camshaft identification

[bigaadams]

other than v-blocking a cam using degree wheel and dial indicator, is there any real way to identify a Mopar purple shaft cam..I cannot see any numbers..any insight here..other than the obvious fact if I don't have the timing card I am out of luck and v-blocking is the only recourse left open.

 

[Kern Dog]

I don't know what V blocking means, but I do have a few tips:
MP cams are easy to identify if you have a dial indicator. You can get them from many sources, even Harbor Freight.
MP cams can be identified by simply determining the valve lift. You will not find 2 MP cams of different durations with the same lift. Find the lift and then look at the MP catalog to see the specs.
You didn't specify whether you have a small or big block. You could have a slant six for all we know. In the case of the big blocks, there is the stock 440 Magnum cam which had a lift of .455. From there the hydraulic came move up. .474, .484, .509 and .533. If this is a solid cam, they had the .528, the .557 and the .590.
Here is a list of the MP cams. Again, find the lift at the valve, then compare it to the list.
http://victorylibrary.com/mopar/mpcam-tech-c.htm

 

[bigaadams]

you quote my very opening statement...V-blocking, dial indicator and timing degree wheel is the very method as it appears there are no identifying numbers...

machinist V-block are use to support the cam each end on a flat machinist table so to be able to rotate and make the reading with the dial indicator and degree wheel and not install the cam to do these checks via a lifter...but as I see now from the cam chart you listed, purple shafts are all straight grind cams..so basically what I have is not a cam I would wish to install...

link to a v-bloc set..just to give you an idea of what they are....

http://www.ebay.com/itm/Machinists-...441?pt=LH_DefaultDomain_0&hash=item462466fef9

Thanks

 

[Daves69]

IMO, V-blocks and indicator are a must and the only way to know for sure on any unmarked cam. Packaging errors do happen, even on the new stuff.

 

[Meep-Meep]

If you take some calipers and measure the lobe heel to toe then side to side then take the difference, which is lobe lift. Multiply that number by 1.5 and you will get the valve lift. From there it will be easy to ID from a catalog.

 

[bigaadams]

If you take some calipers and measure the lobe heel to toe then side to side then take the difference, which is lobe lift. Multiply that number by 1.5 and you will get the valve lift. From there it will be easy to ID from a catalog.

I find error to this method.....the elliptical lobes of even a stock cam let alone the undercut base circle of the stock cam which are used to derive these performance units are what allows for the larger side lobes and higher toe for establishing the very lift and ultimately the opening/closing ramp profiles..the base circle will not be accurately measured with a caliper ...you can confirm this elliptical shape by looking a the lobe profile of the timing card should you have it by reading the degrees degree wheel..establishing BDC at X lift on each ramp..

sticking witht he above logic you will find that taking a base circle reading at the most narrow distance of the side profile you effectively have only 180* to generate a duration greater than the 180 degrees you have to play with..thus the base circle is smaller than the side lobes solely due to the undercut at BTC which is your zero lift in refernece against the increased height of toe as both are referenced to the cam's centerline..

the following is the exact results of the above error in reading the cam by a caliper...with a known stock cam in hand the error is off by .0355 lift when multipled by the rocker ratio (1.5) and this cam is a known 240* duration. the side lobe reading when subtracted by the heel toe reading is .243 and when multiplied by the rocker of 1.5 yields a total lift of .3645 and error of .0355 lift based on Mopars own data on the cam profile of .400 lift.

 

[Cranky]

You probably already know that you should also check the cam for run out. I've found several over the years with as much as .007 on the center bearing journal and had found a few brand new cams with .005 and can account for some issues where bearings seem to be tight. Before scraping bearings, always make sure the cam runs true....

 

[bigaadams]

Cranky...that is always a true statement even if the item is new..I V-blocked a cam once from a well known cam grinder that turned out to be as much a s .030 in lift difference not to mention that duration varied also and this was a straight grind cam..not a split duration..so..yeah..v-blocking is the only way to read a cam outside of installation in a block. I remember asking the guy just how drunk he was the night he ground that cam...pure junk....

 

[Cranky]

I have an engine lathe and I usually just throw things between center. First thing to check is all the bearing journals and if those were right, the lobes were probably ok too but they still got checked. Had always wanted to set up a cam checking tool but just used a block instead. For years, there was usually at least one engine that was in the process of being built and I would throw in several different cams to check and make sure they were as what the card said.

 

[Meep-Meep]

I have measured plenty cams as I described and got results close enough to know I was dealing with a high perf profile or stock. In the MoPar line of cams there is enough variance in lift between grinds that you can zero in on the actual grind. The key is the method is close enough to make an educated guess and you already know it's a purple shaft so much of the battle is won.

 

[bigaadams]

I was really not looking for a guess ...I simply was asking if there were secret numbers...seems there are none....The cam will be v-block as the next step...BUT if I were to take a stab based on your suggested method, it would come out to be a 260 adv. duration cam...whole lot less than I was looking to install...less than the man specified when ordering the cam should that be a viable identification...and less than stock for this engine from the factory...step backwards.........all I can say at this time is....time to break out the measuring devices.....thanks to all...

