Straight Answers on a 964 Cam in a 2.7

[CARRERIC]

Hello Noah,

Thats true. But a 3.0 and 3.2 CIS has some differences from the 2.7. One being the fuel Distributor, WUR, TB. Generally CIS is very sensative to change!

Also the amount of vacum changes with bigger cams.

As yuo know there are different types of WUR's atmosphirical etc..

One of the problems I encounterd with the SC grind was the car would lean out. It took months to dial in correctly and find solutions. went through many different WUR that were new to find what works best.

I think the 964 grind on a 2.7 would need carbs.

That being said. My friend had his 1981 SC done at the same time with a 964 grind, Euro FD and intakes, alot of other popular mods. Car was fantastic!!!!

[DohertyCM]

How can I tell what cylinders I have, looking at the bottom of the motor?

And what is this?
LN Engineering Nickies Cylinders, set of 6, 2.7/2.8l, 93mm Bore, 911 (1974-77)
PEL-LN-103-93 $2799.00

What is the 93mm.....does that take it out to a 3.0 or 3.1?

[T77911S]

carreric
did u modify the WUR to make it adjustable

[CARRERIC]

T77911S, we tried an SC WUR and a modified 2.7 WUR. In the end we used a new unmodified 2.7 WUR and vacum unpluged and open. I believe this is an atmospherical WUR.

[ventana]

I too am the proud owner of a plain Jane 1974, 2.7L Coupe. It 24,000 miles on it and runs very well. Because it sat for 15 years before I owned it, it's sadly now time to pull the engine, fix the oil leaks and possibly make some performance mods.
I emailed ANDIAL and asked their opinion of using the 964 cams along with their Mahle 2.9 cylinders and pistons for upgrading the 2.7- here is Pete Sanchez's kind response.
"The 93mm pistons and cylinders are a good choice.... The 964 cam will work also but from our experience with customers is that they are disappointed with how the car gets from point A to point B. The original cam has a point where the engine tends to put you in your seat after 3400 RPM where the 964 cam is a smoother transition meaning the torque is at the bottom and mid ranges. You get to the same place at the same time it's just not as noticeable and I guess that is where people need the punch to feel they spent their money well."
Thanks;
Ventana

[T77911S]

carreric,
the WUR for 76-77 had 2 fittings, the top one is for full load enrichment and it prvides a momentary enrichment when u press the gas pedal. the fitting on the bottom side is atmosphere. in 78-79 these are reversed.
with the vacuum disconnected on my car, it spit and sputtered off of idle and detonated at high rpm.
the 77 WUR p/n ends in 033

[CARRERIC]

T77911S,

My 1975 WUR has only one fitting on the top. I believe this is only atmosphere.

[DohertyCM]

Ok, it had been delayed....I bought a boxster S and have been playing with it...

Now I got the engine torn apart and found that I have Mahle Pistons and Cylinders (YEAH!) and also found that the pistons are different from other CIS pistons from an ALUSIL P & C....

The "hump" is higher and the "bowl" is more pronounced...
What is the part number for the "S" pistons... Why is there a difference...And what type do I have, I cant find a part number to distinguish it from another.

Im going to put the old Cams on ebay...They are really nice with no wear or pits.

I also found that the studds are steel and there have been no pulled studs from this case.(type 7R)..I am impressed.

Someone took care of this car before I got it.

We checked the clearance from the piston using the turn screw method and it seemed to work...

I will keep you informed.

Chris

[Early_S_Man]

Mahle 2.7 'LS' cylinders were Alusil, just like KBs ... a lower-cost alternative to Nikasil:

[DohertyCM]

I did the magnet test on them, and Alusil are not suppose to be magnetic. Where as Nikasil are...Things are still in good shape.

Chris

[pjv911]

If this input helps I can add a good experience with adapting an aggressive cam profile with a 2.7 CIS system.
About 3 years ago I bought a pimped out 71` coupe that had a steel widebody kit on it. The car was a very cheap impulse buy. It had a freshly built 2.7 engine with R/S pistons(8.5 to 1) and stock 2.7 heads. The engine had the cleanest new looking Webers on it that Id ever seen. I decided to flip the car and keep the carbs.
I couldn't find a set of zeniths in ready to use condition and decided to install my old CIS system that I had kicking around from another project. I swapped in a fuel return line to the tank and high psi pump and gave it a go.
Well....... It worked great ! The S cams did have an effect below 1200 rpm but otherwise it ran better and possibly more powerful than the webers. Below 1200rpm it surged and eventually stalled from the excessive overlap but I adjusted the idle to about 1250 or so and unloaded the POS to a very happy new owner. As far as I know the car is still driven daily and has no problems.
Here is a before and after picture of that abortion.





After with CIS install



Kurt Williams

[DohertyCM]

NOAH, JIM

I got the s heads on along with the cam and I am only getting .060 valve clearance....You guys suggested .080 intake and .100 exhaust.

As it stands it looks like I need a shim for the piston of .060 in.

Does supertech have these?
Does anyone make them?

Does anyone have any other suggestions on how to solve this problem...

[Eagledriver]

.060 is 1.5mm. That is enough clearance assuming you measured at the closest approach (not TDC).

Is this clearance on the intake or exhaust? What is the clearance on the other valve? You might be able to make a slight adjustment on the timing to increase the clearance if you need to.

If you can get to where you can dial in 1.5mm on the intake and exhaust rockers and rotate the engine with no interference you have enough clearance. Be careful to not force things or you'll bend a valve.

-Andy

[DohertyCM]

Talked with Henry at SuperTech and he is going to cut pockets in my pistons. That was his recommendation. So I will get that taken care up immediately. Apparently the "S" heads have a lower deck than the regular...atleast from the 74 "non-S" to the 75 "S"....Atleast the ones I bought.
Anyway the clearance was there on the regular heads prior to removal, When we put it back together the clearance dropped to .060 for all the valves...

I thought about shimming the cylinder with a 1.5mm shim to raise the cylinder head but Henry did not recommend this.

So he is going to fix me up with a solution...


Chris

[DohertyCM]

Well they are in and adjusted as suggested...
It runs very well. We didnt know what to set the timing at so we set the ignition timing to a stock value.
So help on that would be appreciated if needed.

How do you really know if it is timed right....It sounds good and runs pretty good.

Although since being in the shop, now that the motor is back in the car I have seemed to pick up another problem.

After the car runs for awhile and then shut off and sits for about 10 mins, it will not start...
No fuel is being pumped into the cylinders to start it.
But if I push up on the plate the fuel injectors kick on spray fuel and it starts......Someone remind me of what this is so i can get it fixed.

[Jim Williams]

It is likely that your problem is caused by a drop in start-up fuel pressure due to a leaking check valve at the fuel pump, or accumulator not holding pressure. Leaking injectors can also cause the problem. Also, when the engine is hot, you don't have the Cold Start Valve helping with additional fuel as with a cold startup.