Double check my (Elgin) cam timing please

[jfpound]

Greetings All,
I've installed a set of Elgin Super C2 cams in my 964 motor. I've read everything I can find on setting the valve timing and believe I understand it. I'd like you guys to give me a little assurance that I'm know what I'm doing on the fine adjustment. The way I see it, after I set the course adjustment, I rotate the engine 360 degrees and check my dial indicator on the #1 intake, then rotate the cam as needed to get the indicator within the tolerance for "Lift @ overlap with std lash" as shown on the scan of the Elgin spec seet below. Right? Is there anything special I need to do to be sure the chains are tight? I don't think so, I think that assuming I never turn the engine backwards they stay tight. Also, if someone could check my conversion of the numbers from mm to inch, I'd appreciate it.



Thanks!!!

[ChrisBennet]

You need to keep tension on the chains. The hydraulic tensioners are not enough. See this thread on Cam Shaft Timing
-Chris

[aigel]

Ditto on the tension. Tensioners are not enough. You need to assist with a tensioner tool (P204) or c-clamps / Vise grips.

You do not ever move the cam in the procedure, all you operate is the crank. Put the cam on the right overlap value, remove key, rotate crank to Z1, install key.

Double check both sides twice. Also, run a piston to valve clearance check after you timed the cams. Do this for intake and exhaust, number 1 and 4. This is mandatory on any cam install. It will also help to uncover any serious goofs that may have happened during timing the cams.

George

[aigel]

I wanted to add:

Your conversions are good. Next time get a metric dial gauge. Then you won't get brain cancer converting things. You know, switching between the systems has created more than one catastrophy already.

Set the cam at 2.3mm, or as close to it as you can get. If you are off a bit, due to limits in adjustability, make sure both sides are off in the same direction. Your cam box or sheet should tell you to install at 2.3, the range should be secondary info.

George

[jfpound]

Thanks guys, You've given me the confidence I needed.
George, what is your prefered method for checking the piston to valve clearance?

[aigel]

Ah - we have discussed that earlier here:

piston to valve clearance, why static???

I'd just be VERY careful and do a full 720 with valves set at 1.5 / 2 mm. This is because you didn't build the engine from scratch, right?, and those cams *should* not cause any interference. If in doubt or if you want to be more carful, go with the method Wayne explains in his book.

George

[Eagledriver]

I believe my factory manual says to turn the cam to the proper spec to do the fine adjustment. I'm sure turning the crank would work but you'd have to hold the cam steady while you moved the crank. There is usually enough slop in the pin to get the setting exactly right.

[aigel]

Eagled.,

You are right, one can turn the cam IF the pin is out. Reason why I say you want to turn the crank only, is to avoid that you start turning the engine over on the cam... many ways to skin a cat...

Cheers, George

[camgrinder]

I agree with George, always check valve to piston clearance on any camshaft change.
The Super C2 cams have 1mm more intake
lift at overlap then the standard 964 cams.
Never heard of a v to p issue with these cams in a 964.
My preffered method fo checking V to P ,
is the light spring method.
I am not sold on the screwing the rocker arm down 1.5/2mm method. The next time I have a cam in the checking set-up I will take some readings with std lash and the screws turned down. I will then compare the valve lift curves.

[ischmitz]

I had Ryan make me some mechanical tensioners for the 964. A plate of quarter inch aluminum with a thread for a 14mm long scew and a couple of 6mm holes bolted to the chain housings instead of the tensioner caps. I used large nylon washers to protect the chain ramp area where the tensioner acts upon and voila. Timing was a breeze. BTW: I am using Elgin's Super C2 as well. I like'em.

Ingo

[jfpound]

OK, so I made a tensioner tool and set up the timing as prescribed, got it very close to the middle of the tolerance. I did the V to P clearance check and I don't know if what I found is acceptable or not. On the #1 intake I only get ~1.25mm, and on #4 intake I get ~1.5mm. The exhaust side is >2mm on 1 and 4. The Super C2 cam is not the hottest out there so I guess I expected more clearance, am I OK or does it sound like something is wrong?

Thanks in advance...

[Tinker]

Ingo,

Can you comment on the "seat of the pants" difference between the stock cams and the supers?

Thanks,

Tinker

[aigel]

I am not the one that's going to tell you "sure, go ahead, go 1.25mm". I sure would try to retard or advance the cam timing just a hair to get it to 1.5.

I also would try to measure the 1.25 via a dial, not just the 1 1/4 turns on the screw.

Sorry I can't be of more help. Write John at elgin a private message. I am sure he will have a more educated opinion. Retarding and advancing has somewhat of an effect on the hp/torque curve but it is less dramatic on these engines than it is on others.

Cheers, George

[camgrinder]

I dont have a problem with the turn the screw in method. but to be safe retard the cam about .2mm and recheck it. I would like to see the intakes @ 1.5mm clearance.

[ischmitz]

Hard to say. They feel more agressive once I get over 4000RPM. Idle when cold is less stable which is expected. I like them a lot. I have to get the car onto a dyno with Jack's car, MikeZ's car and Ryan's car to get some comparison data.

Ingo

[jfpound]

OK cool, I realized that for some unknown reason I was removing all the lash before I checked the valve clearance, making things hard on myself. So I set the timing to the bottom of the tolerance (2.2mm) and now with the lash properly adjusted I get ~1.75 mm clearance on both #1 & 4 intake. Still >2mm on the exhaust side. Yippy!!!! I'm done Now I just have to get my tranny buttoned up and stick everything back in the car. Thanks for the help guys, you've kept me from going insane, really.