Piston lettering

[hondahunter]

What do the letters A-D located on the top of the pistons mean? Would I have any problem using B pistons, when my originals were C, is there a size difference?

[black86glhs]

The letters are the grades the pistons got in piston school.





No, they correspond to sizes. But i do not know what they are. Someone will pipe up with the info soon.

[BadAssPerformance]

Yep, sizes, so you gotta replace an C with a C unless you plan to hone it out a lot and use a D... IIR, A is smallest, D is largest.

You can measure the bore with a bore gauge and mic the piston to calculate clearances

[hondahunter]

Alright thanks for the info. Does anyone have 2 C sized 85 G head pistons?

[CNH320]

From the 92 FSM....

Sizes A thru E (A-low limit, E-High Limit)

2.5 Turbo I
87.453/87.492mm
(3.443/3.444 in.)

2.2 Turbo III
87.442/87.507mm
(3.443/3.445 in.)

[Directconnection]

I don't see an issue if you get a "D" when you need the "C" or even a "B"

From memory.... each letter size was only a few tenths (ie: .0002 to .0003) and judging from the post above, it might be correct.

So, if your "C" pistons are 3.4447 and you get the "D" of 3.4450 you will be ok as your bores are most likely quite worn anyways (along with the original pistons)

Measuring them before installing them along with the bores is always a SMART thing to do, vs. assume though....

[black86glhs]

I don't see an issue if you get a "D" when you need the "C" or even a "B"

From memory.... each letter size was only a few tenths (ie: .0002 to .0003) and judging from the post above, it might be correct.

So, if your "C" pistons are 3.4447 and you get the "D" of 3.4450 you will be ok as your bores are most likely quite worn anyways (along with the original pistons)

Measuring them before installing them along with the bores is always a SMART thing to do, vs. assume though....

Yeah, but assuming is so much easier.