CIS & 964 cams

[Kevin70914]

Could you give me some details about putting 964 (C-2) cams in a 3.0L CIS engine. What is needed and how much HP/Torque is gained ? thanks

Kevin

[Jeff Alton]

The engine comes out for starters. You need recondition rocker arms lots of gaskets and a bit of patience. Yes, that is the short answer. I just put 964 cams in my 3.2. With all the work involved to just change the cams, I thought it worthwile to just rebuild the motor while I had it out!

Power, I can't say a number, but the car pulls harder and longer than it used to-- I am very happy with these cams. Pretty smooth idle and a good boost when the engine "comes on the cam".

Be aware though, changing cams is not like turbo charging, it is a mild increase, not dramatic.

[rdane]

Do a search for cams. CIS seems to be better served with 20/21 cams.

[aigel]

I believe that you want the 964 cams only in the higher compression (80 and up?) 3.0. There is slightly milder patterns (overlap) that would serve the lower compression engines better.

I disagree with rdane. "Better served" is relative. The webcam vs. 964 pattern has been beaten to death, do a search to see the different opinions.

Changing cams is a big job (compared with a pushrod V8). Engine comes out, all rocker arms come out, sprockets, tensioners, you name it. The cam holding tools and the cam timing tools are a must have also for this job.

If you look for more power, I think the exhaust has the biggest bang for the buck. Of course if you have the exhaust, then the cams will make a bigger impact too jaddajadda --- 3k later and you'll be happy.

Cheers, George

[camgrinder]

The 964 cams do like at least 9.3-1 compression.
The early 8.5-1 engine likes the sport SC grind cams best.
The best thing about the 964 grind is ,
it is a factory profile that can pass emission tests.

[afterburn 549]

you dont have to pull the eng.
,,----it is just ezer then working upside dwn

[aigel]

Come on, afterburn, you are kidding, right?

If not, how do you get the bumpsticks pulled out? Don't you hit the body of the car??? Do you have to take all bodywork off and can make it work that way? How do you get all the rocker arms out and back in? How do you take the cam nuts off with the leverage needed (120Nm!)

I mean, it may be possible for a proctologist to do this in the car, but I'd say it would be something you would do as a bet, rather than a regular job!

And he is possibly asking about an SC. You can't get there unless you take the cat off etc.

George

[Jeff Alton]

I guess you could drop the engine down a bit and take off the muffler and possibly the bumper, but that is a lot of work. I liked being able to so mine while I was standing upright.

Jeff

[rdane]

I was going off this post on my comments.

Originally posted by Kevin70914
could you elaborate on what is needed to build a 3.4 twin plug engine using a 3.2 as a base engine?

Thanks Kevin

This from another post that makes comparing the Elgin and Webcam product easier.

Originally posted by camgrinder
I hope this will clarify the grind names...

(Sport SC) is the same as 330 SC and is a one step up camshaft I recommend for 8.5-1 compression ratio engines. It also works well in Turbo engines.

(964 ) is the our version of the factory 964 C2 profile. Its a 2 step up over the SC stock grind and I like to see 9.3-1 or better with it.

(Super C2) is one step up for a 964 C2 and a big step up for an SC. I like to see at least 9.8-1 compression with it.

If you need more cam than the Super-C2 , there are other profiles available and we dont mind doing custom stuff and changing lobe centers.

Hope this helps,
John Dougherty
manager @ Elgin Cams

Web cam says the 20/21 is "Special performance grind for 911SC/ Carrera/ 964 engines." And they say a hotter cam for our use than the 964. I read that to be closer to the Super C from Elgin.

So lots of opinions, you can take a look at the dyno torque curves...not the numbers in this thread. Good comparison on early low compression (mine) and late, high compression(Jim's) SCs can be made from the graphs. I had a good deal more HP he has a tiny bit more torque, same day, same dyno. Both of us whooped up pretty good on the other SCs there and were easily comparable to a later model G50 Carrera.

Lots of opinions, I base mine on experience.

Best Cam Profile For A Stock SC?

Really depends on what you are putting the cam in and the engine you are looking to have in the end.

My take is the 20/21 is the best of the bunch in a 3.4. And would seem to be the most cam you can get in a CIS if Elgin's and Webcam's comments are accepted. My 3.4 CIS dyno HP numbers and torque numbers a good deal higher than most would have quessed here too.

My '79 3.0 with the 20/21 and now my 3.4 with the same 20/21 passed Washington emissions. YMMV.

[camgrinder]

From the duration @ .050" specs , the WebCams 2021 seems to be in between the 964 grind and our Super C2 cam. The 2021 does have more valve lift than both cams.
The closest I can make is the Super-Cup cam.
I/E 242/228 @ .050" .490"/.455" lift
113 lobe centers.

rdane, Do you have to pass a NOX test in Washington?

[aigel]

Originally posted by camgrinder

rdane, Do you have to pass a NOX test in Washington?

Yeah, tell us the exact hurdles you have in WA. Is it on a treadmill or is it at idle?

George

[rdane]

George haven't we done this already?

You have to pass both an idle and a specific throttle speed in a higher gear. Can't remember which gear or how fast. So both a treadmill and idle. But is isn't California or NJ for that matter.

I also had to lean out the mixture to pass and then richen it back up.

The WA test sheet lists:
HC (PPM)
CO (%)
CO+CO2(%)

John, my thinking was most of the cam grinders first duplicated something like the 964 cam as it became a known performance option for CIS and Motronic. Then later added performance grinds trying to better the performance of each specific use, CIS, Motronic and the later 964 engines. I was thinking the CIS specific grind would be the least important from a business standpoint. Any truth to that?

