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Discussion Starter · #1 ·
Hi all,

Never was any good at IQ tests that included engineering type tests so I really need to pick someone's brain on this.

Rebuilt my '72 650 engine with .020, 9:1 pistons. The head was shaved .004". I do not know the previous history on the head, viz, whether a previous owner had the head shaved also.

Achieved .060" sqeeze on the PRTs using the the smallest thickness neoprene seal, and a standard .040" copper gasket.

I am really wondering whether any of these changes from standard are likely to alter the piston:valve clearance. I am guessing it would not make any appreciable difference, but like I said, I'm a dunce when trying to work these things out. RR
 

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The standard copper head gaskets are .048".
It is very unlikely that your pistons and valves will touch.
See:
http://www.triumphrat.net/classic-vintage-and-veteran/111099-nasty-clicking-sound-on-kickover.html
(page 10:eek:)
The plasticine in the piston recess confirmed I had 1/8" or so clearance, but I had fitted a .070" `extra thick` gasket. (There`s reasons for using this gasket, 9.5:1 pistons, etc).
This was a rather extreme situation, I think.
Refurbished head with new valves and seats, new barrels and pistons and no idea how much had been skimmed off.
 

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Discussion Starter · #4 ·
Hi guys,

It occurred to my non-mechanical brain last night, that this is most probably more of an issue where vavle timing and lift are changed.

I am a worry wart for sure, but we all know these Triumphs have a capacity to let us have it in the neck if we drop our guard. Thanks again. RR
 
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