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-   -   HEI Ignition installed (https://67-72chevytrucks.com/vboard/showthread.php?t=291675)

Momboy007 05-14-2008 05:45 AM

HEI Ignition installed
 
Hello All,
I just have a few question for all of you experts. I just installed a HEI ignition on a 1972 Pick up and it leaves me with a few questions. When I went to time it, I could not move the distributor enough to bring into time, because the vacuum advance pig tail hits the intake maniforld, so all I can get out of it is about 2 degrees BTC, do I need to reinstall the distributor? also, what is the correct timing for a stock 1972 350?
After the HEI install, do I need to open up the plugs a bit, if so, How much?
Thank you all in advance,
Rick

Shyguy 05-14-2008 07:04 AM

Re: HEI Ignition installed
 
On mine I put new wires on it for a HEI setup , then I gapped the plugs at .045.

It sounds like to me the dizzy needs to be removed and re-installed so you can set the timing right.

Danny

69long"n"low 05-14-2008 07:10 AM

Re: HEI Ignition installed
 
Timing should be 8 btd and ya jus reposition the dizzy

Momboy007 05-14-2008 07:16 AM

Re: HEI Ignition installed
 
All,
Thanks for all the help, now I have another question, should I use the ported vacuum or the always on vacuum for the vacuum advance?

Thanks all,
Rick

wzuke 05-14-2008 07:24 AM

Re: HEI Ignition installed
 
Sounds like you are off one tooth. Take the dist. hold-down off and take the dist. cap off. Mark the position of the rotor. Raise the dist. just high enough so you can rotate the rotor (shaft)clockwise ever so slightly. (The dist. may have a tendency to go back into the same tooth - keep trying) Compare the "new" position of the rotor. The rotor is should be in a slightly different clockwise position. If you think you have the rotor in the proper position but the dist. will not go down all the way down you can press down slightly on the dist. while someone taps the starter. It will eventually go down. Alternatively, you can remove the Dist. and take a long screw driver and turn the oil pump rod slightly and replace the dist. making sure the rotor is in the correct position. If this doesn't work re install the dist. from scratch (#1 cylinder up on compression, timing marks matched up, point the rotor to #1 spark plug wire position on the dist. cap.

Momboy007 05-14-2008 07:32 AM

Re: HEI Ignition installed
 
Thanks, That is really great advice and I will do that tomorrow and retime it.
My only other question is the vacuum from the edelbrock carb, should I use the ported vacuum (no vacuum at idle) or the full vacuum?
Thanks again,
Rick

msgross 05-14-2008 01:21 PM

Re: HEI Ignition installed
 
I believe its ported vacuum because as engine RPM increases you want the timing to increase as well.

I set mine up about 9-11 or so on timing, and did open the plugs to .45, but that's just my situation...

Did you also run a new 12 volt wire? DOn't use the old coil wire because its not a full 12 volts....

70GMCer 05-14-2008 02:22 PM

Re: HEI Ignition installed
 
The vacuum advance hit my intake as well. Easy fix, on the distributor cap, move all the plugs wires over one on the cap. That will give you the adjustment needed for the timing.

VetteVet 05-14-2008 02:51 PM

Re: HEI Ignition installed
 
Here is a good read on vacuum advance.
http://www.lbfun.com/Corvette/Tech/v..._explained.pdf

haysonj 05-14-2008 08:17 PM

Re: HEI Ignition installed
 
Quote:

Originally Posted by Momboy007 (Post 2721180)
All,
Thanks for all the help, now I have another question, should I use the ported vacuum or the always on vacuum for the vacuum advance?

Thanks all,
Rick

You will want full vacuum at idle you get no vacuum from a ported vacuum until the throttle opens. Ported vacuum is something they used on early smog engines.

piecesparts 05-14-2008 08:28 PM

Re: HEI Ignition installed
 
Quote:

Originally Posted by Momboy007 (Post 2721199)
Thanks, That is really great advice and I will do that tomorrow and retime it.
My only other question is the vacuum from the edelbrock carb, should I use the ported vacuum (no vacuum at idle) or the full vacuum?
Thanks again,
Rick

That will be your choice and also tied to how your engine is built. If you are looking at getting your total advance in early, then use the non-ported orifice and if you are running basically stock, then you can go with the ported orifice. I am running mine on my stroker motor and my son's 350 on the non-ported outlet and that is because I bring in the timing advance early on the HEIs that I am using.

Sammy 05-14-2008 10:07 PM

Re: HEI Ignition installed
 
Don't forget about changing the power wire that will make one hellva difference in starting & improvement on using HEI. Sounds to me U need to move #1 one plug hole counterclockwise for more room for Advancement. Use HEI Plugs & Gap.

Momboy007 05-14-2008 11:58 PM

Re: HEI Ignition installed
 
Hello Sammy,
What do you mean by "Change the wiring" How do I check this?
Also, do you think I can simply change the plug wire positioning to get enough travel out of the Distributor?
Thanks so much all,
Rick

Luvlegs 05-15-2008 12:18 AM

Re: HEI Ignition installed
 
your points system used a resistor type wire to the coil that dropped from 12v to like 9v or so - that way the points didn't burn up. Find a key on, 12v power source and run a new wire to your HEI - it needs 12 volts to work properly - Tape off the old resistance wire.

Sammy 05-15-2008 02:42 AM

Re: HEI Ignition installed
 
Yes remove that wire completely it is too small. Get the heavyer guage wire. Install a 20amp fuse in it. Plus I believe the "R" wire that is on your starter can be removed on it too & discarded. Look @ FAQ more detailed.

Momboy007 05-15-2008 03:30 AM

Re: HEI Ignition installed
 
Sammy,
So where do you recommend I get the 12 Volts at? Would you recommend at the battery with a 20 Amp fuse?

Also, where is the FAQ page I need?
Thanks again for all your help,
Rick

tnblazerk5 05-15-2008 03:52 AM

Re: HEI Ignition installed
 
it will be sumwhere here

Sinister 05-15-2008 04:24 AM

Re: HEI Ignition installed
 
I'm running my HEI with a 5 amp fuse. Seems to work OK...

VetteVet 05-15-2008 05:15 AM

Re: HEI Ignition installed
 
Quote:

Originally Posted by tnblazerk5 (Post 2722309)
it will be sumwhere here

or here

http://67-72chevytrucks.com/vboard/s...ad.php?t=13698

Sammy 05-15-2008 03:42 PM

Re: HEI Ignition installed
 
I used a spot off the fuse box on both of my trucks. And If you want you can remove the 20 amp fuse for theft deterrent or make it a circuit breaker.

mtndewmaniac66 05-15-2008 08:37 PM

Re: HEI Ignition installed
 
Quote:

Originally Posted by Sammy (Post 2723010)
I used a spot off the fuse box on both of my trucks. And If you want you can remove the 20 amp fuse for theft deterrent or make it a circuit breaker.

I had located a 12V Switched terminal and connected a 10ga wire for my dist back a few years ago, (I had also ran a heavier gauge wire to the fuse block to run my accessories more efficiently) the conversion, along with the Delco 10SI alternator (higher amperage, internally regulated) swap, made a world of difference.


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