1979 280z piston in l20b

[maredlin1@hotmail.com]

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?

[MicroMachinery]

I thought it was ZX pistons that you wanted for that.. maybe I'm wrong?

[flatcat19]

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. 

[ggzilla]

0.080 inches is approximately 2mm.

 

L28E pistons are exactly 1 mm larger diameter than L20B pistons.

* L20B 85mm bore

* L28 86mm bore

[datzenmike]

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.

[Doctor510]

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

[datzenmike]

Yup, up too long. Thanks for correction, I'm off to bed.