Slapping/knocking? (9:1 wiseco, eagle)

[AK_4g63t]

I bought a 95 GSX 3 months ago with a blown motor. I quickly ran onto ebay and bought a rebuilt kit. It came with 9:1 Wiseco Pistons, Eagle rods, Eagle Crankshaft, ACL race bearings and ARP rod bolts. I also bought a Mistubishi 4-layer HG, new oil pump, new water pump and all the new gaskets. I then bought a used head off ebay and when it arrived I handed it over to a shop where it got rebuilt. After recieving all my parts and reading on this wibsite for hours a day I went at it. Pulled the motor, cleaned it, took measurments ect. Installed the bearings and used the molly graphite lube from arp. everything went great. I also to the BS removal kit while I was there. After installing all the piston rings and installing into the block I measured and wall to piston clearance and it was in spec. I did this about 2 weeks ago but i think it was .004, correct? After getting the motor in the car and starting it up there was this slapping/knocking noise. I did some more research and decided to get the new 3mm lifters. After installing those I found that the noise was still as loud as before. I used my stethiscope with the rod piece installed on it and applied it to random parts of my motor (with it running) to try and pinpoint this noise. I put the rod on the head in random parts but it wasn't really loud at all right there. I then lifted the car and could hear it from the bottom. I placed it on the oil pan but still really couldn't hear it. I then put the rod on the middle of the front off the block just below where the head and block meet and like magic, there it was. This noise is audible at idle and through every RPM. It doesn't go away no matter what I do. I figured it might be predetination (although I have never heard "knocking" before, I've read it sounds like pinging) so I drained my gas tank, added 91 octane gas and through in some octane booster. Up here in Alaska we don't have 93 octane or any of that good stuff. Drove my car around for 10 miles and still making a slap/knock sound. My timming is 100% perfect becuase I've checked it probobly 20 times and i just installed a new hydo. tentioner. Does anyone have any direction as to where or what I should do next?

 

[luvmygst]

.004 is a little high got piston to wall clearance I believe.. I wlil have to consult my manual and get back with the correct number, but I dont think its that high. You could be hearing piston slap.

 

[luvmygst]

you are hearing piston slap would be my guess. the spec is .0012-.0020 So basically one thounsadth to just up to 2 thousandths . you are way to high. I tried to post a copy of the section but I cant cut and paste from a pdf file. Try this link its real helpfull. Its for a 6 bolt but it will give you a good idea most of the clearances are the same. good luck

http://www.idmoc.com/Download/1G - 4G61 4G63 4G64 1990-1992 ENGINE.pdf

 

[AK_4g63t]

Is this clearance your talking about total? or if you were to center the piston in the cylinder and the gap from the side of the piston to the wall? because I measured the bore and then subtracted my piston width to get .004. I will check out the manual and your link and then get back to post again.

 

[AK_4g63t]

Okay, I went and looked at all my measurments and compared it with my manual and there is too much space between the piston and the cylinder walls so I will be ordering new pistons in the next few days. I plan on making 350whp and using the big evoIII so would the 9:1 be better then the 8.5:1 if im doing a .20 bore now?

 

[Black94DSM]

Wiseco sugguest a .0024 from the factory. I called them and they told me with 24-27 psi and 30 psi race days i should go with a .0035 piston to wall. To go with a .004 is more of a big boost or nitrous motor set up.

 

[AK_4g63t]

Thanks a lot guys. I just ordered my new pistons last night and I'll be stripping my motor in the next few days and taking it to a local machine shop. I think I'll go with the .0024 piston to wall clearance since I don't plan on boosting 24-27psi. I'm also going to go with the T04B and the Greddy big 26 fmic. This is my first dsm and I've never had it running for more then 2 minutes, I've also done days and days and days of research to not come into this with "noob" status. I'll be assembling this motor myself AGAIN and I'll keep everyone posted on the build. Wish me luck.