406 Running Issue

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mikester

Comic Book Super Hero
Mar 10, 2010
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Last month I took the 406 out of my 81 to take care of the timing chain cover leak. Easy fix. New cover, gasket and I sprung for a new pan gasket. Went together without a single issue and its all back in the car and ready to go.
Now to go back a bit. Two days before I pulled the motor I wanted to check how much manifold vacuum I had. For some reason the brakes just dont feel right. Factory discs in the front and the big drum setup from Moser in the back. Im 99% sure theyre adjusted right and EVERYTHING for the entire system has been replaced.
So Im cranking the car over and its not kicking. No gas getting into the carb. Im thinking the bowls drained over time. It had been months since it ran last. While I was trying to get it running one of my friends stops buy. Hes not a novice. Hes built multiple cars and he currently is working on a big $$$ Vette besides owning 2 others. He suggests pouring a tiny bit of gas into the carb. I get a cup, dump a few drops in and it started. Ran for less then 10 seconds. He tells me to work the key and he'll pour the gas in. Mind you, this is something Ive NEVER really done. I know. The gas could/should have been put into the tube sticking out of the carb or at least sprayed in and not poured. Well, that didnt happen. Water under the bridge at this point.
Im sure anyone that works on motors knows what happened. HUGE backfire. Flame shot up. It wasnt good.
So, get back to now. Yesterday I hooked up the 6AL with some butt connectors to make sure I could get it running. Cranked it for a few minutes, Started getting gas in the carb. As soon as it started it ran like crap. Rough as hell. Cant idle right. It feels like its running on 4 cylinders. Never touched the distributor or wires. Had the Holley 750HP sitting on the bench covered the whole time. Put a fresh set of plugs after I put the headers back on. Im stumped. Fresh gas.
Maybe the power valve popped from the backfire ? What do you guys think ? And please, no butt ripping about the gas. I know, the other guy knows, it was a really stupid thing to do.
 

64nailhead

Goat Herder
Dec 1, 2014
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Verify timing with a light. Verify fuel pressure. If either are out of whack then correct.

Have a vacuum gauge hooked up and pour gas into the carburetor to get it to run and watch the vacuum gauge. Best method of putting gas into a carb is through 16 oz soda bottle with a 1/8" or so hole drilled in the cap so you can squirt it in - two man job is best program.

I've dumped fuel into a carb or TB more times than I care to remember. Don't be cheap with it either because it will backfire if it barely has enough to fire. Best not down inside a hay loft though.
 

bracketchev1221

Royal Smart Person
Jan 18, 2018
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Being I didn't see it it IS possible if it backfired hard enough to push out a gasket, or blown a vacuum cap or line off the carb or intake.
 

mikester

Comic Book Super Hero
Mar 10, 2010
2,921
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Small town NY
Being I didn't see it it IS possible if it backfired hard enough to push out a gasket, or blown a vacuum cap or line off the carb or intake.
I looked at the carb when it was off and nothing was missing. I didnt open it to check the power valve because I didnt have any extra gaskets. Im going to run the split loom tomorrow to get the MSD hooked up so maybe when Im done I'll pull it off and open it on the bench.
 

Texas82GP

Just-a-worm
Apr 3, 2015
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How did the oil thar you drained out before you pulled the engine look?
 

Texas82GP

Just-a-worm
Apr 3, 2015
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What distributor are you running on it?
 

Texas82GP

Just-a-worm
Apr 3, 2015
7,987
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Been a while since I bought it but Im pretty sure its the Pro Billet. Not the HEI though. Ive got the separate coil.
I know Hafrod had a similar problem with a new MSD HEI on his 55. Any chance you had a float hanging up?
 
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