sjc115

iTrader: (3)

Not sure if this is the right place to post this, but here goes...

Background info:
I recently put a cam and a set of stock iron swirl port (they were free) GM heads on my 350 SBC. I put them on because I wanted to try porting a sets of head (mostly just bowl work and general clean-up) and I wanted the bump in compression (I took off a set of 76cc chambers, these 'new' ones are right around 60cc).
Intake: Edelbrock Air Gap
Carb: Holley vacuum secondary 4150, 670 cfm, 65 min jet, 68 secondary jet.
Cam: 282 (224 @ 0.050), 0.5" lift, 106 LSA

The car was just as slow as it was with the old '624' 76cc chamber heads and the mild cam (don't know the specs, just going off what I was told when I bought the motor). After some thinking about it, I decided that bumping the initial timing up might wake-up the cam. I bumped the timing from 14° to 18° and the car slowed down. The 0-60mph time (based on a cheap accelerometer) increased by 1.5 seconds. Why would that happen? The only conclusion I have come to is that the carb is way to lean, but I don't have any experience with tuning motors so I'm just guessing.

Does anybody have any suggestions for what I should be looking at? Where have I gone wrong?

five7kid

iTrader: (14)

That's a big cam for swirlport heads. I doubt there's any flow increase above .45" lift, so everything above that is wasted. Pretty much like the 624's.

Initial timing is pretty much meaningless. What you need to set is the total mechanical timing - the full advance at higher RPM without the vacuum advance hooked up.

The stock jetting is probably a little lean, but I doubt that's significantly affecting your power.

sjc115

iTrader: (3)

Where is a good starting point for total timing?

five7kid

iTrader: (14)

Typical for SBC is 34-36.

That's beyond the stock timing tab. You'll either need timing tape on the damper, or a dial-back timing light.