Engine misses - Team Camaro Tech
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post #1 of 9 (permalink) Old Apr 22nd, 04, 05:09 PM Thread Starter
 
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I have a 1980 Z28 camaro with a 74 400 sb in it. The engine started to miss the other day. It only seems to miss at a steady rpm above 2000. I have replaced plugs, wires, cap, rotor,and ignition module. I havent checked the timing yet but i dont know why that would be off. The only thing I could think of was something to do with the carb and or fuel, but i dont know what. The carb is an edelbrock 650 with electric choke, and all of the ignition components are stock. I hope someone can help me out as to why it misses.
Thanks in advance,
Jeff
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post #2 of 9 (permalink) Old Apr 23rd, 04, 02:13 AM
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Bring the engine up to operating temp. Pull the spark plugs, disconnect the ignition power at the HEI, hold the throttle open, take a compression check of the engine on all eight cylinders.

Check the readings on the paper you wrote them onto to make sure they are all within 10% of each other. If the readings are good, say over 150-160 lbs., this will eliminate the the integrity of the combustion chamber.

If you find two clinders reading the same, you might suspect a blown head gasket between those two cylinders.

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post #3 of 9 (permalink) Old Apr 23rd, 04, 04:26 AM
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Check to see if the vacuum advance diaphram is leaking.

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post #4 of 9 (permalink) Old Apr 24th, 04, 10:15 AM Thread Starter
 
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I checked the vaccuum advance diaphram, and it is fine. I checked the compression and the readings are...

8 170 7 165
6 165 5 162
4 172 3 161
2 164 1 156

So is it probable that the head gasket between #3 and #5 is blown?
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post #5 of 9 (permalink) Old Apr 25th, 04, 11:56 AM Thread Starter
 
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Is it possible the timing could be thrown off because of something wrong with the distributor?, like the weights or vaccuum advance?
Thanks,
Jeff
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post #6 of 9 (permalink) Old Apr 25th, 04, 03:16 PM
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how did the plugs look when you pull them? Are any fouled, or, any sign of coolant on them ...You may need to let engine be cool to check for coolant on plugs ... If head gasket is bad, you may notice change in coolant level. look for signs of coolant/oil mixed in crankcase and/or radiator .. Look for whit esmoke in exhause ... Also, make sure the intake is properly torqued and sealing ... A leaking intake will also cause a miss/stumble ...Also, try running the car at night and look for spark arc ...
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post #7 of 9 (permalink) Old Apr 25th, 04, 08:39 PM
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Your compression seems ok. Have you checked/replaced the coil? Could be bad gas too. Will it miss sitting still in neutral reving to 2000 RPM?

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post #8 of 9 (permalink) Old Apr 26th, 04, 01:26 AM
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I would perform the suggestions sdt & Hal have suggested. You might take a look at cyl 3 & 5. Add oil to see if they change independently of one another.

For a last check, pull both plugs, inject shop air into one cylinder, check for escaping in the other cylinder.

Try to eliminate all other items before removing the heads. Maybe even have another person look into the problem, two heads are always better than one.

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post #9 of 9 (permalink) Old Apr 26th, 04, 03:37 AM
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Don't forget to inspect the spark plug wires. Easy to do !
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