Seems like a few of us have this crate engine. I have a slight bog sometimes and I have been trying to tune it. I would really appreciate any tuning advice especially from anyone who has this engine. I set the initial timing at 10, total is about 35. Holley 600 CFM changes: changed the shooters from .031 to .035, changed pink accel pump cam to a green pump cam. Set the .015 pump shot clearance. Twelve inches of vacuum in gear. Power valve changed from 6.5 to 8.5. Float levels set at bottom of plug. Jets are stock 65's. I have tried many different changes (one at a time) with timing (10-16 initial), Jets (63-69), Power Valves (6.5-10.5) and several different pump shot cams. Runs real strong mid to top end. I have not pulled the carb yet to check the clearance between the throttle plate and bore. Idles great with the idle mixture screws set for max vacuum/rpm at about 3/4 turns out.
Sorry so long winded. graemlins/clonk.gif

I don't have that engine but I'll try to help. First, when does the bog occur? and second, is it a mech. or vac. secondary?

Vacuum secondaries. I haven't messed with the spring. I believe it is black. Bog occurs from a dead stop but usually occurs while cruising and then opening the throttle quickly. It seems as though it is pump shot related. I know the green cam provides less cc's of shot but I think the profile provides a quicker shot. Thanks for helping.

Have you checked TDC mark on the balancer with a piston stop? Could just be running retarded.

No, I haven't checked TDC. I don't have a piston stop.

Do you think I could be off a tooth?

I was just thinking the the TDC mark could be off. It wasn't too clear if the COMPLETE engine is new or short block or what. If you have a used balancer on the new motor, the outer rings do move. You might just try bumping the timing 5 or 10 degrees and see if the problem goes away (just watch out for ping/etc)

Complete new engine including balancer, intake, carb, HEI, etc.. I am pretty sure the timing is right. I had allot of problems when the distributor was off one tooth. I have been trying to work with the carb without changing the timing. Trying to limit variables.
:confused: Bad approach?

Went thru this with my 350-300 ( pre-vortec ) version. Found out later after going back to a Q jet that I didn't have the thin adapter plate to adapt the Holley to the Edelbrock Performer Qjet type intake.