[pippintook]

I wiped some cam lobes on my 400. This happened about 3 years ago. When this initially happened I thought I may be able to change the oil/filter a few times and install a new cam/lifters. The consensus seemed to be I was better to do a teardown and inspection. So, finally, 3 years later, I have removed the engine and I am doing the disassembly. I am finding a fair amount of grit in the engine and seeing some signs of wear in pistons/bearings etc. I thought I would post some pics to show guys what I am seeing and what they might expect if they wipe a cam lobe(s) and to get feedback on possible causes for the cam lobes wiping and feedback on the condition of the engine.


Background:
(i) I rebuilt my engine myself. I have rebuilt 4-5 engines. I was careful during assembly, measured all clearances and took my time. Engine is 1978 400 W72. Engine had about 3000 miles/18 months of use before wiping the cam lobes. I used Mobil 1 synthetic oil 15w-50 on my last oil change prior to wiping the cam lobes. Prior to using Mobil 1 I had always used Shell Rotealla 15w-40 diesel oil. With both the shell and the mobil my oil pressure was good (alway above 20psi at idle and 60psi cold). 3 years I was a bit ignorant about the zinc in oils protecting flat tappet cams. I am not sure if using the Mobil 1 had any effect.

(ii) the engine specs were:
400 + .040
Keith Black HYPER cast pistons
Stock rods/balanced/ARP bolts
Stock crank/balanced
Stock Qjet intake and qjet
60 PSI Sealed Power OIL Pump
summit #2801 cam
summit #951? hydraulic lifters
Stock 6X Heads cut .030
summit doubleroller timing chain
7/16" ARP rocker studs
crane kool nuts
Crower 68404 Valve springs
Stock Valves/shields/rocker arms/pushrods
installed in 78 TA, 4psd, 3.42's with headers and dual exhaust

(iii) I did not determine what caused the lobes to wipe.

(iv) There were 3 main worn cam lobes. These 3 lobes were worn approximately 0.10"-0.155". Some other cam lobes were worn 0.015"-0.018". I did not use one valve spring during cam break in. The cam was not too radical (Summit 2801). Crower 68404 valve springs are not too stiff either. The cam ran fine for 3000-4000 miles for almost two years. I thought I installed the cam thrust plate, eccentric and cam gear properly.
The 'step' at the back of the cam gear was right against the first cam journal. The cam did protrude slightly through the cam gear. Everything was properly torqued. There was no scoring/marks on either side of the cam thrust plate.

(v) Most Severly worn cam lobes
---------------------------
Exhaust #2 = 1.493"
Exhaust #4 = 1.459"
Exhaust #8 = 1.428"

Notes, Exhaust #2, Exhaust #4 and Exhaust #8
are all on passenger side head

Approx Measurement of all cam lobes
------------------------------------
1.493 - Exhaust #2 ** visibly worn **
1.566 - Exhaust #1
1.582 - Intake #2
1.584 - Intake #1
1.550 - Intake #4
1.581 - Intake #3
1.459 - Exhaust #4 ** visibly worn **
1.561 - Exhaust #3
1.538 - Exhaust #6
1.568 - Exhaust #5
1.588 - Intake #6
1.583 - Intake #5
1.581 - Intake #8
1.580 - Intake #7
1.428 - Exhaust #8 ** visibly worn **
1.563 - Exhaust #7

* 6 other lobes, also showed some wear, according to measurement *
1.566 - Exhaust #1
1.561 - Exhaust #3
1.550 - Intake #4
1.538 - Exhaust #6
1.568 - Exhaust #5
1.563 - Exhaust #7


(vi) While I would like to know what caused the cam lobes to wipe, I am not too concerned with finding a cause. I am planning to use a Roller Cam for my next rebuild. I dont think I will ever run a flat tappet cam again.

I thought I would post some pics to show guys what I am seeing and what they might expect if they wipe a cam lobe(s) and to get feedback on possible causes for the cam lobes wiping and feedback on the condition of the engine. Would appreciate feedback on how my pistons/cylinder walls/crank journals look. Could pistons be reused? Should I hone cylinder walls? Polish/turn the crank? Any other advice/comments ?


Thanks

[pippintook]

Attaching pics

[pippintook]

more pics

[pippintook]

Last of Pics

[grivera]

Thanks for the pictures! Nice job with documenting...

[old66tiger]

Actually, not bad considering what went through the motor. I had some shot pean that went through mine and trashed all of the bearings, the oil pump, and crank surfaces. I didn't install my bypass plug until after my first oil change and I fear that it was too late at that point. I will never run and oil filter adapter without plugging the bypass.

[HWYSTR455]

Yeah, that's not that bad. Looks like you caught it pretty early. New pump, bearings, cam bearings look good, polish the crank a little, clean it up, should be golden. Rod bearings seem like none of the rods overheated, big ends should be good. You've torn it all the way down, so most of the work is already done. Pull the galley plugs, runs some brushes through there, and you should be good to reassemble. Don't beat yourself up over 'why', and just move forward....


.

[HWYSTR455]

Those rod bearings show signs of det by the way....


.

[vidguy]

Good documentation. Thanks. I am no expert but I was thinking the same thing; that you dealt with it promptly and properly. The pistons and cylinders dont look bad.