We were in TO at my cam /crank grinders picking up a cam he had re ground for Mikes old school hemi rail. (450 lift , 246 deg @ .050" hyd) They were reprofiling a six cylinder cam when we were there so we watched and asked questions. Very interesting machine. This one was a Berco which is some of the higher end machine shop equipment. As mentioned before the extra lift comes off the bottom or base circle and then the cam is ground till the profile is ground 360 degrees with no spaces. I had been through crane in the 70s in Florida (Hallandale plant) and worked in machine shop as well as had my own for many years (but not with cam grinding equipment) but never had the chance to stand and watch the process that long. We stayed about 1/2 hour. Most interesting.
Any of that type of stuff is fascinating. Crank grinding always wowed me. And its not totally rocket science either, just having the right tools at hand and the knowledge of how to use them. Bob
The old portable crank grinding was amazing to watch them grind the crank with it still in the car...Proper equip can do anything.
I heard once from the Sunnen Rep (John someone i forgot his last name) about a guy in Mexico riggng up four Winnona portable crank grinf ders andrunning a lathe at super slow speed with abelt and grinding all for journals on a V8 at once. He said it looked like an octupus but actually worked. Never knew for sure if it was for real or just a salesmans tale. I have thought about it though now for some 42 years since i heard it. Don
Ok back in the 60s there was a cat in Wichita Kansas named Chet Wilson that built his own cam grinder out of a Storm Vulcan Saturday Night Special crankshaft grinder. You talk about an interesting machine to watch !! This guy was a GENIUS and a true HOT-RODDER >>>>.
You've hit on one of those concepts that, when you first think about it, seems like it couldn't possibly work. If you're grinding material off of the cam lobe, how could you possibly end up with more lift??? Yet if you study it with even a basic understanding of physics you'll understand that it does actually work! You gotta love any opportunity to see this kind of work being done and having one of those "A-HA!" moments. On the other hand, I've gotten gotten into arguments with people who swore that they were going to increase their valve lift by switching to longer pushrods.
We used to increase advance sweep in HEI dizzys by grinding the flyweights to retard 6 additional degrees. Then, we advanced the initial (static) timing 6 degrees, therefore getting 6 more on total centrifugal advance. (this was just prior to the availability of the aftermarket spring kits)
10-4... back when I was working at an Enco station we had a local machine shop do several in-car crank grinds (usually on just one cylinder). The feeling was only one journal was bad so why grind 'em all...
yea its one of those things that makes your mind go "Not a chance in hell that it can work" When I was little before heal and ramp etc made any sense to me I used to hear it a lot from some older fellas that ground cams for a living. I got to watch once in awhile and just loved watching it happen. Now I'm older and the terminology makes a little more sense to me, once in awhile when I conjure up the pictures in my head it just amazes me what those old timmers could do. That equipment was way primitive to what is available today.
LOL! That's what I'm talkin' about! You must be one of those people that's got one of them GIANT BRAINS. Actually I'm kind of ashamed that I didn't think of that. I usually get stuck at that "I cut it off three times and it's still too short" stage!
i watched a guy regrind a cam for a triumph 500 cc mc. he did it in a lathe with a toolpost grinder. it worked too. he won that weeken .
Back in HS, I held the flywheel drive motor in my hands for onna the in car crank grinding units so have been there under the car with my Mechanic friend that was trying to get it to work proper................ I want to say that one of the problem's was not being able to dress the stone down 100 percent as needed, but it's been years and years, like 1964? pdq67
"Who in Toronto does a good job on cranks and cams ? " I use John at Canadian Chrome and Crankshaft 33 Peelar Road Concorde Ontario. I have used him for 30 years now and have been very very satisfied. He has made many cams for me and made me a master too for a lost grind no longer avaialble. He kept it mine too even when other shops phoned and asked for Dons grind. Not a chance, he told them. If you want Dons grind call Don. He will sell you one. Then he would phone and tell me who called. I used him on the 4CT engine build and used him on the lemans project build for both cam and crank and he hard chromed the crank for me as well which is his specialty. After 30 successful years of doing business together I have no desire to look elsewhere. Nothing more needs to be said. When John is looking after it I dont need to worry about it. Nor do I second guess him .He knows his craft and knows it well. Don
Cool stuff, good to hear. I'm going to need some oddball stuff done soon. Cams and crank. I'd rather deal with someone local, who will do it right, rather than send it to California.
Found a cool video on youtube of a cam being done. <object width="640" height="385"><param name="movie" value="http://www.youtube.com/v/mzscFuggl5Q&hl=en_US&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/mzscFuggl5Q&hl=en_US&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="640" height="385"></embed></object>
Hi Don,its been a while from e-mail chat on a intake manifold.Ive got a ? i ask and get a run around on,here goes. Why does a cam have to be broken in ? What is the diff if you had a new crankshaft?If there both getting proper oil what is to break in ? Thanks,o/t i found a nos chry/eddy manifold with the same two holes in it that mine have(the pics i sent you 6mo ago)Still questioning that too ,haha...........JB ......Hope you and family are doing well.
