Dadgum Misfire... - Chevelle Tech
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post #1 of 40 (permalink) Old Mar 21st, 19, 11:40 PM Thread Starter
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Dadgum Misfire...

On the way home from the warehouse today, my car started developing a misfire. As the day progressed, it got worse. It is basically numbers 2 & 3 are not doing what they should. Late this afternoon, I pulled the plug wires/plugs and replaced them with new ones. After I fired it back up, it was still misfiring. I then just changed out the HEI module and coil - no change.

I then did a compression test on those two cylinders and they are good - right around 165-170 PSI. When I was putting everything away, I found a brand new cap and rotor - I will put them on tomorrow morning. I am not fond of them as they are the Duralast units that didn't even last me 6 months before (lifetime warranty). But, if I put them on and the problem goes away, the I will have to find a high alkyd content cap/rotor. The MSD units are supposed to have that, but the cap that is on there now hasn't been on there long - maybe 18 months. I truly hate having to track stuff like this down.

1971 Malibu, factory buckets/full gauges/console, 377 roller cammed small block, Turbo 400, 3.42 10 bolt posi (Buick), - All your base are belong to us.
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post #2 of 40 (permalink) Old Mar 22nd, 19, 12:23 AM
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This and vacuum leaks are the worst. I’m sure you are good, but make aure the cap is sitting firm on the distributor.
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post #3 of 40 (permalink) Old Mar 22nd, 19, 12:39 AM
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Re: Dadgum Misfire...

why dont you get a pair of plug wire pliers and pull the wires when it's running to see if you have spark at the plugs.
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post #4 of 40 (permalink) Old Mar 22nd, 19, 1:57 AM
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Wink Re: Dadgum Misfire...

The joys of driving a vintage car ...

David

1966 Fremont 11A, SS396/L35 coupe - 1 of 66,843
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post #5 of 40 (permalink) Old Mar 22nd, 19, 6:36 AM
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Re: Dadgum Misfire...

Get a Standard or Msd cap/rotor and hope for the best.
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post #6 of 40 (permalink) Old Mar 22nd, 19, 6:38 AM
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Re: Dadgum Misfire...

If just 2 cyls are missing, it could be the reluctor tip making contact with the p/up coil for cyls 2 & 3. There has to be a small air gap for a spark to be produced. Bushes in dist body could be worn or p/up loose.

Alkyd material has now been superceded by Rynite for dist caps/rotors. It has superior dielectric properties.
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post #7 of 40 (permalink) Old Mar 22nd, 19, 9:35 AM
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Re: Dadgum Misfire...

Wow, I haven't heard the term Dadgumit in years. Sort of like the "pipe down" which meant the old man was a coming for something no good and you better straighten out.
Anyway hope you can figure out the miss.

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post #8 of 40 (permalink) Old Mar 22nd, 19, 10:31 AM
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Re: Dadgum Misfire...

Not hearing good things about MSD lately. I read they sold the company but don't know for sure.. I'll just put the points back in with lawn mower copper core wires and be done with it. I never crank the engine over 5500 anyhow..
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post #9 of 40 (permalink) Old Mar 22nd, 19, 1:40 PM
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Re: Dadgum Misfire...

Quote:
Originally Posted by hydro462 View Post
Not hearing good things about MSD lately. I read they sold the company but don't know for sure.. I'll just put the points back in with lawn mower copper core wires and be done with it. I never crank the engine over 5500 anyhow..
Holley bought them a while back. Some are outsorced to china and Mexico, their cheaper stuff is all made in china to compete in price with all white box parts. I belive its soon impossible to find a Us made hei distributor.

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post #10 of 40 (permalink) Old Mar 22nd, 19, 4:12 PM Thread Starter
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Re: Dadgum Misfire...

I changed the cap and rotor this morning - no change. Someone mentioned something about the pickup coil, so I pulled everything back off and took a look. This distributor has always had an issue with oil seeping into (or just flat out being put there by too much crankcase pressure). The pickup coil is wet, but I noticed that at least one of the teeth look like they have been making contact. The gaps are not consistent as I rotate it around.

Then for the best discovery - the distributor is a Procomp unit (the guy that built this engine is such a worthless crook). Anyway, I am wondering if that could lead to the issue, since 2 & 3 are 180° out from each other.

I am calling my local Chevy dealership right now to see if they have either of these part numbers in stock: 93440806 or 88961867 (the first one is the performance HEI, the second one is the same, just in billet).

As you look at these pictures, can you tell me if the wear on the distributor gear is normal?? It probably has about 50,000 - 60,000 miles on it. Also, I have a Competition Cams 08-432-8 roller cam. I don't think it requires a special distributor gear.

If someone just happens to have one of those distributors sitting around that you no longer need, shoot me a private message.
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1971 Malibu, factory buckets/full gauges/console, 377 roller cammed small block, Turbo 400, 3.42 10 bolt posi (Buick), - All your base are belong to us.
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post #11 of 40 (permalink) Old Mar 22nd, 19, 4:29 PM Thread Starter
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Re: Dadgum Misfire...

Would there be anything wrong with an Accel HEI unit?? Autozone has this one for $139.99: https://www.autozone.com/ignition/pe...88780_806564_0

1971 Malibu, factory buckets/full gauges/console, 377 roller cammed small block, Turbo 400, 3.42 10 bolt posi (Buick), - All your base are belong to us.
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post #12 of 40 (permalink) Old Mar 22nd, 19, 5:09 PM Thread Starter
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Re: Dadgum Misfire...

Quote:
Originally Posted by cherokeepeople View Post
why dont you get a pair of plug wire pliers and pull the wires when it's running to see if you have spark at the plugs.
It is very difficult to pull the plugs while it is running, especially with the headers. I pulled the number 2 plug wire, installed a spark plug in it, then grounded the plug. The spark was weak and inconsistent. The voltage is getting to the plug, but it is too weak to do anything. After examining the distributor, I am thinking that it is the problem. Just waiting on some member feedback about the Accel unit. It is in stock close to my house and the distributor seems to get good reviews.

1971 Malibu, factory buckets/full gauges/console, 377 roller cammed small block, Turbo 400, 3.42 10 bolt posi (Buick), - All your base are belong to us.
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post #14 of 40 (permalink) Old Mar 22nd, 19, 6:56 PM Thread Starter
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Re: Dadgum Misfire...

Quote:
Originally Posted by Eddie K View Post
This is my daily driver, so I don't have time to wait for one to arrive. I just located one of the AC Delco units (same as the Chevrolet Performance one), but it will take 2 - 3 hours for them to get it. Hopefully I will have it before they close tonight.
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1971 Malibu, factory buckets/full gauges/console, 377 roller cammed small block, Turbo 400, 3.42 10 bolt posi (Buick), - All your base are belong to us.
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post #15 of 40 (permalink) Old Mar 22nd, 19, 7:02 PM
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Re: Dadgum Misfire...

The pattern on the gear looks strange. The gm billet hei is made by msd Ive been told. Lots of people have had luck with ac delco Taiwan 93440806 heis the more expensive billet use bushings for the mech advance so easier to adjust but expensive.

Chevelle Malibu ss 64
489 BB with parts from Lewis racing
Alumitech radiator with dual spals
Th 400 Edge 9.5" converter
57 3/4” wide 12 bolt: Eaton posi, Us gear 3.31, Toms KA 33 splines axles
Malibu ss 64 is online now  
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