Camshaft During Engine Overhaul. Refurbish? Replace? Repent? Retreat?

[Launchpad McQ]

Hi all,

Some of the many helpful frequent contributors may recognize I have an ongoing absurdly longwinded rebuild thread (just like the rebuild itself) but I wanted to pose this question separately since it's fairly specific. About 2.6 seconds after I got off the phone with Ken last week ordering every single moving part the Atomic 4 possesses, I realized we hadn't discussed the camshaft. In other contributors' rebuild threads, the only consideration I had seen regarding the camshaft was the relatively "soft" brass(?) camshaft bearings that could be damaged by "hot tanking" the block or careless reinstallation of the cam. In absence of any clear direction I took my camshaft up to the machine shop who's doing the block work. The shop owner took a look at the cam and cautiously advised I send the cam off to get "cleaned up" and "hardened" and provided the contact info to a company in Oklahoma. (I'm rebuilding the engine at home in Denver even though the boat is in San Francisco) He expressed concern over the surface rust on the cam lobes and hypothesized it would only cost around $65-ish for the necessary work. Understandably, I echo his sentiment that "you've spent this much money/time/effort on this project you might as well leave no stone unturned."

My question is twofold. First, based upon these pictures would y'all be comfortable reinstalling this camshaft in a fresh rebuild? Second, does anyone know what "rebuilding" a camshaft involves? What does a 'hardening' process involve? Assumably if any material was machined off the camshaft, like a crankshaft, would likely need to be replaced with weld and polishing? What about the lobes? How would they assure the profile remained unchanged?









Before someone suggests it, I'll point out that yes, I know our great host sells used camshafts for $125 and that's obviously an option. Frankly my only hesitation is that even the picture in the MMI catalogue appears to have some surface wear on the lobes as well. Moreover I'm just interested in whatever wisdom the braintrust has to offer on camshafts, hardening, tappets, best practices, etc.

[Launchpad McQ]

And if anyone is interested enough, here is the contact that was recommended to me by my machine shop:

http://willhoitescams.tripod.com

(Obviously not an endorsement since I haven't even contacted them yet but in case someone was curious as to who was recommended.)

[zellerj]

HI McQ

I always enjoy reading your posts but now i am confused. Please fill us in on your story. I thought you rebuilt this engine a long time ago and are just now telling your story in a very interesting narrative. What is the real scoop? Are you currently rebuilding your engine or was it done a while ago. If so where are you at currently and when did the historical narrative stop?

[Launchpad McQ]

Hi Jim,

Yeah sorry for the confusion. I know it's generally frowned upon to have multiple threads going for the same engine rebuild but I was trying to avoid confusion since I'm not up to date with my 'rebuild thread' posts. I know I've been a little behind but I'll catch up I promise. To clarify the timeline, I purchased the boat with the non-running A-4 in 2013, tinkered with every engine system from 2013-2015 to diagnose the non-running condition (where my 'rebuild thread' narrative is currently stalled), ultimately got the engine running, then made a couple of significant screw-ups that likely caused enough damage to require the full rebuild, and now am currently in the middle of a slow-but-steady full teardown/rebuild (Oct 2018.) I didn't want to ruin the timeline and quickly skip through the story of how I toasted my engine just to catch up to present-day. It's informative and hopefully entertaining enough to be worth the wait.

-Jonathan
P.S. I hope the A-4ians will forgive my infrequency of posts for the time being. However, if anyone wants a taste of what it's like being in the throws of an ongoing multi-year whole-house renovation while dealing with a crying, screaming, sleepless, teething 13 month old who uses your nose as a chew toy, living in a semi-finished construction zone with 1 functional toilet, sleeping on an air mattress on the floor, covering 2 mortgages and full-time daycare, er, I mean 3 mortgages, supporting a stressed-out, sleep-deprived wife, and then commuting 997 miles to work at a job with a company that's in the middle of a merger, while trying to squeeze in 1 hour/month to work on your old busted sailboat motor, I can post a video on YouTube so you can get a better feel for the audio. Believe me the sound is worse than any rod knock you've ever heard!

[lat 64]

It's kinda hard to tell, but I think you have a little surface rust on the base circle in the last snapshot. Probably from off-season storage.
Not a biggie. Take it to a machine shop and have them lightly polish it. Sometimes they call it "micro polishing".
It looks like the bearings could use that love too.
It's the same grit belt they use to do the final polish on a crank after it's been ground or just handled poorly by mechanic. A polishing belt is best after it's broken in. New ones take too much.

