chevy 292, new HEI, running rough

[rusmannx]

1. rotor points to #1 at TDC (verfied)
2. cap with wire #1 above rotor
3. wires @ 1-5-3-6-2-4
4. timing then set to 4degree below TDC with vacuum hooked up (although i've read these motors also like 8-10 degrees but it didn't run any better).

the timing mark on the balancer stays pretty steady but i'm still getting a lot of popping out the back and an occasional loud back fire. the HEI is a new (in box) OEM style but i can't figure out why this thing is running so roughly. and super rich too. a minute near it and my eyes are watering.

anyone thing of what could be the problem or what i've overlooked?

 

[inkpot]

Howdy! Timing spec is 4 degrees BTDC with the vacuum disconnected. May not make much difference. Try pulling out the plugs to see if you can ID the one(s) thats not running right. JOhn

 

[middlecalf]

My experience with my HEI is that the spec timing is pretty much out the window. I'm not alone, I've heard of other people who end up with timing as much as 20 degs out of spec but running the best (performance, mileage, smoothness, etc etc). So, try advancing and see what happens. One thing nice about the old chevy engines, they'll run over a long range of timing settings, some better than others.

 

[rusmannx]

thanks for the replies.

I unplugged the vacuum and set it to about 10degrees where it idles smoothly. when i hook the vacuum back up it falls right on it's face. sputtering, popping, and generally trying to die. i pull the vacuum back off and right back to a smooth idle.

besides that problem, when i have the vacuum unplugged and it's idling smoothly, i can rev it up slowly or quickly and it sounds great, but i get a lot of popping from the tail pipe as the revs drop off. related issues?

thanks again!

EDIT: watching some TV and thinking it just occurred to me that the port i have the vacuum hooked up to has vacuum at idle. i believe i should be on a port that has no vacuum at idle but gains vacuum with RPM. right?

i'll play with it some more in the morning.