rjb2968 Posted December 28, 2020 Report Share Posted December 28, 2020 Hi, I'm looking for the exact car(s) that people source the pistons from for a 77-78 mm overbore in the TR6. Also any insight to the modifications to the wristpins or pistons themselves. Please no generic answers such as "mazda or VW" as there are 100's of models to choose from. I'd like to know the exact car so I can order a set. Quote Link to post Share on other sites
TriumphV8 Posted December 28, 2020 Report Share Posted December 28, 2020 VW Polo BBY engine in 76.5 or 77mm. Piston mußt be opened up 4mm to accept rod. Rod needs custom small end bearing in 19mm. Quote Link to post Share on other sites
JochemsTR Posted December 28, 2020 Report Share Posted December 28, 2020 (edited) The aforementioned pistons have a 16,99 mm piston pin. In lieu of opening up piston, narrowing the rod head is also possible. Jochem Edited December 28, 2020 by JochemsTR Quote Link to post Share on other sites
TriumphV8 Posted December 28, 2020 Report Share Posted December 28, 2020 Yes, it was 17! 19 was the Mazda Piston. Here ist a picture of the 6 small ends, ready to bei pressed into the Maxspeedingrod. Quote Link to post Share on other sites
jr2 Posted December 31, 2020 Report Share Posted December 31, 2020 Do you have to use On 12/28/2020 at 9:49 AM, TriumphV8 said: VW Polo BBY engine in 76.5 or 77mm. Do you have to run custom cylinder head gasket? If so then using Polo pistons is only for early engine block - no recessed groove? Quote Link to post Share on other sites
Dave McDonald Posted December 31, 2020 Report Share Posted December 31, 2020 On 12/28/2020 at 3:53 PM, rjb2968 said: Hi, I'm looking for the exact car(s) that people source the pistons from for a 77-78 mm overbore in the TR6. Also any insight to the modifications to the wristpins or pistons themselves. Please no generic answers such as "mazda or VW" as there are 100's of models to choose from. I'd like to know the exact car so I can order a set. 78mm forged pistons (give 2725 cc capacity) are available for the TR5/6 engine from JE Pistons in USA with their UK Agents, Cambridge Motorsport Parts, John Savage, 01462 684300. Also I believe Omega Pistons, Halesowen, 0121 559 6778. Also try Racetorations, Gainsborough, Daryl Upritchard, 01427 616565. 1 hour ago, jr2 said: Do you have to use Do you have to run custom cylinder head gasket? If so then using Polo pistons is only for early engine block - no recessed groove? Yes you do have to use a custom head gasket, only available in UK from Racetorations as above. If you have a recessed block just have the top of the block skimmed to remove it, there's enough depth. There is a source in the USA, Wishbone Classics. I've used them in the past with significant cost savings, even taking the freight and import duty costs into account. However, I believe they have had trading problems in the last couple of years, so approach with caution. Dave McD Quote Link to post Share on other sites
TriumphV8 Posted January 1, 2021 Report Share Posted January 1, 2021 First the recess is not good. Although some say with 76,5 it will work, I would aim for a block without recess or mill it off. About 0.7mm may be enough to get rid of the recess. Two sources from me for the gasket: https://www.elmeso-reban.de/ and I used the cheap noname silver gasket from Rimmer. The Payen is made too precise in diametre and can not be used for larger bores. Quote Link to post Share on other sites
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