Gremlins in the Thermoquad ? and vacuum circuit, HELP!

Glad to hear it is up and running.

Charlied said:

Problem solved. Returned to the basic golden rule, The KISS METHOD (keep it simple stupid)
Pulled each wire @ cap and one tower showed corrosion (#7) pulled the plug, yup fouled heavy, so little or no spark. Installed new cap and plug ($15 fix). It starts right up and when warm idle is smooth and no twitch.
I wrongly accused the Thermoquad of the problem, never was. So the lesson ( seems to be hard for me) keep it simple ! Thanks for your help,appreciated.
Now bleed the brakes to re-center the proportioning valve and I’m done, at least for now!

Click to expand...

Charlied said:

Problem solved. Returned to the basic golden rule, The KISS METHOD (keep it simple stupid)
Pulled each wire @ cap and one tower showed corrosion (#7) pulled the plug, yup fouled heavy, so little or no spark. Installed new cap and plug ($15 fix). It starts right up and when warm idle is smooth and no twitch.
I wrongly accused the Thermoquad of the problem, never was. So the lesson ( seems to be hard for me) keep it simple ! Thanks for your help,appreciated.
Now bleed the brakes to re-center the proportioning valve and I’m done, at least for now!

Click to expand...

Well, I spoke to soon, the gremlins are back!
Rough idle returned and I hate to say it, but everything points to the TQ. Seems most likely that my meticulous rebuild missed something? To recap,installed new cap and rotor, checked each wire for spark, checked timing, all good. if you recall initial problem was slight mis, which I determined was caused by corrosion in one tower ( #7) the new cap and plug replacement solved the problem, but only for a short time.
A few days later started it up and it was worse (mis) then ever. I pulled the plugs ( a pain in the butt in these big block cars) and the problem became apparent ( I think).
ALL plugs were heavily fouled, plugs had at most 30 miles on them, so carb is flooding badly I suspect. Tweaked around for mix screws, but don’t think if I’m off (too rich) it wouldn’t be this bad ,or would it ?
Mystery is did the rebuild was running fine, except for slight mis, replaced cap and plug, all good for short time, then boom major problem, what happened ? I leave that for another time.
I was super careful in setting float height and installing bowl O rings and new needles and seats, but seems I goofed something.
Frustrated and have become a cranky old man, thought I was pretty good at rebuilding things, but I guess not. Just want to drive with confidence my unique car.
Any and all comments are appreciated as what to look for on TQ autopsy and re-re-build, determined to get it right, on the road, and tackle that stuck proportioning valve, which should be a piece of cake after this. Sorry to be so dramatic,need to vent. Thanks for listening.

Woodruff Carbs said:

Here’s how I set my mixture screws if I don’t have my O2 tapped in. If you pull the 3/8 pcv hose off the base of the carb at idle and the rpm raises and maintains: you are rich. If you pull it and it immediately dies:you are lean. The ideal reaction should be a 100-200 raise in rpm momentarily, then the engine should stumble and die out.

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Hi Dave,
Take a look at my post of today 11/29.
Had followed your instructions above last week and it reacted indicated, all good. Car sat for a few days then boom, super fouled plugs super rich condition.

I don't remember did you reseal the bowl passages? Ethanol eats everything except JB Marine Weld. It took me years to finally find something that holds together.
Another possibility is electrical.
My bulkhead connection from the alternator to the dash melted. My car would randomly die and load up, it fouled plugs and I thought it was the carb till one day it just turned off, it just quit without warning. Ran a bypass and all was good.
Usually when a TQ is dumping a lot of fuel it is hard to start, super rich on exhaust and you can turn the mixture screws all the way in and it will still run.
What primary jets are you running?
What rods?

72sunroof said:

I don't remember did you reseal the bowl passages? Ethanol eats everything except JB Marine Weld. It took me years to finally find something that holds together.
Another possibility is electrical.
My bulkhead connection from the alternator to the dash melted. My car would randomly die and load up, it fouled plugs and I thought it was the carb till one day it just turned off, it just quit without warning. Ran a bypass and all was good.
Usually when a TQ is dumping a lot of fuel it is hard to start, super rich on exhaust and you can turn the mixture screws all the way in and it will still run.
What primary jets are you running?
What rods?

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OK, here we go, it starts easily, exhaust on fast idle (choke) rich, when dropped to normal idle, seems OK.
The rods and jets were not changed at time of rebuild. Weather here bad (cold & wet) and can’t work on it till tomorrow. Planning to carefully reset mix screws, 2.5 turns out, start it as see what goes. Will check if it runs with screws all in which would confirm internal fuel leak correct?
Never had any electrical issues,bulkhead connector and engine harness was replaced with all new from Bill Evans at time of resto,long time ago.
What is frustrating is that when I rebuilt carb I was very careful and meticulous, checking and re-checking each step.
Thanks for the advice and listening, appreciate it. Keep you in the loop.

Are you sure that they are fuel fouled and not oil fouled? It’s not all that uncommon for big blocks to suck oil out of the valley.

Woodruff Carbs said:

Are you sure that they are fuel fouled and not oil fouled? It’s not all that uncommon for big blocks to suck oil out of the valley.

