l20b Cam Identification

[freddat]

I have a U67 Head I bought a couple years ago now. 

Its nicely serviced and port/polished with a CWC stamped cam. 

Im assuming it has stock springs and lash pads as they are way off and will need attention. 

But im just in need of some answers regarding the specs of the cam or where it came from. It has very little info stamped into it.

 

From front to back of the cam it has stamped. 

-EP30       1.5(im guessing this is rocker arm ratio)

-CWC

-C2 D2

-J6

 

31mm base circle, 39mm lobe lift

 

Totally understand this may be a stab in the dark but any info would be appreciated. 

 

Aiming to put this on an l20b with l28 flattops, u67 head (i do have an a87 as an option), electric s2 910 dizzy, twin 45 dcoe in a s1 bluebird.

 

thanks as always. 

 

 

 

 

 

 

[datzenmike]

I can only add some stock specs.

 

Cam base diameter 1.31" or 33.27mm*. If less than this the cam has been reground.

Lobe lift is 0.276" or 7mm

Lobe lift X rocker ratio 1.5 = 0.413"

Duration on the Datsun cam is 248⁰ but seems kind of high. Cam grinders list their duration at 0.050" lift and I doubt Nissan does this.

 

* Your base of 31 and 39 lobe is an 8mm lift  x 1.5 = 0.480" valve lift

 

I have an Iskendrian cam with the similar lift. Says W91M.... 14ms.. 09...1.490... 7101. Really hard to read the letters etched on the end.

 

I measure...

Base 1.15"

Lobe 1.475"

Lift 0.475"

 

If you look up this cam the specs should be very close to yours..

[RLJ]

What would the compression ratio be with a U67 head and L28 flattop pistons?

[Stoffregen Motorsports]

CWC is a cam billet company. They supplied cams to aftermarket cam grinders. But...I thought I remember that they also supplied directly to the OEMs...?

 

Cam ID is usually stamped or scratched into the back of the cam. A stock cam will have a single stamped letter or number. A custom cam will have a number like 46D or 202AE.

[datzenmike]

I've seen CWC on several stock cams.

 

2 hours ago, RLJ said:

What would the compression ratio be with a U67 head and L28 flattop pistons?

 

On an L20B... 8.902

[freddat]

8 hours ago, datzenmike said:

I can only add some stock specs.

 

Cam base diameter 1.31" or 33.27mm*. If less than this the cam has been reground.

Lobe lift is 0.276" or 7mm

Lobe lift X rocker ratio 1.5 = 0.413"

Duration on the Datsun cam is 248⁰ but seems kind of high. Cam grinders list their duration at 0.050" lift and I doubt Nissan does this.

 

* Your base of 31 and 39 lobe is an 8mm lift  x 1.5 = 0.480" valve lift

 

I have an Iskendrian cam with the similar lift. Says W91M.... 14ms.. 09...1.490... 7101. Really hard to read the letters etched on the end.

 

I measure...

Base 1.15"

Lobe 1.475"

Lift 0.475"

 

If you look up this cam the specs should be very close to yours..

thanks mike, will look into it. I thought id be getting more around the 10.2/1 compression mark with the flat tops, might be worth my while to use the a87 head i have to bump up the numbers. I know this has been discussed at length in other topics. 

 

5 hours ago, Stoffregen Motorsports said:

CWC is a cam billet company. They supplied cams to aftermarket cam grinders. But...I thought I remember that they also supplied directly to the OEMs...?

 

Cam ID is usually stamped or scratched into the back of the cam. A stock cam will have a single stamped letter or number. A custom cam will have a number like 46D or 202AE.

yeh my cwc cam has no markings on the back at all so im assuming a grind by a small local shop maybe, but it has much wider lobes than all the stock ones i have, including a "C" cam. 

[datzenmike]

2 hours ago, freddat said:

thanks mike, will look into it. I thought id be getting more around the 10.2/1 compression mark with the flat tops, might be worth my while to use the a87 head i have to bump up the numbers. I know this has been discussed at length in other topics. 

 

 

 

Ask and you shall receive. I have multiple scenarios worked out and read across the wrong line.

 

An 85mm x 86 bore and stroke is 487.75cc swept cylinder volume.

The deck volume is the volume above the piston because it does not quite reach the top and is 2.55cc

The gasket volume, assuming a 1.2mm crushed gasket thickness is 6.8cc

A head that has never been cut has a combustion chamber of 45.2cc

 

Everything above the piston has a volume of 54.55cc

Total volume is 487.75 plus 54.55 divided by 54.55

542.3/54.55 = 9.9413

 

Sorry about that. 9.94 is close to 10.

