this thread. Stroker is a good low cost option. There are guys (Ed Curtiss is one) who will get you a custom ground cam based on your car, its weight, the CI of your motor, trans, gearing, and RPM where you want to make power. Cost is very competitive with "off the shelf" cams, so well worth the cost.

My basic advice is to decide what you want the car to be an stick to the plan. If you want the fastest set of wheels in town, you better have a thick wallet, and plan for every dollar spent on the motor to spend 2 on trans, rear end, suspension, to make the car both safe and fast.

Another option may be to toss a 75 shot on the car and call it a day. Others more knowledgeable about stock Pontiac motor will need to chime in here.

Done rambleing now! :)

If the block and heads are not milled or decked it will be about 9.8:1 and running @160 degrees like any other correctly setup car and 93 octane it should not ping unless you have a very aggressive timing curve (race) a Summit Racing 2801 (very close to 068 size but more lift and better midrange)272/282 .442"/.465" 214/[email protected]" 112 cam is excellent for any 400 street/strip car with stock parts and with the HO 2-1/2" manifolds X-pipe Duals and Stock 68 intake (block heat risers) it will pull good up to about 5700 shifts but start/run/cruise like a stocker with good economy. Use a fuel pump for a 70's A/C application with the larger body. Open Element GM style 14" air cleaner (67-68 HO 400).
Try to upgrade torque converter with at least a 2200 or 2400-2600 for some punch off the line. This setup should yield 13 sec ET's in most mid-weight Pontiacs.