HEI full advance
Thread Starter
Racer
Joined: Oct 2010
Posts: 474
Likes: 0
From: Bishop CA
HEI full advance
Just installed a new HEI and when we checked the full advance at 2000 rpm we got 50. We talked to the place we bought it from and they said to adjust it inside the vacuum advance. But he said that it will only get it down to 45. I was told to not run this motor till I get it down to about 34. Whats the right thing to do here. Will this motor detonate at 45 or is it safe. Any help is appreciated. Thanks
Le Mans Master
Joined: Sep 2004
Posts: 5,116
Likes: 5
From: Livonia MI
If you're talking full mechanical plus added vacuum advance, the 45 range sound's about right. You're really wanting to set up the full mechanical advance maybe 32 or so with the with the vacuum line disconnected and plugged, as there's going to be 0" vacuum at WOT anyway. Just cruising around town with the throttle plate's barely cracked give's full additional vacuum advance for better fuel efficiency.
Pro
Joined: Jul 2004
Posts: 668
Likes: 3
From: Platteville WI
My best recollection on this is that all-in-advance can be around 52 degrees. That's 34 mechanical and 18 from the vacuum can. Your vac can may be 20? So adjust for that. Lars used to have a nice article detailing this. To be sure you are not accidentally getting any mech advance at idle rpm, you can wrap rubber bands around the springs inside the dizy when you set your initial advance. Sound about right anyone?
Jay
Jay
Tech Contributor
Joined: Aug 1999
Posts: 14,379
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
You don't check total timing with the vacuum advance hooked up. Disconnect the vacuum advance and set total timing to 36. Once done, limit your vacuum advance to about 12-14 additional degrees.
Lars
Lars
