PalmettoZ Posted December 18, 2009 Share Posted December 18, 2009 Question for experienced engine builders. I am assemblying my bored out (to 89mm) L28 block with KA24E 2.8cc dish pistons and 133mm L24 rods. I machined the top of the piston down to the flat section of the dish, effectively facing about 1mm off the them to keep them flush with the top of the block. I noted the notch on the tops of the pistons and transfered this notch to the newly machined area at the top after machining. I then cut eyebrows in the tops with a large end mill for valve clearance for both intake and exhaust at 17 degrees for the large cam that I have, an Isky 305 degree .535" lift. I oriented the eyebrows correctly with the notch facing foward on all of the pistons except for the last one (too big of a hurry to get it done). I can't turn this piston around to get the notch to the front and want to just assemble it anyway the way it is and let it go. I know that the notch is so that the offset wristpin all go in the same direction. Has anyone assembled an engine without following this orientation and had problems? I don't plan on racing the engine on a track consistenly, just a weekend driver with occasional runs up to 7000 RPM or so having fun. Quote Link to comment Share on other sites More sharing options...
Xnke Posted December 18, 2009 Share Posted December 18, 2009 You're probably going to bust the skirts off the piston; as the offset is to help keep the piston straight in the bore during the expansion stroke. That's about all i'd be able to say; Hopefully one of our engine builders will be able to help more. Quote Link to comment Share on other sites More sharing options...
Nizm0Zed Posted December 18, 2009 Share Posted December 18, 2009 You're probably going to bust the skirts off the piston yup. The conrod moving up the bore is running at an angle, the offset pin in the piston is to help stop the piston from 'twisting over' in the bore. If you have it the wrong way round, its going to do the opposite and amplify the twisting over effect. I would expect to see busted skirts, busted piston crowns, massive wear in one side of the bore, and probably excessive blow by very quickly. Quote Link to comment Share on other sites More sharing options...
thetremendoustim Posted December 19, 2009 Share Posted December 19, 2009 ASE time!! Press fit pistons are offset towards right side...(from the front) which would be the major thrust side i dont know i really cant remember yesterdays test....yeah that makes the most sense either way just install them with the right notch in the right direction and your good Quote Link to comment Share on other sites More sharing options...
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