Cam options

[AverageJoe]

Hello, I am new to the 4 cylinder scene and I searched for other threads about cams but found nothing. Has anyone upgraded the cams in their Z24 engine. Compcams has two options and I am curious if there are any better options out there. Thank you. 

[datzenmike]

The Z series head is not that great of a design for high revving to make power. It's good for what it does... low pollution and high torque for pulling a heavy truck at low RPM highway speeds well under 4,000 RPMs. Simply put it does not breath well above 4,500 RPM so adding more duration will raise the power range higher. Something with more lift and very modest duration and definitely get stronger valve springs because the stock ones were not really made for higher RPMs.

 

The stated duration for the Z24 cam is 248⁰  but I doubt very much this is at the 0.050" that all cam makers use.

 

The stock carburetor is also a choke point. At 5,000 RPMs it uses 211 cubic feet of air. A 32/36 Weber flows about 270 and is simpler and less complicated than the Hitachi. The engine will still struggle to pull air through the ports size and angle and the intake but not much you can do about this.

 

The exhaust manifold is good enough and the pipe size is 2"? You could reduce the restriction with a turbo style muffler replacement but not one of those straight through type. They get old real quick. Headers are hard to justify the cost for the small gain. If the exhaust needs replacing you could have a custom 2 1/4" pipe and muffler made up.  A 1/4" larger pipe flows 26% more exhaust, more than you need.

[AverageJoe]

Very helpful, thank you!

[datzenmike]

There's an old saying... too little cam and wanting more is better than too much cam and wishing you had less.

[Stoffregen Motorsports]

22 hours ago, AverageJoe said:

Hello, I am new to the 4 cylinder scene and I searched for other threads about cams but found nothing. Has anyone upgraded the cams in their Z24 engine. Compcams has two options and I am curious if there are any better options out there. Thank you. 

Better for what? All out performance or for driving around town? In my experience, big cams just lead to the open can of worms. Once you go past a certain lift duration, you'll need to change your valve springs, adjust your jetting and at a certain point, the head flow will not be enough without porting, a different intake manifold and a good header/exhaust. A mild cam can use stock valve springs and require some simple jetting and timing changes, that's it.

 

So what is your goal and how much time do you have to tinker with it?

 

FWIW - I have never used off the shelf cams on Datsun motors so I can't really advise you on the commercially available stuff. Growing up in NorCal, we were close to Cal Cams and Elgin Cams, making it easy to pick their brains and get something new. You may consider picking up the phone and calling Elgin. Cal Cams is not around anymore.

[AverageJoe]

10 hours ago, Stoffregen Motorsports said:

Better for what? All out performance or for driving around town? In my experience, big cams just lead to the open can of worms. Once you go past a certain lift duration, you'll need to change your valve springs, adjust your jetting and at a certain point, the head flow will not be enough without porting, a different intake manifold and a good header/exhaust. A mild cam can use stock valve springs and require some simple jetting and timing changes, that's it.

 

So what is your goal and how much time do you have to tinker with it?

 

FWIW - I have never used off the shelf cams on Datsun motors so I can't really advise you on the commercially available stuff. Growing up in NorCal, we were close to Cal Cams and Elgin Cams, making it easy to pick their brains and get something new. You may consider picking up the phone and calling Elgin. Cal Cams is not around anymore.

I am just looking for a mild cam. Thank you for your insight. I will definitely give Elgin a call.

[Icehouse]

Let us know what you find out.  I wish my D21 had a hair more power.  Okay a lot more.  Amazon sells a bigger cam for it.  I always wondered if it would help or hurt.  

[datzenmike]

Stick a U67 head on with manifolds, engine brackets and truck oil pan, then swap an L series 71B front case on the 5 speed. The L series is a far better breathing head and way more support.  

[Stoffregen Motorsports]

53 minutes ago, datzenmike said:

Stick a U67 head on with manifolds, engine brackets and truck oil pan, then swap an L series 71B front case on the 5 speed. The L series is a far better breathing head and way more support.  

Right. Quit messing around and make a good motor out of it!!!