Adjusting My Valves
 

Hello friends. I just finished following the Pelican procedure for adjusting my '73 914 1.7's valves. I checked through the hole in the top of the transmission case for the notch on the wheel, and made certain it was at the top. However, when I looked at the position of the rotor in the distibutor, I found it was about half an inch off, to the clockwise position of TDC. I decided to go ahead and continue the procedure, and scribed the wheel 180 degrees from the notch, and used the notch and my mark as basis points for adjusting the valves. Cylinders 1,2, and 3 were VERY tight before the procedure, but number 4 was alright so I left it alone. I drove the car and all seemed fine. MY QUESTION for all of you is: Did I do the right thing by adjusting the valves with the distributor rotor a little off TDC? Did I do the engine any HARM?
MANY THANKS for your replies,
Keith

Sorry this is so long.

There are a bunch of theories regarding this. My opinion is...

First of all, what you are adjusting is the clearance before the screw pushes on the valve. The valve must be able to rest on the block when not actualted so that it can remove heat. The valve also needs to open fully to allow air flow and exhaust flow, or poor running/backfireing may occur.

Now with that said, you are measureing off the cam. The cam is round with some lobes that force the set screw into the valve. The lobes are small and percise. The cam should be round.

Now for the contriversy part...

I beleive that the cam is manufactured well enough that you can adjust the valves at any point on it as long as you are not on the lobe. Their is a very fast way to do this, I now can do a valve job in under 30 minutes, this includes jacking up the car and adjusting 3-5 valves.

TDC is what the specs call for because that is the referance point on the blue prints. The machine shops make sure that all is correct off that point, they do not check the rest of the cam.

Both those things stated, it is unlikely, but possible that the cam is off enough for it to make a differance as long as you were not on a lobe.

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What to look for
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If the engine makes excessive clicking noises after warm up, the valves are not opening enough.

If the engine makes no clicking sounds, it is likely that the valves are not closing fully.

If the engine backfires, or runs very poorly now, then the valves are not fully opening.

If none of these things exists, you did a good enough job. Valve adjustments take more fenese then any other procedure on a car (IMO). Live and learn, you should be fine.

Take care, and good luck.

my guess about the mismatch of the mark on the dist and the rotor is that the timing is off. since the dist can be rotated but the rotor maintains its position relative the the cam and crank positions, they don't match due to dist position. i think the 1.7 and 2.0 are timed 27 degrees at 3500 vacuums disconnected. if someone timed it otherwise, say at 1.8L specs of 7.5 btdc at idle, the dist could be wrong. (hope this makes sense)

No matter what anyboby says, if you follow the article from the PP site here, you can't go wrong. A couple of notes to add, I always loosen the adjuster lock nut and screw even though it might feel okay and adjust the clearance. Since the clearance may not be set just right, it is a pain to have to jack up the car and let it cool and get dirty all over again. Also you can use a whistler or a dowel to find the real TDC which is more accurate than looking at the distributor. Good luck.

To Germain, jmcleod, and John,
Thank you all for your knowledgeable replies. It sounds as though what I did should be alright (Right?). And, John - I like your idea and now wish I had adjusted cylinder 4. But one more question - how do you use a "Whisle or dowel" to check TDC?
Best Regards to all,
Keith

John - I just figured it out.

As Germain said, there is a bit of controversy about the exact procedure used. I believe that it is a very bad idea to measure the clearance on one valve when its "neighbor" is rocking. In other words, if the exhaust valve is open, don't measure that cylinder's intake valve lash.

Of you set the valves according to the factory instructions, and then measure the clearance on a valve while its neighbor is rocking, you may very well find the clearance is larger than what you set. I have observed this on my motor, both before and after a complete overhaul. I think this has to do with the rocker stand moving slightly when loaded by the rocker, but I am not certain. This was confirmed as a "normal" measurement by a couple of 914-experienced people.

Note that this is not necessarily the same as the method in Tom Wilson's book, where you adjust a valve's clearance when the same valve on the OTHER side of the engine is open. That has been recommended by a number of knowledgeable folks as a good method. But personally, I will stick with the method specified by the people who designed the motor.

As Bob Hoover is fond of saying, you are your own best Chief Mechanic. Make your own decisions about your own car.

--DD

Of course there are a couple of alternatives and I am trying both of them. First is the hydraulic cam/lifter/push rod package and it works fine if you stay under 6000 or so. Second are the roller rockers from Pauter and a matching cam and they are set to zero lash, but you do still get some valve noise. At any rate stock with stock method of adjustment is the best to use cost wise I feel.

Using the piston as John mentioned above is the best and most accurate way to make sure the marks are in the correct position. A small dowel pin on the flywheel mating surface of the crank is the only device to ensure the flywheel mark is in the correct position. If that dowel pin is missing, as with mine, the flywheel can bolt up in any one of five different positions. The newest 914 is 24 years old now, and in most cases many hands (skilled or otherwise) have performed maintenace and on all of them. My best advice is to become as familiar as possible with your car by checking to make sure everthing is where it is suspose to be.
Chris

Dave,

I think I might have confused you a bit. I don't recomend adjusting the valve when the neighbor is rocking either. Both valves should be closed when adjusting them. In effect the opposing valves should be open, kinda like the artical attached to the adjusting one.