o.k. i'm at wits end trying to get my 400 to run "normal"
i have issues with pinging at low RPS & popping at high RPMS. i've tried timing ranges from 4 - 12 degrees (initial). i've hooked up vacuum gauges and adjusted my air/fuel screws. i have stock heads, edelbrock 750 carb, performer intake and a crane cam with these spec's:
lift:
intake @ cam - 2934
exh @ cam - 2934
int @ valve - 440
exh @ valve - 440
duration 266
cam timing 4 deg.
min rpm - 1600
max rpm - 4600
valve float - 6500
timing @ .050 / duration 210

i don't think this cam is what's considered "performance"
what am i doing wrong here? i've also got the HEI vac advance hooked up to the "full time" port on the drivers sisde of the carb. that's where everyone here tells me to put it (although the manual says different) ????

HELP, DAVE

I would check and make SURE that the balancer ring hasn't slipped. Pull all the plugs and use a piston stop to find TDC. That's where I'd start.............

That 210 deg dur @.05 cam is very very mild/samll for a 400 cid motor esp if its got fairly high compression so what is the compression?

The cyl pressure could be high setting up the motor for detonation with that short cam timing even with only 9:0-9:5 compression.

But even that very mild cam need approx 16 deg base timing so the 12 you had it at was still retartded for that cam.

Normal setup with that very mild cam would be approx 16 deg base timing and 20 deg mech in dist all in by approx 2800-3k rpm for 36 total in by 2800-3k rpm.

Set base timing witrh vac adv unhooked/plugged and idle at 600-650 rpm.

For street you also need a vac adv for better fuel economy but it caousl also add to ping with such a mild cam that could be creating too hi cyl pressure for todays crappy 93 fuel to tolerate. Yes you do hook it to full vacuum all the time.

If this is lmited use wk end use car only i would optto run the full timing curve mentioned above for fullperf/pwer and run some kemco lead supreme booster ,1 qt kemco to 18 gals 93 fuel = 97.5 octane which should satisfy yoor motors octane needs ans stop the ping so you can run a full power ign timing curve.

Check out the Kemco website for details,its a heck of a lot cheaper the buying race3 fuel or better then retarding the timing looser power and fuel milage to stop the ping.

As for the poping at higher rpms that could simply be a partially fouled/dirty spark plug that was a result of the motor breakin period misfireing under load or too lean of a fuel calibration which is common with a box stock eddy carb.

Scott

thanks scott. I'll re-set the timing and let you know.