Progress Thread Komo's 1990 GT - Parts Gathering Purgatory & Home Remodel

ustacould said:

Yeah, that #7 plug wire would keep me awake at night too ...

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nicholase said:

1)Was the plug wire on but not all the way? If that's the case it probably was firing. You were just hearing the snapping of the spark jumping from the plug wire end to the spark plug.

2)If it wasn't on at all, then the snapping you heard was the spark jumping to the block or whatever was close to the dangling wire end. If this is the case it should have felt like a dead miss.

Either way I doubt anything was damaged. Possible a fouled plug. Pull your dip stick and smell it. If it smells like fuel change it.

But if 2) is what happened I'd be concerned as to why it felt the same as always.

I'd focus on the #7 plug issue and tackle that before doing anything else. Unless I missed more tests (I might have) you just did a compression test on the one cylinder?

What i would do is pull all the plugs to do your test. The engine spins faster that way becasue it has almost no resistance. Your results will be consistent then for all of them. Looking at a single data point with all the other plugs in doesn't really tell much. Do a thorough work up of the tests and results and get to the bottom of it.

Try this, charge the battery well. Pull all plugs. Pull FP relay. Block throttle open.
-photo all plugs on a peice of paper w/ cylinder #'s by them for future refrence like you did earlier.
-compression test all cylinders. Get a remote starter button to make it easier. It goes on the starter solenoid https://shop.advanceautoparts.com/remote-starter-switch-
-Do the dry test. Count how many times it pulses and try to do the same for all of them. Remember your not trying to get the highest number for each cylinder. You want to see how consistent they are across the board. So if you do 6 pulses for one, do 6 for all. Pay attention to how they build on the guage. A big jump on the first pulse is a good sign. If one has equal numbers but jumps up in small increments that can spot a problem too. So compare the numbers, as well as how they got there. So mentally track the first pulse for each and write that down as well the final number.
-go right into the wet compression test for all cylinders and write that number down. This will answer the second question helpers will have if one is low. A 5ml syringe and a length of tubing work well. Use the syringe to measure 5ml, then put the tubing on and stick it in the spark plug hole to squirt it in.
*you don't necessarily  have to do the wet test for all of them. I would, but thats just me. At least do any that look 10% lower than the highest dry test number.

My suggestion is to do the dry test on all cylinders first. You may want to come back and retest a few. If you do a dry / wet test cylinder by cylinder then you really can't go back and get a good dry test again.

Now we have some info to work with.


I remember you posted some images from a borescope. This valve looks suspect to me. Images form those things can sometimes be deceiving, but I'd grab some more. What does the group think of this valve? Looks like a hamburger. Maybe its just a weird reflection though.



Best case for you is a valve problem becasue you just happen to have a nice new shiny set of heads on the shelf

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nicholase said:

Yeah, life gets busy. When you get time dive in. That house "remodel" looks more like a new house build lol. It will be worth it when its done, the house and the car.

Still curious what others think about your valve picture.

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nicholase said:

Looks funky for sure.

The dots on the pistons face to the front. If it's cyl7 its on the passenger side. On the passenger side the exhaust ports are to the front. In the picture it looks like it's the valve over the dots to the front. So to the best of my knowledge its an exhaust valve.

Does it puff out blue-ish smoke when you cold start it? Usually a bad valve seal will smoke more at startup.

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