Duraspark/HEI dropouts

[fordconvert]

Tonight I installed my rebuilt duraspark dizzy with the GM Hei module. It runs but especially at idle the motor has a bad stumble and stalls. When it stumbles and stalls the spark quits as far as a timing light is concerned. It doesnt matter what wire Im on even if Im on the coil wire. The tach does not seem to drop other than with the RPMs but its a analog meter so Im not sure how fast it can respond. My only thought so far is I didnt know there was a polarity to the pickup coil so Im not sure how I hooked it up. 50/50 chance I got it right. It did seem that I had to rotate the dizzy more clockwise than I expected to get it to run and show up on the timing scale. I just figured it was because the oil pump didnt line up right so I had to move it to get it to drop in. Do you guys think I could have the pickup wired out of phase? Would that make it fire between terminals? And thats why the spark seems to disapear? Except when I was turning the dizzy further clockwise it didnt seem to be backing through the carb. There does not seem to be much range in the timing because if I put a pump on the vac that makes it stall too, not sure what the timing light does because I dont have that many hands.

I have steady 14.2 volts to the coil and module.
Old points system was in poor condition but ran ok except at idle where it had a bit of a stumble but never stalled or seemd to have spark drop outs. Compression dry with warm engine 180,175,170,175,180,175.

Its 66 200 6 wC4 and autolite 1bbl stock as far as I know

New MSD blaster 2 coil.
New old stock 4 pin GM module I had in the garage.
Rebuilt single advance dizzy from oriley.
New autolite plugs gapped to 45.
New old stock relay I had to get key on power from the voltage regulator terminals.
Used Intel heat sink from local surplus store.
Misc 14 gauge wire, terminals, and 15 amp fuse.
New regular quality hei style wires.
New regular quality borg warner cap and rotor.

Ideas? Thoughts?

Thanks

TJ H
StPaul/Mpls MN USA

 

[addo]

Try running it with the tacho isolated from your system. I've seen a bad tach cause grief before.

Polarity of the pickup coil wires may be relevant. I don't know what the waveform looks like so can't comment other than that. Do isolate and test the pickup for continuity.

Also double check your coil for continuity on primary and secondary windings, check the heatsink is fully grounded (and so is the motor).

What timing are you on?

 

[MustangSix]

We put a DII distributor on the ocilloscope and found that it generates an AC voltage and a square waveform. I forget the power level. Reversing the polarity on the pickup to the module sometimes helps.

Another thing is that the GM module works best at 12-15 volts. It will run on as little as 7.5, but may not be capable of reliably triggering the coil at higher rpm at that voltage. This is especially true with cheaper replacement modules.

One last thought. Check the voltage to your relay. If you're tapping the regulator for a power signal, there's a possibility that it may be dropping out at certain speeds. You could tect this by simply getting a jumper and powering the module and coil directly frm the battery (hot wiring your car).

 

[fordconvert]

Got out there this morning and it was the pickup coil polarity.

I still have the same stumble at idle in gear but from what I have been reading here I could be chasing that for a long time. At least it dont stall now and I know my ignition system is good. Have to get some more carb spray and a new pcv valve and look for leaks.

It seems slightly smoother running overall but was not as big a deal as some people reported, I guess in spite of the way my old stuff looked it was still in pretty good shape.

I will look for a new card reader for my camera and post some pics soon.

 

[Anonymous]

I will look for a new card reader for my camera and post some pics soon.

If you have windows XP you just plug the camera into the computer USB port and it sees it as an external drive...

 

[fordconvert]

My camera is OLD and only has a 9pin serial out that I lost the cable for because it was so slow. I should get a new one but for this sort of thing 2.1 megapixels is plenty. I spent the $20 for a new card reader that works witout a driver on XP. Now I can read 9 kinds of cards if I ever need to.

I see that on this board you have to link to the photos. Anyone know of a easy free place they can be posted to for the link?

 

[addo]

Easiest is probably Imageshack. Look in the "Eye candy" forum and there's a sticky topic on posting pictures.

Regards, Adam.

 

[Anonymous]

I use photobucket

I never tried imageshack so I can't comment on it