Phil C Posted July 10, 2019 Report Share Posted July 10, 2019 Hi, back so soon! Just a question regarding the County Pistons supplied for my Vitesse rebuild. They have no arrow on the crown indicating which way round they should be installed. The supplier (a nationally respected engine builder/refinisher) says that they are symmetrical and can therefore be installed either way round. The old pistons removed prior to re-bore did indicate which way they should be installed so I guess are asymmetrical. I don't recall coming across symmetrical pistons before albeit my experience is predominately motorcycles! Does it matter? Link to comment Share on other sites More sharing options...
Nick Jones Posted July 10, 2019 Report Share Posted July 10, 2019 Presuming that you are talking about Vitesse 2L, the pistons are indeed symmetrical. AFAIK this also applies to the OE pistons as well even though they do have direction markings. Nick (South Somerset, not very far from Lyme) Link to comment Share on other sites More sharing options...
Phil C Posted July 10, 2019 Author Report Share Posted July 10, 2019 1 hour ago, Nick Jones said: AFAIK this also applies to the OE pistons as well even though they do have direction markings. Yes, I have now measured my old pistons and they are indeed symmetrical but still with direction markings. Perhaps something to do with the thrust side being different/stronger? Having had further discussion today with the supplier, they went back to County Pistons who confirm the pistons can be installed either way round but should all be installed the same way as defined by any markings on the crown - in my case +.020". Nick - how far from Lyme?? Link to comment Share on other sites More sharing options...
rogerguzzi Posted July 10, 2019 Report Share Posted July 10, 2019 1 hour ago, Nick Jones said: Presuming that you are talking about Vitesse 2L, the pistons are indeed symmetrical. AFAIK this also applies to the OE pistons as well even though they do have direction markings. Nick (South Somerset, not very far from Lyme) Hello Nick Why I wonder would the factory have done that? Roger ps been messing with the EFI settings today!!!!!(I am a B****er for tinkering!) I have altered the throttle balance as front 2 plugs look richer(may be oil pollution?)I can not alter the fuelling so thought add a bit more air? Plus altered the idle settings as Spitty kept ticking over at 1000rpm not the 850 rpm I set it at! Plus I have reduced the advance at 1500/2000rpm as I thought I could hear a rattle(pinking)did that yesterday and seems better? the test will come on Sunday when on a TSSC run we have planned(but only 2 degs so nothing drastic)and in the load area. Roger ps We are missing this! plus these 2 classics Link to comment Share on other sites More sharing options...
johny Posted July 11, 2019 Report Share Posted July 11, 2019 wonder if they marked the piston front so that if they were ever taken out later for new rings and/or bore deglazing its easy to know which way to put them back in. I think once a piston has worn to a position its important it returns there..... Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 11, 2019 Report Share Posted July 11, 2019 Often production marked things to save any confusion on the assy line, and when dropping a piston in you need the big end offset the right way round Some engines do have offset pins and do need a > front marker Pete Link to comment Share on other sites More sharing options...
JohnD Posted July 11, 2019 Report Share Posted July 11, 2019 You may recall that the rear transverse spring was marked on one edge "FRONT" for the same reason, even though it was wholly symmetrical and could be installed either way. J. Link to comment Share on other sites More sharing options...
Nick Jones Posted July 12, 2019 Report Share Posted July 12, 2019 About 20 miles Phil. I’m just south Of South Petherton. I would agree with Pete on the reason for the marking, I found the absence of markings surprising the first time I came across it. Nick 1 Link to comment Share on other sites More sharing options...
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