what should I use in a 73 2.4 CIS motor with webbers?

rudy · rudy's Garage

I have a 73 2.4T CIS motor that I am putting webbers on. I have a set of 68L, 71T, and 73T CIS cams and I was wondering which ones would work and be the best upgrade? Or should I just leave the cams in the motor? I know the CIS cams are pretty mild for the CIS to work. I also need some suggestions on plugging the injector holes. Thanks

Chuck Moreland · 12-12-2002, 08:30 AM

Ditch them all and get some S cams. To get the real benefit of the webers you need a more aggressive cam.

I have this exact setup on my 73.5 - webers, S cams. You won't be dissapointed.

You can get injector plugs from PMO. Make sure you specify the 73.5 CIS type.

dd74 · 12-12-2002, 09:45 AM

Wouldn't overlap be a problem with S cams in a 73.5 CIS 2.4 engine, or is the CIS different in a 73.5 than, for example, a 2.7 CIS or 3.0 CIS? Are the pistons and/or compression different with the 2.4? "CIS" and "S cams" raise a red flag to me in 2.7s and 3.0s. I'm wondering if it's the same with a 2.4 CIS.

Thanks

Chuck Moreland · 12-12-2002, 09:56 AM

Overlap is a problem because of the CIS. He is replacing CIS with webers, hence no problem.

Jbabic · Jbabic's Garage

I have a set of Cams from my 2.7L. I will sell at a good price. Let me know:

513-218-1296 Jerry

jluetjen · jluetjen's Garage

Won't S cams and CIS pistons risk a "spatial event" between the valves and the pistons????

dbltrbl · dbltrbl's Garage

About how much power should one expect from 2,4T with webers+ E cams?

Stock is about 130 hp i quess (+-10hp), S cams cant be machined out of T-cams, but i think i have read somewhere that E cams could, is this true?

Or is there better profile nowadays than old E type?

Kristian

Chuck Moreland · 12-12-2002, 11:38 AM

Quote:

Originally posted by jluetjen
Won't S cams and CIS pistons risk a "spatial event" between the valves and the pistons????

Oh yeah, I have S pistons and cylinders too.

jluetjen · jluetjen's Garage

Quote:

About how much power should one expect from 2,4T with webers+ E cams?

Basically the same as the 2.4E (165 HP) - 10 HP = 155 HP since you'll be using carbs rather then MFI. Once again this assumes that you are using at least E pistons since the E cams are still fairly radical (they'll rev to 7000 RPM+) and might cause the valves to clash with the CIS pistons.

If I were you would do a couple of searches on this BBS on "upgrade T". If my memory is correct you will also need to modify the distributor curve to match the more radical cams. I believe that E's and S's had the same ignition timing and curve. The T's had a different curve and timing specs.

J P Stein · 12-12-2002, 12:39 PM

I would (and did) stick with either E or Solex cams.
Your new life as a Weber carbonmaker....er...carburetor tuner will be somewhat easier.

rudy · rudy's Garage

I'm wanting to upgrade cams without changing pistons. The 2.4 is a good running leakfree engine. I'm just looking for a fairly simple upgrade. Does anybody know what cams will work with the stock pistons? Maybe 2.7S cams?

JTH35 · 12-12-2002, 01:32 PM

I ran a 2.4 T motor with E Cams and Webers for many years, with no problems. However I think the reliefs in the pistons are different for MFI Motors, and CIS Motors. The Motor made about 150 HP at the Flywheel with the E cams.

mikequig · 12-12-2002, 02:48 PM

If it were my motor - and it would be fun to build!- I would definitely go with some JE pistons that would give more clearance to accomodate the more aggressive S or similar cams but that would also have a shape that would aid in flame propogation. That and give you something like 10:1 compression instead of the stock 7.5 or 8 to 1 that the present setup gives you.

-Mike

'75 911 w/3.0 Euro