Questions relating to cylinder head removal

[doffo25]

Hi Guys

My 1972 US import roadster (60K miles) has low (110psi) but consistent compression across all cylinders so Im removing head to take a look and a few questions have arisen.....

1/ Ive made up tool to release tension on timing chain. Can I release tension enough to slip sprocket onto bracket (retained by retaining tool) and then release tension and remove tools? Or do I need to release tension fully to lock tensioner in unlocked position? In the latter situation.... is there not a chance that the loose chain might slip a link position at the bottom?

2/The cam looks good except from the white marking on the lobes. It is just colouration and not pitting. What is this?

3/My head domed nuts are smaller that 3/4 AF and a socket won't fit squarely on them as it fouls with the tappet block. Should I remove tappet block?

4/ I was thinking of buying a head puller tool. Assuming this heads never been off what are chances of easy head removal without one?!!

5/ Can I retain studs and nuts to reuse if they appear OK?

Apologies...Im being bit greedy.

regards

David

[MarekH]

Dear David,

1/ I'd put as little strain on the tensioner as possible. When you hook it up to untension the chain (as per the manual), you are pulling the tensioner flat and putting maximum tension into it. That's a bad thing to do to a piece of plastic. My preferred technique is to stick my hand down the A-bank with a 12" ruler and push on the chain and tensioner just enough to pull the A-sprocket off of the end of the camshaft. There is no chance whatsoever of jumping a tooth at the crank.
2/No idea from just a rough description.
3/Get a socket onto it. For the corner bit at timing chain end, either slice the socket up a bit to make a special tool that fits or purchase some crow's feet sockets. These off-set the socket head and are angled such that turning them over repeatedly allows you to always turn 1/12 of a turn.
4/No idea. I think I've lent mine to someone on this list, so you might get an offer of help from there.
5/As you like it. Removing studs and liners isn't fun.

kind regards
Marek

[doffo25]

Thank you Marek...very much appreciated.

Is this any clearer re marks on lobes?

Regarding cylinder liners.....do I really need a tool to prevent the liners moving on a 53 year old engine?

best

David

[MarekH]

Dear David,

I still don't know what those marks are, but they won't affect how the cam lobes work. If it's stain or residue of some sorts, try polishing a bit off. If it's where a bit of metal is missing, then worry what the other rotating parts look like. The crank may or may not look the same.

Scribe all of the cam caps with location identifiers before you remove them. In fact, measure your valve clearances before taking the camshafts off. It may give you some useful information for later, even if that is just "what shims do I want to put back here?".

Since the pistons move freely, it is unlikely they'll dislodge a liner.

kind regards
Marek

[doffo25]

Thank you Marek you have helped me enormously!!

best

David

[MarekH]

The more of it you take apart, the more expensive it'll be to put back together. 110psi is about 7.5 bar according to my bicycle track pump, so what is "low" about the low compression? If the engine number has an "L" in it then the US spec would be 7.8:1 iirc.

kind regards
Marek

[doffo25]

Marek...my engine IS an "L" 7.8:1......arę you saying that these test results may be normal for this old engine?

A. 95 95 87 95 93 100

B 110 112 115 115 108 110

Would you recommend 20thou off the head to spice it up a bit?

David

[MarekH]

Measure your valve timing first.

There might be a simple reason why one bank is different from the other, e.g. one camshaft isn't at the same angle (at cylinder 1A TDC) as the other. There is nothing unusual about the intra-bank variation. Your main question ought to be "why is A consistently lower than B?". Use the cam timing tool to check where the cams are when cylinder 1A is at TDC.

Your engine is a flat head, so skimming will not "spice it up". The compression ratio number is from how dished the pistons are and how thick the head gasket is, not from the heads. (The opposite is true for an HE engine, where the pistons are flat topped and the heads have the combustion volume.)

kind regards
Marek

EDIT:- If your cams turn out to now be subtly mismatched to each other, take a look at https://www.jag-lovers.org/snaps/snap_v ... 1381505777 and see whether your timing chain is how worn and stretched.

[doffo25]

Hmmm...interesting.....I did notice that at TDC I can get cam set tool on Bank A but in this position Bank B is couple of degrees out...

However.... its Bank A that appears poorer compression....


I can see that this might affect a running engine but would this couple of degrees out affect a compression test?


David

[doffo25]

Having removed my heads I notice that the coolant level is close to top of the top of block. I drained the system by opening radiator tap. I have previously copiously flushed out system but nevertheless there is thick sludge I can feel around the liners.

If I release a lower hose will that drain this coolant?. Ideally Id like to wash out with hose but that won't work if coolant won't drain.

Any suggestions?!!

David

[chris420sa]

Hi - i found the best way to drain the coolant and (most of) the contaminants is to insert a 1/2" clear tube through the header tank hole amd through the hose on the base of that tank to the base of that hose and siphon out using a hand-held siphon bulb.
Would have been better if you'd done that before head removal so you could also flush the whole system once or twice.
There could still be some build-up in the heater matrix which can be flushed by removing the heater inlet and outlet hoses.
Be sure to refill with 40% by volume Bluecol 2 year anti-freeze but before that check you have the correct thermostats and that they open at the design temperature (quite a lot on that topic on the Forum)..
Best regards
Chris

[doffo25]

Thank you Chris......I found that you cannot drain this coolant from around the liners. I did it by soaking up with rags and hoovering up the sludge. On both banks around cylinders 5 and 6 there was about 40mm of scale grit and sediment. I understand coolant circulation is poor in this area and with that amount of sediment Im amazed I didn't have overheating on those cylinders.

David

[doffo25]

Hi All

On rotating my engine with head removed in order to de-coke, one of the liners popped up an inch. It went back easily enough...

..however...have I broken a seal...or was it never sealed...

Ive read that the compressive force of the cylinder head nuts, with the liners being proud of the block, is enough to seal them dry...

...but then the thought of a coolant leak into the engine....

Has anyone heard of such a leak and what should I do?

regards

David