dead cylinder

[coupecop]

i just noticed that i have a dead cylinder its the #2 cylinder and also the # 6 cylinder has only 120 compression all the others have 150 or more can some tell me why i would have a dead cylinder also had heads checked there good.

 

[347HO]

How was the cylinder head checked?

When you had the head off, what did that cylinder look like down the hole?

When you put the head back on and you rotate the engine, how's the rocker movement?

 

[coupecop]

i did the compression test with the heads on all the rockers were moving fine then toke them off toke them to a shop and had them checked no bent valves good seals what else should i check.

 

[347HO]

Leak-down more than a compression test.

I'm sure the rockers were moving. How much were they moving? You can take the measurement off the top of the retainer using a dial gage.

So the shop you took the heads to "rolled" every valve on a flatstone? Did they also do a quick alcohol leak test on the seats? Did they check your spring pressures on the nose and on the base? (if you know appx your lift #'s)

You didn't say what your cylinder walls looked like?

 

[coupecop]

they checked every valvls and the lift of the springs are goood up to 600 lift

 

[347HO]

they checked every valvls and the lift of the springs are goood up to 600 lift

Okay... so your valves are GOOD. Good.

What the springs are "good" to is not really what I'm getting to.
Are your springs seat pressures where they are designed for and are the springs also where they're supposed to be at maximum lobe lift? (your camshaft's lobe)

Did the shop say anything about your valve seats? Every cylinder head shop I know... the seat, bowl, and stem angle are the first things they look at.

I doubt your cylinder wall is so bad that ring seal is an issue (or even damaged rings)... but did you notice anything with that?

 

[coupecop]

on cylinder 6 we put oil on it and it sustained compression at 150 so i thing the rings are bad on cylinder #2 there is just no compression and the shop told me that every thing in the heads was OK all they were going to do is clean them up

 

[347HO]

on cylinder 6 we put oil on it and it sustained compression at 150 so i thing the rings are bad on cylinder #2 there is just no compression and the shop told me that every thing in the heads was OK all they were going to do is clean them up

Only one last idea from me and I'm all out bud;
put the cylinder head back on with both valves closed, pressure it up as high as your compressor allows through the sparkplug hole and listen where the air is leaking out.
This is probably moot... since all your evidence points to bad rings.

Hopefully someone has an idea that will isolate the problem better for you!

 

[coupecop]

I'm just going to change the rings