LUVTruck.com

A buddy of mine has just reworked this Buick motor and it has problems. He got a remanufactured shortblock and a rebuilt set of heads. The motor runs but it has a slight miss to it. It's a constant weak hit of one of the cylinders. The motor has new plugs and wires, cap and rotor. The carb looks like a good one(Rodchester 2bbl, pre-computer) the caps have been removed to allow for adjusting. The motor will belch out a heavy cloud of smoke when started up. This seemed to be a bad valve guide seal but now im thinking that an oil ring is at fault. And possibly a broken ring causing a weak hit on one of the cylinders. I've also noticed a slight puff of smoke come out of the valve cover hose. This tells me that there's a little blow by into the crankcase. Im certian that the ignition and carburaton is correct and i hate to think that the flaw is internal. It's a fresh motor but i dont know the guy or group who rebuilt it. I dont want to lay this out to my friend because i dont want him to think he's got a bad motor without being absolutley sure. Im going to insist on doing a compression check on the motor. At least this will isolate any cylinder that could be a problem.
Anyboby have any thoughts or ideas on this?

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

they might have over adjusted one of the valves. i would do what you said ,first check the compression. also those carbs have a bad habit of the base plate screws underneath the carb coming looseand leaking.

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don`t have the luv no more but I still like em.72 el camino,
00 & 06 silverado one 4x4, turboed vw sandrail,99 banshee, 06 raptor 700, 02 polaris trailblazer.

The valve rockers are on a shaft. There isn't an adjustment to them. As for the carb, it seemed to be in good shape after dealing with the adjuster caps. It had that steady sound of air running thru the venturi and no droplets of fuel can be seen.

_________________
Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

as far as the miss i would attach the pickup of the timing light onto each plug wire and make sure they are all firing. you will know if one is not because the timing light won't flash or it wont flash regularly. As far as blowby, that can be expected since the motor has no miles on it and the rings have not had a chance to seat. Is the smoke blue or black? does the motor oscilate? If it constantly smokes blue then its probably rings. if it only puffs blue at startup and then clears up then its probably a bad valve guide. make absolutely sure that the carb is not running rich during the break-in period or the excess fuel will "wash" the oil off the rings and they will never seat correctly causing blow-by and premature wear.

The ignition system is all redone because of the initial, lousy idle it had. We diagnosed each wire by arcing them at the cap to find a miss. It didn't provide a conclusive answer because the motor would have a hard miss with a wire pulled. taking plug readings showed that all of the plugs were firing and none of them looked out of sorts. The smoke color is blueish-grey. I guess a compression check is the next step in isolating the problem.

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

check firing oder and you lifters, one could have collapsed. And also check your cam it may have a flat spot on it.

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1980 LUV 4x4, going under re-construction...

The firing order is 1-6-5-4-3-2. It's fool-proof. And the problem is a weak hitting cylinder, not a total miss. The new lifters got pre-pumped before being installed so finding a collapsed one would have been noticed. As for the cam, it was pre-installed in the shortblock. I hope it isn't the culprit because something like this would kill him and his wife will shoot him. I want to rely on the engine builder and look at every other possible reason for the problem before going into the block. I dont want to see him cry like a chick.

_________________
Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

IF YOU HAVE ACCESS TO AN INFARED TEMP GUN CHECK EACH EXHAUST AFTER WARM UP THAT SHOULD AT LEAST TELL YOU WHICH ONE IS THE CULPRIT. WATER WOULD PROBABLY WORK TO THE COLD CYL WOULD EVAPORATE SLOWER.

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don`t have the luv no more but I still like em.72 el camino,
00 & 06 silverado one 4x4, turboed vw sandrail,99 banshee, 06 raptor 700, 02 polaris trailblazer.