Pontiac Tri-power

[amckid6970]

I may be into AMCs but my dad loves his Pontiacs. I have a couple questions regarding the Tri-powers. My dad has a 66 Grand Prix and is running a 67 428HO with a 66 Tri-Power. He was running 14.50s in the 1/4 and the motor had 150,000+ miles on it when he put it in the car. all that was done was a dual point distributor and headers. After tearing the motor down for a rebuild (finally) he descovered it has an 066 cam in it! He's done a lot on # crunching and there wasn't a posability that that cam ever came in a 428 let alone an HO motor. I beleive the HO cam was a 288/302 duration. The motor came out of a Bonneville Funeral home car that had every option in the book including the hydraulic power bench seat. He said all the guts point to an HO motor except the cam. But my question is this, were the 670 casting heads designed for use with the Tri-power? I've heard that the heads were designed before th GM ban on triple 2s. That car flew for it's 4550lb weight! It's curently getting bored .030 over, RA4 replacement cam, and a NICE set of Doug's headers. He's hoping for 13's with the TH400 and 3.43 gears.

[tjs44]

FYI,I would not use that cam with that heavy of car and those gears.If you are really married to it you will need Rhodes lifters.That cam with the higher floing RA IV heads was only avail with 3.90 to 4.30 gears in a WAY lighter car.The 2801 Summit would be a way better choice.Tom

[JLP]

Try the following sites also. I answered last nite but somehow it did not show up today.
http://www.performanceyears.com
http://www.classicalpontiac.com
http://www.wallaceracing.com for codes.

Engine code is next to water pump on passenger side of front of block and is stamped. It is 2 letters or a number and letter combination of 2. Year is back by the distributor and is cast into the block.

No multiple carbs except for the plastic bow tie after 1966 for GM. Wanted to keep them on the top of the heap. Couldn't have another division on the top as they were in 59-62 in both NHRA and NASCAR. Especially, 1962 NASCAR where they won 32 of 52 races.

Oh, well, someone has to let them win.

By the way 'Tripower' is a Pontiac trade mark.

[amckid6970]

Thanks for the info guys. I think he is using Rhodes lifters in it. the reason for the cam choice is money's tight and I had it lying around from a 455 that I have and gave it to him knowing he needed it more than I did. He has a code book that breaks down all the #s for every Pontiac V8 they made, it coded as a 360 horse 428 but had the windage tray and oil gaurds over the rockers. Those are HO only aren't they? It might be an assembly line goof. I hear it wasn't too uncommon for parts to get mixed up during assembly. Sorry I misspelled Tripower guys.

[tjs44]

670s are fine,with a tripower.REALLY better do a good calc on the CR.You should try and be around 9-9.25 for a pump gas engine.Also you might need a elect vac pump and can for the power brakes to work more than once even with Rhodes.Tom

[amckid6970]

I think the comp. ratio will be around 11 to 1. Dad doesn't really care about it being pump gas since we live close to a Muni airport. (100LL from the tanker trucks) It's still 3 something a gallon but it smells better than 93 when burnt. Now to make sure before I let him know the problems he may run into, I said it was a RA4 replacement, but it's what I think it is because of the duration. It's a Performer RPM cam. RA4 was 308/320 right? The lobe separation is the same, and as for the 670s, I thought they flowed the best of any head on the intake side and were choked off on the exahust. I probably totally goofed calling it a RA4 replacement didn't I?

[tjs44]

all 72CC hi comp heads flo about the same,with the advent of our piss gas they have lost their shine and 6X heads are the most popular these days.I think that is a clone RAIV cam and will act about the same.The CR will really wake up the engine.Tom

[amckid6970]

So he may still encounter the problems you mentioned?

[tjs44]

may,wont know untill its in and running.Tom

[amckid6970]

Okay, thank you for the tips, I'll let dad know!