maredlin1@hotmail.com Posted April 19, 2015 Report Share Posted April 19, 2015 I am installing 1979 280z pistons in a 1978 l20b (will be 80mm over in l20b) How many thousands should the piston to cylinder clearance be? Quote Link to comment
MicroMachinery Posted April 19, 2015 Report Share Posted April 19, 2015 I thought it was ZX pistons that you wanted for that.. maybe I'm wrong? Quote Link to comment
flatcat19 Posted April 19, 2015 Report Share Posted April 19, 2015 ZX NA pistons are the ticket. 80mm plus 80mm tells me you need to do your math again. Do you mean .080 over? Better off staying stock. L18 pistons will drop in with no work and bump up your compression. Peanut head will bump up your compression. My guess...you have the pistons and thats what you want to do. The cost outweighs the benefit. Quote Link to comment
ggzilla Posted April 19, 2015 Report Share Posted April 19, 2015 0.080 inches is approximately 2mm. L28E pistons are exactly 1 mm larger diameter than L20B pistons. * L20B 85mm bore * L28 86mm bore Quote Link to comment
datzenmike Posted April 19, 2015 Report Share Posted April 19, 2015 I am installing 1979 280z pistons in a 1978 l20b (will be 80mm over in l20b) How many thousands should the piston to cylinder clearance be? Generally 0.0010" to 0.0018" piston to bore clearance. (corrected) Check with the ZX manual but an 86mm bore L20B has a top ring gap of 0.0098" to 0.0157" or about ten to fifteen thousandths. second ring gap of 0.0118" to 0.0197" or about twelve to nineteen thousandths oil ring gap of 0.0118" to-0.0354" or about twelve to thirty-five thousandths. (corrected) End gap is critical. Too loose leaks compression. Too tight, and if the engine ever runs hot, the gap will close and the rings break. Quote Link to comment
Doctor510 Posted April 19, 2015 Report Share Posted April 19, 2015 Mike, check your explanations. Generally 0.010" to 0.018" piston to bore clearance. your numbers should be 0.0010 - 0.0018 Clearances are .001-.0018" one to one . 8 thousandths top ring gap of 0.0098" to 0.0157" or about one to one and a half thousandths. (10 thou to 15 thou) second ring gap of 0.0118" to 0.0197" or about one to two thousandths (12 thou to 20 thou) Piston diameter in inches X .0035" for top gap Quote Link to comment
datzenmike Posted April 19, 2015 Report Share Posted April 19, 2015 Yup, up too long. Thanks for correction, I'm off to bed. Quote Link to comment
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