Specs/Info on RC424 Cams (Russ Collins)

That's a nice looking Hot Rod Ya' got.
I seen the old  RC Eng. and had to look. Can't remember #'s back then. 
Plus I knew the older guys that hooked me at 17. would send stock cams to Kenny Harmon in California to have hard welded and re-ground! Before he made his K-1's & 2's
But when I sold out. I had a set of the R.C. Eng. modified lifter buckets.
Found them in a big picture file I had.
Plus I had a nice black 4 into 1 pipe I bought a few years back, it was like new!
They had no oil grove up top, where shim sat and they had holes in them for?? Lighter? More oil? Quicker revs?
I used them with Andrews 3X cams. Never spit a shim out. Plus never revved my small engines over 9,000 r's either.
Marty in Buffalo

Thanks alot Injected.  I want to have as much info as I can before I attempt to install and degree these cams.  I do have a set of slotted cam gears I bought from APE. 

I saw Summit racing has a cam degree kit which includes a degree wheel, dial indicator, magnetic holder and a TDC stop for $115.

Very cool looking bike Marty.  I really do like spokes on the KZ.  I'm really looking forward to getting this bike running with this set up.

While installing these cams last night I ran into a bit of a problem.  Two of my heli coil threads failed under my cam caps.  Is a time sert the answer since the hole for the heli coil was drilled with a 1/4" bit?  If I use a time sert, what length should I use.  I'm not positive but I think the time sert insert has a bottom which means the stock cam cap bolt will bottom out even if I use the 19mm insert.  This is the longest insert they have for M6x1.00.  The stock bolt measures 20mm of thread sticking out the bottom of the cap.  The failed threads are also where the dowel pins are located.  Anyone have any advice?

You should be able to source "open" time serts that the bolt will pass through. I believe length wise 1.5 times the diameter of the bolt is the minimum to get the holding strength of the bolt
EDIT: just re-read your post, a time-sert may not be the answer because of the "dowel pin" has the heli-coil pulled out or is the thread deamaged? replacing the helicoil and "loctiteing" it in place may be the solution without effecting the dowel pin location

Thank you Wookie58.  I did attempt to clean up the threads and reinstall a heli coil with no luck.  I will definitely need to do something else.  Each exhaust cam cap has one failed thread in the dowel pin hole.

I guess if all else fails you could get a machine shop to drill the head and caps to reverse the dowels, you could then use timer-serts

 

This kind of damage seems common as "heavy handed" PO's have pulled the threads out. When I do mine the intention is to use "studs and nuts" during assembly and disassembly (this way the studs will be securely installed in the full depth of the thread when fighting the valve springs (swop out one bolt at a time during disassembly, then loosen the nuts to remove the caps. assembly would be the reverse - pull the caps down with the nuts then swop out the studs for the bolts one at a time) might seem like "overkill" but the threads in these old motors are very forgiving. (especially given you are using high lift cams so the bolts will be in even less when you come up against the valve springs)

I recently fixed a messed up M8 upper case bolt with a modified 7/16" NC hex bolt. The details are here :

www.kzrider.com/forum/11-projects/618809...-transplant?start=36

You could do the same with a 3/8" NC hex bolt if you have a lathe/mill available.

The problem with Heli coils is if they strip out a Time cert may not work. I had to go with a m6xm8 insert. Drilling while on the bike can get you into trouble fast. I had to make an extension to clear the frame. Almost munged it up for good. 
Steve
rumble.com/v26mqro-installing-the-insert.html?mref=6zof&mrefc=7


Barely pulled this one off. 

rumble.com/v26n196-finished-the-insert.html?mref=6zof&mrefc=8

 

I use a method similar to Wookie's except I use a set of longer bolts for a first step instead of studs and nuts, then exchange them for the shorter correct bolts one at a time.  As I remember, it's a trick I learned here on KZRider.  

Can’t comment on repairs, but I like Wookies process. Replacing one bolt at a time with studs. I’d add to this the stud should have/be a long set with a hex Allen key top. It could be held steady while lefty lucy of the nuts. Example unsure of actual length needed

 

Mikaw wrote:

Can’t comment on repairs, but I like Wookies process. Replacing one bolt at a time with studs. I’d add to this the stud should have/be a long set with a hex Allen key top. It could be held steady while lefty lucy of the nuts. Example unsure of actual length needed

 

 

The stock bolts are M6 X 43mm, the hex head adds 5.5 mm so total length is about 49mm for a stock bolt. On a 75 Z1 head I measure the thread holes depths at 30-31 mm and the cam cap height at the bolt hole is 22.5 mm. Going to full depth without deepening the holes requires a stud/nut combo of around 60 mm.

If your going to run bigger cams that stock you may want to increase the length because you need to push down on the cam when bolting it in. In that case you would need to figure out how long of a stud you can run without fouling on the cam cover.