Piston Pin Modification - Which Way to Go?

[rocklord]

I didn't want to hijack the 255 piston thread, so I started a new one for my question

I'm looking at a set of non-Ford pistons for an engine rebuild that have pins smaller than the 0.9122 ones found in our six.

My question, would it be better to ream out the non-Ford pistons to accept a 0.9122 pin, or to install a bushing in the small end of the connecting rod to accept the smaller pin?

Thanks in advance.

 

[Thad]

Answer depend on difference in pin size. One thing to remember if you bush the rods the pin would be floating and the piston would have to have grooves for circlips or some other type pin retainer.

 

[rbohm]

8) you also have to deal with if you have enough material to enlarge the small end or not.

 

[rocklord]

8) you also have to deal with if you have enough material to enlarge the small end or not.

Some of the piston pin diameters are 0.9272; 0.9050; and 0.8660 instead of 0.9122.
The differences would be + 0.0150; -0.0072; and -0.0462 respectively.
15 thousandths oversize shouldn't be that much for the small end, would it rbohm?
I agree that the amount of material on the small end would be critical when enlarging it to install a bushing.

Thad, thanks for the input about the pistons having to have floating pins and circlips when using bushings on the small end.

 

[rbohm]

8) you also have to deal with if you have enough material to enlarge the small end or not.

Some of the piston pin diameters are 0.9272; 0.9050; and 0.8660 instead of 0.9122.
The differences would be + 0.0150; -0.0072; and -0.0462 respectively.
15 thousandths oversize shouldn't be that much for the small end, would it rbohm?
I agree that the amount of material on the small end would be critical when enlarging it to install a bushing.

Thad, thanks for the input about the pistons having to have floating pins and circlips when using bushings on the small end.

the pin diameters you are looking at are fine. if you decide to float the pins, my advice is to have the grooves for the pin retainers cut double wide and install two pin retaining clips. and make sure that the sharp edges face away from each other. this will give you maximum reliability.