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It’s fuel not oil, dry black carbon, see attached photo.Question I have, sorry if I’m repeating myself, could bad mix setting cause this,or more likely internal fuel leak.
Thanks

Charlied said:

OK, here we go, it starts easily, exhaust on fast idle (choke) rich, when dropped to normal idle, seems OK.
The rods and jets were not changed at time of rebuild. Weather here bad (cold & wet) and can’t work on it till tomorrow. Planning to carefully reset mix screws, 2.5 turns out, start it as see what goes. Will check if it runs with screws all in which would confirm internal fuel leak correct?
Never had any electrical issues,bulkhead connector and engine harness was replaced with all new from Bill Evans at time of resto,long time ago.
What is frustrating is that when I rebuilt carb I was very careful and meticulous, checking and re-checking each step.
Thanks for the advice and listening, appreciate it. Keep you in the loop.

Click to expand...

72sunroof said:

I don't remember did you reseal the bowl passages? Ethanol eats everything except JB Marine Weld. It took me years to finally find something that holds together.
Another possibility is electrical.
My bulkhead connection from the alternator to the dash melted. My car would randomly die and load up, it fouled plugs and I thought it was the carb till one day it just turned off, it just quit without warning. Ran a bypass and all was good.
Usually when a TQ is dumping a lot of fuel it is hard to start, super rich on exhaust and you can turn the mixture screws all the way in and it will still run.
What primary jets are you running?
What rods?

Click to expand...

Warmed up here today so got to it. Carefully reset mix screws (sweet spot seems to be 2.5) started right up. Did run the screws in and it stalled out, so I assume no internal leak, yes?
seems to run well.
What bothers me is at cold start ( choke full engaged) and fast idle exhaust is very rich,( kicks off my smoke alarm )
When down to curb idle (1000) exhaust fumes normal, what am I missing? Not sure I have the metering rod adjustment dialed in, would that make a noticeable difference?
Also looked down the throat of the primary, no fuel drips.
Will pull a few plugs tomorrow to check fouling.
What do you think? Any crazy chance mix screws, which I carefully cleaned be bad?
Have a 77 Vette and when I cold start it idles high but no choking fumes like the Mopar.

Charlied said:

It’s fuel not oil, dry black carbon, see attached photo.Question I have, sorry if I’m repeating myself, could bad mix setting cause this,or more likely internal fuel leak.
Thanks

View attachment 1033983

Click to expand...

Carefully reset mix screws (sweet spot seems to be 2.5) started right up. Ran the screws all the way in and engine died, so I guess no internal fuel leak, yes?
Seems to run good. Will pull a few plugs tomorrow and check for fouling.
What is puzzling is on cold start, and choke fully engaged exhaust fumes heavy, kicks off my smoke alarm. When on curb idle exhaust fumes normal. Am I missing a setting or adjustment. Not sure if I have the metering rod adjustment dialed in, check tomorrow,would that have any effect ?
Thanks for listening. Wondering if mix screws themselves could be an issue, carefully cleaned at time of rebuild, could they be pitted?
Look forward to hearing from you. Be safe. Stay warm.

Charlied said:

Carefully reset mix screws (sweet spot seems to be 2.5) started right up. Ran the screws all the way in and engine died, so I guess no internal fuel leak, yes?
Seems to run good. Will pull a few plugs tomorrow and check for fouling.
What is puzzling is on cold start, and choke fully engaged exhaust fumes heavy, kicks off my smoke alarm. When on curb idle exhaust fumes normal. Am I missing a setting or adjustment. Not sure if I have the metering rod adjustment dialed in, check tomorrow,would that have any effect ?
Thanks for listening. Wondering if mix screws themselves could be an issue, carefully cleaned at time of rebuild, could they be pitted?
Look forward to hearing from you. Be safe. Stay warm.

Click to expand...

Think I found the bad actor, the choke, it stays engaged too long, would explain heavy fumes at start. Thinking that Electric choke control not functioning properly. How do I check it?

Charlied said:

Carefully reset mix screws (sweet spot seems to be 2.5) started right up. Ran the screws all the way in and engine died, so I guess no internal fuel leak, yes?
Seems to run good. Will pull a few plugs tomorrow and check for fouling.
What is puzzling is on cold start, and choke fully engaged exhaust fumes heavy, kicks off my smoke alarm. When on curb idle exhaust fumes normal. Am I missing a setting or adjustment. Not sure if I have the metering rod adjustment dialed in, check tomorrow,would that have any effect ?
Thanks for listening. Wondering if mix screws themselves could be an issue, carefully cleaned at time of rebuild, could they be pitted?
Look forward to hearing from you. Be safe. Stay warm.

Click to expand...

Choke is the problem, staying engaged too long, it’s electric,how do I test ?

Woodruff Carbs said:

Are you sure that they are fuel fouled and not oil fouled? It’s not all that uncommon for big blocks to suck oil out of the valley.

Click to expand...

Think problem is the choke, stays engaged too long, giving heavy fumes and causing fouling. When choke off exhaust fumes normal. How do I fix? Has electric choke control.

72sunroof said:

I don't remember did you reseal the bowl passages? Ethanol eats everything except JB Marine Weld. It took me years to finally find something that holds together.
Another possibility is electrical.
My bulkhead connection from the alternator to the dash melted. My car would randomly die and load up, it fouled plugs and I thought it was the carb till one day it just turned off, it just quit without warning. Ran a bypass and all was good.
Usually when a TQ is dumping a lot of fuel it is hard to start, super rich on exhaust and you can turn the mixture screws all the way in and it will still run.
What primary jets are you running?
What rods?

Click to expand...

Think I found the problem the choke is staying engaged too long. Getting heavy fumes and some blue smoke, once kicked down smoke gone and exhaust normal. The prolonged choke would cause the fouling leading to mis.
Car has electric choke control,which I suspect not working, how do I check and correct?
Thanks