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Relationship between head warp and cam journal warp - b230ft

will740turbo

Member
Joined
Jun 15, 2006
Location
Portland, OR
Hey, folks. I finally have time (thanks, SARS2.0) to get my engine in to the machine shop.

I think these guys were kind of knuckleheads because they said they thought the valves must be bent because they could see daylight through 3 of the valves with the buckets removed. But that was just light through the oil galleys. Rotating the valves (with a spring compressor in place) does not show any bent/off-round valves. I think these guys either didn't want to be bothered or didn't think I was serious enough for some reason.

Anyway, I ordered an engine refurb manual off ebay for pretty cheap, but I want to edubacate myself.

The bottom side of the head is warped about 9 thousandths on the long axis (less on the short axis). The machining limit is *39* thousandths.

But if the whole head has essentially bowed up on the bottom, it has also bowed up on the top - like flexing a loaf of bread.

How much misalignment is tolerable in the cam journals? If the journals are out of spec, are they fixable?
 
There is a spec limit on warp, I think it’s 20 thou measure with the straight edge diagonal on head. There really isn’t a practical machining limit on the head, as it’s not uncommon to remove 80-120 thou to increase the CR.

Lucky for you (being in Portland) there is a head shop that can align bore Volvo cam journals for ~$150. Aluminum Head Rebuilders is the shops name.

If you need any assistance, let me know.
https://forums.tbforums.com/showthread.php?t=349975
 
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There is a spec limit on warp, I think it?s 10 thou. There really isn?t a practical machining limit on the head, as it?s not uncommon to remove 80-120 thou to increase the CR.

Lucky for you (being in Portland) there is a head shop that can align bore Volvo cam journals for ~$150. Aluminum Head Rebuilders is the shops name.

If you need any assistance, let me know.
https://forums.tbforums.com/showthread.php?t=349975

Dude, you rock! I've been asking people for recommendations for a while, and everybody had some recommendation for somewhere they used to live.

It sounded like they thought there were 9 thousandths on the bottom and they thought there would be half that on each end at the top. Where is the limit measured?
 
The acceptable limit is actually 20 thou (and service limit is 40 thou!) when measured with the straight edge set to diagonal corners of the head. Max measurement is should be taken in the middle of the head between cylinders 2/3.

See image here:
https://flic.kr/p/2jbvNjF
 
The acceptable limit is actually 20 thou (and service limit is 40 thou!) when measured with the straight edge set to diagonal corners of the head. Max measurement is should be taken in the middle of the head between cylinders 2/3.

See image here:
https://flic.kr/p/2jbvNjF

I found a snippet of a page from the service manual on Matthews volvo site that showed similar numbers, but said just end to end and not diagonal. I found one of those manuals on ebay and ordered it.

What I am trying to find out is this:
If the head always warps a similar amount on the cam journals when the bottom warps, then does the install/machine limit apply to the cam journals too? Or are they assuming that will be dealt with separately?
 
I’m honestly not sure. The service manual makes no mention of straightening the head or line-boring the cam journals. I’ve seen heads that had cam journals that were warped over 10thou, and they were running for a long time like that. There’s usually a bit of scoring on the #5 cam journal when this happens. I’ve also measure stock cams that were bent .005” or more, so.... what really is the limit on a redblock volvo?

It seems to me that the general limit on cam journal warp is ~.004-.008” from asking around.
 
I pulled my rearmost bearing cap and found my cam and " bearing" surfaces wiped. I was not happy.
 
Thanks, I appreciate it.

I bolted the cam back in and torqued the nuts to 14ft-lbs (168 in-lb). It moves easily with 2 fingers. I'm not going to worry about the cam journals.

I *can* see it rock just a little, and I can see a tiny tiny gap on one end, but it looks like maybe 1 or 2 thousandths. I may try to get a feeler gauge in there later today, but I doubt I could even fit a sheet of paper.
 
A strip of plasti-gauge is what you probably want to use.

Red plastigage showed clearances of 0.0025 to 0.003 on all journals. Seems like a good sign. It's at the machine shop now. That guy had a B230 that was getting ported and big valves on the work bench, so I have a lot more confidence in this shop (G & A Cylinder head) than the first one.
 
Red plastigage showed clearances of 0.0025 to 0.003 on all journals. Seems like a good sign. It's at the machine shop now. That guy had a B230 that was getting ported and big valves on the work bench, so I have a lot more confidence in this shop (G & A Cylinder head) than the first one.

Glad you?re getting it sorted. I haven?t used G&A, but they have great reviews and some awesome equipment!
 
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