HEI Ignition installed

[Momboy007]

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]

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]

Timing should be 8 btd and ya jus reposition the dizzy

[Momboy007]

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]

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]

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]

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]

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]

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

[haysonj]

Originally Posted by Momboy007

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]

Originally Posted by Momboy007

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]

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]

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]

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]

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]

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]

it will be sumwhere here

[Sinister]

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

[VetteVet]

Originally Posted by tnblazerk5

it will be sumwhere here

or here

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

[Sammy]

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]

Originally Posted by Sammy

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.