CIS camshaft compatibility question
 

I'm looking at building either a 2.7 or hopefully a 3.0 SC engine for my '75 over the winter.

I know 964-profile cams have been used successfully with CIS cars, can I go with anything more aggressive than that with CIS or will I begin to have problems with intake reversion?

I plan on doing the Bitz EFI conversion later on, but since I'm doing this on a budget I will probably do it in stages.

This motor may eventually see a turbo as well, so the camshaft would have to play nice with a turbo motor.

Thanks!
SmileWavy

You should ask this question to www.drcamshafts.com or www.elgincams.com or www.webcamshafts.com. Be prepared to provide a lot more info about your car than you've provided us - this way they can match the proper cam to your requirements/expectations.

The 964 profile usually will not clear the stock 2.7 pistons. They will clear the 3.0 pistons.
Depending on which turbo you go with, the 964 is usually the most aggresive cam for a street driven turbo.

There are other options, but like Don says, you have to provide more info.

John,
Thanks for your input. It's looking like I will most likely be building a 3.0SC motor for my car. I will probably be using stock pistons, but depending on my budget at the time I undertake this project I may use a Bitz EFI setup and go with custom JE pistons. This car will be primarily street driven, but will get DE / AX use when the suspension and brakes are sorted. It sounds like the 964 is the way to go.

Your welcome Michael. The nice part is the 964 profile goes on the 3.0 cams easily. If you can find a 1980 - 1983 3.0 litre with 9.3-1 pistons.

Be careful with the Bitz system if you plan on deviating much from SC spec. It does not have a throttle position sensor as part of their kit and relies only on the MAP sensor for acceleration enrichment. This works for the mild CIS engines, but may not for wilder cams. I looked at their system a year or so ago, so maybe they have made changes. I'm sure you could add a TPS if you needed it since they are using the megasquirt controller.

I've just had a 3.0 CIS motor built with camgrinders super C2 profile which I think is a couple of jump ups from the 964 profile.

It works great and the the motor is so much stronger above 3000 rpm.

The idle needs to be set at about 1000 rpm to cope with the cam overlap but that about the only drawback

This thread contains pretty much everything that I was able to learn about this type of question.