DOHC pistons, and boring a DOHC out

[StEvEzAsYcHo]

I am going to be remiving the pistons and rods from my 96 DOHC.. Are these cylinder specific? I intend to number them anyway, but I just want to know.. IF I decide to bore the thing out, I dont see how the pistons can be as cylinder specific..

Also, as far as boring it out does go, what is a safe, but noticable amount to do so?

[patgizz]

they're not cylinder specific in size but it would be best to put the piston/rod back where it came from. this all goes out the window should the block need bored to clean up scratches, a ridge, taper, out of round.

boring the engine - only do what is necessary to clean the cylinders up, and make sure they do it to an off the shelf oversize piston. the larger you go the thinner the cylinder wall gets, the more prone to cracking/overheating it will get. i've never seen lots of machine work on 60* motors but most engines in general can safely take a .060" overbore before being paperweights. but if you go as small as possible you leave room for another future rebuild on the motor without having to find a new block.

[StEvEzAsYcHo]

Thanks Pat.. I'm probably not going to bore it more than necessary to cean the cylinders up.. I am having forged pistons made for it anyway, but i wanted to make sure there weren't any issues with matching up the cylinders to their pistons because of any weight variances.. What's the best way to go about boring? A machine/performance shop? I'll speak with my dad and see if his company does aything like that..

If there is no serious damage or need to do any boring to the cylinder, I wont need to get larger pistons, but I am still having forged ones made. Those are not at that point cylinder dependent correct?

[DrRodey]

Steve...

I have a machine shop up here that I'm using now, will clean, inspect, and rebore the block for $75 (+tax) Great guys, great work. I'm sure if you look around down there you sould be able to find someone who can do it for ya, and for as cheap as it can be done it's not worth trying to do it yourself and possibly grind a cyl. sideways.

[patgizz]

$75 is CHEAP

here its 75 to clean and check for cracks before they even start, then it's cost per hole to bore/hone.

[StEvEzAsYcHo]

Dan, where are you living now? I might tear the block down and bring it up there for a road trip.. Its worth it for 75+tax and the gas to get there and back! I think I simply want to clean/hone the cylinders.. Nothing too fancy.. How then does one go about getting pistons made? What diameter do I send the piston shoppe? THe diameter of the cylinder? Not sure as this is new territory for me, boring, and honing and forging, oh my!

[DrRodey]

PM Sent. Steve

[series8217]

Evne though you're replacing the pistons you should still keep track of what journal each rod came from, because they may be machined different to have the proper side clearance in that journal..

[crustycar]

Punching out

30 over is a normal amount to punch with out too much worry.
pistons are easy for that size.
As far as the rods - unless you spend the money to have the assemblies balanced keep them in the same positions.

I would save the money on forged pistions for cast and have the thing balanced. All pistions and flywheel/flexplate, rods and damper.
Most machine shops don't have the equipment for this job, and you'll have to look around for one.
Stock engines are not really balanced there just close.

Once you drive a truly balanced motor you'll have it done every time.
Its not cheap but its worth real smooth HP that you can feel.

[dohcfiend]

i forget all the sizes but the biggest off-the-shelf set of replacement pistons for a lq1 are .040 that i know of. he is right though, the block can be good for .060 but pistons would most likely be high.