C4inLA

Would I be correct in the assumption that absolutely any change to cam timing must be followed by valve lash adjustment?

Steve Weiner-Rennsport Systems

Valve lash adjustment must be done BEFORE cam timing is done.

C4inLA

Hi Steve,

For example, I have read about the backside method to checking valve lash (go/no go) on backside of rocker vs cam lobe... So, I am visualizing that cam timing is altering the position of cam lobe when setting each cam, hence, changes existing valve lash? Or, if I have .1mm (.004 inch) lash on all cylinders per bank and change cam any degree, I have just altered valve lash too? Is that incorrect? I'll refresh from workshop manuals before ever playing with this process.

Steve Weiner-Rennsport Systems

JMHO, but I'm no fan of the "backside" method of valve adjustment due to issues with accuracy. This is not an easy procedure so I understand why people look for shortcuts.

Valve lift is a critical spec in setting valve timing as those specifications are predicated on precise lash settings in order to get accurate cam timing.

crg53

Had some time in the garage today. To set the cams spot on is not a simple task, and the better your timing tools are the easier the job will be. I probably spend 4 hours getting them to where I could say "that's close enough". I was aiming for 1.25 mm and ended up with right side at 1.26 mm and left 1.27 mm, again that's a far cry for where they were before.
If you are doing this at home and find you have trouble get to the numbers you are after, I.e. Pin in one hole too little, pin in next hole too much, what I did was take the cam sprocket off and turn it 1/4 of a turn in relation to the chain and reassemble, that fixed it for me. Before you take it apart, make sure cam is set at the # you want and the crank at Z1, then just pop in the pin. Worked for me on both sides.

C4inLA

May pick up that gauge holding tool as I have the digital gauge. Curious, when do you hope to be putting engine back in the car?

crg53

I am doing this job with the engine in the car. Took off the rear bumper, makes it a walk in the park. Also modified the A/C bracket so it will come off without taking off the crank pulley. I should have the car on the road in the beginning of April. Really looking forward to drive it with proper cam timing.

PS. I followed RICARDO"S thread, very informative and lots of excellent pictures.

crg53

I can tell you that nearly all the valves in my engine were loose after I reset the cam timing to 1.25 mm from where the cams were before.
And of cause I reset # 1 & # 4 intake valve before I started the cam timing.

C4inLA

Tricky thread, I saw the engine on stand and just realized there are two CRG's in this thread Now I'm on same page . Yes, I would expect lash to have changed. I need redundancy to feel good on doing those adjustments. I will check set lash before, after, measure with go/no go and check that with feeler gauge, check with dial gauge just because I can and then feel good...

Cheers!

crg53

I just reset my valves today, set them with the proper Porsche tool, I am beginning to get a good feel for how tight the feeler gauge should be, when done I check using the back side method, and all of them were spot on. Don't overthink it, I know the Porsche tool is a learning curve, but well worth the time spent.

-nick

Valve lash is absolutely not affected by cam timing. But cam timing is affected by valve lash (on #1 and #4 intake). Valve lash is set with the cam lobe pointing away from the rocker always. Make sure you understand cam timing very well before setting/changing it.

crg53

You are right, but when the cams were as far off as mine were, it is good practice to double check after you reset them, and in my case the majority were just a split hair on the loose side.

crg53

I took the car out for it's first run today, checking all the work I did over the winter. I was very happy with the way the engine runs now after the cams are set to the proper spec. The pick up in the mid range is noticeable quicker and when I run it up close to redline and shift into next gear, it now feels like what I would imagine a close ratio box would be like, it just picks up and keeps going.
Now off for a good wash and polish.

Rocket Rob

Glad to hear you fixed it! Now go out an enjoy the car.

vwomar

not sure if anyone can help me here but I ran into a sang. I put new cam housing/o-ring/ cam gaskets on and when I check parallelity My left cam is way off. It is set too deep. When I took it apart it had two shims on each cam and now the left is so deep with 6 shims it is still not right.* Here is the bonehead disclaimer. I bought a hungarian cam holding tool off ebay and it would not quite line up with the cam gear so I gave it some taps with a hammer to try to tease it in. I finally had to file the cam tool to get it to fit. The only thing I can think of is I drove the flywheel side bearing cover back a couple mm and that is letting the cam slide back too far. Is that a possibility? Any other suggestions would be appreciated.