Elgin has great prices and lots of options. Wish I had known about you when I did mine originally. Only suggestions I heard were 964 and the 20/21. Maybe the Super C2 would be a good option for a Motronic 3.2 to 3.6 with 9.8:1, that I will be doing next. Care to make a suggestion?

Thanks!

Dane

[camgrinder]

Usually when someone has a failure the cam ends up in a shop like ours for regrinding.
We make (4) masters for the 911 engine and then touch up the original cams. After the masters are made we can grind the new profile on other camshafts. When a factory profile does not meet the needs we have to make the masters from scratch. From design to a useable master can take a few days. It is expensive too.
The Super C2 cam is one of the profiles that came from scratch. If we had the Evo style cams we might not have made the Super C2 cams. If I remember right the first set went into an RS car which was raced in the PCA. Worked great and we sold a lot of them in the late 90's .
A set of Super C2 cams will work great but with 3.6 litres and motronic we can get more creative.

[rdane]

John, thanks a bunch.

More questions if you have the time. My recent 3.4 rebuild kept CIS and has a 9.8:1 compression both intentionally. I used the 20/21s because I had them and had been very pleased with the results in my 3.0.

In a same day comparison on the local dynojet my early '79 SC had a torque curve that stayed flat to around 5500 rpm. While a later '83 dropped off at around 4900 with the same cam but higher compression. I understand some of what is going on with the bigger and smaller intake runners in the SCs. But when I went to a 3.4 with 9.8:1, matched my intakes and did a number of little things to get the last bit from CIS I also ended up with a torque curve that more closely duplicated the '83 SC with 20/21s. I lost that last 600 rpm of making good power on the torque curve. No complaints really as I ended up with 250# of torque.

Do you think the Super C2 would make any differenece or be an advantages to the 3.4?

I know Elgin offers 3 cam grinds for use in CIS cars, choices are compression dependant by your comments. Would you agree with George's comment below?

Originally posted by aigel
There is only so much that mild cams like these can differ. There isn't the magic grind that will produce 10% more than the other. George

Finally I like this quote:

ELGIN CAM DESIGN PHILOSOPHY

You probably have figured out by now that I am not an advocate of extra high lift, unnecessarily long duration, or very high compression for any street driven car. I prefer instead to use maximum velocity in the camshaft design which allows my cams to have more duration

I would like to improve my current engine and do a better job on the new one. I'll call you on the 3.6 motronic project.

[aigel]

Originally posted by rdane
George haven't we done this already?

Dude, you would have found it! It scares me what you dig up!

Originally posted by rdane


The WA test sheet lists:
HC (PPM)
CO (%)
CO+CO2(%)

And what are the actual limits that they will pass? That info would be helpful.

Interesting questions you had, I hope John will have time to write some more!

Cheers, George

[rdane]

what are the actual limits

No clue, sorry. May be try a google search?

I was just thinking you and I had already had the entire, cams: pro and con, discussion already

Cheers,
Dane

[aigel]

Dane:

If you kept your smog cert, it will have the limits on there. If you are only half as good digging up paper as you are diggin up old threads, you should have no problem finding it!

We had the cam discussions before. No smog tho, AFAIR!

Cheers, George

[emcon5]

Here are my smog numbers, with 964 cams.

15 MPH, HC, max 141, measured 11
25 MPH, HC, max 113, measured 21

15 MPH, CO, max .99%, measured .13%
25 MPH, CO, max .79%, measured .24%

15 MPH, NO, max 1144 PPM, measured 212
25 MPH, NO, max 978 PPM, measured 173

Smoked it.

Tom

[rdane]

George, you expect me to be able to read!?

The '04 WA test sheet for my '79 3.0. My 3.4 is actually better now with 2000 miles on the engine. I am thinking twin plugs will clean it up even more if Tom's new 3.2 is any example.

HC (PPM)
cruise limit 240 (my #s126)
idle limit 600 (332)

CO (%)
cruise 2.6 (1.8)
idle 3 (2.3)

CO+CO2(%)
cruise = or > than 6% (15)
idle = to or > than 6% (13)

O2 was N/A on my sheet

cruise 4000rpm on a roller
idle 950rpm at rest

I passed with back dated 2 in, 2 out Dansk, SSIs and a 20/21 cam It took three tries but I did actually pass!

[camgrinder]

Dane,
I would like to see the dyno sheets on your car. I suspect the port size is the problem.

An example would be to run an engine with a mild cam and then with one a little bigger cam. The expected result would be to lose a little torque and pick up HP. The bigger cam will improve the VE. Meaning more airflow into the cylinder. Increasing the VE without increasing the port size can cause the problem you have. The airspeed at the minimum cross section in the port can go supersonic at a lower RPM than with the mild cam, effectively stalling the port.
Its like trying to run a 500 cu in Chevy with a 2bbl carb. It will run to a certain RPM and just stop.
Going to a camshaft with more duration, like from a SC to a Super C2 , the point where the intake valve closes on the compression stroke is delayed. This shortens the compression stroke. Just because you build an engine with 9.8-1 static compression does not mean it sees anywhere near that running. think about the engine and its 4 strokes, on the compression stroke the intake valve closes somewhere around 70 degrees after bottom dead center. This leaves only 110 degrees of piston movement left for compression.
Typically the running or "Effective compression ratio" is around 7-1. Race gas, twin plugs etc will let you raise this ratio up to the low 8-1s.
I like to pick camshafts based on RPM range first. The compression ratio is important but should be set after the intake and exhaust systems, displacement, port sizes, and camshaft are chosen.
If the customer wants a power band from 3000 to 7000 rpms, but has 8-1 CR it makes my job tough. I need to let the customer know the trade off of making power at 7000 and losing a bunch of torque at 3000. Or keeping the driveablity with a smaller cam and reducing the shift point.