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Head-bolt tightening
David Jenkins - 4/2/05 at 01:08 PM

A simple question... when I rebuilt my x-flow I followed the correct tightening sequence for the head-bolts, and they're now at the full torque.
The manual says that the bolts should be given a final tightening to the full torque after the engine has been run up to full temperature. Does this mean "tighten while hot" or "tighten when it's cooled down again"?

cheers,

David

flak monkey - 4/2/05 at 01:20 PM

AFAIK it means tighten when its cooled again. As heating up then cooling releases stresses and lets everything settle.

Anyway i wouldnt want to be tightening head bolts on a hot engine...

David

David Jenkins - 4/2/05 at 01:34 PM

quote:
Originally posted by flak monkey
AFAIK it means tighten when its cooled again. As heating up then cooling releases stresses and lets everything settle.

That's what I thought... my guess is that heating up compresses the gasket a bit, so the idea is to take up the slack again...
quote:

Anyway i wouldnt want to be tightening head bolts on a hot engine...

Too true - I have to loosen my carb to get the rocker cover off, which is a PITA.

cheers,
David

rusty nuts - 4/2/05 at 07:22 PM

You are also supposed to remove the rocker shaft to retorque xflow head bolts , but if you have a very shallow socket and a thin extension it's possible to do the job without removing shaft. Snap on used to sell a one piece tool for the job, may still have one somewhere. Think you may find you need to torque down head with engine hot and again in about a 1000 miles?

David Jenkins - 4/2/05 at 09:00 PM

I've managed to get at the bolt heads without removing the rocker shaft in the past... I have had to re-adjust the tappets afterwards, of course.
Maybe it's to avoid the risk of bending a rocker or push rod on a badly-adjusted tappet.
DJ

[Edited on 4/2/05 by David Jenkins]