6.9 head removal

[koan]

Oh God, I thought I was over the hump. I had a feeling the servo was going to be a pain; worse than the EGR?

Hmm... you asked for tips and I gave you a future headache, sorry.

Anyway other folks say it's not that difficult so maybe I made it hard or it's my aversion to working under the dash.

By the bye, is the lower comp acheived by head or the concave pistons I can now see?

Yes, it's all in the pistons, there's a table in the m100 engine manual giving piston numbers for various compression ratios. While you have the heads off it might be worth recording the piston and bore sizes/grades just in case.

Here's a picture of a +1 bore (stamp in block at top) and +1 piston.



koan

[Big_Richard]

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[TJ 450]

The 1+ is denoting the tolerance for the standard piston, ie there are certain classes.

You can only use 1+ pistons with a 1+ bore, and there can be pistons of differing tolerance used in the one engine.

Oversize pistons don't have a specific tolerance class system, so it's up to the machinist to work out the suitable bore size.

Tim

[koan]

My m100 manual is on loan so I can't dig out the details but I seem to recall there are several tolereance classes in the standard bore, 0 0+, 1, 1+, 2 and 2+. The differences are minute.

My engine is has "1+" bore and pistons in right bank but "1" on left bank with matching pistons except for #8 which is a "1+"in a "1" bore.

koan

[Big_Richard]

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[TJ 450]

Indeed, you're correct MT.

A 1+ in a 1 bore? they must not have been satisfied with the clearances.

Tim

[koan]

A 1+ in a 1 bore? they must not have been satisfied with the clearances.

Or it was 4PM Friday my engine was built.

koan

[Big_Richard]

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[WGB]

Not only were the 6.9 engines hand built but they were all run and tested before fitting weren't they?

Bill

[Big_Richard]

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[WGB]

Probably about the same number that seems to be the usual discrepancy between the VIN and engine numbers.

Bill

[dburkitt]

I little update for those of you kind enough to help.

Being totally fed up with removing things, I studdied what might be required to NOT take off the servo. I have a fair collection of extentions and UJs, so, with the help of a friend, we set to work. And bugger me with a fish fork if we didn't succeed. Took the cam and carrier off bar the back bearing which had to stay put as the head bolt wouldn't clear the servo, but this came with the head. So, both heads off now and ready for checking and the removal of a couple of studs. Just for the record, I had no loose bolts at all, and all came out with a satisfying "crack".

Now I just need to order the gaskets and some coloured vacuum pipe, Ken, do you have a list of the colours required by length?

DB

[koan]

Well done on the head removal with booster in place.

So you removed the cam which I thought you didn't want to do?

The vacuum lines, can't find the list of colours, maybe I have a hard copy somewhere which never made it to computer but it doesn't matter, I have the original bags with part numbers and colours on them. I ordered the lines from one of the US suppliers, European Parts Specialists in California. His web catalog has been taken down but still in business, the vac lines weren't in the catalog anyway, had to be done by email.

I have a scan of the vacuum set up with lengths scribbled on which I'll get to you.

Also need some right angle elbows, two, three and four way bits.

koan