Checking Cam Timing

Can someone clue me in on checking my cam timing after I have the timing cover on and the head off. I see the push rods going up and down as I turn the motor over, but I just want to check it again and make sure it is right before I install the head. I followed Mick's and the workshop manual so I am pretty confident, just want another check. Can someone give me a clue when the rods are supposed to be opening and closing the valves as I turn it through the complete 720 degrees? I looked for a cam timing chart but none of them make any sense to me. I'm using the standard 750 cam.

Dave
69S

You must set it up with the crank pinion mark at 12:00 position aligned with the idler mark at 6:00 position, then the marks on the camchain sprockets aligned a certain number of rollers apart (I don't have the book handy)

Yes, I set it up like the book said with the timing marks on the pinion, etc, and it is 6 links from the idler mark to the cam mark. Did all that. I am not worried about max lift, etc. Just want to check when things are opening and closing to make sure it is all good. Can't trust the marks eh?? That doesn't give me much confidence, which makes me want to check it with the timing wheel, I do have one that I can put on the drive side.

Where is the camshaft diagram?

OOPs, I see what you mean about determining max lift, just like TDC. That may be what I need to do.

Dave
69S

6 links apart?

Better be sure they're 10 ROLLERS apart.

Yes, 6 links mark to mark equals 10 roller pins between the marks. Count 'em.

Dave
69S

Each link has two rollers; simple math says 6 links = 12 rollers.

Still, as long as you set it up by the book, it should be fine with stock hardware.

Like I said 6 links mark to mark equals 10 pins between the marks. Count em.



Dave
69S

DogT said:

Like I said 6 links mark to mark equals 10 pins between the marks. Count em.

Dave
69S

Click to expand...

Simple misunderstanding. They do math in Texas a little different. :mrgreen:

I wasn't looking at a picture, just counting rollers.

Anyway, with that setup done properly, the engine should rotate through 720 degrees (and a virtually unlimited number of revs thereafter) with zero issues.

No problemo, I figured that is what he was up to. Mick even uses those numbers in his DVD. Yes, that's the way I set it up. I'm not having a good time trying to check the max lift since I don't have a good dial indicator setup. I would assume if I could check one, they would all be good, this thing ran just fine with the same cam I put back in. It seemed like I was getting some interference when I first test fitted the head, second time seemed fine, so maybe one of the rods was not seated correctly. That is what was worrying me. I'm still waiting on a rocker arm, so I have a day or so to see if I can figure out a way to measure one of the cam lobes.

Thanks, all.
Dave
69S

DogT said:

Like I said 6 links mark to mark equals 10 pins between the marks. Count em.

Dave
69S

Click to expand...

hey Dave,
where did you get that diagram? its missing in the workshop manuals I have found.
Thanks

Steve

A cheap and easy method with the barrels in place and the head off is to use a steel ruler. Drop one end into the lifter tunnel so it is resting on the top of the lifters. As you rotate the engine past TDC in the overlap position you will see the ruler gets lower as one lifter goes down. As the engine passes TDC the ruler will stop going down as the other lifter rises. It will tell you if you are in the area.

It only works if the lifters are the same length. If one has had the stellite pad ground down because of cam failure it will be off.

To get more exact you would want to use a pair of dial indicators set at zero on the base circle of the cam. At TDC of the overlap position both indicators should read the same lift if the cam is installed "straight up."

If the cam is not installed "straight up" Then the point where both indicators show the same lift is the amount of advance or retard in the cam.

This is the quick and dirty method. It only works with symmetrical cams. [nearly all Norton cams]. It is not as accurate as finding the lobe splits but it's a lot faster. Jim

Unless there's major manufacture error or substituted-worn parts, once the dots aligned with 10 links between and chain tension set that's all that's needed to run with confidence its as good as it got from the factory. Easiest way to double check for tedium mechanics practice is intake centerline method to degree cam.
http://www.carcraft.com/howto/116_0701_ ... ewall.html

What would be cool and educational for us would be for you to play with advance or retard to dial in the power band ya like most. Low geared drive sprocket that rev's engine might like retarded as peaks power up higher while long legged cruiser gearing might feel better advanced for more low down broader breathing power.

DogT said:

No problemo, I figured that is what he was up to. Mick even uses those numbers in his DVD. Yes, that's the way I set it up. I'm not having a good time trying to check the max lift since I don't have a good dial indicator setup. I would assume if I could check one, they would all be good, this thing ran just fine with the same cam I put back in. It seemed like I was getting some interference when I first test fitted the head, second time seemed fine, so maybe one of the rods was not seated correctly. That is what was worrying me. I'm still waiting on a rocker arm, so I have a day or so to see if I can figure out a way to measure one of the cam lobes.

Thanks, all.
Dave
69S

Click to expand...

Go ahead and install the head with one rocker arm missing. It is a lot easier. Rotate the engine until the lobe with the missing rocker is at full lift. That way the other three will be down and the head will set in place on the gasket without having to compress a valve spring as it is drawn down. It is a lot easier to confirm that the pushrods are all seated correctly that way. It is very easy to install the last rocker once the head is in place. That is how I do all of them anymore. Jim

Hey, this is a real old thread, guys, my last post was from August 2010.

I got that picture of the cam chain from my 68 workshop manual.

Dave
69S

I just figured you were like a lot of the rest of the nuts out there- building another one. :?