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I have now assembled my engine to find that as a result of the block being skimmed over the years, the pistons stand a smidgen proud and strike the head without the gasket in place. Allowing for flex in the crankshaft when in use, I am concerned that the pistons will still hit the head when the engine is in use.
It is a long shot, but does anyone have a block shim spare which they would be willing to sell?
Regards,
Jamie.
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Location: West Yorkshire
Car type: Type 65 1934 + RP 1932
John Barlow had some a couple of years ago.
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Location: Scotchland
I bought a number from David Cochrane earlier this year.
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Location: North Yorkshire
I have one from David Cochrane as well. Solved the same problem for me.
Steve
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I could try John Barlow: thank you. Thank you for the suggestion of David Cochrane, but they are out of stock on David's website, sadly.
Jamie
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Location: Scotchland
Maybe I bought the last of the stock - email me on dunford1@aol.com if John cannot supply you.
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Thank you, Ruairidh.
I have e-mailed John. I shall let you know what he says.
Kind regards,
Jamie.
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Location: Darkest Bedfordshire
How much of a smidgeon Jamie?
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03-06-2021, 11:54 PM
(This post was last modified: 03-06-2021, 11:57 PM by Jamie.)
Chris: it is a little less than the thickness of the head gasket as the pistons clear the head with the gasket in place, but I shall measure the protrusion in the morning.
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Location: Darkest Bedfordshire
04-06-2021, 08:39 AM
(This post was last modified: 04-06-2021, 10:30 AM by Chris KC.)
Just my personal view Jamie, but rather than have pistons protrude from the block I'd have their crowns skimmed, there's easily scope to remove 10 or 20 thou from a "Seven Workshop" piston. On a 3-bearing engine I'd run them flush with the block, on a 2-bearing I'd allow another 10 or 20 thou for crank whip (e.g. if you miss a gear at speed).
An alloy shim plate is a neat solution, but if unavailable I have in the past doubled-up paper gaskets to get a bit more thickness. It didn't leak any worse than any other arrangement I've tried. Typical paper gaskets compress to around 15 thou thickness in use.
On my 3-bearing engines (with Reliant con rods) I use rather more substantial spacers i.e. 1/8" or so. These are hand-made from sheet aluminium, I think it would be tricky in anything less than 1mm thickness. Keep in mind when inserting spacers you need to watch out for pistons hitting the deck at bottom of stroke too.
