quick info needed.., from expirienced 7a engin builders.....plz Options

[mandrek]

hello all, i just have a quick question.. I'm in the process of gathering parts for a boosted 7a.. i have located a set of OEM, from the factory, Toyota 4agze pistons, and for a great price since the guy is just looking to get rid of them (change of plans..#.. thing is that they are .050" oversized..

now my question is.. is this a option that was made available to give Toyota service techs a slug that would provide tighter clearance on an old motor? #as i am suspecting# or is this an OEM replacement for use in a motor that has had to have the cylinder walls worked on #say to remove scoring) and thus the reason for the increased bore diameter..

the motor I'm looking to put these in is a 96 7a, and had 218K on it.. the walls of the cylinders are smooth as glass, and there are next to no markings showing wear. ill post a pic if need be.. but i don't think that it would be needed to answer my question..

i guess that what i am really getting at, is this... if i get these pistons will i need to have the block bored to accept these, or is this kind of o/s a tolerance check measure?

thank you..

This post has been edited by mandrek: Oct 22, 2011 - 11:24 AM

[Smaay]

.050 is way too much, the most you want to bore out on a 7A is .040 any more than that you take a chance on compromising cylinder strength. are you not confusing .5mm because thats the same as .020 over? 350 can be done but i would NOT use OEM pistons! get something like Weiscos. the 7A stock rods i think will handle that just fine. they are much stronger than 1ZZ rods. just make sure you have a good tune