greencamaro

Just rebuilt the 305 in the 89, used flat top .030 rebuilder hypers, about .035 in the hole with slight deck cut, .041 gasket with slight cut on heads. I figure scr should be about 9.35. Using a Ramjet 350 roller cam 196/206, intake closes at about 28 deg abdc at .050. Stock 305 swirl heads.

Before rebuild had about 150 psi compresion with .041 gasket and stock medium dished pistons and the peanut roller cam. Now I have 190 psi with the bigger cam. Computer is toast so we are running a Edel 1406 carb and early non computer HEI.

I want to run this thing on 87 octane and have pulled the intial timing back to 4 deg advanced, total is around 24 deg at about 2700 rpm, and 10 deg in the vac advance, but I swear I still hear some ping, but we have some exhaut leaks too. Did I screw it up ? Should I pill it down and put in dished pistons ??? Arrgghh........ Help.............

jonmark1985

Definetly not. You are in great shape.

It may not hurt at all to run 10-12° initial timing before any mechanical or vaccum advance comes in.

Supervisor42

I wouldn't do that just yet . It depends on "when" it pings. You should change the weight & spring setup in the dizzy first to let the advance come in a little later.
An adjustable vac advance will let you trim out some of the advance if it pings under light load (not accelerating).
But most of all, if you have an auto trans, you should move the shift points up some with a governor spring & weight kit to keep it from lugging the engine. The stock 700r4 shifts very early and lugs way down before downshifting for MPG. This will help if it pings under light acceleration low in the rpm range.
Each of these cost less than $100. Do the changes one at a time.
Or you can use 89 octane...

crazycuda

First and formost fix the exhaust leaks. The edel 1406 is know for running lean in light throttle position so you might want to change your metering rods around. The carb should have come with a book to explain the settings/adjustment
I would set my base line timing at 10 and set the max advance at 32 at 3200. plug the vacc advance for now till you get the dist curve set correctly. I have had to braze the advance slots closed before and file them open again to get the curve set right. Also make sure when you hook the vacc advance back up it goes to ported vacc not direct manifold vacc.