Forgot when it was but hotrod had a article showing how the nascar boys weld there cam blanks to obtain a larger base circle and a harder surface to handle the extreme opening pressures. They are still required to run flat tappet cams so they take it to the next level for shure.cool stuff
While it looks like all a cam has to do is provide lift and timing for valve opening and closing events, there's a lot of other technical "funny business" going on as well. I think that most, if not all, modern flat tappet OHV engines are designed such that the lifter runs slightly offset from the centerline of the cam lobe. In doing so the lobe's movement across the lifter face causes the lifter to rotate slightly. This effect is easily seen in the pushrods rotating in a running engine with the valve covers removed, It prevents the lobe from running continously on the same area of the lifter and wearing it out prematurely. If you get the chance to inspect a dis***embled engine sometime, look at the wear patterns on the lifter face and the matching cam lobe. The lifter wear should appear as a narrow circle maybe a third of the way in from the edge, showing that it's been rotating properly. Rotate the cam and look at it's wear pattern. On the base circle it should start at the edge of the lobe and then move inward as it approaches the nose. The lobe is actually gound with a slight taper to produce this "moving" wear pattern. And when the engine's running, the cam and lifters are only supplied with splash oiling which is trying to be flung off the cam while the lifter tries to "wipe" as much oil off the lobe as it can. Again, it's amazing that the whole set up works as well as it does. But only if it's broken in properly so that the wear faces develop the proper finish to live with the little bit of lubrication they're given. But I've never heard of a connection between camshaft break in and the installation of a new crankshaft. Can't say that there's nothing to it, but I'll be interested to see if anybody else comments on it.
Why . Always a good question. Unlike a cank where a soft bearing is floating on a sea of oil (AKA hydrodynamic wedge) A cam has two hard materials rubbing on each other. At first they dont like each other but after a while of rubbing together the high spots get worn slightly away and the surface become a lot tougher , a little smoother and more compatible. During the break in process when this wearing in or mating is going on lots of oil is required to prevent things from getting overheated. While an engine does drip oil constantly on the cam it is enough for maintanence but not enough for breakin if there is anything more than the minimum of mating to go on. The largest and best supply of oil is thrown up on the cam from the crank. So by keeping the engine at 2500 for 20 mintes we ensure that more than enough oil is supplied to these new surfaces as they get worn in and used to each other. After 20 minutes the process is complete and if not then probably never will be. During that 20 minutes if allowed to idle a cam lobe can wipe in a split second so we keep it bathed in the slimy stuff till the honeymoon is over and togethernesss begins. Most guys do pretty well although some do not get the "Dont let it idle for even a second " and wind up with a 7 cyl cam . And then there are the boneheads that crank the engine over on the starter till they get oil pressure. One of the major cam manufacturers once said in a bulletin "more cams are worn out on the starter than any other way." I completely agree. An engine that starts will get oil pressure in seconds while and engine cranking on the starter may never get it till all those new parts are rubbed dry. The cam and lifters being the first to be sacrificed on the altar of stupidity. That is why it is so important to make sure the engine fires immediately when you first start it. Ie timing close enough it will start for sure, fuel in the carb , etc etc. Don
Thanks ClayMart and Don,i knew about the offset and the lifter turning/circle on bottom of lifter,BUT Icould not put it togeather on why 2500 rpm for 20 min.Just seems like a long time with no pull,and neighbors dont help haha.To tell the truth ive never done it correctly then.Thats hard to admit guys.I now know why i had a lifter fail on a 383 rebuild.Lifter started making noise so went to work on it and found a lifter with a cut 1/4 inch up from the bottom of the lifter and width of cam. Only took 20+ yr to find out why,it happened but i know i hurt the cam now and therefore hp on others.Thanks guys,i knew there was a reason i stoped on the 413,soooo in a month maybe i can make 20 min of NOISE....................YG
One more Question. So with proper breakin done if reusing cam and lifters in another motor or a rebuilding same one ,is it most important to keep each lifter with each lobe ? Im thinking Yes (but cking) Also if one lifter failed and replaced,does the breakin start all over for one lifter?My brains excited and ????? of all kinds on this subject are comming up...This is cool ,great sat night.thanks....................YG
Don did a better job than I did explaining the need to keep everything well lubed during the break in period. That's the reason GM would not warranty a new cam if it wasn't installed with a good coating of their EOS oil supplement/***embly lube. I would say always put the lifters back in the bore they came out of if they've been run-in at all. Make sure everthing's got a good clean coating of oil on it. If the motor is going to sit a while before starting a coating of EOS or some kind of ***ermbly lube wouldn't be a bad idea. You probably wouldn't have to go thru a formal break-in though. Replacing a lifter or two on a used cam might be a bit of a **** shoot. If the wear pattern on the cam looked bad at all I think I'd rather change both the cam and lifters with new. If you need to watch the expenses it might be worth trying replacing just the bad lifters (if the cam still looks good) and breaking it in like it was all new. But only if you won't be too disappointed by the possability of having to do it over sooner instead of later.
I see this thing in a whole new light,i ask but never got answers or if i did ,i didnt get it but this makes sence.I never thought of the cam as having to mate itself to the lifter or vise versa(flat surface on cam/flat on lifter).Two flat surfaces whats the big deal.I now know whats going on.Its not just a bump stick anymore,haha............YG.....Thanks
I personally would put new lifters on a used cam. Using the old ones is a gamble to my way of thinking. In a machine shop I worked in my early years we did probably 5 to 6 engines per week ALL had new lifters on the old cam . It was just the norm. I dont ever recall one coming back. Running the cam in costs nothing and insures a reasonable level of success. Don
interesting, I always wondered if this might work but usualy by the time I've torn a motor down that far it gets rebuilt. on a side note but still cam grinding related I picked up this little book a while ago check it out, grind your own cam!
The Jalopy Journal
