DanielH Posted March 11, 2022 Report Share Posted March 11, 2022 Hi TR6-folks, I've posted my question in the GT6-forum already, but I guess I should ask you guys, since we share the same blocks and pistons :-) I've got new county pistons which miss the datasheet. My machinist is asking for the clearance he should account for when boring the block (GT6, should be identical to TR6). The part number is: CP800K Manufacturer is "County". But I cannot look them up in the internet! The rimmerbros item number is 149976 (https://rimmerbros.com/Item--i-149976020COUNTY) The pistons are 20 thou oversize. My machinist says, that the info in the workshop manual and Vizard might not be valid for that particular brand/make of the piston. I am happy for your input :-) thanks Daniel Quote Link to post Share on other sites
BlueTR3A-5EKT Posted March 11, 2022 Report Share Posted March 11, 2022 Ask Classic and Modern Engine services. I think They were once part of the business that produced County branded stuff. Not now though. As reconditioner and machine shop they will probably use these pistons on a regular basis. http://cmesuk.com/ Quote Link to post Share on other sites
Waldi Posted March 11, 2022 Report Share Posted March 11, 2022 I would ask your supplier (Rimmer), they will have a direct contact with the fabricator. If the design (shape) and metallurgy are the same (more or less), I would follow the WSM. Waldi Quote Link to post Share on other sites
John L Posted March 11, 2022 Report Share Posted March 11, 2022 If you look on the Chris Witor site, https://www.chriswitor.com/proddetail.php?prod=149976-***K, it gives a recommended bore size for the oversize pistons. advise .00225" to .00275" Skirt clearance, In the county box of pistons I bought it did give the recommended skirt clearance. John Quote Link to post Share on other sites
Nigel Triumph Posted March 11, 2022 Report Share Posted March 11, 2022 +1 I bought +20 thou County pistons from Chris Witor for a 2.5 litre saloon engine I built for my GT6 a few years ago. The machinist who rebored the block followed the same clearance spec John mentions above. He also said the 6 pistons were remarkably consistent in their dimensions. The engine runs very well and has so far clocked up about 3,000 trouble free miles. Nigel Quote Link to post Share on other sites
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