Chevy HEI Distributor problems

[kdavies3]

Some great replies guys and thanks for all.

The problem originally started at around 200 miles old when the ignition timing retarded itself at this point I assumed that the dizzy had rotated due to being loose. I retimed it and all seemed well for a while.
Then at around 800 miles It happened again slowly getting worse over a 200 mile run to a local kit car event.
Having marked the dizzy I could see that it hadn't moved but the timing had.
Reset it again and all was well but not for long went on a track day around 250 miles later, and the engine began to pink (ping) and got gradually worse over a couple of laps.
Checked the timing trackside and it was all over the place, again the dizzy had not physically moved.
Do to the higher cylinder pressures caused by the timing maladies I broke a piston top land.
Piston now replaced but ignition problem goes on.
I've checked the balancer and carb and gaskets all is OK.
I just pray that if I fit a new HEI all will be sweetness and light and I can enjoy our all too brief British summer.

[Clois Harlan]

Kdavies,

I once had a GTO that I use to drag race and it developed the same symptoms as yours. Checked and replaced everything I could think of and finally one of my friends came over and pulled the distributor and told me I had two problems. 1. Distributor bushings were worn and 2. my rotar cap was warped. Replaced the whole distributor and everything was back to normal and car was running great.

Just a thought.

Clois

[wilf leek]

Kev - pull that back-to-front engine out and fit a Ford like I told you to in the first place!!

Seriously - I can't believe the stock HEI dizzy is up to the increased ignition requirements of your modified stroker engine. They were marginal in terms of spark energy at higher rpms on stock lumps.
You should seriously think about going the MSD route.

BTW - why did you start this thread in the "Consumer Watch" area??

Love and kisses

[kdavies3]

Hi Wilf, long time no speak!
If I did it again it would have a Dissy at the front.
The only reason it hasn't is that my chassis was already set up for a Chevy when I bought it as an unfinished project.

The HEI in mine is the high voltage jobbie so it should be OK.

I removed the Vac can and locked the vac advance wheel at the weekend still runs like sh1te.

I think this confirms that my problem is in the electronic side.

I hope my new HEI will arrive very soon if not I'll going MSD as recomended.

What do folks think is the best one to go for and with what coil etc.

[wilf leek]

Kev - MSD6AL (built in rev limiter) for the spark box and blaster 2 coil and you won't go far wrong. Millions of the d**m things out there working away.

You would only have to choose between a vac or no vac advance dizzy. Really, the only way to go would be with the vac advance, if your engine doesn't like it you can always lock it out. My old Rover would not take vac advance after I had recurved the dizzy to give it the advance curve it wanted, but those engines will take (and like) much more advance than stock, probably more so than a sbc.
The MSD dizzy in my current car has let me set up the advance curve my "proper" engine wanted very easily.

Hope you get yours running better very soon - you can't waste the weather we have been having.

[kdavies3]

HI Wilf, just spoke to UPS and my new HEI will be with me Wednesday, Florida to Derby less than 24 hours, Derby to south Wales 4 days where's the logic?
I prey that this cures it.
I'm planning to run it up to Silverstone for British Grand Prix on Thursday. i've just checked the long range forecast and it's all down hill from here (sods law).

[kdavies3]

Well gang ,
the new HEI arrived yesterday, fitted timed up the beastie and now the problem has gone.
Thus proving that the problem was in the electronics of the dizzy I think.
I've fitted the old cap/ coil and plug leads so it obviously wasn't them.

OH JOY I'm back on the road.

[wilf leek]

Kev - good news, now try to keep your pistons in one piece.

Did you ever establish exactly why you broke that top land? Was it overheating/detonation because of the ignition timing problem? Or were the ring gaps a touch tight?

[kdavies3]

Hi Wilf,
my best guess is that it was the increased cylinder pressures created due to the faultering ignition timing, combined with the detonation I had at Elvington on the track.
The piston top land looked like a mechanical failure as opposed to being melted in typical detonation style.
The piston was also cracked thru the 2nd land and all the way down the skirt.
Oh boy was I lucky to get away with driving it home the 250 miles.
I could easily have totalled the engine.
I'll be giving it a run to Silverstone tomorrow.

[sagacious]

you sure the vacuum line on the carb isnt clogged? i found a ball bearing in my hose, the engine shut off immediatly after plugging the vacuum advance in...