I got a junk yard 79 305 and put my 85 305 tpi heads and everthing else on it and a little bigger cam. My question is the pistons from the the 79 didn't have the 4 vavle releifs I guess they weren't flat tops. So my commpression must be lower does this mean that with the new cam I should advance the timing more than stock. Right now it seems like my car runs best at 10 degrees base and sucks at 6. Also I can't hear any pinging is this becuase of lower compression. It also acts like it could use more timing but I don't want to go to far from the factory setting. Need Advice Please!

 

if i remember correctly advancing the cam will make more torque and retarded will build more HP, straight up is a trade off between the two.

------------------
ICON Motorsports

1st & 3rd
MM Black Diamond 538 F&AM

 

Are you asking about advancing the cam timing, or advancing the ignition timing?

 

Advancing ignition timing

 

the optimum timing is more dependant on the fuel type and air/fuel ratio than on the piston. Just use the same power tuning method you use with any other engine.

 

What ODB said, the goal is Complete combustion before TDC.. ( or Close )

So depending on Combustion Chamber charactoristics, Compression, Octane, Air temp, ECT... it will Change...

Generally, Time yourself up to right before You Ping. Its not incredibly precise or scientific, but For most of us its the best we can Do.

I had a 79 305 In My firebird, and It Liked just about 12 deg.

Don't worry about moving away from the stock setting. In case You hadnt Noticed, GM didnt have performance On top of the priority list With these Engines.



------------------
60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver
Reader's ride -> My Ride

Just another Hot Rod kid, or thats what they all tell me.
Livin' the Stereotype