Cam ID Help

[AWDBOB]

Hey R3V-

I have three aftermarket cams that I am having trouble identifying.

This one has an engraving at the end of the cam. Doesn't appear to be a regrind, no "K" or IE blue stripe.

Any ideas?

Untitled by Bobbie Morrone, on Flickr

[roguetoaster]

Look for a tiny engraving on the rough cast surface somewhere.

[AWDBOB]

Look for a tiny engraving on the rough cast surface somewhere.

These are the only other markings present- they didn't lead me anywhere on my search, sadly. I hoped that the hand engravings in the OP would possibly be a clue for someone who has seen one of these.

Base circle was 28.05mm, lobe height was 35.10mm on both intake and exhaust.

For reference, I measured two stock OEM BMW K stamped cams and base circle was 28.05mm as well, but lobe height was 34.34ish mm on both.

Untitled by Bobbie Morrone, on Flickr
Untitled by Bobbie Morrone, on Flickr

[AWDBOB]

M20 rocker arm ratio changes pretty dramatically through its motion, but I figure there has to be some semi ballpark estimate for lift, as lift can be measured in the head physically.

Internet generally agrees that m20b25 cam lift is 10.1mm.

So I take my 34.34mm overall lobe height minus 28.05mm base circle and divide lift by that number to get approximate rocker arm ratio.

Using my measured stock b25 cam numbers above, that puts me at a "1.6mm" rocker arm ratio.

Using that rocker arm ratio applied to the taller lobe of said random cam above, that puts me at 11.1mm lift, so about a mm of total lift more than stock cam, which confirms two things, one directly, and one indirectly:

1) the above cam isn't stock
2) lift isn't too aggressive

We can also possibly deduce that....

IF the cam were a regrind, it should, in theory have the "K" stamp or BMW marking of some sort, and IF it was a regrind, I don't think it's possible to add lift (and if possible, not much), so it's likely that this is not a super aggressive, yet "upgraded" cam. And if a cam manufacture (who apparently wants to remain nameless) made a cam with a subtle 1mm lift increase, I can't image the duration would be aggressive, as the only time that I know of where duration is aggressive and lift is not, is on a regrind, which I do not believe this cam to be.

That is all, folks. Thanks for coming to my show.

[82eye]

hand engraving means the cam has been reground. the engraving is to inform the next builder they do not have a stock profile.
i have a 272 regrind and no k stamp. the end has been hand engraved.

[AWDBOB]

hand engraving means the cam has been reground. the engraving is to inform the next builder they do not have a stock profile.
i have a 272 regrind and no k stamp. the end has been hand engraved.

This cam isn't a BMW cam. That would imply that this, and yours, were reground from an aftermarket stock cam. A new Febi cam + regrinding service is more costly and worse in performance than a cam built from a proper blank, of similar spec. Doesn't mean it can't be done, just means it isn't cost or performance effective.

Is your engraving similar in fashion to this one?

[roguetoaster]

It just came to me that it might be a dbilas cam with the marking on the end.

[82eye]

This cam isn't a BMW cam. That would imply that this, and yours, were reground from an aftermarket stock cam. A new Febi cam + regrinding service is more costly and worse in performance than a cam built from a proper blank, of similar spec. Doesn't mean it can't be done, just means it isn't cost or performance effective.

Is your engraving similar in fashion to this one?

there's a bit more info on it. i'll have to see if i can get a pic. it's a known reground as i had it done at colt cams in bc.

[TobyB]

I don't think it's possible to add lift (and if possible, not much)

Sure you can- just reduce the base circle. Make the small number smaller. Good idea? Welllllll... there are limits...
Likewise, that is how you can add duration under a stock profile- cut down the base circle.
That said, your base circle number doesn't seem particularly low.

It's also possible to buy blanks- Ireland had a source many years ago, and now Schmick is using them too.

Then you can grind whatever you'd like that fits under the blank circle.

Welding's also a cost- effective option, but the cams I've had welded showed evidence of it on the edges of the lobes.

lotsa options,
t

[AWDBOB]

It just came to me that it might be a dbilas cam with the marking on the end.

Good call, I’ll send them an email!

Sure you can- just reduce the base circle. Make the small number smaller. Good idea? Welllllll... there are limits...
Likewise, that is how you can add duration under a stock profile- cut down the base circle.
That said, your base circle number doesn't seem particularly low.

It's also possible to buy blanks- Ireland had a source many years ago, and now Schmick is using them too.

Then you can grind whatever you'd like that fits under the blank circle.

Welding's also a cost- effective option, but the cams I've had welded showed evidence of it on the edges of the lobes.

lotsa options,
t

That’s why I compared this base circle reading with two stock cams- my first m20 cam was a regrind that had reduced base circle that required oversized eccentrics, which I wasn’t a huge fan of.

Regarding blanks- yes, but the companies who buy blanks don’t sell those cams as regrinds, they fetch a premium by selling them as “billet”, whatever that means, or “custom grinds” as top end performance (who does IEs cams) sells them as.

[TobyB]

Yeah,
I'm particularly unimpressed with Schrick's new habit of using the generic blank.

That said, if mere mortals like you and me could get our mitts on the blanks,
then it's off to the cam shop with us. Because an aftermarket cam grinder can
move the base circle to wherever there's cast iron (billet, my butt) and do lots of
duration, etc, without the base circle compromise.

That's kinda what it looks like you have- a 3rd party marking and grind on a full- depth blank.

but heck, Iwho really knows?

t

[AWDBOB]

Yeah,
I'm particularly unimpressed with Schrick's new habit of using the generic blank.

That said, if mere mortals like you and me could get our mitts on the blanks,
then it's off to the cam shop with us. Because an aftermarket cam grinder can
move the base circle to wherever there's cast iron (billet, my butt) and do lots of
duration, etc, without the base circle compromise.

That's kinda what it looks like you have- a 3rd party marking and grind on a full- depth blank.

but heck, Iwho really knows?

t

Agreed! If there were ever a time that a mere mortal could get there hands on a wholesale product, it's now- I suppose. There would have to be enough demand for it, of course. RaceTEP also uses the same blanks, and they do (did?) the cams for IE for a while, so I assume they're all coming from the same place.

And yep, lift isn't outrageous enough per my measurement that I think I'm just going to run this thing instead of shelving it forever because I don't know what it is. If it totally sucks I'm sure I can swap it with one of the other 3 random aftermarkets I have lol.

[digger]

Throw it in a spare head and measure it out. Printout a small degree wheel scaled to 5 to 5.5” diameter and glue to cardboard hot glued to cam gear.