Camshaft Timing

vouvray · 02-07-2003, 01:07 PM

Is there any other way to set the cam timing in a "73 911 without a dial gauge? I'm trying to get my engine together this weekend and do not have access to one.

yelcab1 · 02-07-2003, 01:13 PM

Impossible.

john walker's workshop · 02-07-2003, 01:22 PM

don't try it! the old "haste makes waste" addage relates here.

osidak · 02-07-2003, 01:28 PM

Where are you located, If close enough by you are welcome to use mine

Superman · 02-07-2003, 03:21 PM

You're welcome to use mine. Or if you live next to a Harbor Freight Tools store, they go on sale for $7.

vouvray · 02-07-2003, 03:30 PM

There is a Harbor Freight near me. I looked at their catalog on-line and didn't see a dial guage. I'll try looking at the store.

Thanks for everyone's help.

Superman · 02-07-2003, 03:35 PM

Regular price is something like $13 or so. Oh, and you would need a holding fixture. One of those magnetic things MIGHT work okay but it would be a struggle, but the P-207 (?) tool is best. Again, if you're near someone who has one......

Gunter · Gunter's Garage

Vouvray: You need the holding fixture and the dial indicator (metric) Also, make sure that the valves are adjusted (0.1mm) or (0.004") before timing the cams. Cheers.

RWebb · RWebb's Garage

Update - I have tried to use a magnetic holding fixture with multiple arms and was never able to get results I trusted. That was with the carb'd motor out of the car but sheet metal etc. installed. I was not trying to check the cam timing but to get the entire lift/duration curve...

P207 tool is now only $37 incl. shipping here so folks should just get the p-207.

Mo_Gearhead · 09-04-2007, 07:05 AM

I guess it depends on the user. I used my Starrett indicator and magnetic holder with success. Used a piece of angle iron, drilled to slip over the cam tower studs, magnetic base held to that. Worked easily.

2.7RACER · 09-05-2007, 07:16 AM

vouvray,
Don't let anyone tell you it is absolutely necessary to use a dial indicator to set cam timing. These people have forgotten about a degree wheel.
With a degree wheel all you need is a feeler gauge set and the cam spec.
Porsche cams are specified at 1mm initial opening. That is if your cam is spec-ed to open the intake at 16 degrees for a '73 T or E, the cam has actually opened the valve 1mm.
Install and zero the degree wheel.
Rotate the engine clockwise to 16 degrees BTDC, the spec for '73 911 T and E.
Set the rocker arm gap to 1mm, (0.040"). Forty thousandths.
Rotate the cam counter-clockwise until the intake cam just touches the intake valve. Pin the cam at this position.
Rotate the engine clockwise 720 degrees and recheck that the rocker just touches at 16 degrees BTDC.
Once it checks out, do the other side.
When finished reset the gap at the swivel foot to 0.1mm (0.004"). Four thousandths.

Point of information. The dimension used with a dial indicator is derived from first setting cams with a degree wheel, measuring how much the cam has moved the intake valve, then publishing that info.

304065 · 07:52 AM

Doug,

The Porsche spec is intake VALVE lift at overlap TDC with 0.1mm valve clearance. Wouldn't you subtract the clearance to arrive at the final value?

Zef · Zef's Garage

Quote:

Originally Posted by 2.7RACER

vouvray,
Don't let anyone tell you it is absolutely necessary to use a dial indicator to set cam timing. These people have forgotten about a degree wheel.
With a degree wheel all you need is a feeler gauge set and the cam spec.
Porsche cams are specified at 1mm initial opening. That is if your cam is spec-ed to open the intake at 16 degrees for a '73 T or E, the cam has actually opened the valve 1mm.
Install and zero the degree wheel.
Rotate the engine clockwise to 16 degrees BTDC, the spec for '73 911 T and E.
Set the rocker arm gap to 1mm, (0.040"). Forty thousandths.
Rotate the cam counter-clockwise until the intake cam just touches the intake valve. Pin the cam at this position.
Rotate the engine clockwise 720 degrees and recheck that the rocker just touches at 16 degrees BTDC.
Once it checks out, do the other side.
When finished reset the gap at the swivel foot to 0.1mm (0.004"). Four thousandths.

Point of information. The dimension used with a dial indicator is derived from first setting cams with a degree wheel, measuring how much the cam has moved the intake valve, then publishing that info.

Soooooooo much easier with the dial indicator...

2.7RACER · 02:58 PM

Hi John,
One of the Porsche specs refers a dimension when the engine is at TDC.
This is the spec that most of us use to time a cam with a dial indicator.
Another spec for cams refers to crank shaft degree when an intake valve has opened to 1mm until it is nearly closed at 1mm. The accepted duration.
For a '73 US 911 T or E, the cam opens the intake valve at 16 degrees BTDC and closes it at 30 degrees ABDC.
This spec uses an opening of 1mm to establish the point at which the valve is said to be opening.
Therefore, if the cam is properly timed, by whatever manner you may choose, the intake valve will have begun to open prior to 16 degrees and at exactly 16 degrees BTDC the intake valve will have been opened 1mm (0.040").
With the method I described the intake cam will have opened 1mm (0.040") at 16 degrees BTDC.
Of course the cam will continue to open the intake valve further.
In the next 16 degrees of crankshaft rotation the intake cam lobe will open the intake valve to whatever the published dimension is. I don't happen to have it at hand. I think this is the dimension you are referring to.
Whether using a dial indicator or a degree wheel the net result will be the same.
In fact as I pointed out, the dimension used at TDC with a dial indicator has been derived from first timing a cam with a degree wheel, then using the dimension at TDC for shop use.

Zef,
The question was "Is there any other way to set the cam timing in a '73 911 without the use of a dial indicator?"
I agree using a dial indicator is simpler. It is not the only way.