Which cam on 2,2E with high dome pistons ?

[71er E]

Grady, thanks for your post. I´ll try to answer exactly.

Here´s the engine nr:

the other half of the crankcase should be 901.101.102.3R.
Can you confirm?

Yes i can

Intake valve lift at TDC Overlap with 0.1 mm valve clearance - - - 3.00 mm to 3.30 mm with ‘desired value’ 3.15 mm.

OK that´s identically how it´s mentioned in Waynes book and in the Porsche books

This afternoon I’ll call JE and ask why you got no response to your five emails.
I may have posted an incorrect (or not monitored) email address from their website.

You were absolutely right. The email adress is listed on their website...

You can also choose smaller valve pockets, more suitable for your valve size and 911E cams.

Indeed they could be a little smaller i guess.

It is not clear (to me) if these are for a 2.0 head or a 2.2/2.4 head.

The heads use the CE-gaskets so i guess they are for the 2,2 or 2,4

What does the piston-to-cylinder clearance actually measure?

Haven´t measured it yet. My Porsche mechanics just checked the dimension difference (piston to cyl.)

Have you considered twin ignition for this engine?

thought about that, but after 4 years of not driving the P-car i feel i have to be thankful when it is just running. The build up of my house stole my time and my money..and a little of my enthusiasm.

@John

Essentially the window of acceptable timing will have shrunk since you're increasing the CR

as mentioned in the most technical Porsche books i read it´s better to have the ignition a little late when firing up the engine and then adjust it with the strobe. Do you see any problems when setting it late until the engine is warm ?

[jluetjen]

If you're running the engine with no load, I don't think that detonation is a big problem, although others are welcome to disagree. I don't have a whole lot of experience with that situation. But the first time that you run it up on a dyno, I think that a little retarded is better than too advanced. I'm pretty sure that the key is to be in the right neighborhood though so that the engine will start and run.

[Grady Clay]

Armin,

The exhaust valve side clearance of 1.96 mm is about right.
Is the intake side clearance similar?
This may seem like a lot but this is suitable considering some day it may be run with worn valve guides.

During test-assembly, measuring the valve-to-piston clearance with the cams properly timed is critical.
Be aware that this clearance needs to be confirmed either side of TDC overlap as the piston ‘chases’ the valve closed in some situations (usually with very ‘wild’ cams).

Are these original Ate valves?
Spec for original exhaust valves is 40.0 ± 0.1 mm (intake 46.0 ± 0.1 mm).
I have never seen them out of spec too-large.


The head appears to have recent machine work on the cylinder seating surface.
It is wise to measure the heads to see how much metal was removed.
There is potential interference between the head and piston at the corner (red arrow) of this cut.

Is the surface (green double arrow) the same depth as the (yellow double arrow) cut?
Has the surface (teal arrow) been cut?
The carbon marks on the (yellow arrow) surface appear to be exhaust blowing past a gasket.
Be sure this surface is ‘true’.
If the heads have been (undocumented) modified, you must pay careful attention to every detail.

How do the valves and valve guides measure?





Yes, that is a 2.2/2.4 head gasket and matching cut head.
Check the gasket in the top of the cylinder and in the head.


Measuring the piston-to-cylinder clearance is quite an ‘art’ and requires the exact ‘right’ tools.
The measurement is complicated by tapered and out-of-round cylinders and tapered and otherwise shaped pistons.
The key is to set a bore gauge in the cylinder and then use a micrometer to measure the difference to the piston – or vice versa.
There has been a lot of discussion about this.


After you have cleaned, lubed and installed new points in the distributor, run it in on a distributor machine for several hours.
Document the advance from static to 3000 (distributor) rpm.
With these numbers, you can set the static timing before you start the engine and the 6000 (engine) rpm timing will be exceedingly close to the intended number.
After the engine has ‘run-in’ a bit, always final check the 6000 rpm timing with a strobe light.


The nice aspect of the 911 project is you can pause at almost any step.
Take a deep breath.
Proceed when the enthusiasm strikes.
Think how much fun it will be when finished.

Best,
Grady

[71er E]

Grady thank you very much again for your detailed technical answer. I´m sure one of your forefathers was German..

The valves are the original ATE´s . I´m sure that i did not measure it correctly. That was just roughly for the picture.
The head´s were overhauled by our local engine-shop and i trust them very well, because they do some cars for the 1000km race on the Nuerburgring. When they measured out my JE-pistons they couldn´t hold on to tell me that Porsche-driving is expensive and i´d better go and buy some good "Mahle´s" instead of this "Walmart"-pistons

The carbon marks are caused by a mounting error caused by me. I forgot to tight up some screws with the correct torque.

BTW: Did you ever saw how the valve-piston clearance is measured in Waynes book ?

[71er E]

..oh and if somebody is interested, here´s the car i´m trying to reanimate..

[Flieger]

Sehr Schoen. Reminds me of the "Nurburgring Legends" DVD where they shot the intro sequence with the 911ST and Alfa on the way to the Nordschleife.

[71er E]

...the story continues. I`m finished with mounting cyl. 1-3 and set the intake valve lift exactly to 3.15mm. Wayne describes in his book a necessary valve clearance of 1.5 mm for intake valve and 2.0mm for the outlet-side. I measured more than 2.0mm for intake and 1.6mm for outlet. Does anybody know if the 1.6mm for the outlet is too critical ?

[Grady Clay]

Armin,

Wayne describes in his book a necessary valve clearance of 1.5 mm for intake valve and 2.0mm for the outlet-side. I measured more than 2.0mm for intake and 1.6mm for outlet. Does anybody know if the 1.6mm for the outlet is too critical ?

I don’t understand.
Valves (intake & exhaust) are always set to 0.1mm clearance between the ‘elephant’s foot’ adjusting screw and the end of the valve.

Best,
Grady

[71er E]

I meant valve-piston clearance. I set the clearance between the "elephant foot" and the the valve to zero. Then rotated the crankshaft to the point where the inlet (or outlet) valve is at the closest point to the piston. Now tightened up the screw on the rocker until the valve hits the piston. One complete turn (360°) means 1mm valve movement. I was able to turn the screw for the inlet valve more than 720° (means 2,00mm + clearance between valve and piston) and the one from the outlet valve just about 550° (ca. 1,60mm).