Damaged Cams on 7m-gte?

[GotBoost?]

Hey wassp. Months ago I pulled my engine due to bhg (which had been "repaired" by the previous owner). The bottom end has been fully rebuild, and I just got a call from the shop a few minutes ago about the head. He says whoever replaced the head gasket before i bought the car) inverted the intake and exhust cam caps (intake with exhaust side), and now the cams are toast. My question: if the cam caps were swapped, is that enough to damage the cams? I hope you can understand my question. But I am gonna go by the shop to see whatever cam damage he is talkign about. Is the damage gonna be obvious?
Effn monkey PO... Thank you all.

 

[s383mmber1]

THe cam journals on almost every 7m is scratched, and its "normal"

If its the cam journals, tell him not to touch it!

 

[MassSupra89]

THe cam journals on almost every 7m is scratched, and its "normal"

If its the cam journals, tell him not to touch it!

I've heard this a few times before, and still don't know how I feel on it. My journals are smooth with no scoring, but I've heard people saying that indents and scoring is "Normal for the cams on a 7M"

 

[s383mmber1]

When i jsut had my head done, i told my machinist--

"Dont worry about" And he finished my sentence "cam journals, i know about 7m's!"

:icon_razz

 

[Nick M]

I am in disagreement, again, with this idea that it is normal. It isn't normal, it is why people here upper end knock.

 

[suprarich]

Yes, shell gaming the caps around is a no no. If they where installed wrong, then heavy scoring could have happend. Each cap needs to be in its original position.

 

[boltz]

With your cams out sit random caps on random locations and feel your finger on the joints up and down, i gurantee you will feel the edge where as if it is in its proper location you shouldnt feel a sharp edge.

If they were wrong it is prety lucky that the cams didn't bind. Perhapse the previous work done on the head whoever did it used caps from a doner head and possibly found very close match and sanded to fit... which is still not a great thing. I dont think the head can even be line bored.

 

[7MGTEsup]

How can one get the cam caps in the wrong place they have numbers on them to identify there location:wavey:

 

[irocznissan]

^^^its pretty easy to do so if u dont spend the time to read the caps

 

[johnathan1]

I hope my machine shop put all of the cam caps back in the right places. :icon_conf

 

[mk3forme]

reading horror stories like this is why im glad im rebuilding myself. I feel for you guys that dont have the resources to do this as well. I dont like other people touching my car if I can possibly do the work myself. Every time I take my car to get something done, something ends up broken or messed up. :icon_evil

 

[suprarich]

I dont think the head can even be line bored.

Sure they can, we just mock that sucker up on the boring mill and ream the cam line with the caps torqued down. Provided the head is not warped of course.

 

[lzalusky]

The cams have a soft babbit material coating on the journals. This soft coating is what is scoring, not the actual cam. The coating is kinda like a backwards bearing, where the shaft is soft and the bearing saddles are hard. On a side note, I have yet to see a head that didn't have somewhat "scored" journals. It doesn't seem to hurt anything unless it is really bad.

 

[GotBoost?]

So I went by the machine shop to see the cams. Sure, they're scored right at the camshaft cams. He said "i'm surprised they didn't seize". He showed me the difference in the journal gap when the caps are placed correctly vs. incorrectly. When the right cap is used at the right location, i couldn't even feel the gap. I sure did feel the gap when the cap was at the wrong. He says I need new cams, as he warraties his work for 12 months, and he obviously doesn't wanna use questionable parts. He showed me water jacket corrosion by cyl 1, which it's gonna cost $200 to repair. He said after line boring, a valve job, machining the deck (it's warped 12 thou), new cams and all, I'm looknig at around $1200. Time for a new head? Where do i read about the soft babbit material that i can show him? Maybe that'll convince him the cams are fine.

 

[s383mmber1]

I'm looknig at around $1200.

Sounds like a deal to me!

I was quoted double that.

 

[mk3forme]

Post a pic of the cams so we can see. I thought mine looked pretty rough but I had them polished and they look pretty good now

 

[GotBoost?]

I mentioned to him abt polishing the cams. He said polishing them would create too large a clearance. I will post good pics later on tonite.

 

[3p141592654]

I posted some pictures a while back on another thread (link below). Do yours look like this? Note how the cam journals look bad, but the saddles in the head and on the caps looks perfect.

Has he plastigauged the clearances on each journal with the correct caps installed?

http://www.supramania.com/forums/showthread.php?t=16390&highlight=babbit

Where do i read about the soft babbit material that i can show him? Maybe that'll convince him the cams are fine.

 

[sponsored1]

Scored cam caps, while "normal" on 7m's, is still not good at all. If they installed the caps incorrectly im also surprised the cams didnt seize in the caps. And if it actually ran like that for more then a little while, i would say that the whole head is junk. It doesnt take much to warp aluminum, much less when its a little tiny cam cap. I picked up my last couple 7m heads for around $50 each bare. I normally try to use an N/A head because they dont normally have the water passage corrosion, nor do they have cracks inbetween the valve seats like some of the turbo heads.

 

[boltz]

Knowledge is power. If you know the proceedures and what should be done and why not to mix parts then you can make visual inspections and ask questions.

I take my stuff to a performance shop, and still inspect things like cap locations. If you find something wrong ask why it is wrong and if it was done for a reason.

Even crank main caps can't be mixed or swapped from one motor to another with out line boring a very close fitting doner.