240 Compression Problem

[cyphertext69]

Alright, so over the weekend I rebuilt my 240. I just got it back from the machine shop and slapped a new piston, rings and all that good stuff.

When it didn't kick over the first time, I did a compression check and it only registered at 60 psi.

Luckily, I had a regular bore 200cc jug and piston laying around, I put that on and did a compression check and it came up to 115 psi, no problem.

I changed all the gaskets, tightened it in the torque pattern, everything was done correctly, but I just can't figure out why I am only getting 60 psi.

Can anyone tell me what the problem could be?

 

[fmxr47]

are the rings on the 240 new?, that would be my only thought if the rings are shot, but a new rebuild i would assume not

 

[bigdblaster]

are the rings seating correctly in there..and did u take the piston to the shop with the head??

 

[Valhalla]

sounds to me like the new bore/hone are a little bigger than they are supposed to be. the rings are making contact, but its not as tight as it should be with your current piston

 

[cyphertext69]

everything was new, rings, piston, gaskets, bearing, everything.

I am going to check the rings themselves tomorrow to make sure it's not them. I will let you know what the deal is.

 

[00blasterRESTO]

get ya a depth Mic. out and make sure that they didnt bore it bigger than your piston

 

[fmxr47]

you can get rings fore the overbore and use the same piston, im not sure about the 240 kit though

 

[bkg479]

There are 3 over sizes for a big bore, 72, 72.5 and 73