71 340 running bad

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bballfan1

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Everything is new. Car makes no vacuum. If you put it close to where it is supposed to be timed it quits. 4972 thermoquad rebuilt by harms, seems rich? Car gas fouled two sets of plugs just trying to keep it running. Help please
 
Harms does beautiful work. BUT it is possible that the "O" rings may have been distorted or split on the secondary jets when installed.The other thing is the fuel bowls are epoxied and is possible they are leaking.
Both will cause a rich condition. These are just possibilities.
No vacuum ? Double check for vacuum leaks ? Maybe manifold gaskets ? Base gasket ? Is it a stock cast iron manifold ?
 
checked no vacuum leaks at manifold. I tried a second carb and it acted the same.
 
Are you using a vacuum gauge? What else have toy done?
 
no did not have vacuum gauge. Checked compression spark tdc all good
 
bballfan1 said:
Everything is new. Car makes no vacuum. If you put it close to where it is supposed to be timed it quits. 4972 thermoquad rebuilt by harms, seems rich? Car gas fouled two sets of plugs just trying to keep it running. Help please
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When you say everything is new do you mean it is a fresh rebuild or just the carb. Ignition? Many unanswered questions.
 
Swap on one of your known good Edelbrock 1406 carbs, and listen to it Perrrrrr.....

Process of Elimination

Will answer a lot of questions right quick.

Screenshot_20200807-121328_Gallery.jpg


Edit:
See you already tried a second carb....

☆☆☆☆☆
 
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bballfan1 said:
Everything is new. Car makes no vacuum. If you put it close to where it is supposed to be timed it quits. 4972 thermoquad rebuilt by harms, seems rich? Car gas fouled two sets of plugs just trying to keep it running. Help please
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Check your ignition. When ignitions do not fire correctly they can give you a so called "rich" burn. Do a cylinder pressure test and if everything is fine it would most likely have to be ignition related. Also keep in mind "Ignition" means everything from the alternater to the plug. I have seen just a half a volt drop out of the alternator with a pulley change produce a black plug without touching the carb.
 
everything is brand new. All ignition parts, no vacuum leak at manifold, compression good.
 
New doesn't mean functional. Systematically verify that everything is functional. How do you know there's no vacuum, if you haven't put a gauge on it?
 
This is almost as bad as "help my car is running bad, it's red".
 
bballfan1 said:
Everything is new. Car makes no vacuum. If you put it close to where it is supposed to be timed it quits. 4972 thermoquad rebuilt by harms, seems rich? Car gas fouled two sets of plugs just trying to keep it running. Help please
Click to expand...
assuming all the vacuum ports are either employed or plugged, and that your secondaries are fully closed, that your brake-booster is not sucking air, that your PCV system is correctly plumbed and working properly, that there is no manifold vacuum in the crankcase, that the metering rods are staying down, and that you have proven your TDC mark is at least close;

At Idle, your engine will respond well to massive timing, just start it up, and without regard to the numbers, just pull in the timing as much as it likes. You will know that it is liking it by the fact that the idle speed just keeps going up. As you go, keep backing off the speed screw to keep the idle speed in check.
When you reach a point than additional timing does not produce additional rpm, stop and back up to the last adjustment that did. Now you can read the timing. If you have a Multi-strike ignition, you will need a compatible timing light.
If the number you get is greater than 90 degrees, you are on the wrong Plug-wire; back up/go forward, one cylinder in the firing order. Keep trying wires until you get one that reads about 25>35 degrees. Now yur on the right wire.
Do not drive it like this.
If you already are on the right wire, and getting a number in that range, then; shut the engine off, take the plugs out, and with the engine still hot, see if you can rotate the crank manually with a regular Johnson-bar.
If you find it to be extremely difficult, yur gonna have to figure out why and my guess would be that the ring gaps are too tight. To prove it rip the valve covers off, remove the valve gear, and try it again. With the gear off you no longer have to fight the valve springs, so if it still turns over real hard by hand, then sorry, I would be taking that engine apart. Another symptom of too tight rings at a normal timing of 14 to 18 degrees is that all that ring-friction tends to drive the engine into overheating or at least very high coolant temps.
While the gear is off, this is a good time to find split overlap, and see if it's at least close.

This happened to me. I added ~.004 to the top ring, and ~.002 to the second, and that was all it took. Yeah it was a PITA, but I was out of options. That engine got a whole new personality.
 
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Thanks for suggestions. The engine is a factory over the counter engine. I can't believe the rings came from the factory with wrong ring gap.
 
Being that everything is new Mike , and your leakdown checked out good I don't think you have nothing to worry about if something minor that you'll get figured out and when you do you'll be laughing about this it'll be no time I pray everything comes together shortly you've got a lot of time and dedication in this heirloom...best of luck, Will......was cam broken in correct....
 
Make sure there is no dirt in the fuel line, causing the carb to flood. If it is flooding at idle, you will see fuel dripping from the brass nozzles in the primary boosters.
Stick with the TQ, they are great carbs.
 
Mtrhead said:
Being that everything is new Mike , and your leakdown checked out good I don't think you have nothing to worry about if something minor that you'll get figured out and when you do you'll be laughing about this it'll be no time I pray everything comes together shortly you've got a lot of time and dedication in this heirloom...best of luck, Will......was cam broken in correct....
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If he don't have nothing to worry about, that means that he has a lot to worry about!
 
71 TQ is very different from 72 up. No wells to leak, no o-rings to seal the primary jets. Might be time to pull the top off the TQ to check float levels, jet sizes, rod numbers, and such. What cam are you running? Did you find true TDC? Did you centerline the cam? What compression are you getting? Get a vacuum gage. New factory engine means nothing, I could tell you stories. Who did the heads?
 
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