Timing setting?

[Tom S.]

I have a 69 L-46 350/350 h.p. the tag on the cowel say's the timing should be set at 4 degrees. The owners manual says the same. I have a 1969 motors manual that say's 8 degree's .Where should it be set to run the best? I have a friend that say's his runs best at 12 with no pinging or dieseling at shut down.Where is the best setting?

Tom Stanton #41491

[Duke W.]

Re: Timing setting?

You want to total of initial plus full centrifugal to equal about 38. The OE timing map is biased toward acheiving emissions bogeys, not fuel economy or performance, and CA models may have different timing maps, including recommended intial setting than 49-state models.

Complete timing map details are in the CSM and GM restoration package.

Duke

[Joe L.]

Re: Timing setting?

Duke and Tom-----

For the 1968 and 1969 model years, there were no differences between federal and California emissions specifications or emissions equipment. For most other model years in the 1966 to 1982 period there were differences, though.

[Joe C.]

Re: Timing setting?

Tom:

Give your engine as much initial advance as it will tolerate. Detonation usually occurs with part throttle loads, with ported vacuum advance.

[Randy Adams]

Re: Timing setting?

Joe, I'm not trying to throw a monkey wrench into this timing question, but, if you advance the timing even a little too much doesn't it often make the car hard to start when the engine is heated up? How can you figure how much to advance it before having this problem? As you may have guessed I have this problem now. I have the timing set at 36 deg. total advance. Runs great but hard to start hot.

[Duke W.]

Re: Timing setting?

I doubt if timing has anything to do with your hard hot starting - more likely flooding (float level) or vapor lock.

Initial timing in the range of 0-18 degrees should be okay for starting and most initial timing specs for Corvette engines range from 4-14 degrees.

Duke

[Joe C.]

Re: Timing setting?

Randy:

Do you mean "hard/slow cranking" like the starter is laboring when the engine is hot? If so, then you didn't mention it. That is a common problem, especially with big blocks, and more advance WILL exacerbate it. But, the problem is not the timing, rather a weak battery and/or starter. Do you have a heat shield on your starter?

IF slow cranking is your condition, AND once you get it fixed, THEN give the engine as much advance as it will tolerate WITHOUT DETONATION. This is done by trial and error. Bump the timing up, a few degrees at a time, and road test. Continue until engine begins to detonate, then retard the timing 3-4 degrees.

Joe

[Randy Adams]

Re: Timing setting?

I'm sorry guys, I didn't mention it as Joe said it is a hard/slow labored cranking. I do have a heat shield and my battery is old. I guess I should start there. Duke and Joe, thanks for your input.