#1 Cyl has no compression - Team Camaro Tech
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post #1 of 11 (permalink) Old Jan 7th, 08, 11:14 AM Thread Starter
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#1 Cyl has no compression

This is a newly built 383 still on the stand. All cylinders show pressure when spinning the crank by hand except #1.. I can hear the it blowing out the exhaust port.. Anything else I could try before pulling the head off? I did remove the exhaust rocker to make sure the valve wasn't being held open. The heads are fairly new Edelbrock RPM's, with the RPM Roller cam. If its a bent valve, Im a bit worried how it got that way. Ideas?
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post #2 of 11 (permalink) Old Jan 7th, 08, 11:21 AM
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Re: #1 Cyl has no compression

My first thought is , a valve is not closing. Is intake pulling in air? Can you release intake valve some? Will cly pressure up for leakdown? Did you install rings on this piston?

Don
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post #3 of 11 (permalink) Old Jan 7th, 08, 11:44 AM Thread Starter
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Re: #1 Cyl has no compression

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Originally Posted by zdld17 View Post
My first thought is , a valve is not closing. Is intake pulling in air? Can you release intake valve some? Will cly pressure up for leakdown? Did you install rings on this piston?
I'm assuming the intake is puling in air.. I plugged the spark plug hole up with my thumb and can feel it start to pressure up but before it pops my thumb, I can hear the pressure release out the exhaust port.. And that's with the exh rocker removed. I also checked the adjustment on the intake valve, its ok. The engine was built at a machine shop, so I would hope the rings are there. But by the way its acting, I'm sure they are installed.

Like you said, I'm thinking the valve isn't closing, or perhaps its even bent.. I'm in denial on it being bent, I just dont see how that could have happened. Maybe some trash on the valve seat? The heads do have about 5,000 miles on them and I did clean them up before installing on the new engine. Should I try blowing some compressed air in the exhaust port with the valve open? Or do I just need to pull the head and check it?
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post #4 of 11 (permalink) Old Jan 7th, 08, 11:49 AM
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Re: #1 Cyl has no compression

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Originally Posted by zeb596 View Post
I'm assuming the intake is puling in air.. I plugged the spark plug hole up with my thumb and can feel it start to pressure up but before it pops my thumb, I can hear the pressure release out the exhaust port.. And that's with the exh rocker removed. I also checked the adjustment on the intake valve, its ok. The engine was built at a machine shop, so I would hope the rings are there. But by the way its acting, I'm sure they are installed.

Like you said, I'm thinking the valve isn't closing, or perhaps its even bent.. I'm in denial on it being bent, I just dont see how that could have happened. Maybe some trash on the valve seat? The heads do have about 5,000 miles on them and I did clean them up before installing on the new engine. Should I try blowing some compressed air in the exhaust port with the valve open? Or do I just need to pull the head and check it?

Release rocker arms on both cly, pressure up with shop air via air chuck / spark plug hole tool, piston will go to bottom so make sure you dont have any breakovers on crank bolt . Listen to exhaust port and if intake is off, listen there or thru carb or manifold and crankcase, You should hear something. What do the lifter bottoms look like?

Don
TC # 349
Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

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post #5 of 11 (permalink) Old Jan 7th, 08, 12:00 PM Thread Starter
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Re: #1 Cyl has no compression

Quote:
Originally Posted by zdld17 View Post
Release rocker arms on both cly, pressure up with shop air via air chuck / spark plug hole tool, piston will go to bottom so make sure you dont have any breakovers on crank bolt . Listen to exhaust port and if intake is off, listen there or thru carb or manifold and crankcase, You should hear something. What do the lifter bottoms look like?
Ok, will try that.. Do they carry the "shop air via air chuck / spark plug hole tool" at most auto part stores? Or perhaps Northern Tool? The lifters are new rollers. Thanks!
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post #6 of 11 (permalink) Old Jan 7th, 08, 12:28 PM
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Re: #1 Cyl has no compression

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Originally Posted by zeb596 View Post
Ok, will try that.. Do they carry the "shop air via air chuck / spark plug hole tool" at most auto part stores? Or perhaps Northern Tool? The lifters are new rollers. Thanks!

Some of these tools are part of compression testing equiptment but they can be made. You may find them at parts stores, Harbor freight. You can have an old spark plug body (break out center) welded to the suitable air chuck nipple. A farm / tractor store may have this as some people use the cly pressure to air up tires.

Roller lifter eliminates the worn cam lobe syndrome.

Don
TC # 349
Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

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post #7 of 11 (permalink) Old Jan 7th, 08, 01:03 PM
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Re: #1 Cyl has no compression

Quote:
Originally Posted by zdld17 View Post
Some of these tools are part of compression testing equiptment but they can be made. You may find them at parts stores, Harbor freight. You can have an old spark plug body (break out center) welded to the suitable air chuck nipple. A farm / tractor store may have this as some people use the cly pressure to air up tires.

Roller lifter eliminates the worn cam lobe syndrome.
Boy, that would make a great episode for Mythbusters....... Can tires explode if filled with fuel-air mixtures?

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post #8 of 11 (permalink) Old Jan 7th, 08, 01:51 PM
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Re: #1 Cyl has no compression

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Boy, that would make a great episode for Mythbusters....... Can tires explode if filled with fuel-air mixtures?

alan
Normally these tractors guys are using diesel and those that use spark plugs, use propane which is worse but the same as some topping off tires with such. All tractor tires I saw were loaded with water, but you are correct, there is a mixture. Maybe the Myth guys will cross that some time.

Don
TC # 349
Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

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post #9 of 11 (permalink) Old Jan 7th, 08, 07:05 PM Thread Starter
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Re: #1 Cyl has no compression

Checked it out tongiht and ended up being some trash on the valve seat. I pulled the head, cleaned the valve. Then bolted the head back up and no more blow by past the exhaust valve.. Just got to buy an intake and head gasket.. Thanks for the replies!
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post #10 of 11 (permalink) Old Jan 7th, 08, 07:55 PM
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Re: #1 Cyl has no compression

cool.
I built a compression tester with a plug fouler ( Azone) and a fitting from the hardware store. worked great.

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post #11 of 11 (permalink) Old Jan 8th, 08, 04:52 AM
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Re: #1 Cyl has no compression

Quote:
Originally Posted by zdld17 View Post
Normally these tractors guys are using diesel and those that use spark plugs, use propane which is worse but the same as some topping off tires with such. All tractor tires I saw were loaded with water, but you are correct, there is a mixture. Maybe the Myth guys will cross that some time.
We bought when I was on the farm and I still have, a tire inflator and we had gas engines. Took forever to fill a front tire. And yes, air/fuel mix.

Liquid in the rear tires is an antifreeze gel and is used for additional weight to pull an extra one or two extra plow shears from the OE design, a traction device. If tractor was designed to pull 3-shear plow, add weight and could pull 4-shear plow, gear down one gear and could pull 5-shear. More shears, less time in the field(s). Or, go an inch deeper in the cut to remove the 'shelf' generated only the several years of using the same plow with the same tilling depth.

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