Intake cyl 1 & 4 opening separation in Crk degrees
 

Dear Forum

I am working on my engine project and currently timing my camshaft with a Z-block
and a grade disk on the crankshaft

The opening of intake 1 & 4 is not 360 degrees seperated. I have an offset of 35 degrees crankshaft.


How should I proceed now.

BR
Bob

Sounds like you are 1 tooth out on the chain.
Bob

HI Bob

that you for the reply,

do you agree that the opening should be 360 deg. separated.

My Cams are not the original and I don't know how they are specified. I am starting on TDC and both camshaft dot are at 12 o'clock position.

My approach is to syncronize intake 1 & 4 to have a 360 deg offset.

My reference in 0.2mm openting of intake valve 1 & 4 and then made a mark on the reference disk. I choose this reference with the assumtion cam profile A & B are the same and timing is importend.

Currently I saw that my camshafts were re-machinend with an lower lift as original and a wider opening & closing.

I have no budget for new ones so I would like to stay with what I have.

so I positoned the engine at TDC no. 1 and mounted my Z-Block. The valve 1 is closed and adjusted the gauge to zero.

Then I turned the engine Clockwise from the pulley side. That is the engine rotation. (correct) I used the dizzy finger for reference.

When I achived 0.2mm lift on a valve I marked the disk.
Opening at 60deg BTDC.
Then I turned the engine 360deg. I saw I have 8deg offset at 0.2mm lift on 4.
I opened the 46mm nut and corrected the offset.

Now I have opening of intake valve 1 @ 60deg and 4 at 420deg. Remember I have no data of the camshaft

720 is a full firing order so 1 & 4 valve opening should be 360 deg. speparated.

Is my approach wrong?

BR Bob

You need the spec setting for the cams, without them youre wasting time because the application of the cam is the setting. The cams do have to be 360 degrees apart regardless of the settings or spec just to be matched.
Bruce

Here some pictureshttp://forums.pelicanparts.com/uploa...1323000355.jpg


http://forums.pelicanparts.com/uploa...1323000394.jpg


http://forums.pelicanparts.com/uploa...1323000441.jpg

http://forums.pelicanparts.com/uploa...1323000477.jpg

Hello Bruce is 60 deg opening BTDC is a std value for any stock cam from Porsche?

http://forums.pelicanparts.com/uploa...1323001074.jpg


As you can see my intake profile.

I have a lift of 10.62mm over a duration of 330 degrees crank.

What do you think about this profile. It came of of a 2.7RS engine.

Are you turning the crank clockwise or counter clockwise.
The chain tension has to be tight also
There is a factory tool for pretensioning the tensioners but just pushing them up should do.

From the arrow on your timing card looks like counter clockwise.

From the arrow on your timing card looks like counter clockwise.[/QUOTE]

I DID IT WRONG.

I am turning clockwise.

I, as a generalization, build stock CIS and the cam starts lifting at about 30-35 degrees before Z1 to get to about 1.0mm to 2.0mm valve opening depending on the spec. On a carb cam it would be conceivable that it could start as soon as 60 degrees BTDC but say a T cam might start at 35 BTDC and lift faster but I never pay much attention to that except to know that 30 to 35 is where I start looking for movement on a CIS cam.
Bruce

Green= power, Gray= exhaust, Blue= intake, Red= Compression.


http://forums.pelicanparts.com/uploa...1242665497.jpg

Yes, 1 and 4 are 360 degrees apart.

Your cam timing point is overlap TDC with 0.1mm valve clearance.

What is the cam setting in MM? That is all that matters. You lock the flywheel at Overlap TDC and turn the cam so the set number lines up and tighten the nut. Then turn the engine 360 degrees and do the same to the other bank. The settings are always 360 degrees out of phase.

I see what you are trying to do. You are mapping out the cams to determine what you have and then you'll be able to know what setting to use. There are cams that have 330 degrees of intake duration. I would look at the Elgin cams website and Bruce Anderson's book to see if you can determine what you have. These sources (as I recall) will tell you what the lift is and how they define the beginning of the duration in lift. From there you can figure out what you have. You should end up with something like this: Intake 330 degrees 10mm max lift. Exhaust 280 degrees 9mm max lift, overlap angle 97 degrees. Once you have that you'll know what cam you have and can find the setting for the timing procedure.

-Andy

Yes, 1 and 4 are 360 degrees apart.

Your cam timing point is overlap TDC with 0.1mm valve clearance.

What is the cam setting in MM? That is all that matters.


What means MM?


BR
Bob

MM means millimeters. Nobody can tell you what your cam setting is until they know what cam you have.

-Andy

Go to elgincams.com and look at the Porsche cam profiles. That page will show you the settings for about 50 different camshafts.

-Andy

Here my profile for Cyl. 1.

What cam do I have?http://forums.pelicanparts.com/uploa...1328701314.jpg

Exhaust opens @ 129°
max lift 9,48mm @ 264°
coloses @ 417°

Intake opens @ 310°
max lift 9,89mm @ 464°
closes @ 601°

overlapping @3mm 348°
overlap from 310° to 410°

What type of cam is that?

BR
Bob

The right cam shows an S on the front of the cam nose below the dot.
The measurments are for early (1973) S cam
Intake opens 38 degrees BTDC
Intake closes 50 degrees ABDC
Exhaust opens40 degrees BBDC
Ex closes 20 deg ATDC

This is over 720 degrees

you have a 911e cam

Thank can you post the data for me as well?

Br
Bob

Hier Dougherty Racing Cams Porsche 911, 930 and 964 camshaft profiles

9.89mm intake lift /25.4 = .389" , 9.48mm exhaust lift /25.4 =.373, 3.0-3.3mm lift at overlap TDC ("setting")
911e is closest match