N1 Andy

I put this motor together about a month ago, it has p30 slugs, itr rods w/arp bolts and a gsr crank, the p72 head has supertech springs, retainers and valves and toda b cams. C/R should be around the 12.2-12.5:1 area with a 2 layer h/g and flat faced valves. The motor has about 700miles on it since the build and I have yet to get it tuned, rings have seated great, compression test shows 260psi all across +/- 3-4psi

I noticed yesterday a slight ticking that sounded like the early stages of a rod knock. I thought it may just be loose p2w clearance, but it didn't go away after warmup. Rather than destroying the bottom end I decided to take it apart to inspect for damage to bearings. It looks to me like some debris got in the oil passages on the crank judging by the light scoring in the middle of the bearing. But what do you think caused the rest of the stress? I am a fairly novice engine builder, therefore I do not totally know how to read what happened by looking at a bearing.

Arp rod bolts were torqued to 23ft lbs. I did NOT plastiguage the rods. I will on the new set however, does it look like the clearance was too tight? I just don't want this to happen again on the new set of bearings, thank god the crank is still good.

heres pics:

Scott_Tucker

How does the crank look? Was there any metal transfer to the crank? Its hard to tell what the bearings look like because the pics are a little blurry.

kyden

those are definitely not normal. you're supposed to get the rods resized when you put arp bolts in. and shame on you for not checking the bearing clearance!

Scott_Tucker

It almost looks like the babbit has fatigue cracks in it which would indicate possibly too much clearance. But like I said its hard to tell from the pictures.

N1 Andy

I know, shame on me...It won't happen again thats for sure.

as for metal transfer, I need to look closer today but I took a quick look last night and it looked perfect still.

I'm sure the rods were resized after arp's were put in, the big end has crosshatching in it like it was honed or something. My friend had the machine shop install them.

N1 Andy

any other suggestions?

FIGARILA

iTrader: (1)

can't you plasti-gauge the old bearings to see what clearance its at now?

N1 Andy

that is a good idea Figarila, I think ill try that tonight before I install and plastiguage the new ones.

96bstdgsr

dont bother after that kind of damage your clearances wont be correct and it will tell you nothing

ExospeedAMcrx

Measure clearances next time please.

Lubo_25

plasti-gage does not count...measure them properly...

96bstdgsr

not entirly true, yes you need to do it properly but it is an excelent way to double check yourself