My father, rest his soul, always told us never to keep a set of tires for more than 4 years. And he would never buy used ones. I've pretty much stuck to that all of my driving life.

I'd certainly avoid trying to make use of the 100mph sticker that was placed on the km/h speedometer.

My 1972 FSM lists the L20A in addition to the L24. It shows a compression ratio for the L20A of 8.6:1. The models given are the (L)230Q(U) "Datsun 200C" and the L230QT "Deluxe". It does later show the L20A as having a single carb. The standard piston diameter for the L20A is listed as 77.92-77.97mm versus 82.99-83.04mm for the L24.

Mike,

Like I said before, beware what you see in the English-language manuals relating to L20As. Not all L20As were created equal. The Fairlady Z version is different to the others.....

John,

I want to urge you to not give up on sourcing a set of replacement pistons for the L20A. Just because you can't find them on the 'Net doesn't mean that they aren't available. You will need to get them from Japan, and for that you will need a kindly contact there who will source them for you. I think this is your best course of action. The 'Net is NOT the cure for all ills or the answer to all questions - especially for the owner of a Fairlady Z.

Even if you did use the L24 pistons ( your risk to overbore by that much ) you'd still have the small valves, small ports and small manifold passages of the L20A, as well as the 'small' Hitachi HJG38W carburettors.

Food for thought?

yes, it is food for thought. I would rather find some replacements than raping the l20a block....with that being said, anybody speak japanese?

Oh, for those who are concerned...she now sports new 14inch tires on all corners.

Mike,

Like I said before, beware what you see in the English-language manuals relating to L20As. Not all L20As were created equal. The Fairlady Z version is different to the others.....

I'm sorry if my post wasn't clear. I was just trying to back up what you posted earlier about the differences between L20As. The only thing that surprised me was that the 8.6:1 seemed fairly close to the 9.0:1 that you had mentioned and that 9.0:1 doesn't seem "high" to me. Is that term just used to differentiate the two?

did you ask you local nissan parts dealer to check with Japan, just because they have no listing locally does not mean the parts are not available, I always get them to check with Japan sometimes they come back and say yes we can get it.

Re the question about L24 rods. I believe the L20a rods are the same as the L24 rods the piston pin height is different to match the stroke. Yep I can confirm that I just looked up my S30 parts catalog (Japan Local Market catalog) both the L20a and L24 have the same part number for the rods.

I'm sorry if my post wasn't clear. I was just trying to back up what you posted earlier about the differences between L20As. The only thing that surprised me was that the 8.6:1 seemed fairly close to the 9.0:1 that you had mentioned and that 9.0:1 doesn't seem "high" to me. Is that term just used to differentiate the two?

Hi Mike,

OK - thanks for the clarification. My mistake. I thought you were falling into the trap of thinking that all L20As were the same.

Regarding compression ratios; The earliest Fairlady Z and Z-L models had 9.5:1 and 8.6:1 as the 'high' and 'low', but they later switched to 9.0:1 and 8.5:1 - and I think the car in question falls into this bracket judging by its age. The better translation would probably be "higher" and "lower" compression, and it was sometimes expressed in fuel grades ( 'high octane' version and 'low octane' version ).

Alan T.