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Re: Runs like crap now (2/12)
 1/17/23 8:14pm
manchestersharkLifetime Member
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Equinunk, PA - USA

Vette(s):
1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.


Joined: 10/31/2007
Posts: 2200

Do you have a cross fire cap, and are the wires in the correct position?



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Re: Runs like crap now (3/12)
 1/17/23 8:20pm
sdinino
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Rock Hill, SC - USA

Vette(s):
1977 White/Red


Joined: 8/2/2017
Posts: 30

manchestershark said:

Do you have a cross fire cap, and are the wires in the correct position?

Not sure I know what you mean by a cross fire cap. It has HEI, and I'm 99% sure the wires are in the right positions. But it's a good question, I will check tomorrow. If that's what's wrong I'll really be embarrassed lol.



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Re: Runs like crap now (4/12)
 1/18/23 8:22pm
danascar
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Germansville, PA - USA

Vette(s):
1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats. . 1999 C5 Convertible, 6 speed, Atomic orange, Oak interior.


Joined: 1/28/2010
Posts: 828

Well, here's a possibility, had it happen to me. Same deal car would start fine and idle fine up to around 1500 rpm. Past that point it would cough, stumble and seem to miss. After tons of trouble shooting and finally replacing the HEI with a friend's HEI it ran fine. I changed everything I thought I could in the HEI but overlooked the tiny little unit fastened to the base plate that I assume is the equivalent of a condenser on a standard points distributor. that solved my problem!



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Re: Runs like crap now (5/12)
 1/18/23 8:53pm
sdinino
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Rock Hill, SC - USA

Vette(s):
1977 White/Red


Joined: 8/2/2017
Posts: 30

That's a thought. I hadn't considered that, thanks.

I did double check the wires today. They're all in the right place on the cap and headed to the correct cylinder. So at least that's eliminated.

I had decided today that I'd try swapping back the other QJet (with the choke problem) to see if the rough running goes away. But I'll try swapping a different capacitor on there and see if it makes a difference first. Easier than swapping the carb :-).

 

Steve



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Re: Runs like crap now (6/12)
 1/18/23 9:44pm
F4Gary
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Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.


Joined: 8/26/2006
Posts: 1237

Re: Runs like crap now (7/12)
 1/19/23 5:48am
sdinino
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Rock Hill, SC - USA

Vette(s):
1977 White/Red


Joined: 8/2/2017
Posts: 30

I have a spare ignition control module. I didn’t think they failed slowly- I thought either it works or it’s dead. Have you seen them cause this?



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Re: Runs like crap now (8/12)
 1/24/23 5:27am
sdinino
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Rock Hill, SC - USA

Vette(s):
1977 White/Red


Joined: 8/2/2017
Posts: 30

I had a chance to swap the capacitor Sunday and test drive. No change , so I’ll try my spare ignition module next. 

To be clear, all the ignition parts I’m trying have run fine on the car previously. I checked them out and put them away specifically so I’d know they were good in case I needed to replace a component. 



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Re: Runs like crap now (9/12)
 1/24/23 5:57pm
F4Gary
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Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.


Joined: 8/26/2006
Posts: 1237

I think there is a special grease you have to put under that module.



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Re: Runs like crap now (10/12)
 1/25/23 1:39pm
turboj91
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Any possibility that a plug got bumped and closed the gap?

 

You recurved the timing.  Was that at the exact time of the cap/rotor swap or a completely different procedure after the fact? 

Re: Runs like crap now (11/12)
 1/25/23 1:51pm
sdinino
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Rock Hill, SC - USA

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1977 White/Red


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turboj91 said:

Any possibility that a plug got bumped and closed the gap?

 

You recurved the timing.  Was that at the exact time of the cap/rotor swap or a completely different procedure after the fact? 


Yes, I suppose it’s possible. I thought I was being careful reinstalling but I want to pull them anyway to see if one or more are fouled so I’ll regap them at that time. 

I set the timing curve separately last fall before the carb swap. I had it up to 3000 rpm to check all-in timing and it seemed to run fine then, but it wasn’t under load. 

I do use Arctic Silver on the heat sink of the ignition module so that ought to be fine. 

in regard to the “crossfire cap” from the first reply… is that maybe referring to inductive crossfire? I hadn’t thought of that, but I’ll check plug wires 5 & 7 and make sure they’re separated. I’m using Taylor Spiro Pro wires. I’d think they would not be prone to induction but I’ll make sure those two are separated. 



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Re: Runs like crap now (12/12)
 1/25/23 2:14pm
manchestersharkLifetime Member
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Equinunk, PA - USA

Vette(s):
1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.


Joined: 10/31/2007
Posts: 2200

Yes, The Taylor wires are worth the extra money and work well..



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