Engine: Cam specs- what does this mean (don't speak "cam" :-)

[bsrosell]

Hi,
wrote and asked the shop my cam got sent out to (from person who supposedly was supposed to do everything but just farmed out all the machining and then had me pay him when I picked them all up).

The guy did write back from the cam shop, says: "Camshaft spec stock grind Ex and Intake lift on lobes 260 each Duration at 50 206 each mechanical lifters the black coating is to help prevent rust and help to hold the prelube".

the guy doesn't waste any words. :-)
He builds race cars with these other guys who did my block, crank, rods.... so I can only hope there is taper as well; (just got done reading a post about that being critical for keeping the lifters rotating....) Never thought 'make sure they did', again I'd hope that is standard for a professional cam shop, especially used to high performance engine work... How would you even measure that (I've installed the cam, but oil pan is still off til I get my new gaskets).
Probably too subtle to measure with a Vernier, maybe can't even get at it under the crank now to do so...
Guessing it is fine, but thought I'd ask about the cryptic 'answer' I got back on what was done to my original cam...
thanks

[JoeHall]

The quote you provided is actually three sentences: after, "206 each", there should be a period, and after, "lifters", there should be a period. The first sentence says the cam is within spec, as for lift and duration. The second sentence simply states the cam is used in conjunction with solid lifters. The last sentence is to explain why he sent it back with a black coating.

The first sentence speaks to your question, and assures lift and duration are within spec, but does not say if he had to regrind it, or simply inspected it. More importantly, it does not speak to lobe taper, but SHOULD. That is sometimes a topic modern cam grinders are not even familiar with. If familiar, they may not have equipment to measure it, or to do it. The reason it is a lost topic is because most modern cars, and many classics, have been converted to roller lifters, or OHC. In those cases, there is no cam taper. Long story short, cam taper, mated with offset, spherical lifter face, is what makes our Stude lifters rotate. The cam taper is so slight, it is measured in minutes, instead of degrees. (One degree equals 60 minutes.) Lifters are checkable, at least for being convex, by placing the face of one against the side of another; it will rock ever so slightly. But you cannot check to insure they are truly spherical that way.

Ideally you woulda sent the cam to Phil Harris, and used his lifters, but its a little late now. If I were you, I'd reassemble, and see what happens. How you will know if there is a problem: if the lifters do not rotate upon startup. Some will spin fast, like a top, and some will rotate very few seconds,, but they all should rotate. If not initially, note the ones that do not, and re-check in 1000 miles or so. Sometimes they will begin to rotate as they scrub in, and mate with the lifter face. If they do not rotate, you could run pure DZZP, and it still would not keep the cam lobes and lifter faces from, "wipe out".

Bear in mind, any changes from OEM, will make all the above even more critical; stiffer springs, and/or more aggressive cam ramps only destroy the cam lobes and lifer faces quicker. This phenomenon is also known here as, "wiped cam" syndrome.

[swvalcon]

Who was used for the cam? Wasn't Berry cam here in MN by any chance was it? If it was cam was done right. I've had him grind 100's of cams for me. His Dad who past away in maybe late 90's knew more about cam shafts then anyone I had ever met. The 260 and 206 at 50 is your cam Duration and the at 50 Means at .050 lift. There should also be some more numbers on the cam card with more specs. Only way to check to see if a cam is within specs is to set up a degree wheel and check it that way then from there you can change the timing gear setting to what you need to set it where you want it.

[altair]

Curious only, don't know anything about cam grinding, wouldn't the shop duplicate the original spec and wouldn't they have the spec in a chart. I had my 259 cam ground and the operator (old timer) just set the machine and walked away, we sat and talked in the office and when the machine was finished it automatically stopped. When I took the lifters in they were concave and when I took them out they were convex, I didn't see the machine grind them, I don't know if the grinder rotates the lifter or the stone is pre-tuned to the shape. All my lifters totate gently and evenly and after initial adjustment required a second minor adjustment on one lifter and it remains quiet thereafter. I don't quite understand the need for cam spec confirmation after the fact when the cam shop grinds it to a specific spec. You should be able to install the cam and go. I have installed several cams in engines with full trust in the cam shops with out any issues.

[JoeHall]

Curious only, don't know anything about cam grinding, wouldn't the shop duplicate the original spec and wouldn't they have the spec in a chart. I had my 259 cam ground and the operator (old timer) just set the machine and walked away, we sat and talked in the office and when the machine was finished it automatically stopped. When I took the lifters in they were concave and when I took them out they were convex, I didn't see the machine grind them, I don't know if the grinder rotates the lifter or the stone is pre-tuned to the shape. All my lifters totate gently and evenly and after initial adjustment required a second minor adjustment on one lifter and it remains quiet thereafter. I don't quite understand the need for cam spec confirmation after the fact when the cam shop grinds it to a specific spec. You should be able to install the cam and go. I have installed several cams in engines with full trust in the cam shops with out any issues.

