Miss @ 6

[Anonymous]

Today we did wet/dry hot/cold compression checks hoping to figure out what is wrong with #6. Cold, 1-5 give 175#, wet 205#'s. #6 gives 150# cold, cold and wet, 185#. Hot, 1-5 give 175#, hot and wet 205#. Hot, #6 went to 150#, hot and wet it got 195#.

We also put 40# of compressed air into each cylinder listening for leaks at the carb, exhaust, radiator and valve cover. We do not have the guage to do a proper leakdown test. The only thing we heard or felt was air coming out the valve cover.

Talked this am to the shop that did the rebuild. He said the rings may not have set due to the engine running rich. Also told me to check for a intake leak as I have only 16 inchs of vacuum at idle.

The carb I had on it was running rich so we swaped it last saturday for another 5200. At that time we sandblasted the plugs. This is how they looked today after 200 miles.

Does any of this information help?

If any of you don't know my sad story click here...

http://fordsix.com/forum/viewtopic.php? ... ght=#39170

don

 

[MustangSix]

Looks like #6 is not firing well, but not rich.

Check out your ignition thoroughly. With that much compression, it should be running pretty much the same as the others. Maybe a wire, maybe a bad cap, maybe even a bad plug. But probably just a coincidence that it is the beat up cylinder.

 

[Anonymous]

Ignition was upgraded to duraspark with the gm module, plugs gapped to .45, I was sure that would fix it. 12 volts to coil, I was positive that would fix it. Wires were replaced, again I was sure. Plugs were swapped, now not so sure.

In the short time it took us to warm the engine for the hot compression test the #6 plug came out almost as black as in the picture.

I know it is firing because the engine changes when it is unplugged. Also shocked the snot out of me. My brother said "just don't touch the car when you do it" so I didn't touch the car and it shocked the snot out of me again. Then he said I was standing to close and I fell for that one too.

We are thinking of putting the 170 head on just to make sure it is not the head. I'd put the one on it it came with but I don't have a carb to fit it.

What do you think?

don

 

[addo]

The wet test being 45 pounds higher on # 6 says forget the head as culprit.

Split bore (running hot?), as I mentioned inverted or un-indexed rings, stuck rings, damage to the piston or bore, wrong bore or piston... All are possible. Yes, take the head off. Look for gasket leaks. Rotate the motor and inspect the bore thoroughly. If you see nothing, check it for round. Still no ideas, then you have to pull the oil pan and push the piston/rod out the top. That way you will find the problem for sure.

Adam.

 

[Anonymous]

Thank you gentlemen, "I shall endeavor to perservere."

Josey Wales

don

 

[Anonymous]

Split bore (running hot?), as I mentioned inverted or un-indexed rings, stuck rings, damage to the piston or bore, wrong bore or piston... All are possible. Yes, take the head off. Look for gasket leaks. Rotate the motor and inspect the bore thoroughly. If you see nothing, check it for round. Still no ideas, then you have to pull the oil pan and push the piston/rod out the top. That way you will find the problem for sure.

Adam.

I printed this out, took it to the shop friday, they pulled the piston out today...top compression ring is stuck..bore is fine, valves are fine, he'd have it back together now but they sent the wrong rings with the new piston.

Fingers crossed, should have it back together and FIXED tommorow.

The piston was also really BLACK, the others are a little. He said it seemed to be running a little rich, although the plugs are white. This could be from the first carb which had a stuck choke.

THANKS to all,
don

hmmm, how do you break in one piston?

I'll try to post a pic tonight

 

[addo]

I hope that has fixed the problem.

 

[Anonymous]

Turns out I had two problems. That top compression ring was pinched stuck AND the valve lash needed to be adjusted. The OZ head came with an adjustable rocker arm but it would not work with the pushrods so he swapped it with the non-adjustable one from the big bell. SO with the new piston in the car still had the miss. He backed off the end bolt holding on the rocker assembly a 1/4 turn and the motor smoothed out. He shimed it all the way down with a 1000th or 10,000th shim<not sure which>. Anyway it is now purring like a kitten and I am so happy to have that problem out of the way.

Now should I take the adjustable rocker arm from the 170 or leave well enough alone. The pushrods are rounded on top.

Happy in the swamp,
don

 

[Anonymous]

I now have a new set of ball and cup pushrods. I was going to use the adj rocker assembly from the 170 but now I see the one that came with the 250 OZ head is adjustable. Were all the OZ 2V heads this way or was this added on? Mine also had hardened seats which I know was not original.

Thanks,
Don

 

[addo]

Only the four-mainer 200s had non-adjustable rockers here. Yours from the 2V are likely the originals.