HEI system and dwell angle?

Reply Subscribe

Thread Tools

Search this Thread

Mar 30, 2013 | 08:21 PM

7vette6

Thread Starter

Instructor

Joined: Mar 2012

Posts: 171

Likes: 0

From: Sayreville NJ

HEI system and dwell angle?

I finally got around to setting my timing and changing the springs in the distributor. I know step one is checking the dwell angle. But since I have HEI system do I need to check my dwell angle or is it preset and unchangeable?

Mar 30, 2013 | 08:24 PM

jnb5101

Le Mans Master

Joined: Jul 2006

Posts: 8,117

Likes: 104

From: charlotte north carolina

i've installed two hei's. never gave the dwell a thought! you do have to adjust the vacuum can, though.

Mar 30, 2013 | 08:27 PM

7vette6

Thread Starter

Instructor

Joined: Mar 2012

Posts: 171

Likes: 0

From: Sayreville NJ

Oh really? could you please give me some info on this?? what did you do to your vacuum cannister and why?
I just thought my current vacuum advance would work fine with increasing the timing and switching to manifold vacuum

Mar 30, 2013 | 08:51 PM

69427

Tech Contributor

Joined: Jun 2004

Posts: 20,804

Likes: 959

From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.

Quote:

Originally Posted by 7vette6

The dwell angle automatically changes with RPM and battery voltage. It does this to keep the coil charged up at high RPMs, and preventing burning up the coil at low RPMs. It also compensates for the battery/alternator voltage being too high or too low.

The module does all the work. Nothing you need to do.

Mar 30, 2013 | 09:06 PM

jnb5101

Le Mans Master

Joined: Jul 2006

Posts: 8,117

Likes: 104

From: charlotte north carolina

go to msdignition.com. they have installation info on their street fire hei distributor that has a chart showing the engine vacuum, degrees of advance and the number of turns the advance screw needs to establish that number of degrees. there may be other sites that have the same info. just google it.

Mar 30, 2013 | 10:20 PM

7T1vette

Team Owner

Joined: Jan 2006

Posts: 37,637

Likes: 3,113

From: Crossville TN

That is for an MSD electronic ignition system...not a GM H.E.I. system. The only 'adjustment' on the HEI system is to reposition the distributor.

Mar 30, 2013 | 10:24 PM

7vette6

Thread Starter

Instructor

Joined: Mar 2012

Posts: 171

Likes: 0

From: Sayreville NJ

yes. Now im pretty sure I have the ar-10 vac can. which has a 3-5 start "hg and 9* distributor advance. My main question is if this can is o.k. to use, or if I need to buy a new one.

Mar 30, 2013 | 10:51 PM

7T1vette

Team Owner

Joined: Jan 2006

Posts: 37,637

Likes: 3,113

From: Crossville TN

The type of vacuum advace can you have is (or should be) dependent on the amount of vacuum your engine produces at idle. Lars has a good write-up on this issue. You should send him an e-mail and request a copy of that paper.

V8FastCars@msn.com