I agree, we should be able to install and go, and most have blindly trusted the modern cam grind wizards, and did just that. Then, when a cam, "wipes out" in a few hours/miles, we have blindly believed it was because we did not use DZZP. A better place to look when trouble shooting, would be lifter rotation, from the first start up. If not rotating, go upstream in troubleshooting.

Believing a cam wipes out simply because of DZZP is akin to running over our toes with a lawn mower, then believing it would not have cut our toes, if we'd had socks on.

[JoeHall]

Here is the cam card from my Phil Harris cam , that we verified here after receiving it .

Skeeter cam by Bill H, on Flickr

This is a modern cam card, for a modern cam. That's exactly what I am trying to splain here. Taper is not even addressed, yet it is critical for Stude motors. I should say critical for folks who plan to drive their Studes regularly. ForTQs, and folks who only go 1/4 mile at a time very quickly, its a non-issue.

[altair]

When I took my cam and lifters into the shop for grinding I was barley within 10 feet and the operator said you have a Studebaker 259. I asked him how did he know he just said I have seen them before. He had several cams in the shop and they all looked the same to me.
I then felt very confident in the operator. I installed the cam and have never looked back.

[TWChamp]

Curious only, don't know anything about cam grinding, wouldn't the shop duplicate the original spec and wouldn't they have the spec in a chart............

Because the cam will be a smaller diameter than original, it's impossible to duplicate the original cam profile. either the lift or duration has to be different.

[doofus]

I have 6, V8 cam cores in my shop, fodder for future projects. a cam still within "Spec" is a treasure for sure. odd thing is all my cam cores checked out with .001 under spec journals, every one! checked micrometer with standard and it was spot on, go figure! Doofus

[bsrosell]

Who was used for the cam? Wasn't Berry cam here in MN by any chance was it? If it was cam was done right. I've had him grind 100's of cams for me. His Dad who pasted away in maybe late 90's knew more about cam shafts then anyone I had ever met. The 260 and 206 at 50 is your cam Duration and the at 50 Means at .050 lift. There should also be some more numbers on the cam card with more specs. Only way to check to see if a cam is within specs is to set up a degree wheel and check it that way then from there you can change the timing gear setting to what you need to set it where you want it.

Sorry, I don't know why I never replied to this, too many posts going during this time I think and never came back after satisfied with the first reply? But YES, was Berry cam, I brought the whole block up to Annandale, and "my contact" sent out the crank, cam and block three different shops. But it was Berry cam, so I appreciate your affirmation! (I'm looking for an old post I know I did, and stumbled across this one and re-read for fun. ;-)

[PackardV8]

Because the cam will be a smaller diameter than original, it's impossible to duplicate the original cam profile. either the lift or duration has to be different.

I'd have to disagree with the above. When cams are reground, the original profile, lift and duration should be replicated. Only the total lobe height changes slightly, necessitating tightening down the rocker adjuster screws a few thou to take up the slack.

jack vines

[Studebakercenteroforegon]

I'd have to disagree with the above. When cams are reground, the original profile, lift and duration should be replicated. Only the total lobe height changes slightly, necessitating tightening down the rocker adjuster screws a few thou to take up the slack.

jack vines

Precisely. Some reground cams will note the “BC” which means base circle. It will be smaller than original due to maintaining the desired profile. The base circle number is just a reference number.

[TWChamp]

I still stand by my original statement, that a cam can't be reground and have the same lift, opening, and closing, as the original cam had. Rate of lift, total lift, or opening and closing can't all be the same as the original. It can be close, but not exact.

[PackardV8]

I still stand by my original statement, that a cam can't be reground and have the same lift, opening, and closing, as the original cam had. Rate of lift, total lift, or opening and closing can't all be the same as the original. It can be close, but not exact.

You are welcome to your own opinion, but not to your own facts. I've checked many reground cams and they are as exact as the factory original. There is no mechanical or geometric reason taking a few thousands off the entire lobe changes the lift, opening and closing. Can you reference any source saying it can't be the same?

jack vines

[TWChamp]

As the cam diameter is decreased by grinding, the speed of the cam running across the lifter is decreased, so if you want the same rate of lift, the profile needs to be changed slightly. I know these are only very small amounts, but we are using the term "exact" in this discussion, so "close" doesn't count.