HEI w/ adjustable vac. advance help pls

[Greubin]

I've installed a 350CI 290hp GM crate engine, topped with Edelbrock performer EPS, 1406 carb and a Summit Racing HEI distributor. I got the engine running this past weekend, but had a couple of issues. First off the engine wouldn't fire initially, then surged bad when the gas was slightly blipped. Once started, it ran steady for the 2000RPM break-in. Today, I had problems starting the engine, then finally discovered I had the vac. advance hose connected to the unported side of the carb ( drivers side ). Disconnecting this hose allowed the engine to start right up. I scrounged up the HEI directions and sure enough it states the vac. advance should be connected to "ported vacuum" which IIRC is the pass. side vac. port of the carb. With the vac. adv. connected to ported vacuum, the engine starts fine, but I still have a slight hesitation when the engine is barely rev'ed above idle. Back to the HEI instruction sheet, it states to turn the vac. advance adjustment screw fully clockwise, then test drive and look for a "spark knock", and to adjust the screw counter clockwise until the "knock" disappears. I've done this, and now I"m about 3 turns out from full clockwise, engine still has a small stutter just above idle. OTOH, the engine seems to runs fine with the vac. advance disconnected??! Timing is currently set to 10deg BTDC.

Any HEI experts out there? Please help - I'd like to get this sorted out so I can move on to the 700R4 test drive.

thanks

[Oldtruckfanatic]

It sounds like the advance weights and springs in the distributor might be coming in too early too. When I set up my HEI's I just set the base timing where I want it and check the total advance at about 3000 rpm. It shouldn't be more than 40 degrees. I think the directions in your crate motor say to set total at around 34-36 total. The distributor probably came with different springs for the advance weights didnt it? either way try turning the initial timing back to 8 degrees and put the hose back on the vacuum advance and try your adjustments from there. The adjustment to the vacuum dash pot is only for fine tuning so if it needs more than the adjustment allows you have to either recurve ( in your case with stiffer springs to keep the weights from advancing untill a higher rpm) or take a couple of degrees of initial timing out of it. which is what I would try first because it may be a simple fix. hope this helps.

[Fred T]

Try this article on curving the hei

http://www.chevyhiperformance.com/ho...438/index.html

[dwaite72lnghrn]

It sounds more like a carb/accelerator pump issue than Dizzy.

[Greubin]

Thanks for the replies! I'll work more on it tonight and report my findings.