HELP ENGINE GURUS! ca18det piston to wall clearence

[frftw]

I am building a ca18det that includes a honed block and 83mm (oem bore) cp pistons. I went ahead and did my ring gaps and put the crank in ect and when the time to put the pistons in their was an excessive amount of slop wich really bothered me so I called up cp and found out the recomended piston to wall clearence wich was .0035-.0040 inches, I measured the diameter of the piston skirt and the bore and their were differences in diameter of up to .0075. is this motor runable or am i screwed? the rings were all close to their recommended gap so i thought I was on track to a tight build...:picardfp:

[frftw]

any input??

[frftw]

After thinking about it overnight Im thinking I need to get .5 over pistons and hve the block rebored, unless i got it sleeved to 83mm... has anyone done this before? Im going to go talk to my machine shop to see what they think. in the mean time, anyone want unused 83mm cp pistons?

[rcdad123]

if a block is cheaper and easier to find, get another block. just make sure it has not been bored yet.

[jacobs13]

If cp wants .035 to 0.040 then make sure your clearance are within spec. Engineers are smart and know what they are doing. Ive machined a few blocks and know that even 0.010 can make a huge difference. If you really want to stay 83mm then go ahead and get sleeves, they cost about the same as cp pistons and will be way stronger than the oem sleeves if you go with darton or whatever. The shop shouldnt charge you too much to put them in as its not that hard. They are the ones who bored the block? I would make them pony up for the new parts since they over bored it. Its pretty easy to mess up measuring down to thousandths. Thats why I check my work many times before I bore.

[frftw]

would I not then run the risk of having the same problem: to get the cylender walls smooth and honed might bring the bore over spec. I emailed the person I got the pistons from asking if I could do a partial exchange for 83.5 mm units, in wich case that will be the route I go. If I get another block I would need it to be re-machined on top of the price of the block itself and It would need a couple new gaskets as I installed the oil pump, oil filter block and rear main seal. part of me wants to just track down a ka swap and throw that in for the winter so I can finish this engine the right way AND drive my car

[frftw]

If cp wants .035 to 0.040 then make sure your clearance are within spec. Engineers are smart and know what they are doing. Ive machined a few blocks and know that even 0.010 can make a huge difference. If you really want to stay 83mm then go ahead and get sleeves, they cost about the same as cp pistons and will be way stronger than the oem sleeves if you go with darton or whatever. The shop shouldnt charge you too much to put them in as its not that hard. They are the ones who bored the block? I would make them pony up for the new parts since they over bored it. Its pretty easy to mess up measuring down to thousandths. Thats why I check my work many times before I bore.

just read this after my last post...
I will try to talk to the shop but it was 6 months ago that they did the work (this has been a time consuming project as I have been funding it slowly as I go) so I dont know if they are going to help me... I also dont know if I want them to touch my block agian if they already did it wrong once

[jacobs13]

Even if it was 6 months ago they still did. Threaten them with a bad rep and they should take care you. That much clearance is unacceptable. You will have piston slap and your cylinders will be far out of round in no time.

[frftw]

haha piston slap would be an understatment

[Copper280z]

Is their spec clearance 'on the side' or difference in diameters? I think most of the time it's 'on the side', which means that you're dead center in the middle of the range.

[gotta240]

where are you located? If in socal, I have a spare block i'd let you have for a very reasonable price.

[TheWolf]

I am building a ca18det that includes a honed block and 83mm (oem bore) cp pistons. I went ahead and did my ring gaps and put the crank in ect and when the time to put the pistons in their was an excessive amount of slop wich really bothered me so I called up cp and found out the recomended piston to wall clearence wich was .0035-.0040 inches, I measured the diameter of the piston skirt and the bore and their were differences in diameter of up to .0075. is this motor runable or am i screwed? the rings were all close to their recommended gap so i thought I was on track to a tight build...:picardfp:

IF you could measure all this accurately. Why didn't you when you got the machine work back?

Are you using a micrometer on the pistons and a dial bore gauge on the bores or are you using a harbor freight digital caliper that you got for $12?