Thread: SBC timing

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2 engines, a 350 and a 400, want to run 40 and 42 deg. on the street. Less than that and they are dogs. 350 is a crate and the 400, home built. everything double and triple checked. Only common ground is the distr. They are from summit. Initial timing set @ 10 and 12. No pinging, hard starting, or overheating. Called Summit and they are baffled also. Any ideas. BTW the 350 runs 89 octane and the 400 runs 93. The plugs are clean and the right color.

Here's a suggestion (and it is free <g>)....

Loosen up the valve keepers and compare the way it runs 'loose' as compared to normal.
If it changes the running pattern, you may want to change the cam timing, or the cam itself.
Worth a try, and it won't hurt anything.

Jeff

It should be fine running them like that, if its not detonationg, All motors are different, what springs do you have in the distributors? That could do it also.

Sounds like a fuel problem,areyou getting any where it matters???

Thank you all for trying to help. Here's the run down. The 350 is a crate engine. The 400 is custom built at home. They both have new harmonic balancers that have been vedrified for TDC, new flexplates, and identical distributors from summit. The distributors springs have been changed to the black (heavy) ones. The readings are total advance (initial, vacuum, machanical). The vacuun is ported and pulls in approximately 22 degrees.

Guess what I did just now. I changed the vacuum advance, coil (accel), and cap from the ones summit sent me. I am now running 12 degrees initial and 36 total advance. The engine appears to run fine although a little rich. I'm thinking of bumping it up to 38 total and see what happens. I think the vacuum advance was the problem.