 

If you were to fly cut 0.012" off the head this would remove about 1.7cc of chamber volume and this would raise the compression to 10.22. Head should be trued up anyway.

 

0.012" is about 3 sheets thickness of newspaper.

 

Or use a thinner head gasket.

 

[freddat]

5 hours ago, datzenmike said:

 

Ask and you shall receive. I have multiple scenarios worked out and read across the wrong line.

 

An 85mm x 86 bore and stroke is 487.75cc swept cylinder volume.

The deck volume is the volume above the piston because it does not quite reach the top and is 2.55cc

The gasket volume, assuming a 1.2mm crushed gasket thickness is 6.8cc

A head that has never been cut has a combustion chamber of 45.2cc

 

Everything above the piston has a volume of 54.55cc

Total volume is 487.75 plus 54.55 divided by 54.55

542.3/54.55 = 9.9413

 

Sorry about that. 9.94 is close to 10.

 

If you were to fly cut 0.012" off the head this would remove about 1.7cc of chamber volume and this would raise the compression to 10.22. Head should be trued up anyway.

 

0.012" is about 3 sheets thickness of newspaper.

 

Or use a thinner head gasket.

 

ahh nice. close enough to 10:1 is good for me and a street vehicle on 98 here in aus. 

as for the cwc there are so many contradicting opinions on them, some hate them some have no wear issues.

mine has the oil holes on the lobes and will only be using higher zddp oils, and seeing as i have a kinda sizeable selection of cams and heads to replace it in case it does go bad,  i might run it and see how it goes with some careful break in and good lubrication. 

 

now to source some lash pads and get it set up right. 

 

thanks as always. 

 

[Crashtd420]

6 hours ago, freddat said:

ahh nice. close enough to 10:1 is good for me and a street vehicle on 98 here in aus. 

as for the cwc there are so many contradicting opinions on them, some hate them some have no wear issues.

mine has the oil holes on the lobes and will only be using higher zddp oils, and seeing as i have a kinda sizeable selection of cams and heads to replace it in case it does go bad,  i might run it and see how it goes with some careful break in and good lubrication. 

 

now to source some lash pads and get it set up right. 

 

thanks as always. 

 

Check out this place.....

Been used and recommended by a couple members... had it saved for when I might need some...

 

https://www.precisionshims.com.au/

[banzai510(hainz)]

my Scheider cam has a CWC on there Im sure I have 100k miles on that head.

however I used a stock out and a Perf inner or vise versa and its under the .475 lift so thr stock spring will not bind. cam wears fine.

 

call Datsort or Mad Dat in Adelaide

 

https://www.precisionshims.com.au/ 

you can use the stock valve retainers as they are counter sunk like the stock lash pads. In the USA most were flat thus sticking up higher on the stock retainer and thus could fallout. In USA you have to buy retainers with a high wall height.

 

key is in knowing you lash pad height is to know if you have a regrind cam or a new one and even then yiou have your valve seats ground all plays in the math.

My L16 with new cam was about .140

my other motor with regrind cam was about .180  But I had sets of all sizes incase it varied.

 

a perfect head would be if valves installed and you could put a straight edge on top and its even then you know you can use one size.

 

I used a ink pen and added the rocker one at a time get the pad wear center. then mark and pull it out and go to the next rocker.

 

I have the head mounted on a empty engine block bolted down or the pistons half way in bore not to hit a valve

 

 

Edited January 15 by banzai510(hainz)

[freddat]

19 hours ago, banzai510(hainz) said:

my Scheider cam has a CWC on there Im sure I have 100k miles on that head.

however I used a stock out and a Perf inner or vise versa and its under the .475 lift so thr stock spring will not bind. cam wears fine.

 

call Datsort or Mad Dat in Adelaide

 

https://www.precisionshims.com.au/ 

you can use the stock valve retainers as they are counter sunk like the stock lash pads. In the USA most were flat thus sticking up higher on the stock retainer and thus could fallout. In USA you have to buy retainers with a high wall height.

 

key is in knowing you lash pad height is to know if you have a regrind cam or a new one and even then yiou have your valve seats ground all plays in the math.

My L16 with new cam was about .140

my other motor with regrind cam was about .180  But I had sets of all sizes incase it varied.

 

a perfect head would be if valves installed and you could put a straight edge on top and its even then you know you can use one size.

 

I used a ink pen and added the rocker one at a time get the pad wear center. then mark and pull it out and go to the next rocker.

 

I have the head mounted on a empty engine block bolted down or the pistons half way in bore not to hit a valve

 

 

interesting, i do have some spare blocks i can do this with to make sure. 

precision shims is where ive been pointed to in the past so that seems to be the go. 

the cwc cam i have is fresh and unused so id say ill be closer to the .140 as you say. 

thanks.