bent cam???!!!!

[worked]

that title makes me laugh just saying it
ok, i'm aiming this at the gurus, i'm not a rocket scientist, but i don't think i'm a fucking idiot either!
here is the story
my housemate is building an r32 gtr, recently we replaced the stock turbos with gt2860 -5s, wopped it back together and went for a spin
it was a nice drive, thanks for asking.
however, the waterpump spilt and the motor got hot, not cooked but not ideal in the old temp department
chucked a new waterpump back on and he was just checking everything and noticed the engine was nearly impossible to turn over by hand, eliminating all we could we found the inlet camshaft was so hard you had to stick a bit of wood against the camgear and hit it hard with a hammer to turn the camshaft, warped head from getting it hot we figured
pulled the engine out and stripped it down, took the head off and found its perfectly straight
the exhaust cam always moved freely so is it possible the inlet camshaft is bent??
i fail to see what else could possibly have gone wrong, i'll put the cam in the lathe tomoz and see if its bent
i'm just wondering am i really off the mark here, or if i'm right, what is the go and is has it happened to others etc

[H8CHIR6KU]

nah i wouldnt say your off the mark. and sounds like your going to find out anyway

ive had bent camshafts in toyota camrys that have been cooked. similar situation to you guys. do the head etc and found it difficult to turn over cause the cams are bent. swapped cams over and was sweet as

[Gunner]

Have you put a straight edge in the cam valley? Did you have the 6mm bolts in the corners of the heads?

Drop the cam back in minus the valvetrain, see how it sits, if theres a nice bow in the middle of the cam, she fucked. I'd be replacing both cams, and having the head checked properly, and making sue those 6mm bolts are in the corners on reassembly.

[Sam-Q]

regardless that head might need to re-annealed

[worked]

all 6mm bolts were in the corners of the head, we have now laid a straight edge on the top face of the head where the cam caps bolt onto and its straight too, head is loking good

next some results.......
spinning the cam by hand mounted vertical on two points i set up a jig and measured to see if the cam is bent

very back cam journal 0.08mm our of round

close to center journal 0.20mm

and very front journal 0.35mm

while spinning it by hand and looking you can see the journals wavering a little, although its not as bent as i would have though i may take the other cam and do the same for a comparison

[Gunner]

Thats odd, haven't seen that before. Journals will need to be checked too.

I wouldn't fuck around, and I'd go right through it, and make sure it is ship shape in every aspect (especially cam cap retaining bolts) before putting the car back together, gtr with a snapped cam is messy.

[worked]

tru dat, actually we have another whole head to go on, with jun cams all machined and shimmed ready to bolt on.

[TODA AU]

all 6mm bolts were in the corners of the head, we have now laid a straight edge on the top face of the head where the cam caps bolt onto and its straight too, head is loking good

next some results.......
spinning the cam by hand mounted vertical on two points i set up a jig and measured to see if the cam is bent

very back cam journal 0.08mm our of round

close to center journal 0.20mm

and very front journal 0.35mm

while spinning it by hand and looking you can see the journals wavering a little, although its not as bent as i would have though i may take the other cam and do the same for a comparison

Your results sounds like a bent cam

[munki]

Yeah nice and fucked. are the rb26 the same rocker arm setup as 25's and SRs?

[TODA AU]

Yeah nice and fucked. are the rb26 the same rocker arm setup as 25's and SRs?

Rockers? No the RB26 is shin under bucket. The 25 is hla.
Closer to a 4ag than an Sr...

[worked]

rb26 are bucket and shim, rb20 and 25 are hydraulic lifters, sr are rocker arms

[munki]

interesting, dont really know much nissan stuff apart from the sr