Got this back from a reputable camshaft machine shop. A friend who saw this and took the pic ran his fingernail across the lobes…said his nails caught the grooves. By just looking at…..opinions? Is this an acceptable finish?

 

What "reputable camshaft machine shop" did this ?

 

Better question is why would a machine shop touch the lobes?

 

Whoa. That looks absolutely terrible unless it is some new process they are using but i doubt it. Looks like their grinding wheel was dressed way wrong or was chattering. I think you need to get in touch with the person who ground the cam before you do anything else. I dont guess you want to tell us who it was ?

 

BillK, there is no sign of "chatter". It looks to me like a very coarse dress on the grinding wheel and "traverse" grinding.

 

Probably not the right term to use. I was just trying to emphasize that it definitely was not correct. The whole thing just does not look right, Almost like it was rough ground and never finished. I am pretty sure that cams are plunge ground with the taper dressed into the wheel so they would not be traversing the lobe anyway.

Either way it needs to come back out of the engine and replaced or finished properly.

 

That camshaft is now junk.

 

I asked Mike Jones from Jones cams to take a look and he said it is because they did not dress the wheel correctly for the finish grind. I guess they do a rough grind with the wheel dressed "rough" and then go back and finish grind.

It might be savable if all they need to do is put it back in the grinder and finish grind it. Either way it needs to go back to them.

 

BillK,"chatter" was an incorrect description. Even chatter would have a much smoother surface finish. "Rough grinding is leaving material for "Finish grinding" after the grinding wheel is dressed. The amount left for finish grinding depends on the material and shop practice. Usually .005" to .010" on diameters. This is .0025" to .005" per side of actual material.

When a grinding wheel is used, the sharp corners of the "grit" get rounded off which greatly reduces the cutting action of the grinding wheel and increases pressure against the part being ground. When the grinding wheel gets dull enough,the part will show "chatter". Once you have seen "chatter", you'll recognize it in an instant.

If the grinding wheel was allowed to dwell in the same spot it could have minimized or eliminated the lines going across the lobe. The rotational speed SFPM (surface feet per minute) of the grinding wheel is very high and part rotational speed (headstock) is so much slower, you should never see lines running across the lobe like these.

It very definitely looks and is incorrect. It should ruin a complete set of valve lifters rapidly and at the same time. This should have been found long before it was installed.

BillK, the next time your favorite crankshaft grinder is grinding main journals, have them call you and go watch how its done.

 

Ralph,
I know exactly what chatter is. No need for the details. Like I said earlier I just used that term to emphasize that there was an issue.
It wont happen again

 

The cam was roughed but not finished. Send it back and they can finish it.

 

BillK, sorry to upset you, but correct terminology is important. The "details" are a learning experience. If not for you. then for others.

 

I can safely assure you that you did not upset me even the slightest bit I should know better because I am always harping on people not to reply to technical posts unless they know exactly what they are talking about.

Its all good !!!

I would love to know who the cam was from but probably more importantly what they are going to do about it once they are informed.

 

It seems to me-(I'm not a expert-by far) That the cam is ruined. If it has that same "finish" for the cam bearings as pictured for the cam journals, then it can't be further machined as after further machining will be too small for cam bearings?? Is that true?

 

It would be easier, faster, cheaper, and result in a better cam profile to buy another camshaft with a "modern" profile.

 

Thanks for your thoughts/input/opinions…….just backed up what I thought/was thinking. A new cam is on its way!

 

From the same place ? What did they say when you showed them this ?

By the way in your picture I dont see any cam lubricant of any type on the cam or lifters ? Make sure you load it up with whatever lube the cam manufacturer suggests. Preferably theirs.

 

Bill, used assembly lube it install it and and then pasted a heavier lube on all the lobes after installation to avoid a dry start. Wiped off the heavier lube for the pic..

 

Ok. Just checking. You should use the same lube on the cam and the lifters though. Dont mix that stuff up.

 

Good point…..I’ll make sure to do that,
Tom

 

I have always used a moly paste cam lube, HRL or Crane in the past. Still have some; don't know who offers it today.

 

Still curious about this.

 

I tell my customers to use whatever assembly lube the camshaft manufacturer recommends. That way there is no question if there is a problem.

 

Me too