Triumph Repair: Compression Problem 80 Spitfire, high performance engines, valve job

Question
Jim,

If I am not making any since it's because I am banging my head against the wall.  After I had the valve job done and new rings and bearings still 50 lbs. in #1 cyl.  Pulled the engine took it back apart, head sent back to shop and vacuum checked, block measured and magnafluxed for cracks, pistons checked, everything checked great. Put everything back together and still 50 lbs. in #1.  The only thing that changed before this problem is I put a Weber downdraft in place of the Stromberg.  We are thinking of putting the Stromberg back on to see if that changes anything but I don't think that could be effecting the compression (could it?).  You asked for the number of the block and head before, the block is FM132740UCE and the head is KC1410, that is the only number I can find.  The shop that is doing this is very good and specializes in rebuilding high performance engines especially the old muscle cars.  This is about to drive them crazy because this is not the most complicated of engines.   It's got to be escaping some where. I have looked back and I don't see where anyone has had this problem, it has got to be something simple that we are overlooking. Any other suggestions?

Thanks again,

Dan
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The text above is a follow-up to ...

-----Question-----
Jim,

Yes -Did both tests and it has std. size pistons and cylinders.  We are double checking the gasket now.  It does have the metal rings around each cylinders witch we thought was questionable but why just one cylinder and not all?  Just trying not to have pull the engine and replace sleeves.  I was just hoping it was something simple we are over looking.  Thanks again.

Dan
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Followup To

Question -
Jim,

Thanks for the quick reply...yes, we have double checked the valves.  The machine shop that did the work is one of the best and they did all the presure checks before retuning the head and we checked again also.  We pumped the cylinders up and swoped the springs the see if was a weak spring.  We pumped the clynder up to see if it was losing preasure and it was but thay all were.  It really sounds like the sleeve is warped.  I just can't believe it would happen that quickly.  The only time my mechanics have really seen it is in alluminum blocks.

Thanks again,

Dan
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Followup To

Question -
Jim,

I bought a 1980 Spitfire that sat in a warehouse for 8 yrs.  It is in great shape, no rust, good paint, very well taken care of except for sitting last 8 yrs.  Got it started and it was running well except for running very rich.  All of a sudden it started running rough, like it was running on 3.5 cylinders.  Checked the compression and all the cylinders were 125 - 130 except no 1 was 50 lbs.  Pulled the heads and had a valve job and while I had the head off put new rings in.  Put everything back together with all new gaskets and still only have 50 lbs. in #1.  We have done leak down tests on the valves and cylinder and checks OK.  Getting ready to measure the cylinders to see if warped (waiting on mic that was ordered).  I don't see any other problems in the subject history of anyone with warped or oblong cylinders.  Do you have any suggestions or have seen this before?  Thanks for the help.

Dan

Answer -
Dan,

Two thoughts.  One is that it is possible that the cylinder is ovalled.... that's why it's not sealing.  

Another thought is to check the valve train and make sure the #1 valves are opening and closing fully.  After sitting for a while it's possible that a lifter might be stuck.


Cheers,

Jim

Answer -
Dan,

Did you try a wet compression test, or only dry?

And what size pistons are in the block?  Std or oversize?

And I have heard of people being given the wrong head gasket, the correct one for the 1500 has an "0-ring" of extra metal that sits in the cutouts in the block top.  If the headgasket doesn't have those then you likely just blew the gasket.



Cheers,

Jim
-----Answer-----
Dan,

There aren't "sleeves" in the Spitfire block, it's all one casting.  The depression in the block deck was machined by the factory to allow the head gasket metal ring to act as an "o-ring".

One thing to do would be to pull the head and look for evidence of blow-by from #1 along the head gasket.  If you don't see it there... then you're either not sealing with the rings or the valves aren't seating correctly.

One thing.... you've seen the head and all the valves are seating evenly?  Triumph did use several different size valves over the production run of the 1500, so it wouldn't be a big surprise if they got mixed up at the part supplier.

BTW, what's the block # and the head part # (stamped on the top flat near either the front or back end of the head).


Cheers,

Jim

Answer
Dan,

All I can suggest is doing a tear down to check the cam.

If you're not getting good compression #s it means one of the following:

1)  Head gasket not sealing
2)  Valves not sealing correctly.  This can be the valves themselves or the valve lash
3)  Rings not sealing
4)  Valve train problem (valve, lash, bent push rod, damaged cam)
5)  cracks in either the block or head
6)  blockage in the intake system.

It seems straightforward, but sometimes it can be the craziest thing.  With what you've done already I'd lean towards some sort of problem with the valve train (valve lash, pushrods, worn rocker bushings, bad cam) as it's about the only thing left.

If you do manage to find the cause, please do let me know.


Cheers,

Jim