Cam clean-up?

GB SISSON

GB SISSON

Well-known member
I went up into my attic over the shop last night and retrieved this 8CM cam. I was given a merc engine that had been rebuilt many years ago and overheated badly on the initial drive. 3 or 4 cracks. I used the crank back in the 90s, but the cam was still where I left it. I have since found a std merc 4"er and got it turned. Question: Can I clean this cam up at home with scotchbrite or something? The journals look like they will clean easily, but lobes not so much. I continue to collect parts for a 255 to replace the 221 in my truck based woodie, a Heavy car for sure.
 

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That is too much rust for my liking - as you'll have a lot of pitting on the lobes. Maybe have Pete1 regrind it for you . . . maybe even a bit more performance into it.
 
Hard to say now. Give it a brisk rub on a wire wheel and then show us the extent of pitting. Could go either way .....
 
I would think to be usable it would need to be reground. Probably could be done to 8CM specs. Cam Grinders is in Seattle, Delta in Tacoma. Might be cheaper to find a better one.
Good Luck!
 
Pete is in Washington and does an awesome job .
It will look almost new when he gets done

In my opinion,,,,those lobes look pretty darn rough,,,,,and will in turn be very rough on the lifters riding on them as well

Tommy
 
To use a phrase that I got from Joe Mac (long ago owner of Ford Obsolete, on Signal Hill, and also trans rebuilder during retirement years), thems pits are good for holding extra oil, for better lubrication. lol
 
Greetings Everyone. GB it does look a little weary in the current condition. But maybe this helps...

Option 1 - It's Junk - Whatever you do can't make it worse.

Option 2 - It's gonna need regrinding - You probably can't remove enough if you don't get medieval.

Option 3 - It's ugly now, but wait - Hit it with something? You can always go back to 2 and 1.

Would you guys use Evaporust/Rust911? Would the 'blackening' be a problem?

Then something to see where the pitting ends? Scotch-Brite is pretty gentle, and you can step up/down in 'grit.' A wire wheel sounded like an okay suggestion, but carefully.

https://www.3m.com/3M/en_US/company...0644+8710812+8710964+8711017+3294857497&rt=r3
 
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Only have a wood lathe.... No pits on pump lobe or any I can see on the journals, ran it hard onto my wire wheel. Still some deep pits, so looks like a regrind. The woodie is no hotrod, but it's home turf is hill country. No interest in a 'lopey idle'. I don't even get why that is supposed to be cool. My engine experience comes from the one lung engine and antique tractor world. I would tow all my machinery to the yearly meet behind my 38 tonner with the 59ab and merc crank. SOOOO many old timers at the show only wanted to listen to the flathead V8 idle. I had to warn the newbies that that silent engine was actually running and stop putting your fingers so near the fan blade. In review, I love the added torque/hill climbing of the merc crank, but no interest in extra HP and no interest in hard to adjust lifters from the small base circle, special wrenches, shorter lifter bore etc. I will take some pics of the wire wheeled cam, but as usual my 10 year old phone is dead on my truck seat......
 
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GB SISSON said:
I don't even get why that is supposed to be cool. My engine experience comes from the one lung engine and antique tractor world. I would tow all my machinery to the yearly meet behind my 38 tonner with the 59ab and merc crank. SOOOO many old timers at the show only wanted to listen to the flathead V8 idle. I had to warn the newbies that that silent engine was actually running and stop putting your fingers so near the fan blade.
Click to expand...

Brother from another mother from another seashore?

P.S. I'm so delighted that my 8 year old phone just got a NEW BATTERY this past week and it perked it up so well. Anybody's 3 year old phone got that option? I think I'm buying another battery so I can use it a few years from now?!?
 
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My 6" bore, 12" stroke goes miss, miss, miss for 30 seconds before it hits like a cannon and coasts for another 30 seconds. I reground the cam (one lobe) with my belt sander. The intake valve has no cam. It is atmospheric. Has a light spring and when the piston is on intake it just sort of chatters and draws in what it needs. It is a simple check valve..
 
OK, my phone charged up but it's way past bedtime.... Some pics of the good, the bad and the ugly. Once it's reground is an 8cm cam any different than any other?
 

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I believe the 8cm has the better low end torque required when mercs were heavy, and the new trend was automatic trannys. good cam for the woody on the hilly island
 
I don't think even I would try and run that one, GB. Do you not have any other potential cores to hand?

Mart.
 
There was an article in Hot Rod a while back that explained (and I don't know if this applies to OHV's only or all engines) that the lobes on the cam have a very slight taper when viewed from the side and lifters have a slightly spherical shape on the ends. This allows the lifter to contact the cam somewhere off center, causing the lifter to rotate, a bit like a ring and pinion. Thus there is really no sliding contact. If both surfaces were flat, they would both be wiped out fairly quickly, especially with the higher spring forces found in OHV engines.

Having said this, I'd say give it a go! There might be enough taper to get the required action.
 
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