Leyland Car Owners - Referrence point of Vee

From Laurie.
: Date: Wed, 31 Mar 2004
: Mick (Chadwick)
: That was an excellent articile on manifold leaks, had a few problems over the years with them.
: One of the sources of major problems is the heads/ block having been machined at some time in its life.
: This means the manifold does not sit down in the Vee to the correct depth.
: Does any one know some sort of reference measurement to check here?
: Lots of heads are now floating around that have been converted to LPG compression.
: regards,
: Laurie.

From: "Mike Chadwick"

: Date: Wed, 31 Mar 2004

: Laurie,
: Thanks for the positive comment on my article.

: I'm curious about heads that have been skimmed to give "LPG compression."
: How much is taken off? If it is too much, the inlet manifold gaskets will have to be hand made to suit the new valley measurements, and the inlet manifold itself will need to be skimmed along the flanges to reduce the width.
: That is a point of 'no-return', in that the manifold will only be usable with those heads or heads of similar dimensions. Make sure head bolts don't bottom in the block. I would suggest a machine shop of good repute to do the latter for you, and he will find his own dimensions.
: So far as the manifold gasket is concerned, it might be possible (i.e. to find the size) to cut an old gasket into two pieces down the length of the valley, and then putting the two flange parts in situ and measuring the overlap in the middle.
: The amount of overlap is the amount by which the valley panel should be reduced. It might only be minimal (I've never
: done it),but if you want a proper fit, it might be necessary to go to this extreme.

: My position is previously given: Keep the engines as standard as possible for LPG, especially as I'm told that the percentage of butane to propane is becoming greater, effectively reducing the octane rating of LPG, which reduces with LPG at higher rpm because of increased turbulence.
: I know from experience, a P76 V8 can ping on LPG if the circumstances aren't right;
: I managed that by fitting a cam grind not suited to the standard inlet manifold.
: It was a valuable and expensive learning experience.

: Mike.

Leyland P76 Owners 2004

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Referrence point of Vee - Manifold to Heads

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