Cam selection for a warmed up 2.4
 

Ok now is the time to seek some expert advice.

The engine in question was originally being assembled as a warmed over 2.4 but the final use will now be mostly street and some DE. The basics- 2.4 7R with all the mods, new Mahle 2.4 S P & C's (plus 10.2:1) JE's. Twin plug S port heads, Haltech engine management, TWM throttle bodies, heads were cleaned up and now cc at 64.5. The original cam selection was WebCam 120/104 which is quite aggressive with marginal lower end, remember this was originally a track motor build.

Now the questions, which cam assuming I retain the 10.2:1 pistons?

Do I bite the bullet and put the stock S pistons with S cams in and run with the twin plug heads ?

Personally I like the idea of running the 10.2:1 JE's with an Elgin Mod S cam Specs are .395 - 270 E and .470-296 I. Am I going in the right direction for a street/ DE engine ?

Thanks
Chris

Hi Chris,
I think the mod-S is a good choice.
My only question is what RPM band do you want?
Btw the exhaust lift is .440" not .395".

John

Looking for a 2,000 - 5,500 Rpm range, Mod S still the best choice ?

One other note final compression ratio after some adjustments to deck height measuers at 9.6: 1 not 10.2:1. As I have the twin plug heads I will still run them although not really required.

Thanks
Chris

I've got Crane 288s which make peak HP at 6,200 on 9.8:1 CR...runs like a top...

For a power band in that range I would grind a "Mod-Solex" grind.
I use the solex cam lobes on 102 lobe centers. Solex cams are originally 97 and E cams are 102. So find a set of good E cores and its an easy regrind.
This grind is touch a milder than the Crane p-288 grind.

The 2.4S is getting to the point in displacement where the effects of a hot cam have less of an effect on low-end torque. I would go with an 'S' or mod-S cam - I don't think that you will be disappointed.

On the other hand, if you go with an 'E' cam, you'll probably be looking for more power, and disappointed with the results. My technical editor for the Engine Rebuild Book (Tom Woodford), builds many, many engines for clients, and each time they come asking for an 'E' cam, he "convinces" them into putting the 'S' in instead. Needless to say, every single one comes back and says he was right - no one has complained once...

-Wayne

Is there a chart that has all the aftermarket grinds, etc., laid out in order of "radicalness"? Ie., 911E, then Solex, Mod-Solex, Crane 288, S, Mod-S, (then what?), RSR, 906? GE60, GE 80 and GE100 in there too somewhere? What cam is a really nice one to use in a 2.2 (assume the pistons are safe for pretty much any cam)? BTW, does anyone have any graphs of dynos for all these cams? Seems like someone (me maybe) would do that...If you have one, send it to me. Thanks.

Try Bruce Andersons performance handbook p.189