My Compression Numbers 4.7

[Ole Buck]

Was in the process of doing a motor swap but discovered that the donor had a nice crack just below the freeze plug in the block. My current motor had a blown head gasket so before the dismantle begins I figured i would do a compression check on all 8 cylinders. Well that's what I have. Now i know a complete upper end rebuild including a full timing set is coming. My question is do these numbers automatically tell you that the lower end ( short block ) is trash? If needed should i be looking for a reman short block or have my local machine shop do rebuild mine? I acquired two HO cams and an HO intake for my rebuild. 04 4.7 with 185k Oh and the plugs must have been the original Champion plugs. On 5 Of the 8 there was no electrode left sticking up. Just the L shaped arm and no tit to arc to.

Thanks !!!

 

[VicinSA]

Do a leak down test. If there isn't a major leak past the rings and your oil pressure is good, then your short block should be serviceable. However, I would also check the rod bearings for excessive wear, if you are able to pull the oil pan.

 

[njjeff201]

I’d be wary of any cracked block. I’d much prefer to work with what you have. Blown head gasket is not a big deal. What were the other cylinders comp numbers?