SPITFIRE MK2 1147CC OVERSIZED PISTONS

[oliproctor]

Hello all,

I am just doing some research on new oversized pistons for my 1965 1147cc Spitfire engine which is currently at the machine shop being inspected and measured up. It currently has .030 oversized bores and will need to go to either .040 or .060 (depending on how the inspection goes this week).

I found this an incredibly helpful comparison between NOS and aftermarket pistons (http://www.wbclassics.com/tech/tr6/engine/triumph-tr6-cast-piston-comparison). My engine builder is old school and specifically asked me to find NOS pistons if I could and didn't like the quality of County, although I know their quality has dramatically increased over the last few decades (and possibly even overtaken AE).

I was wondering if anyone has a set of NOS .040 or .060 pistons so I can compare prices and see what the engine builder would prefer to use? I'm based in North Yorkshire and learning as much as I can, being in my early twenties, from those who have been engine rebuilding for decades so just want to see whats out there before I go in head first!

It seems like NOS valves, tappets, rings seem to be a little easier to find which is good. Are these considered the best quality or is there an aftermarket supplier in the UK thats best to buy these engine overhaul components from?

Have a look at my car on my profile, I did all the bodywork over university summer holidays a few years ago but now I'm on with a full mechanical/chassis/suspension rebuild during the COVID lockdown!

Many thanks,
Oli

[Clive]

County seem to supply Grant rings, or have with the ones I have had. But rings are normally supplied with pistons.

NOS piston sets turn up on ebay and there are a few specialists who sell NOS components. David King...(something, which eludes me)  and Mick Dolphin.

Of more concern than pistons are the bearings. If possible I would try to find vandervell (though they are VERY hard to find now) or failing that Glacier or other "proper" brand. Failing that County bearings are easily available, but having tried their trimetal/hd variety I don't think they are better than the tin/ali variety.

VAlves, usually reusing the existing is OK, but again, proper stanpart would be fine, or let your engine builder source them. I assume you are having hardened exhaust valve seats fitted? Madness not to. 

By tappets, do you mean rocker arms or cam followers? If cam followers, Newman cams sell quality versions. 

I recently had an engine rebored, and I am happy to use the county pistons the machine shop supplied. And I intend using county bearings. (this is a dolly slant engine)

[oliproctor]

Hi clive,

Thanks for all the info. I'll call Mick and Dave tomorrow to see what they have. Seems like I may have found some Vandervell bearing but just need to know sizes after the engine inspection this week.

Thanks!

[Nick Jones]

In my experience (not with 1147), County pistons are at least as good as the OE ones and the Grant ring packs they come with are probably better.

Clive is right about the bearings.

[oliproctor]

County don't seem to have direct website. Where is the best supplier to buy from please? Thanks

 

[Colin Lindsay]

I bought mine from James Paddock; good price compared to the 'bigger' suppliers and more importantly people you can talk to for advice.

[DanMi]

If looking for old stock pistons beware of the ones with the split skirts, ie an extra oil control ring below the gudgeon pin, these should be ok in a lower powered Herald but I wouldn't put them in a spit.

I put the King HD bearing in mine and fine 3 years on (though low mileage)

[oliproctor]

I'll give James Paddock a call and see what they say. Thanks!

[DippedHeadlights]

I've got a later 1147 engine (GA210983) in my shed that was previously "fully rebuilt" Head is on so I can't measure bores but looking with an endoscope I see the bores nicely honed and new pistons with no markings on except the number 70.  I assume that's 70 thou?  Seems quite a lot?  I've only seen up to 60 before. Or could they be American as I think 1147cc is 70 cubic inches 

[Colin Lindsay]

70 thou is a lot... most of the suppliers seem to stop at +60. 

[PeteH]

I`ve never heard of anything above +60 either?. I suspect many Bore`s wouldnt tolerate being machined beyond that?. Casting tolerances being what they where back when, there is a potential issue with breaching the cooling spaces?. I know some Engines (many Marine one`s) which had separate liners, could be relinered back to O/E spec;

 

Pete

[DippedHeadlights]

Yes, I was surprised, here is a pic. Clearly new pistons (all bores the same) and rebored or at least honed. It's a GA 1147 so a bit more space than a 1296.  Maybe 70 means something else?