HEI IGNITION & TIMING question.
Thread Starter
Melting Slicks
Joined: Aug 2010
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From: Palm Beach Florida
St. Jude Donor '12
HEI IGNITION & TIMING question.
I have a 77 base L-48 Auto. I will be installing dual exhausts tuesday. Later this week or next, I want to tackle the timing. I have read/copied all the articles to get familiar with the distributor and it's functions. Besides getting a New kit (Mr Gasket part # 927 or 928) is there anything else I should look into or get. I also learned to move the "ported vacuum" to the "full manifold vacuum" port. Also do I have a "dwell" on my 77 Distr.? I have yet to take the shield off and look at it. I know that Lars use to fabricate a kit for HEI's. But he stopped this awhile ago. So does anyone else know if there are any tricks I need to know about? Thanks. By the way thank you Lars & BarryK for thier write ups!
Last edited by daanbc; Nov 14, 2010 at 09:11 PM.
Le Mans Master
Joined: Dec 2007
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From: McHenry Illinois
No the 77 doesn't use dwell. You will need either a regular timing light and a timing tape or a dial back style timing light. Also you are probably better off reusing your original distributor weights and changing the springs to get the advance correct. I reshaped some weights to get them to give enough advance.
Last edited by '75; Nov 14, 2010 at 09:10 PM.
Thread Starter
Melting Slicks
Joined: Aug 2010
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From: Palm Beach Florida
St. Jude Donor '12
I heard that I should reuse my orig. weights and change only the springs too. Why did you not use your originals? and reshape others? Also will I need to get a new Vacuum Advance Kit?
Le Mans Master
Joined: Dec 2007
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From: McHenry Illinois
I couldn't get the originals to advance more than 10 deg because of the shape. Same with the Mr Gasket ones. I rounded the ramps on these Mr G weights, you can see a little of the sharpie mark on one of them where i marked it before grinding. The tails on the ones I had seemed too long. I did this on a friends car. Mine has the summit weights, which worked pretty good.
Le Mans Master
Joined: Dec 2007
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From: McHenry Illinois
Others have had different results, but for me, the summit kit was easier.
http://www.summitracing.com/parts/SUM-850030/?rtype=10
http://www.summitracing.com/parts/SUM-850030/?rtype=10
Last edited by '75; Nov 14, 2010 at 09:52 PM.
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
No the 77 doesn't use dwell. You will need either a regular timing light and a timing tape or a dial back style timing light. Also you are probably better off reusing your original distributor weights and changing the springs to get the advance correct. I reshaped some weights to get them to give enough advance.
.....
.....
The (stock) internal module has an adaptive dwell control system in it. It varies the dwell time/angle depending on the RPM and system voltage to arrive at the desired maximum primary current for most conditions.
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Race Director
Joined: May 2003
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From: California
Every inductive ignition system uses dwell. (No dwell equals no energy in the coil.)
The (stock) internal module has an adaptive dwell control system in it. It varies the dwell time/angle depending on the RPM and system voltage to arrive at the desired maximum primary current for most conditions.
The (stock) internal module has an adaptive dwell control system in it. It varies the dwell time/angle depending on the RPM and system voltage to arrive at the desired maximum primary current for most conditions.
nicely put
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
Every inductive ignition system uses dwell. (No dwell equals no energy in the coil.)
The (stock) internal module has an adaptive dwell control system in it. It varies the dwell time/angle depending on the RPM and system voltage to arrive at the desired maximum primary current for most conditions.
The (stock) internal module has an adaptive dwell control system in it. It varies the dwell time/angle depending on the RPM and system voltage to arrive at the desired maximum primary current for most conditions.
Last edited by '75; Nov 18, 2010 at 09:53 PM.
Thread Starter
Melting Slicks
Joined: Aug 2010
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From: Palm Beach Florida
St. Jude Donor '12
You answered my question, Thank you. I know they have dwell, I wanted to know if I had an adjustable one or self contained. (have yet to take the shield off) Thats why I asked. By the way, figured out my problem with the timing. Someone in the past must have taken the Distr. out, and when they place it back in, the #1 cylinder was not at TDC. It was put in just enough for the engine to run. Thats why I could not get the timing mark anywhere near the timing tab. I will tackle this next week.
Last edited by daanbc; Nov 18, 2010 at 10:13 PM.
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Well, perhaps you should have said that, instead of posting a technically erroneous statement. There's constantly new people getting into this hobby, and it doesn't cost any more to type a correct answer the first time rather than the second time.
Team Owner
Joined: Jan 2006
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From: Crossville TN
(picky, picky, picky...)
'75 I see that you used one [very] light spring and one medium spring. I just worked on a friend's dist/eng in which I did the very same thing. It was on a '60 Chev Impala 348 tri-power...and that combo worked perfectly.
'75 I see that you used one [very] light spring and one medium spring. I just worked on a friend's dist/eng in which I did the very same thing. It was on a '60 Chev Impala 348 tri-power...and that combo worked perfectly.
Thread Starter
Melting Slicks
Joined: Aug 2010
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From: Palm Beach Florida
St. Jude Donor '12
When setting "initial timing" with the timing mark at the degrees it is suppose to be, where should the **** on the back of the timing light be set at? Or does it not matter for "initial timing". Thanks.
Thread Starter
Melting Slicks
Joined: Aug 2010
Posts: 2,487
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From: Palm Beach Florida
St. Jude Donor '12
Thank you. I want to set the car to what the factory had it(which is 8 degrees BTC) Then start from there.
