[Fot] SCCA Archives

[Bill Babcock]

As I understand, the standard TR3 is 83 mm, the TR3B (some) are 86,  
the TR4 is 87, and there are lots of 87.5 MM and 89 mm piston and  
sleeve kits available, in fact they seem to be the prevalent  
replacement. If I were building a street TR3 (which I sort of am) I'd  
use the 89 mm and a mild cam, no head shaving, just a bit of porting.  
It would make a very nice motor.

The block is fine for 89mm liners, if you want to go to the 92mm then  
you need to have the block machined. And yes, those are available. I  
think Gillanders has them, and probably others too.

On Dec 22, 2006, at 8:58 PM, WEmery7451 at aol.com wrote:

> In a message dated 12/22/06 6:40:41 PM Pacific Standard Time,
> jaboruch at netzero.net writes:
>
> << I am using 87mm, but since I am racing SCCA that is the max that  
> is legal
> for EP.  I have a set of custom made Ross 89mm pistons that I used  
> one year
> with SCCA Vintage.  They are nice pistons, but one has a valve  
> stemed size hole
> thru the dome.  Too expensive to have 1 made to fix the set, so  
> they will just
> sit on the shelf till I get tired of looking at them.  Joe(B) >>
>
> I guess that my engine is presently legal since it has the 87 mm  
> Cosworth
> popup pistons.  Down through the years, it seems that most people  
> using the flat
> dome Heppolite pistons were secretly adding on 0.030" or 0.040" to  
> the 87 mm
> pistons.
>
> I have always taken stock liners and a block to my machinist.  He  
> clamps the
> liners into the block, and bores them to the proper size for the  
> pistons.  For
> much larger pistons, I guess that special larger bore liners would  
> have to be
> purchased, and that the liner holes in the block would have to be  
> enlarged.
>
> <>
>
> Isn't this the size of one of the stock pistons?  The TR-3 and TR-4  
> manuals
> list a few different sizes of pistons, from the earliest to the  
> latest.