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cam degreeing on a RFVC motor

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Posted by: ochster

I know all of the info say's to use .040 valve movement, as a baseline. But I'm finding the set-up, and concurrent movement of the cam/crank, a real pain with the valve cover/rocker set-up needing to be removed for adjustment. I keep thinking, there should be no reason, I can't just put indicators on the lobes themselves, and leave the cover and rockers off. If I did, what measurement would be accurate, or indicateable. Any movement at all? still use .040? Will someone please set me straight, am I not seeing what I should be?

Thank You!


Posted by: Ol'89r

ochster.

I don't believe you could get a proper reading by going directly on the cam lobe. You would have to consider the radius on the rocker arm where it meets the cam and also the rocker arm ratio of both the main rocker arm and the sub arm.

I normally use a long piece of wire on the end of my dial indicator that reaches down into the rocker box and sits directly on top of the valve spring top collar. Then, I take up all of the slack in the rocker arm and measure all of the movement directly at the valve. When the valve moves .040, that is your opening figure. Don't really know of a quicker way of making changes other than removing the rocker assembly.

If the cam grinder recommends .040 as an opening and closing figure, I would stick with that.

Just my $ .02

Ol'89r


Posted by: SFO

I also scribe a reference mark on my cam and sprocket, after a few corrections, I can get a feel for how much indexing=how much real change in lobe centers so I am not just shooting in the dark and getting frustrated.
I found on the yz-f the width or a scribe line was giving me almost a whole degree of indexing.


Posted by: ochster

Ol'89r,
I understand the ratio changes, was just thinking it made no difference, if you could accurately locate the lobe centers on the cam themselves. After further thinking, I see though, that the lobe angles, and even lobe tip, would be tough to locate, down to the degree. I will try using a piece wire!

SFO,
Part of my frustration, is also in the lack of integrity with my mag base and indicator setup. The backbone on the frame, etc., are small diameter tubing. I think I will take the time, to make a platform that bolts on to the head stay, for the mag. Maybe I should try/buy another indicator holding set-up.

Thanks! gentlemen


Posted by: Ol'89r

Quote:
Originally posted by ochster


SFO,
Part of my frustration, is also in the lack of integrity with my mag base and indicator setup. The backbone on the frame, etc., are small diameter tubing. I think I will take the time, to make a platform that bolts on to the head stay, for the mag. Maybe I should try/buy another indicator holding set-up.


ochster.

What I use for this is a bolt that screws directly into the head and the dial indicator mounts directly to the bolt. I made an extended bolt and machined it down so the dial indicator clamp slips over it. This takes all of the excess play out of your set up. :thumb:


Posted by: SFO

I use a piece of 3/8" allthread through a motor mount lug and the indicator clamp will tighten on it. Make sure you remove the clearance from your screw adjuster too so your lash is at zero.


Posted by: ochster

Great tips! I knew thier was a reason I needed a lathe...Thanx again.


Posted by: techman

If you're creative you can "lathe" small pieces in a mill/drill machine. You only have to make a small tool holder for your vise. It's not a lathe, but gets small jobs done like screws and short stub shafts etc.


Posted by: John K

I've degreed cams in V8 motors with multi keyed timing sets, but how are you guys acheiving the adjustment? Is there some aftermarket gear available or did you modify the standard stuff?


Posted by: SFO

I beleive that Ochster is running a slotted sprocket on a megacycle cam.
You can slot your own sprocket if you have the equipment, or buy a falicon slotted sprocket. The press on style sprockets are a different animal though, this only applys for a bolt on cam sprocket. Then with a slotted sprocket you can index the relationship between the cam and the sprocket to degree the cam.


Posted by: John K

SFO: Thanks, thats exactly the info I was after. Where can you buy the falicon sprockets? I do have access to a fairly extensive machine shop, how many degrees around would you slot it? This would be particularly good for my bike as its had the cylinder decked 20thou. Also, would there be any problems with it slipping using slotted holes? I know some of the multi keyed timing sets for cars have multiple TDC alignment marks, can you get a sprocket with multiple holes rather than slotted ones and multiple timing marks to suit. Thanks for your time.


Posted by: SFO

Quote:
Originally posted by John K
SFO: Thanks, thats exactly the info I was after. Where can you buy the falicon sprockets?


http://www.faliconcranks.com/

If your application is not listed call them.




Quote:
Originally posted by John K

I do have access to a fairly extensive machine shop, how many degrees around would you slot it?



It doesn't take much to get plenty of breathing room when slotting, I don't add more than 5 degrees in any direction.
These things are pretty hard, I'd say around 58RC. I use a 12"rotary table that I have a 3jaw chuck mounted on because a deviding head or index head is too light weight to handle this opp. The rotary table also damps out some of the screetch of cutting hard stuff. I also use a smaller od cutter than the hole, say if it is a 8mm hole I'll use a .250" EM to whittle away so I don't have to pull the full radius of the cutter at any time. I also use regrinds because they don't last so whats the point of smoking a 40$ cutter on a 25$ job. I have had good luck with 5flute data flute stainless roughers C-11 grade and they like to run dry.

Quote:
Originally posted by John K

Also, would there be any problems with it slipping using slotted holes?


I like to run a thin hardened washer under my bolt head, I believe it is an oem honda thing but I have some kicking around that are also surface ground so I get plenty of purchase with my clamping force in addition to blue locktight always. I have never had slippage.

Hope this helps, Bill


Posted by: John K

Thanks SFO.



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