[Zimtok]

I have a 1972 455 YC engine with 7M5 heads, 1966 Tripower. It was bored .30 over. But otherwise stock.

The cam has .281 int lift and .296 exh lift with 278 int duration and 288 exh duration. Lobe centers ar 108 int and 116 exh.

The dist is stock with the point dwell set to 30.

Question #1
What would I set the timing at with this engine combination?

Question #2
Any ideas for the jets on the tripower carbs? I now have 68 in the center and 70's in the outer carbs.

...best if used on or before date indicated...

[Zimtok]

I have a 1972 455 YC engine with 7M5 heads, 1966 Tripower. It was bored .30 over. But otherwise stock.

The cam has .281 int lift and .296 exh lift with 278 int duration and 288 exh duration. Lobe centers ar 108 int and 116 exh.

The dist is stock with the point dwell set to 30.

Question #1
What would I set the timing at with this engine combination?

Question #2
Any ideas for the jets on the tripower carbs? I now have 68 in the center and 70's in the outer carbs.

...best if used on or before date indicated...

[WARIARGTO]

Hard to say without knowing a few more things about the car/drivetrain, but generally, for a 3800 pound car with 3.36 or better gears, 8:1 compression(7M5 stock 455 heads for 72?) 1) 32-38 degrees,I'd start at about 34 and see how it likes that.Should work great.Important thing is initial timing- I'd advise like 12-16 initial,thereabouts with around 20 degrees mechanical for a total of 32-36 in by 3000.(unless its a full size tank with an automatic and 2.73 gears or something). That initial number may be too high, just run as much as you can without having a hot start binding problem. Then adjust your total accordingly by working the distributor. 2)your current jetting should be fine. You may eventually want to go up a jetsize in the secondarys at a later date.

1965 GTO
Nitrous Injected Tripower 464" Aluminum heads, Hydraulic cam
Vertically Gated M22 4-speed

[Zimtok]

It is in my 65 GTO, 4 speed manual trans.I'm unsure of the gears in the rear but it is a posi.

The hot start binding is the major problem. I get the timing set so it runs the strongest and then it has problems starting.
I set it so it starts OK and then it seems to be at a loss for power.

I will start over with your sugestions and see where I end up.

Thanks for the reply, I can always count on getting a prompt response here.

...best if used on or before date indicated...

[WARIARGTO]

What you need to do is set up the curve in your distributor. Find the point where you can run the most initial timing without binding you require,say 12 degrees. Then find the point where you want your total for max power without detonation. Say 34 degrees. Then tailor your mechanical advance to provide 22 degrees(in this example). That way you can run as much initial and total timing as your engine wants, just by modifying the mechanical advance mechanism pin and slot. There are several ways to do this, some folks weld up the slot to provide less mechanical advance, others fabricate a stop. While you are modifying your distributor, use a set of light/medium tension springs and weights to obtain max timing advance in around 3000rpm.Check your gear/housing endplay as well, keep it tight, not sloppy to affect timing, around .005". Use a set of high-tension points 32OZ and you won't have any timing problems to 6000RPM.

1965 GTO
Nitrous Injected Tripower 464" Aluminum heads, Hydraulic cam
Vertically Gated M22 4-speed