Camshaft Wear

[Bruno Molly]

My machine shop informed me that the Camshafts were a little worn on the Bearing surfaces. Looks to me like normal wear with minor but present ridges. Isn't this normal for the 7MGTE? roughly 190k on the clock. He recommends replacing them. Everywhere I have looked or come across I find the Same Wear in just about every engine I find. Cylinder 1. Both Exhaust and Intake Camshafts seem to wear here. Should I just use the Old cams? Anyone have any decent 7MGTE cams they want to sell?

89 7mGTE Stock
+.20
7M Crank
Stock Rods
-- Planning on Arp Heads, Arp Rod studs, Cometic HG
Engine is still apart, waiting on Crank to be polished

thanks
-= BM

 

[figgie]

Well

what does the tsrm say?

 

[Bruno Molly]

Well

what does the tsrm say?

Gives the Min and Max specs.. I'll get them to measure the lobes and the journals.

thanks...

 

[black89t]

if they have enough meat on them have the machine shop polish the bearing journals to get rid of the scuffs.

 

[grimreaper]

^ and then lap and line bore the cam caps/tunnel.

 

[aljordan]

If you're looking at the scratches in the babbit material, then it's fine. Don't remove the babbit material either. Just let it go, it'll be fine.

Read Reg Reimer's tech notes on the 7m at www.supras.com (follow the SONiC link) for more information.

 

[Bruno Molly]

TSRM Says:

Standard Lobe height: Intake = 1.5098
Exhaust = 1.5098
Min Lobe Height = Intake = 1.4961
Exhaust= 1.4961

Std Journal Diameter No.1 journal = 1.0610 - 1.0616
No.2-7 journals = 1.0586 -1.0620


Intake
TSRM Specs- Std Journal Diameter No.1 journal = 1.0610 - 1.0616
No.2-7 journals = 1.0586 -1.0620
My measurements:
Journal
1. 1.059 (-002)
2 1.057 (-.0016)
3. 1.056 (-.0026)
4. 1.056 (-.0026)
5. 1.058 (-.0006)
6. 1.057 (-.0016)
7. 1.059 (+.0004)

Lobes
TSRM Specs:Standard Lobe height: Intake = 1.5098
Exhaust = 1.5098
Min Lobe Height = Intake = 1.4961
Exhaust= 1.4961

My Measurements:
Cy1 1.508 (+.0119) 1.509 (+1.029)

Cy2 1.511 (+.0149) 1.511 (+.0149)

Cy3 1.510 (+.0139) 1.510 (+.0139)

Cy4 1.509 (+.0129) 1.509 (+.0129)

Cy5 1.511 (+.0149) 1.511 (+.0149)

Cy6 1.509 (+.0129) 1.510 (+.0139)


Exhaust

TSRM= Std Journal Diameter No.1 journal = 1.0610 - 1.0616
No.2-7 journals = 1.0586 -1.0620

My measurements

Journal
1 1.060 (+.00014)
2 1.058 (-.0006)
3 1.058 (-.0006)
4 1.059 (+.0004)
5 1.058 (-.0006)
6 1.058 (-.0006)
7 1.059 (+.0004)


Lobes
TSRM= Standard Lobe height: Exhaust = 1.5098
Min Lobe Height = Exhaust= 1.4961

My Mesurements

Cy1 1.509 (+.0129) 1.509 (+.0129)

Cy2 1.509 (+.0129) 1.509 (+.0129)

Cy3 1.511 (+.0149) 1.510 (+.0139)

Cy4 1.510 (+.0139) 1.510 (+.0139)

Cy5 1.510 (+.0139) 1.510 (+.0139)

Cy6 1.510 (+.0139) 1.511 (+.0149)

Comments???

 

[CyFi6]

Journals seem a bit under sized, try plastigauging the cams. If you have the valves in it, you can put the plastigauge on the underside of the journal so the valve spring pressures dont squish it.

 

[Bruno Molly]

Journals seem a bit under sized, try plastigauging the cams. If you have the valves in it, you can put the plastigauge on the underside of the journal so the valve spring pressures dont squish it.

well, At this point it's basically clear...too much clearance in certain locations. Once I put this engine back together I don't won't other internals starved of Oil Pressure because of too much clearance in the camshaft journals. Has anyone else ran into this? If so what did you do? All the used cams I have found so far are far worse!!!
Who sells NEW 7MGTE Stock ground Camshafts at a decent price other than the Stealership?
Where is a good place to get a NEW oil pump?
What's the consensus on going with a NEW oil pump vs Shimming the old one?

7m=Migrain

 

[grimreaper]

these clearances will play a part in your low rpm oil psi. Idle, low rpm cruise etc.. The pump should over come the lose as rpms climb. Look at driftmotion for a nice upgraded pump.

Talk to suprarich. He does stock re grinds..

If it were me, send the cams and head into a good shop, have the cam caps lapped to tighetn up the clearances and then line bore the cam tunnel. problem solved. Have the cam run out checked too. I havent seen a bent intake cam yet but every exhaust one i've measured (about 6) has been right at the max run out spec or over.

 

[CyFi6]

My clearances were out of specs, and i had found a guide on here explaining how to repair the common issue. Basically, took all the valves out and plastigauged the cams, then where clearances were too large, you take those caps and lightly sand them down evenly and recheck the clearance until it is in specs. I have done this to all my caps, and never had it line bored. Yes, the bores are out of round, but with the camshaft it is not a big issue. I have been running it like this with great oil pressure (About 10psi idle, rebuilt engine, shimmed pump) and no problems whatsoever.

 

[Bruno Molly]

these clearances will play a part in your low rpm oil psi. Idle, low rpm cruise etc.. The pump should over come the lose as rpms climb. Look at driftmotion for a nice upgraded pump.

Talk to suprarich. He does stock re grinds..

If it were me, send the cams and head into a good shop, have the cam caps lapped to tighetn up the clearances and then line bore the cam tunnel. problem solved. Have the cam run out checked too. I havent seen a bent intake cam yet but every exhaust one i've measured (about 6) has been right at the max run out spec or over.

Ok...so are you saying have the cam stands and caps lapped? then Line bored? This tightens up the already worn Cam journals....So do I also have the cam journals Polished so they don't chew up the line bore job?
Who do you recommend to do the head work? (lapping and boring)
How much does this cost for all this?
I will talk to suprarich about regrinding.
Thanks to everyone for the Info. Now i'm getting somewhere because used parts are scarce, and usually worn out or have marginal to less than minimal acceptable condition.
BM

 

[grimreaper]

My clearances were out of specs, and i had found a guide on here explaining how to repair the common issue. Basically, took all the valves out and plastigauged the cams, then where clearances were too large, you take those caps and lightly sand them down evenly and recheck the clearance until it is in specs. I have done this to all my caps, and never had it line bored. Yes, the bores are out of round, but with the camshaft it is not a big issue. I have been running it like this with great oil pressure (About 10psi idle, rebuilt engine, shimmed pump) and no problems whatsoever.

for an in car repair id say go for it. Technically its not the correct fix though so I dont mention this. I have done the above with good results as well.

Considering the heads off the car you might as well do it correctly.

op: Your going to have to shop around in your area for a machine shop, or get it done from one of our vendor's. Yes you'd need to have the cam journals polished as well.