chevy small block timing

[nawlins-tim]

the info i found for adjusting a chevy V8 for performance is:
initial + mechanical = max 36 @ 2500-2800
max with vac 52
http://www.corvette-restoration.com/res ... v_Spec.pdf

so according to this? mine is initial (20) + mechanical (30) = 50? in order for this to work id have to retard my timing alot? i really really feel im missing something here

You are forgetting to factor in the VACUUM ADVANCE effect. Initial plus mechanical plus VACUUM should equal 50 or so they are saying.....right?

 

[lt1 kenobi]

Vacuum advance has NO effect on TOTAL timing. You set your total timing w/the vac advance unhooked and the port plugged. Rev it up until your mechanical advance is maxed out usually around 3k to 3500 rpm. I set mine to 35*. At idle I have around 20 degrees. Now connect your vacuum advance and you'll be reading even more at idle. You can't figure the vacuum advance into your total timing b/c when you are at wide open throttle there isn't any vacuum so your mechanical advance takes all the way over.

 

[Doober]

While it doesn't have an effect on WOT timing, it does while you're cruising. Vacuum is built up under cruise, and as a result timing is added via said vacuum (pickup coil is turned via vacuum canister). Best bet overall is to use an adjustable vacuum advance canister, that way after you have the engine set to maximum mechanical, you can fine-tune your vacuum advance for cruising.

 

[lt1 kenobi]

While it doesn't have an effect on WOT timing, it does while you're cruising. Vacuum is built up under cruise, and as a result timing is added via said vacuum (pickup coil is turned via vacuum canister). Best bet overall is to use an adjustable vacuum advance canister, that way after you have the engine set to maximum mechanical, you can fine-tune your vacuum advance for cruising.

I understand that.... but he was adding the vac. advance as part of his total timing, which is incorrect. I haven't had any issues w/pinging at all w/my old dist which was a crappy delco remy... or my new one msd which has the adj. vacuum canister and I haven't touched it yet. If you set it right you should be fine w/good gas. I only run 93.