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MG TD TF 1500 - fly cutting the block for valve clearance

I need to fly cut a XPAG banana hole block .045" for the exhaust valve clearance, add an additional .060" for insurance = .105"
(High lift cam, & a cylinder head that has been milled to the limit.)
Has any one done this, what would the maximum depth be?
Len Fanelli

Len,

Does this mean youire going to put the valve gude off-centre? Wat about rockers? off centre too?

Gord
Gord Clark

Len,
When tuning Morris Minors, and a 1275cc head is fitted on the 1098cc Morris Minor block, there can be an issue with valve and block collision. The done thing is to sink the valves rather than fly cut the block. I have done it on mine.
Maybe this would work in your case as it is a lot easier than pocketing the block.

Regards
Declan
D Burns

Hi Len, here is a picture of milled XPAG block. The race engine is long gone to a new home so I do not have any dimensions.
Cheers, Hugh

H.D. Pite

Since the valves are Over the Pistons, won't you also need to mill the Pistons also?


Jim B
Jim B in NJ

Gord, no. Declan, thanks but no new valves new seats I do not want to drop the valve seat by .105".
Hugh comes through again! Thanks! just what I needed.
Jim, no problem with flat top pistons, the piston is at 108 degrees ATDC when the valve is at full open.
Len Fanelli

Len we fly cut our block for the 236/236 cam. We began by affixing a 40 grit sandpaper disc to the exhaust valve and chucked it in a drill to spin it with the head in place. A long a tedious process. We simply put a dial indicator on the valve and measured the total drop then calculated the total lift at the valve and cut the pocket the differing amount. And added .010 for added clearance Ended up taking it to our machinist to do it it on their mill for consistency. Your total depth will depend on your head gasket thickness

Cheers

Bill Chasser jr
TD4834
W. A. Chasser Jr

Pic of our block

W. A. Chasser Jr

This thread was discussed between 29/08/2015 and 31/08/2015

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