Piston Clearance ????

[stephenrussell]

ok guys hope you can help me here with this (I am a air conditioning repair man not a mechanic) but anyways.....

I was trying to figure out what my clearance was between my cylinder wall and piston today on my 2.2L, because I wanted to know If I was near specs to install new forged pistons std size.....

When I measured the cylinder it was between 3.434" and 3.436"
When I measured the Piston (A new cast one standard size) I was getting say 3.438 and 3.440 measured at bottom of piston on the skirt...

Now I haven't honed the cylinders yet ( But I am going too )...

So when I take a average I think I have a Clearance of .004 " (3.439 - 3.435)

DOES THIS SOUND RIGHT??????? did I screw up???? What clearance should I be looking for say to install forged wisco pistons????

THANKS GUYS

[turbovanman]

That looks about right. I think Wiseco's recommend .0045 so you'll be close. A good hone should clear that up. Did you check for taper?

[mpgmike]

Quote:

Originally Posted by stephenrussell When I measured the cylinder it was between 3.434" and 3.436" When I measured the Piston (A new cast one standard size) I was getting say 3.438 and 3.440 measured at bottom of piston on the skirt... So when I take a average I think I have a Clearance of .004 " (3.439 - 3.435) DOES THIS SOUND RIGHT??????? did I screw up???? What clearance should I be looking for say to install forged wisco pistons???? THANKS GUYS

You say you have a piston that measures 3.438" going into a hole that measures 3.436"? Could it be that you have your numbers reversed?

mpgmike
'88 Shelby Daytona
'91 Spirit R/T
'84 Rampage
'89 Masi TC

[stephenrussell]

I used my friends telescoping gauge i believe, and there didn't seem to be any warpage or anything like that and all cylinder walls look the same...so i would say no taper at all

[stephenrussell]

checked again cause ya that didn't make sence did it.....

seems to me (on my gauge) that piston is a tad bigger on the bottom than the top, but anyways bottom of piston is 3.439, and I took my telescoping gauge and checked the cylinder, And now I just measured that measurment 3.442 / 3.443..

so does that sound better,, cause 3.442 - 3.439 is 0.003

[stephenrussell]

Ya I must of screwed something up there, I think those were measurments from top of cylinder wall with the taper or whatever... But I did it again and I believe I got about a 0.003 clearance

I will check again later after i hone it, is that a good Idea???? If I hone it and Find out I got a clearance of over .004 will that be too much, cause I was told that forged pistons should be tight so they dont make noise when motor is cold but then i heard that they should have say .007 clearance cause they expand more than cast do....

I really dont know anymore, just dont wanna spend the money if I end up using the $800 pistons for ash trays when i dont eaven smoke...

[turbovanman]

Quote:

Originally Posted by stephenrussell Ya I must of screwed something up there, I think those were measurments from top of cylinder wall with the taper or whatever... But I did it again and I believe I got about a 0.003 clearance I will check again later after i hone it, is that a good Idea???? If I hone it and Find out I got a clearance of over .004 will that be too much, cause I was told that forged pistons should be tight so they dont make noise when motor is cold but then i heard that they should have say .007 clearance cause they expand more than cast do.... I really dont know anymore, just dont wanna spend the money if I end up using the $800 pistons for ash trays when i dont eaven smoke...

Venolias are .007". Best bet is to phone the vendor your getting the pistons from.
If you can remove .002 honing, then your a better man than I,

[stephenrussell]

ok thanks again simon...

I am getting a hone for a drill this weekend, so after I am done I will check everything out, post my clearance and find a piston to match ( I hope )

[Tim_K]

I think you better find someone who has some idea of what they're doing to hone the bores before you go and screw it up for yourself. Pay a machine shop / engine builder to do it.

[mo' parts]

Quote:

Originally Posted by Tim_K I think you better find someone who has some idea of what they're doing to hone the bores before you go and screw it up for yourself. Pay a machine shop / engine builder to do it.

agreed.
it would be a big headache to go through all that work and have a piston seize in the bore. plus its always a good idea to start with a fresh, clean bore/hone. and i recommend a tourqe plate. plus you can have some arp's installed in the rods while getting the bore/hone.
wiseco calls for .0035 clearance, which i believe is about the tightest forged piston clearance available.

[91DSX]

Stephen, I agree with Adam & Tim, go see my machine shop "Harold's Automotive". I had my whole bottom end done there: Wiseco's, ARP Main Studs, ARP Wave Lok Rod Bolts, Shot Peened CB Rods, Turned Crank, Hot Tanking, etc etc. Motor runs HARD!
Good, honest, and fairly priced guys over there!

[stephenrussell]

Roger do you know what the part number was for the wiseco pistons that you have, and where you bought them from would be a help too.

[mo' parts]

www.******************** carrys wiseco. mine were .020 over pistons

[91DSX]

Quote:

Originally Posted by adam89shlbydayt www.******************** carrys wiseco. mine were .020 over pistons

+1

Yup got my 2.5L .040 over pistons from Chris W/TU too, awesome service and they come with everything you need, Stephen.