HEI Distributor weights and vacuum advance question.

[joeyg1973]

I have looked for this answer everywhere and can't seem to find the answer. I have an old 4 pin HEI distributor for a straight 6 that I have converted to a 7 pin. While there is plenty of documentation on how to wire up the 7 pin to the MS2, it doesn't mention what needs to be done with the vacuum advance and weights. Do I simply not connect the vacuum advance and tack weld the weights in place or do I connect everything as normal?

Joe

[73Eldo]

I had plans to do the same thing for my Cadillac but ended up finding a dizzy from the one year they had computer controlled timing for my engine so I didnt have to do it.

My plan was to remove the weights and springs and lock that part down either with a pin or tack weld. The tricky bit is you will have to 'index' the pickup coil so that it will be firing the coil when the rotor is aligned with the terminal on the cap. My plan for that was to remove or modify the vacuum advance can with some sort of locking clamp so I can adjust it from the outside when the engine is running. After it adjusted I could then remove the cap and lock it down tight. To get it indexed you would want to get a clear cap or drill some holes in an old cap around the terminal so you can see the end of the rotor. Start the motor and get the timing in the ballpark the normal way then hook a timing light to the wire you drilled out around and then adjust the pickup coil so its firing fairly centered on the terminal. During this process you would want to leave the dizzy in the fixed timing mode so MS doesnt try and adjust the timing while you are doing this becasue as you adjust the pickup with the special modded vac thing you will be changing the timing and have to then rotate the whole dizzy to get it back where you want it. This is why I feel the need to have that easy adjustment because there will be some back and fourth getting it dialed in. After you get a few miles on the thing you should be able to see the marks on the terminals where its arcing most of the time. At that point you may decide to tweak it slightly more to get it right on and get the most spark to the plugs under the most conditions. If you have ever had to pull a dizzy on the first chev vortecs you will know about this process.

I hope I explained it well. There are people that claim they can do this in their shop with some sort of a jig but are unwilling to share the details so this was the only way I could come up with to do it myself. I wonder if I could take some measurements from the OE fixed one and transfer that to the old style one?? May have to look into that.

[joeyg1973]

Well I am using the HEI distributor on a Toyota 2f motor... and to tell you the truth after hearing your description of what I need to do... that EDIS setup is sounding better and better.

Joe

[73Eldo]

I have heard the EDIS is a good way to go and there are a bunch of them in the junkyards so they should be easy to get and cheap.

[joeyg1973]

My big issue with the edis is mounting the 36-1 toothed wheel. On a Toyota 2f the harmonic balancer is riveted right to the crank pulley, the whole thing is attached to the crank pulley via huge 48mm nut that is set deep into the double pulley. Granted I could drill out the rivets and put some really long studs on to mount the wheel out in front, but that is so ghetto engineering I would like to avoid it. Fabricating a toothed wheel to work with this is going to be hard. You can see what I am dealing with in this picture here.

http://www.man-a-fre.com/explodedview/e ... tm#2fcrank

I have the first "W" pulley listed.

It would be a whole lot easier if I could use something like this from MSD

http://www.msdignition.com/tc_17.htm

Just attach the button thingy to the harmonic balancer at TDC. Any ideas? Suggestions?

Joe[/url]

[73Eldo]

What type of ignition system do you have now? I was thinking that MS2 could do direct coil control from just about any electronic distributor.

What do you have to do to fit that chev HEI?

[joeyg1973]

I don't as I the engine is still in the shop. I used the HEI conversion on another FJ-40 I owned and the difference from the stock Toyota makes this a no brainer. The HEI module I used at the time was a 4-pin.

Rather than explain it I can just point you to the link I used to modify mine. I made a 7 pin HEI mod on my own, but it was fairly straight forward to do.

http://carmutations.com/tiki-index.php? ... ser+2F+HEI

[devojet]

The Quick way to do it if you just want to try it out, is remove the springs and weights and just tie some wire around where the springs were. Also remove the hose from the vacume canister. Set the trigger angle to 10 degrees and see how it goes. If you have any problems with miss firing try adjusting the dissy angle and trigger angle.

The other option is to remove the springs and weights and make a plate with four holes to sit over the four posts where you removed the weights and springs or just weld it after testing the first method.

[joeyg1973]

The Quick way to do it if you just want to try it out, is remove the springs and weights and just tie some wire around where the springs were. Also remove the hose from the vacume canister. Set the trigger angle to 10 degrees and see how it goes. If you have any problems with miss firing try adjusting the dissy angle and trigger angle.

The other option is to remove the springs and weights and make a plate with four holes to sit over the four posts where you removed the weights and springs or just weld it after testing the first method.

Silly newbie question. What the heck is the dissy angle and what is the trigger angle? The vacuum canister is attached to the VR ring.

[devojet]

Dissy angle is the angle you set the dissy to like when you set a standard dissy. the angle is the angle before top dead centre that the ignition is triggered. Trigger angle I should have said "trigger offset" which is a setting in Megatune that tells the MS what angle the dissy is set to.

So to set it up to 10 degrees for example, Set the Trigger offset to 10 degrees then use a timing light to adjust the dissy until you get 10 degrees with the timing light.

I hope that helps.

[73Eldo]

Just thinking after reading other replies here..... If I got it right in my head, with the adjustments available in MS you wouldnt have to do the mechanical adjustment I was talking about with the pickup coil, you could just lock it down. You would still want to do the thing with drilling holes in the cap and the timing light to make sure you are firing near the terminal but the adjustment can be made in MS. As before in my earlier theory it may take some back and fourth to get it right since all the adjustments will interact. Only remaining issue would be making sure the 'limp' mode timing still works which it should as long as you have the stuff locked down within the range it could have been operating in when it was in its original state.