[RedSpecialSS]

I had a miss... can you find it for me?

 

[Beaux]

 

[RedSpecialSS]

also on a serious note, can anyone ID those pistons?

 

[Kim57]

They look like low compresssion truck pistons from the early 90's.

 

[EkS]

So what's the answer?!

 

[BB_Mike]

Cylinder #2. :yes:

So what the hell caused that, was the plug gap set to ZERO. Was the plug connected? Did you clean it and just not tell us.

I concure on the low compression part. I don't even see why they have a valve relief.

 

["Janets Ride"]

Piston looks washed out by coolant, bad head gasket or possibly cracked head?

Rich

 

[RedSpecialSS]

alright I'll give you the guys an answer in approximately 24hrs.

But I'll give you a couple hints. 0psi cylinder compression, and was not a blown head gasket.

EDIT - Also, those saying low compression would you roughtly know what ratio they are? are we talking 8:1? 9:1?

 

[ironhead]

OK..I'll bite.#2 intake pushrod drilled thru the rocker..bound up and held the intake valve off its seat.The cylinder pressure is pumped into the intake and fuel wash on the induction stroke polished the piston top.The #2 primary pipe is too dark for coolant in the cyl IMHO.Do we win anything for the correct answer?lol.

 

[32551]

a real flat cam.

 

[Dave]

Hope you got that battery cable unhooked.

 

[RedSpecialSS]

OK..I'll bite.#2 intake pushrod drilled thru the rocker..bound up and held the intake valve off its seat.The cylinder pressure is pumped into the intake and fuel wash on the induction stroke polished the piston top.The #2 primary pipe is too dark for coolant in the cyl IMHO.Do we win anything for the correct answer?lol.

on the right track there but not the right answer. Concept is there though.

 

[Bowtie-72]

Rod/piston became separated from crank. You can see piston is at top, can see where sparkplug kept firing, matching marks on edge of piston.

 

[RedSpecialSS]

alright, so the story is someone did a valve job on the car and when they did it they ground the seat of the valve down way to much, so the valve was sitting up into the head. Therefore when the rocker was tightened the valve was opened. When you loosened the rocker the valve would fully seat into the head and the compression in the cylinder would go up to 125psi.

Make sense?

 

[Schurkey]

alright, so the story is someone did a valve job on the car and when they did it they ground the seat of the valve down way to much, so the valve was sitting up into the head. Therefore when the rocker was tightened the valve was opened. When you loosened the rocker the valve would fully seat into the head and the compression in the cylinder would go up to 125psi.

Make sense?

Well...no. Not with an adjustable valve train.

That is, yes the seat may be too deep. Yes, the valve tip may therefore be too high. Yes, that would cause valve train geometry issues. But: Back off the rocker adjustment, and it will run. Might be hard on valve guides, though. There's just no reason to crank the rocker adjustment that far down on that valve.

125 is still not enough compression pressure. It will run, but not like it should.

Don't feel bad. I bought a boat with a 454, previously owned by a "Ford Guy". I had 0 compression on ALL 8 'cause the guy had the rocker adjustment cranked too far down. I had the engine running nice in an hour--had to loosen all 16 rockers about a turn.

 

[RedSpecialSS]

the vavle is sitting 3/8" higher then the rest of the valves in the head. Then loosening the rocker enough to get compression left the rocker completely loose and only held on with a couple of threads.

I didnt keep spinning the engine just enough to get a little compression and was happy.

 

[ironhead]

alright, so the story is someone did a valve job on the car and when they did it they ground the seat of the valve down way to much, so the valve was sitting up into the head. Therefore when the rocker was tightened the valve was opened. When you loosened the rocker the valve would fully seat into the head and the compression in the cylinder would go up to 125psi.

Make sense?

Only if the the valve train is factory stacked and rockers bolts torqued.Assuming that there is no pushrod pinch/bind occuring...a stud/nut would have the intake valve seated when zeroing the lash prior to preload.Is this a mechanical cam vs hydraulic and what Gen is the BBC?

 

[ironhead]

the vavle is sitting 3/8" higher then the rest of the valves in the head. Then loosening the rocker enough to get compression left the rocker completely loose and only held on with a couple of threads.

I didnt keep spinning the engine just enough to get a little compression and was happy.

At .375" higher than the rest....that is one seriously recessed valve seat/face or the incorrect valve stem length to begin with.Hopefully your 125 psi will improve..once the fuel wash is eliminated.:thumbsup:

 

[Wolfplace]

alright, so the story is someone did a valve job on the car and when they did it they ground the seat of the valve down way to much, so the valve was sitting up into the head. Therefore when the rocker was tightened the valve was opened. When you loosened the rocker the valve would fully seat into the head and the compression in the cylinder would go up to 125psi.

Make sense?

=
Highly doubtful
I would bet that one of two things happened
The valve recessed into the head because of a soft seat & crap fuel
Or it had a seat installed that came out.

In 40+ years of doing this stuff I have never seen a valve seat intentionally ground .375 into a head,,
Post a picture of the chamber.