509 rat

I was wondering what you guys on the forum think about my module going bad in my 69 vette hei dist.heres the scenario it started running real crappy , like on 7 cylinders, it does start and run better at higher rpm, but at idle terrble wont idle.I have replaced all the plugs , distributer wires, coil ,roter and cap , when I bought the car a year and a half ago, but remembered I did not replace the module in the distributer.i read somewhere that when you replace your coil mine being a accel coilyou need to replace the module the same accel brand as well and be sure to use the lube or grease they give you for heat for the module.the only thing I have not checked yet is the spark on all 8.im just curious what the symtomes are of a bad module, thanks for your help.

gabriel1025

A bad module will cause the poor running and what seems to be a misfire at the lower speeds. You are right if you do not use the thermogrease that is provided the module will burn up within a day. It is not necessary to go back to an accel module, but I would either use an accel or MSD to stay consistant with the set up you already have. Hope this helps.

509 rat

I ordered the module, havent checked spark yet, I take it that snce I have 5 wires that go to distributer that its a 5 pin module,thank you for your help.

jdmick

Real easy to pop the cap and rotor off to see what you have. Personally, I would ditch the Accell coil and go to a standard one unless you pair it with and Accell module as has been stated. Every module that's failed for me did so completely. Usually when you try to restart the car. Finally got the best one they had at NAPA. So far it seems to be holding up better than most.

509 rat

I think they only make a 4 pin for the stock style hei dist.Im going to change it out either way.so I guess it can make a car run like on 7 cylinders or rough.

TimAT

HEI pretty much works or it doesn't.. The module and the pickup coil are the only things in there that are in one of two conditions. Working or not working. I've never seen one cause a miss on one or more cylinders and still run at all. A miss as you describe could be the coil itself firing internally (bad insulation internally), a problem with the cap or a bad wire. The grease under the module is a heat sink compound to draw heat away from the module itself.

509 rat

I put the module in, did nothing, no fouled plugs,I have spark at all the plugs, still runs like on 7 cylinders.maybe I have a bad cylinder, what do I do next , a compression check.

69427

A quick no-cost test you might try is to disconnect the vacuum advance and see if the misfire changes/improves. At idle and low RPMs the manifold vacuum is high and the vacuum canister will rotate the "breaker" plate quite a ways, causing the two wires from the VR sensor to flex a lot. Over the span of several years the internal wires can fatigue and give an intermittent output connection from the VR sensor, causing the engine to run rough or die.
If your misfire issue is a regular repetitive dropout then the problem is probably elsewhere, but this test won't cost you anything to eliminate this area as the problem.

chevygod

Years ago I had an HEI pickup coil fail (The thing around the star wheel with the inward pointing teeth), and it caused a misfire at idle that was not noticeable at cruise.

Checking each wire for signal via firing a timing light showed each wire was sending spark to the plugs, just not at the right time. I pulled each plug one by one and noted RPM loss on every other plug. The motor actually felt like an idling 4 cylinder.

Hope you get this solved.
Tom

509 rat

I have my vacume advance disconected , so not sure if that will help.

509 rat

[QUOTE=chevygod;1589454961]Years ago I had an HEI pickup coil fail (The thing around the star wheel with the inward pointing teeth), and it caused a misfire at idle that was not noticeable at cruise.

Checking each wire for signal via firing a timing light showed each wire was sending spark to the plugs, just not at the right time. I pulled each plug one by one and noted RPM loss on every other plug. The motor actually felt like an idling 4 cylinder.

Hope you get this solved.is there a way to test coil its only a year and a half old.your right on the idle thing, like a 4 cylinder, smoothes out with rpm but still skidish.if i had a bad cylider wouldnt the plug be all fouled out from lack of burning the fuel.or if a flat cam a loose rocker or ticking sound.

condor7

[QUOTE=509 rat;1589461597]Just thought I would put my two cents in. This may not be an ignition issue. Not sure about your set-up but here is my experience. Have a 670 Avenger sitting on top of a mild 355. Went to get gas and started having a bad miss at idle. Sort of went away at cruise but was again very noticeable at idle to the point of almost stalling the engine. Well got home and started checking. Could not really find anything wrong with ignition. Started the engine, grabbed a can of brake cleaner and started checking for a vacuum leak. Sure enough the primary throttle plate shaft bushing developed a bad spot and that created a severe lean condition but only on one bank. Replaced the base plate and no more issues. Just a thought as sometimes these sudden things relate entirely to something that we don't expect. Hope you find the cause and get her running again.

chevygod

When my pickup coil started to fail, I still had fire at each plug, just not where it should have been in the cycle on 4 cylinders. Kind of like the timing was off on every other cylinder. Therefore the plugs were pretty clean and normal looking.

The vac leak is also a good one to look for.

Good luck,
Tom

509 rat

im going to do a quick compresion check tommorrow, and will have a second set of eyes, I will look at the vacume leak thing as well. thanks for the help, I will post what I find tommorrow.going to check coil, vacume, and compression.

509 rat

I think I figured out the problem.the compression check I did was very good.all spark looked good, ignition parts all good.with a second set of good eyes, not that mine are all that bad, my buddy found that while the engine is running there is fuel dumping into the carburetor, its not comming from the spraying jets that spray fuel into carb, not a carb guy here so bare with me.the fuel is comming from the middle of the carb bubbling out of another area.and it quit a bit, it gets better with high idle, so basically its flooding out at low idle.the carb is a holly 650 with no choke horn, its open.the carb is a year and a half old.I jst dont know the name of where its comming from, do you guys, thanks for the help.

'75

[QUOTE=condor7;1589463519]A word of caution, don't use brake cleaner for this test, when that stuff burns and comes out the exhaust, the fumes can drop you like a sack of potatoes. Carb cleaner, not so much, but brake cleaner is very bad.

doorgunner

The float might be set too high and the gas is coming out of the round vent tubes (and everywhere else).....or the needle could have small debris caught on the seat keeping it from shutting off excessive fuel. Do you have a good in-line fuel filter before the gas enters the fuel pump....or before the gas enters the carb?

509 rat

I do have a fuel filter just the stock one, im going to replace the filter and clean the carb out, but youre right its a probably a small stuff stuck in the seat .

509 rat

its called throttle boosters, from what i can tell looking at a parts catalog.

TimAT

Gas dripping from the boosters is just about always a sign of a float level that's too high or a float that is saturated and too heavy. A chunk of anything in the needle and seat it' would run all the time. Check the float level. Won't hurt to pull the needle and seat out and take a look. At worst you'll have to replace the o-ring seal on the needle and seat.