[Formulajones]

Originally Posted by racerboy

So I got my block from machine shop. The pic below shows all the work they did:


The machinist is someone I’ve known for 25 years and has built 3 engines for me in that time. He doesn’t have the bandwidth to build this one (I think he wants to retire at end of year). Anyway, I called up a Pontiac engine builder today that’s within driving distance and now have more questions than answers. The fellow I was talking to was super nice and I’m not posting anything negative, but I am definitely in a bit of a pickle now.

Here are my highlights/questions.
1. Builder will only use my block if he blueprints it himself. He said having it honed w/o a Pontiac torque plate was a waste. He said he would need to bore it to .040 with a torque plate. I was trying to keep it at .030, but am not opposed to going to .040 if that’s the safe bet. He also talked about squaring the bores and having to machine the mains. Way over my head.

2. Heads. He would build my heads with new valves, 7/16 studs, porting, etc. the thing that surprised me was that he would not install hardened seats. Says he never uses them. He would just recommend using an additive in the fuel at each fill-up. Again, I’m not being negative, but I thought installing hardened seats was kind of standard. In fact, for all I know, my heads already have hardened seats.

3. Carb. He was saying that running a q-jet was going to be problematic because of all the ethanol in the fuel. I told him this was a numbers-matching car, so running anything else was a non-starter.

4. Intake. He was saying that a standard Performer was a better option from a driveability perspective than my stock intake. Again, a non-starter (besides, I have a ‘70 intake currently getting the Cliff Ruggle’s modifications by someone who used to work for him).

5. Camshaft. Doesn’t suggest using hydraulic roller cam because they don’t make Pontiac-specific lifters. Also suggested that the required bronze distributor gear could not endure daily-driver use. I’m not looking for every ounce of power, but I thought one of the advantages of a HR cam was that it reduced friction and made up for low zinc levels. My Trans Am gets driven, but certainly not a daily-driver.

6. Stroker crank/rods. I currently have a deposit on a Molnar 4.00” stroker crank (3.00” mains) as well as a set of Molnar Pontiac-length rods (6.625) with BBC journals. He thinks I should just go with a Scat 4.250 stroker because I would be getting a bigger engine w/ more torque for same money. I have an M21 with a 3.73 rear. I’m pretty sure that the torque from a 433 is going to be perfectly adequate. I understand that the bigger engine is going to make more torque, but I’m really not looking for every ounce of power.

My biggest question has to do with boring the block to .040 with a torque plate. That does seem to make sense to me, and I’m not opposed to it, but just wanted to throw this out to the experts. I’m assuming that any builder I wind up going to may tell me same thing.

I know this was a long note and definitely want to hear some thoughts from the experts out there.


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1) 100% on par with how I want my engines done. I've had "honed" engines rehoned with a torque plate and the difference is rather horrifying and makes you wonder how rings seal at all, and at the very least would last any length of time. I'm talking 40-50,000 miles before issues arise. Ring seal is a big player in longevity and HP as well as oil consumption, blow by, all kinds of things.

2) That's been a debate since the 70's. These days I do hardened seats just because it seems I'm in there changing the valve job or valve size anyway, and replacing guides on heads that are 50+ years old, so why not.
That said I still have engines here with original 50-60 year old heads with original seats and still running perfectly fine on unleaded gas. With mild lobe camshafts and mediocre spring pressures you aren't beating the seats out of them anyway :shrug:

3) No problems Q-jet or Holley carbs here on todays ethanol gas and I've been daily driving them for years.

4) Stick with the 70 intake.

5) That's BS, there are in fact hydraulic roller lifters made with different oil band heights. I'm running them. Been talked about to death on here and we've all posted pictures of the differences in the past. There are hydraulic rollers that work just fine for Pontiacs. The problem these days is getting them, like anything else. I don't have any problems with Brass, Melonized, or Composite distributor gears, even with big 80psi pumps that everyone says kills the distributor gears. Old wives tail. Dress the drive gear on the cam and it'll live a long happy life.

6) I agree with the bigger crank. Darn things cost about the same and with not that much of a price difference for these rotating assemblies I hate to spend my money and get less. That's just me, I prefer more bang for my buck, and I've never had anyone complain about a bigger engine making more power for the same money LOL.
Eventually you'll likely ditch the M21 anyway if you really want to drive the car anywhere so that's a non starter for me. I'd be tossing in a 5 speed right off the bat. It's only money

That's my take on it anyway :shrug: