Measured Lobes on new & old Cam.

[Anonymous]

At last my new cam arrived yesterday (still be end of next week before machinist can come out and dial it in).
I thought I would do a cam comparison by measuring the base circle and lobe height of my new cam from Wade and compair it with my old cam (5000 km approx old) from Camtech.
The Camtech cam is supposed to be .278 inch lift at cam and the new one is supposed to be .284 on inlet and .287 on exhaust (cam lift).
The first thing I noticed was the shape of the lobes was very different, the Camtech cam had sharper peaks on the lobes and had worn a bit on this area. The contour of the Wade cam lobes looked a lot better.
That aside the thing that surprised me was the variation in the lobes. The Camtech cam varied from the lowest lobe being only .250 at cam and the highest was .272 at cam. Unfortunatley the new Wade cam was worse with the highest lift being .292 at cam and the lowest being only a .264 a variation of .042 of an inch = 1.08mm.
To tell you the truth I was definitely not impressed, but not very surprised. Im still not sure if this would adversly effect anything or not.
Ill give some of the other readings of lift at cam in mm for compair. You can see most are good but theres a few bad ones in the bunch.

Camtech starting at front at 1 was 6.76mm, 6.90, 6.93, 6.70, 6.70, 6.80, 6.69, 6.70, 6.86, 6.80, 6.35, 6.70.
Wade was 1 at 7.31mm, 7.09, 7.16, 7.20, 7.10, 7.27, 7.30, 7.11, 7.30, 6.71, 7.07, 7.43.
The Camtech cam has been run for 5000 km with high quality springs at a near perfect seat pressure of 90 lbs. I used a very accurate tool to measure the lobes and did many twice to check.
Comments?

 

[Anonymous]

Variations stated of 042=1.08mm is at valve not cam lift.

 

[Anonymous]

I have seen posts on a Corvette website regarding the quality of some cams. Seems like one guy used to trash Comp Cams for their variation in lift. Maybe you can get a refund or exchange. It seems he hounded Comp for the same. I wish I knew enough about them to be able to furnish a recommended vendor.

 

[addo]

I'm assuming you deducted each base circle from the peak, rather than treating them as the same, too. Without naming names, what would happen if you emailed Crow with your findings? Would they commit to a better level of accuracy?

 

[Anonymous]

Thats right I deducted the base circle from the peak. The digital calipers I used did say they can vary 0.03 of a mm not enough to make any difference. Ive already e-mailed Wade but I dont think they like me as I have pestered them a Bit "Huh".
I might do as you say Ill e-mail Crow and see what they have to say.

 

[66 Fastback]

I read your post again. Are you comparing lobe measurements on a cam and valve lift measurements on the other cam?
If so, that would not be a valid comparison. The rockers may have a 1.5 or 1.6 "nominal" ratios. The stock rockers have a lot of slop and variation in the actual ratios. Aftermarket rockers may have a tighter variation, but there is still going to be some variation that may explain some of your measurements.

 

[Anonymous]

66 Fastback
No both cams out and side by side I just multiplied the lift a cam by 1.5 to see the variation increase for valve lift.

All
This is the reply I got from Crow cams

Hi

Although Wade is a direct competitor they are a competent cam company and I would be almost certain that the cam will have correct lift within
tolerances the problem will be in the way you are measuring the cam The best way to measure lift is to measure the Diameter off the base circle and
subtract it from Height of the cam as the tolerance on the base dia is plus
or minus .010" just measuring the heights off the lobes will give errors off
.040" or more
We have the A Adcole cam measirnig machine built in the USA and is on a 2 Ton Granite slab base this measures every lobe we need this kind of
equipment becuase we make cams for the GT falcon for FPV
But in normall production we check every cam
if you would like a read out on this cam you can send it in
Yours Ray

My reply to them

Thanks for your quick your reply,
-----"If theres a machine like that I cant argue although I did make sure I held it the same way each time and detracted the base circle off the height. The cam that varied by 1.08 mm I checked a number of times just to make sure and many of my other readings were very consistent".

Im beat, but I still dont get it. I did get a substantial variation as to how much exactly, maybe Im a bit out due to my method (dont have a machine) ???

 

[Anonymous]

Another reply from Crow (these guys are good)
Hi
we use computer driven cam machine with minium operator input and every lobe is ground the same amount off time and finish
Wade use manual machines but each pair off lobes is ground with the same master and the master cam has 1 inlet and 1 exhaust lobe this is indexed to the correct position for each cylinder so to vary the lift the master would have to be changed on the machine in the middle off grinding the only other thing it could be is if the lobe was not cleaned up on rough grinding then not finished ground
yours Ray

 

[addo]

Tim, due to legal restraints Crow will not be more critical than that. If you'd not named the cam other than identifying it as Australian, you may have got some more "interesting" detail.

I like Crow, for a couple of reasons. They are a cam company, not an engine building service. Getting the cam right is their priority, as it's their income. Also, they have invested heavily in equipment and learned how to drive it (like masterless grinders). As A7M says, a lot of "hot" profiles are off 1940s BSA performance cams. :roll:

That said, they usually seem conservative in grind recommendations... If they knew 100% you weren't going to pin anything on them, they might loosen up. (Maybe a cam with all brand/grind identifiers ground off.)

Adam.

 

[Anonymous]

I feel like an Idiot. Last night Wade cams relpied to me that they did not think they were and fault and would regardless of this refund the full cost of the cam to me if i wished.
I then went home and re-checked two or three times the two lobes on the Wade cam I thought were the worst two and found I got a different reading (much better).
Its obvious to me now the its very difficult to measure a cam this way and its best to leave it to the experts.
Ive apologised to Wade cams. They obviously operate with exceptionally high intergrity. And for value for money they are extremely hard to beat. I would highly recommend them to anyone.

 

[addo]

The side angle that's imparted to the lobes during the grind may have contributed to the discrepancies in measuring.

I'm keen to see how it shapes up, if you're going to install it.

 

[80broncoman]

one the best ways to measure a cam is to do it in a block. use a dial indacator on the outside of the lifter. if you happen to have a degree wheel you can get a close reading on opening and closing events.

 

[Lazy JW]

Having wasted a great deal of my mis-spent life measuring lumber with calipers, and trying to teach others to do the same, I have arrived at the conclusion that it is largely a matter of proper technique. The first mistake that most folks make is to try to hold the calipers with one hand while holding the board (camshaft?) in the other hand. Good luck getting the same measurement twice :roll: Using calipers is a lot like catching a baseball; if you are serious about it, use both hands whenever possible. Also, digital calipers are somewhat more difficult to use, due to the fact that it is hard to tell when they are straight. With a dial caliper, you can rock it back and forth slightly and watch the needle moving plus and minus, thereby indicating when it is straight. Not that digitals can't be accurate, but I find them annoying to use, and what's the point of trying to measure precisely and then not using the measuring device precisely? I have won several gentleman's wagers (I don't bet) by proving that I could use a vernier caliper to measure within .001" of the other fellow using a good digital micrometer. It's just a matter of technique.
Joe