 

[Meep-Meep]

It's not all about lift and duration. LSA (or overlap) is a huge component to consider. The Road Runner cam is a .450" / .458" with 268 duration on the exhaust I believe and a 115 LSA. The cam I'm running is a .455" / 272 with a 112 LSA. My car runs high 12's with a stock iron intake and 2" headers - far better than the published 440 GTX numbers in the day. Not counting the highly tweaked Ronnie Sox test cars. I'm just saying look at ALL the data.

 

[bigaadams]

It's not all about lift and duration. LSA (or overlap) is a huge component to consider. The Road Runner cam is a .450" / .458" with 268 duration on the exhaust I believe and a 115 LSA. The cam I'm running is a .455" / 272 with a 112 LSA. My car runs high 12's with a stock iron intake and 2" headers - far better than the published 440 GTX numbers in the day. Not counting the highly tweaked Ronnie Sox test cars. I'm just saying look at ALL the data.

yes...and only by reading the cam with a dial indicator and degree wheel can this data be established...you come out first saying take a WAG and now you down to "know the specifics" , the very point I made in my opening statement

 

[Meep-Meep]

Your question was about ID-ing a Purple Shaft cam for a BB. My original point was the lift specs are far enough apart to measure as I suggested and come up with an answer - in 5 mins. You can then look up the specifics or proceed to measure as you suggested.

 

[bigaadams]

Meep Meep...I am going to drop the thread as it is not adding any value to the forum at large...I believe our exchange is mainly an "agree to disagree" ..there is in my opinion a need for facts and leave all guessing behind..while you and I may know this or that, we got to consider the ones that are just getting started..they already have to many misconceptions of how things work as it is. As older members we both have a duty to take more than a WAG when answering a post..Too many folks building engines with the 'close enough' approach....looking at the cam chart for purple shafts and you will find some close enough to each other that the very proven difference I posted above will make your suggest method come up in error and could mislabel a cam...maybe not in the wilder top end range..but sure in the lower performance selection...so in the end it all boils down to this..there are no numbers on the cam and that is the only answer I wanted from this thread..thanks for trying to help

 

[62 Dart Convertible]

Meep Meep...I am going to drop the thread as it is not adding any value to the forum at large...I believe our exchange is mainly an "agree to disagree" ..there is in my opinion a need for facts and leave all guessing behind..while you and I may know this or that, we got to consider the ones that are just getting started..they already have to many misconceptions of how things work as it is. As older members we both have a duty to take more than a WAG when answering a post..Too many folks building engines with the 'close enough' approach....looking at the cam chart for purple shafts and you will find some close enough to each other that the very proven difference I posted above will make your suggest method come up in error and could mislabel a cam...maybe not in the wilder top end range..but sure in the lower performance selection...so in the end it all boils down to this..there are no numbers on the cam and that is the only answer I wanted from this thread..thanks for trying to help

You perhaps don't realise how rude you are being to a guy who goes out of his way to help so many.

I've read a few posts where I think your attitude is a bit strong. This confirms it.

 

[bigaadams]

You perhaps don't realise how rude you are being to a guy who goes out of his way to help so many.

I've read a few posts where I think your attitude is a bit strong. This confirms it.

I am not in any manner trying to be rude but only stressing that facts be posted...perhaps you do not understand that the question was if part number was available on the cam, not how to make a guess.....I even stated in the very first posting that I can read a cam and I can read it accurately...and his method is not accurate...look at the entire thread and see where I posted fact that proves his method is less than adequate to know what you have......follow his method on a known cam and see the error for yourself......I am sorry this sits wrong with some people but please lets deal in facts and not WAGs...usually the info here is pretty much good to go and I have tried to let it go as a agree to disagree...he is happy with his method..I find it lacking...

 

[Meep-Meep]

Meep Meep...I am going to drop the thread as it is not adding any value to the forum at large...I believe our exchange is mainly an "agree to disagree" ..there is in my opinion a need for facts and leave all guessing behind..while you and I may know this or that, we got to consider the ones that are just getting started..they already have to many misconceptions of how things work as it is. As older members we both have a duty to take more than a WAG when answering a post..Too many folks building engines with the 'close enough' approach....looking at the cam chart for purple shafts and you will find some close enough to each other that the very proven difference I posted above will make your suggest method come up in error and could mislabel a cam...maybe not in the wilder top end range..but sure in the lower performance selection...so in the end it all boils down to this..there are no numbers on the cam and that is the only answer I wanted from this thread..thanks for trying to help

Then why even bother asking the question if you know the answer? Throw your existing cam in the scrap bin and get a new one with a card. Job done.

 

[bigaadams]

at the time I did not know the answer...which this thread does prove to be a big no, there aren't any identifying numbers...so yes, thanks to those that said there are no numbers and left it at that....I guess my career dealing with facts and close tolerances just makes me a stickler for the facts and well to some it makes me appear to have an attitude..sorry I thought knowing over guessing would be of importance...