Camshaft Specifications

[vstibbard]

Hi all,
I've been tracking down specs for some of my camshafts recently from two Australian Cam grinders, Waggott Engineering and Wade. I've decided to having them dialled up by a cam doctor, so thought it maybe worth opening a topic for people to submit camshaft specs for future reference purposes.

I'm sending 8 different cams out to be dialled up so I know what I've got. I'll upload details in due course.

I'm keen to find details on the following which are currently installed in engines:
RF450 (Racing Fabrications grind?)
BRM Phase IV
DB2 - 122D - (Dave Bean Engineering grind?)

Hope others think this is a useful resource to have

Cheers

V

[vstibbard]

DB2 - 122D spec - .510" lift inlet cam, 264 duration, dial cams to 103 to 105 ATDC lobe centres, cold clearance .008" +/- a thou
DB2 -121D spec .480" lift exhaust cam, 264 duration, dial cams to 106-108 BTDC lobe centres, cold clearance .010" +/- a thou

designed for open wheelers, where gear ratios can be matched to the circuit. These modern profile cams, have a faster & steadier lift rate with less low lift duration than the old Brian Hart grinds (ZL16 and ZL1, .490" and .460" lift
respectively). They give much better mid range torque while sacrificing nothing on the top end over the BH grinds. With large valves (1.625" - 1.7" inlet and 1.4" - 1.44" exhaust valves) and this much duration both can be issues and you must check clearance very carefully.

All done at 9000RPM.

[rgh0]

I presume the durations for the DB cams is at 50 thou lift ?

Cams like this give great power but the narrow power band makes them to hard to drive in something like an Elan and lap times are actually slower due to lack of drivability out of corners. A light open wheeler with the ability to select ratios for a circuit is a different proposition.

cheers
Rohan

[vstibbard]

Hi Rohan,

I have a Rennmax BN2 that raced with Lotus Twin Can in period Tasman and also GP's throughout Asia, It also ran with both 1600 and 2.0ltr Waggott TCV4 engines, if i could find one of those it would be the perfect conflation for an Aussie built open Wheeler.

I've asked them to confirm they are at 50 thou lift, as I expect it is. I have a Doug Kiddie bottom end, aires 12.5 forged pistons, and the BV Brian Hart head that it raced with in period, this is to be rebuilt with full valve train and the DB2 cams which are a lot kinder on the gear that the original BH cams and make more midrange torque.

Cheers

V

[SJ Lambert]

Those figures must be timing at 50 above the seats. Too tame otherwise.

Seems as though just about all the North American manufacturers have adopted the Iskekandarian approach, makes 'em easier to set accurately too!

[nmauduit]

Those figures must be timing at 50 above the seats. Too tame otherwise.

that contributes to the difficulty to compare profiles with cams that are measured from lift to close, plus the lack of intermediate points that actually make the ramp of the profile : it'd be convenient to have curves or points every 10 degrees or so, that would let one derive valve acceleration profile (vs. spring requirements and wear) and also to integrate the whole opened time (flow*duration for the various openings timeslots). As a blunt example, a triangular shaped cam and a convex cam of identical total duration and lift do have different flow characteristics.

somehow most of not all camshaft grinders appear reluctant to provide any kind of data, at best lift and duration when prying...

[nmauduit]

On the same topic, can someone confirm what would be the duration of McCoy 450 (or Qed 450 / Newman 450 ph5 or similar profiles) 5 thou to 5 thou, and possibly 50 thou to 50 thou ?

side question would be the base circle value.

I'm considering getting some camshafts reground locally, so would like to be more precise with specs than what I have been able (or unable) to find out from vendors so far... One question I also would like to clarify for instance is opening speed and total time spent opened (say 5 thou from maximum lift, then 50 thou from full).

[rgh0]

Detailed specifications for the McCoy 450 that I have had measured

at 0.010 checking height ( nominal seat to seat numbers)

centreline 110 degrees
duration 285 degrees
Area 38.36 Inch deg
cam lift 0.44 inch
valve lift 0.43 inch

at 0.050 checking height

duration 252 degrees
Area 37.91 Inch deg


at 0.200 checking height

duration 190 degrees
Area 33.91

Base circle of 1.05 inches

Yes it would help if more cam makers published more detailed data. But data can be misleading and it would lead to a tendency of bigger numbers are better rather than how well do the actually work in an engine and are all the other factors you need to consider in the overall engine build. But it would save me buying cams and springs and the like just to measure them up to see if they suit my needs.

If using cast iron cams you need to do the long bolt modification for high lift cams like this. You will also struggle to get this sort of profile out of a standard cam -- you need to start with new blanks

cheers
Rohan