Posted By: Pat_Whalen
Low compression big block initial timing...? - 04/29/10 10:25 PM
What is a good baseline to start at with a low compression late 70s 440 as far as initial advance goes. I've currently got mine set up at around 10* BTDC, but it seems to idle better and have higher vacuum at around 14-16*. Is this suitable?
Posted By: Dougsmopars
Re: Low compression big block initial timing...? - 04/29/10 10:32 PM
That is fine. Give it all it will take with out pinging.
Posted By: hooziewhatsit
Re: Low compression big block initial timing...? - 04/29/10 10:35 PM
yep, just keep an eye on the total to make sure it doesn't go too high.
Saw something about rotating the dist until you get the highest vacuum reading, then backing it off enough to lower it 1". In theory you should end up around 15ish.
Posted By: 70Cuda383
Re: Low compression big block initial timing...? - 04/30/10 12:38 AM
don't know about the backing it off thing, I thought you advanced it to max vacuum, then set your idle speed where you want it, and start over...back and forth, back and forth,
Posted By: DaytonaTurbo
Re: Low compression big block initial timing...? - 04/30/10 03:17 PM
Go with as much advance as it'll take and still allow the starter to turn the motor over when hot. You may have to shorten your advance slots, or you'll over-advance the total timing. But this would be a good opportunity to put a new advance spring in there anyway. Trust me the effort is worth it, especially on a low-comp smogger 440, it really helps wake them up in terms of driveability.
and when you get the initial right you will most likely have to shorten the slots to stay @36-38 total (vac adv disconnected/plugged) though some people have had good luck w low compression BB's w ~40 ish expecially 383's.