I've bought some time ago a set of used forged SRP pistons.
Today i was cleaning them and I also did some measuring.
Pistons are SRP part nr. 138084 - 0.020" overbore:

Here is what I've got:
1. 4.0153
2. 4.0152
3. 4.0152
4. 4.0148
5. 4.0151
6. 4.0164
7. 4.0156
8. 4.0153

I've measured at .5" from the bottom of the piston, as suggested by JE/SRP.

So I have a few questions:
1. Doesn't difference of .0016" look too big (piston 6-4)?
2. My machinist will not do clearancing for each piston individually.
What would be the best way to tell what bore size do I need
(+ the clearance)?

What is the recommended clearance from the mfg when installed for piston to block?

From manufacturer, .0025 - .0035, but that sounds a little
bit too tight to me for forged pistons.

Quote:

High silicoln alloy piston with low expansion rates.

Follow the mfg specs on side clearance, or they will rattle forever..

-- Joe

Quote:

That stinks.
A good machinist will "hone to fit" each cyl.

Thanks for the inputs!
I just spoke with my machinist and he agreed to make
individual bores!
I'll go with mfg specs, but I'll try to aim on the higer
side. Since this will be street but also road race engine,
it will see some high temperatures and a lot of abusing.

Quote:

That's good.
It's not like it's a big deal to do each cyl. Reseting the mic and bore gauge for each pistion takes about 30 seconds.

I know, he told me so, and he also told me that price won't be much higher. When I first said that my machinist won't do it, I jumped to conclusions before I discussed details with him. He said that it's not something that he usually do, but if I wan't it, it's not a problem.
But you wouldn't believe how much forward is USA vs Europe
in machining and materials.
Just to give you an idea; nobody here (I'm talking about machinists) uses torque plate. If somebody brings it with itsef OK, but if you don't, you won't get block honed with torque plate.
And align boring/honing is science fiction to most machine shops. There are only two shops in Croatia that can do it.

Sliding have him clearance it to their specs, dont go overboard. As anesthes said they are tight these days, my Manleys are no different.

The days of forged needing 4-6 thou are long gone, better metals out there now.

Thanks for the advice, I'll do it so.