No compression

Re built cylinder heads after overheating issues. All went back together ok and no more overheating.
The engine will not run very smooth and misfires. After checking the usual electric bits I done a compression test. Right hand bank perfect with 165psi on all cylinders. Left hand bank has no compression or very little in all cylinders.
Could this be that the valves are not closing? Lifters stuck open?
Or if the cylinder head has been skimmed beyond its limits would this cause the whole rocker assembly to be out of spec?

Any thoughts?

Is that the gas flowed head? Because if it is it had probably already been skimmed to raise the CR and you had it skimmed more which may have fecked it completely as in push rods now too long to allow the valves to close completely.

Think i mentioned early on in this saga it is not a good idea to have a high compression bank and a low compression bank for a start, it will never run properly if you have that. You may have to fashion spacers to go under the rocker shaft to raise it up and give the tappets a chance to work. Lots of things can build up to cause this, over skimming, valve seats cut too deep Etc. If the head has been played with then i would think that maybe the case.

Datatek said:

Is that the gas flowed head? Because if it is it had probably already been skimmed to raise the CR and you had it skimmed more which may have fecked it completely as in push rods now too long to allow the valves to close completely.

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This is the side with the gas flowed head. I just wish I had gone with my gut feeling and put 2 new heads on. I did question the chap who rebuilt the heads for me if they would be ok. He said they would be ok.
I going to start stripping it down again!

It was folly to rebuild with unbalanced heads.

V8 Vouge said:

This is the side with the gas flowed head. I just wish I had gone with my gut feeling and put 2 new heads on. I did question the chap who rebuilt the heads for me if they would be ok. He said they would be ok.
I going to start stripping it down again!

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You asked questions, you were given advice, you ignored it. There are people on here giving advice that don't know their arse from their elbow. There are just a few who really do know what they are on about, you should learn to listen.

wammers said:

You asked questions, you were given advice, you ignored it. There are people on here giving advice that don't know their arse from their elbow. There are just a few who really do know what they are on about, you should learn to listen.

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Well I will deffinatelty learn from this. Thanks for everyone's help.
I'm going to start looking for a new pair of heads.

What is a high compression bank and what is a low compression bank? Do you need to perform compression test to know this?

Yep - or if you're quite handy with a vernier/micrometer you could measure it to tell the difference....

Also they have different part numbers no doubt stamped somewhere - visually I believe they are identical

qwertz said:

What is a high compression bank and what is a low compression bank? Do you need to perform compression test to know this?

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It is about the volume of the combustion spaces. If the head is over skimmed the combustion space is less therefore the compression ratio is higher. For instance if you had a diesel head skimmed you would fit a thicker head gasket. In this case possibly the head has been over skimmed and the valve seats cut so deep there is no room for the tappets to expand and they are binding on the back of the cam shaft.

heads should be identical ,there is a post/spot cast into combustion chamber in head you measure depth of this from head face ,both heads should be the same within a few thou , the difference between high and low compression engines is done by the pistons ,if you alter by skimming one head you should do both

Thank you!