Compcams CRB XE 268H -10 cam

[polyjohn]

So we tried to fit this cam into our 1969 440 to replace a 509 Mopar performance cam.
We spent out on a Cloyes rollerised 3 bolt chain set and...

On checking the cam timing at 50 thou lift it was nearly 30 degrees out!
So we re-set the chain with maximum advance and still over twenty degrees out.

After about four hours of head scratching we moved the chain one sprocket advanced.
Now with the maximum advance (we calculate) we can get close to the correct setting.

Pictures to follow when I can load them DOH!
How can this set-up be so WRONG???

 

[Don Frelier]

 

[gtxrt]

check it with the old chain and gears. think the cam could be that off I don't ?

 

[6PKRTSE]

Yeah, something doesn't sound correct. I would try the old chain and gears for mock up as well if you still have them.

 

[polyjohn]

OK, this is what is wrong!

Compcams gives instruction example to find Intake centreline @106 in the manual (not cam-card)
That is what we did and it was fine, but not actually written the cam-card.

So we followed the @50 for intake and exhaust and both were a mile out!

Intake BTDC 28 @50
Close ABDC 60 @50

Probably about 20 degrees out showing 8 degrees BTDC @50.

So I have now checked the 268H single bolt cam-card and guess what?
It gives the same numbers, BUT NOT @50....

 

[PRHeads]

Intake BTDC 28 @50
Close ABDC 60 @50

Since Comp has been taken over by Edelbrock, the cam cards are just wrong, in many cases.

28btdc/60abdc = 268*
The XE268 is not “[email protected]”…..so that info is incorrect.

The cam itself is actually [email protected] on the intake side, so for a 106 intake c/l the .050” timing would be:
6btdc/38abdc

The 28/60 numbers are the specs for .006” tappet lift(advertised duration).

I’m sure the cam itself is fine.

 

[6PKRTSE]

Yes, things have been a disaster since the Comp/Edelbrock merger. It seems almost everything is out of stock, especially in all the F.A.S.T. products. Anything special order such as custom grind cams usually takes much longer. If they even have the cores in stock to grind them. Most cases they never have the cores anymore.