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Piston Sizing
#5
Tony

Knowing who will have likely bored it, It'll be imperial.

I'll clearly have to mic it, and once I know that made a decision as to which way to go.

Not having done this sort of thing before (in my other hobby where cylinders are irreplaceable we take minimum bore to clean, then make the pistons, rings etc to suit) Just been measuring various unused piston sets in stock. Via vernier not mic. And have therefore believe I have learnt that pistons are undersize vs nominal bore plus the oversize. Some +40 Heptolites are 'broadly' 2.225 . Some +30 Wellworthy 'broadly' 2.218. Incidentally I did a course check on he vernier my measuring the bore of the GE cup engine (standard pistons) and the vernier is in the right ballpark.  So Bore 'should' be 2.2 + whatever oversize. ID?. We shall see.

Chris

Starting the car is troublesome, better now with a recent battery, but when the old one went off the boil is was a worry as it wont go on the handle. 

Basically the compression is well down, and I was always taught oil leaking passed the spark plugs was bad news on an Austin. I've also had to go up a heat range on the plugs to keep them from fouling to quick, which makes the starting worse. Its a H/C head.

Sooner or later the oil in the water will become water in the oil, and I don't want it buggering up what is a pretty fresh bottom end.

I have identified the oil leak that I have been chasing is block to case, so its got to come off. The way I see it the block is either glazed, or the rings have lost their spring (or both). There is a flatness issue between the block and head somewhere, possibly also block to case. I know this block/case combinationhas suffered 2 broken cranks, so who knows what I might find when I take the block off. I have a block to do a transplant, I have plenty of cases to do the bottom end if need be. But this block is not going back on if its coming off.

Car is booked in to Audlem at the end of the month so it will be going there with wife at the helm. At some point beyond that its coming to bits.
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Messages In This Thread
Piston Sizing - by Hedd_Jones - 13-07-2021, 11:48 PM
RE: Piston Sizing - by JonE - 14-07-2021, 08:05 AM
RE: Piston Sizing - by Chris KC - 14-07-2021, 09:21 AM
RE: Piston Sizing - by Tony Betts - 14-07-2021, 12:05 PM
RE: Piston Sizing - by Hedd_Jones - 14-07-2021, 01:57 PM
RE: Piston Sizing - by Chris KC - 14-07-2021, 03:53 PM
RE: Piston Sizing - by John Cornforth - 14-07-2021, 05:13 PM
RE: Piston Sizing - by Howard Wright - 14-07-2021, 05:31 PM
RE: Piston Sizing - by Hedd_Jones - 14-07-2021, 05:50 PM
RE: Piston Sizing - by Bob Culver - 14-07-2021, 08:30 PM
RE: Piston Sizing - by Hedd_Jones - 14-07-2021, 08:32 PM
RE: Piston Sizing - by Bob Culver - 14-07-2021, 08:54 PM
RE: Piston Sizing - by Chris KC - 15-07-2021, 08:11 AM
RE: Piston Sizing - by Ivor Hawkins - 15-07-2021, 09:28 AM
RE: Piston Sizing - by Hedd_Jones - 15-07-2021, 10:48 AM
RE: Piston Sizing - by JonE - 15-07-2021, 11:45 AM
RE: Piston Sizing - by Chris KC - 15-07-2021, 11:58 AM
RE: Piston Sizing - by Bob Culver - 15-07-2021, 12:00 PM
RE: Piston Sizing - by Chris Garner - 15-07-2021, 12:25 PM
RE: Piston Sizing - by JonE - 15-07-2021, 01:08 PM
RE: Piston Sizing - by Michael D - 15-07-2021, 01:08 PM
RE: Piston Sizing - by JonE - 20-07-2021, 10:35 AM
RE: Piston Sizing - by GaryCullen - 20-07-2021, 10:09 PM
RE: Piston Sizing - by Bob Culver - 20-07-2021, 11:55 PM

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