Re: cam grinding, When an old cam(a core) is ground, the base circle is ground too. The lift remains the same. Or , if you are modifying it like a hot rod, some changes are made in the new profile. I think they may flame harden after this(?)
A regrind probably costs more than a good used cam from MMI. I have even installed cams without polishing them in a few old timers—it's a judgement call.


Rock on,
Russ

[joe_db]

So how about a hot cam?

[ndutton]

When evaluating this have a critical look at the lifter surfaces in contact with the cam. Decades ago I rebuilt a Ford 390 that included a new camshaft. I learned there would be no warranty unless a full set of new lifters were included on the same invoice.

[Launchpad McQ]

Thanks for the responses guys as always. I spoke with the camshaft shop in Oklahoma and I'm leaning towards having them grind it and send it back. Of course I'd always prefer to give the business to Moyer but in this case it sounds like I'll save money, reuse and original part, and they would be able to "clean up" the lifters as well if I send them as a group. Honestly I'm also a little curious to see how polished they can get it. Heres some pics of the lifters cylinders 1-4, in order from left to right.


Cylinder 1

Cylinder 2

Cylinder 3

Cylinder 4

[Grant]

The surface rust that your photos show will cause the lobe to go soft. Cams are usually nitrided after a grind. That is a high temperature soak in a nitrogen enriched environment.(there is more to it) . Nitriding hardens the surface for more wear resistance. Surface rust goes thru the nitriding and will allow much faster wear on the lobes. Make sure they do the lifters also because a rough surface on a lifter can eat a camshaft very quickly. Good luck. Grant.

[lat 64]

When evaluating this have a critical look at the lifter surfaces in contact with the cam. Decades ago I rebuilt a Ford 390 that included a new camshaft. I learned there would be no warranty unless a full set of new lifters were included on the same invoice.

When I was doing a lot of this, that was the general practice on V-8s and other common engines. Lifters were not too expensive then($5). The old lifters were usually worn to a "dished" surface from the cam lobe. The higher spring pressures of those modern(70's–80's) engines helped accelerate wear after the miles racked up and the maintenance got lax.

But,
On old flatheads and oddball motors we often set them right back in if they looked good. It was always a judgement call on those—cost verses life expectancy.
On my A-4 I reground the mating surface. It is a similar job to grinding the tip of a valve stem. That's probably what McQ's Oklahoma shop means by "clean up"

Grant,
Yea, nitridng must be what I meant when I said "flame hardening". We never had the facilities up here for that so I never saw it. I just recall the nice newish gray surface on reground cams from mail-order suppliers.

[lat 64]

So how about a hot cam?

No.


We aim for dependability, longevity, and economy.

Now go clean the chalkboard and reflect these goals.

[Launchpad McQ]

I sent the cam to Oklahoma today. It's only $20 round trip shipping and I want to keep this project moving along when at all possible. The shop owner sounded like a good 'ol boy if I've ever heard one:

Me: "Yes, hello. My name is Jonathan and you were referred to me by Terry in Denver. I wanted to discuss if you'd be able to refurbish an old marine engine flat head cam on a-"

"Yeeeeeeeeeeaaaaaaaah! buuuuudy! you know I ain't dun' gone seen a cam I can fix yet!"

Me: "Great, but this is from a more obscure small four cylinder engine that most machine shops in the midwest don't probably-"

"Yeeeeeeeeeaaaaaah! buuuuuuudddy! Don't chu' go gone worryin' 'bout dat now you know I seen every cam from a Cushman lil' putt-putt to a 1000 hp Mustang ya hear!?"

I'll report back in a week or so with pictures of how it goes...

[tenders]

My town still uses Cushman "lil putt-putts" to collect trash twice a week, so I know exactly what you/he are talking about. Very distinctive three-wheeled utility vehicles.

[lat 64]

You forgot to ask what's the name of his dog.

Probably a one-eyed lab-mix that sleeps all day on a stinky blanket by the door.

Sounds like a good shop.

r.

[Administrator]

Who was it that originally mentioned the shop with the one-eyed dog? I read every single post, but after a hundred thousand or so, it gets a little foggy on the details.

Bill