CB350 camshaft rocker issue (running a '68/69 cam in a '73 head)

G

GRHebard

Been Around the Block
ok, so i decided to put in an earlier cam into my CB350 engine while i'm rebuilding it.
if you dont know what im talking about, the '68/69 cams are more aggressive than the later models (after doing the measurements today, its a decent difference)
so i replaced the stock cam/rockers/shafts with the '68/69 stuff and got the top-end put together.

the issue comes here:
due to the fact that the '68/69 cam has a smaller profile, now the eccentric shafts for the rockers dont left the rockers fit snug against the lobs and valves. there is a few millimeters gap.

what can i do?
do i need to go get the '68/69 head also to make this work?
im pretty certain that people have done this before...

any input would be great, im going back down to the shop on thursday and im hoping to have some more info by then
 
are the rockers the same? seems like honda would rather have one part (the rockers) made differently than have the head redesigned to change the position of the rocker shafts... I've got a box of both at the shop so it's got my curiosity going though
 
The "fat cam" rockers are specific to that cam, later rockers will not work. I theorize that if you can get a few millimeters of material hard welded to the tappet face, the gap can be closed up.
 
i kinda thought i might have to do that.
im confident that i can weld them up and file it pretty perfectly using a dial-cal and everything, but i was curious how quickly that would wear out tho...

by the way, these actually are the rockers that were in the head with this cam, thats why im kinda confused.
also, i forgot to mention that its from a CL350E-1XXXXXXX, i dont know if it makes a difference that its from a CL or not...

* RockCityCafe, let me know if those rockers are drastically different, and if you are willing to part with them
thanks!
 
why not just swap the rockers with the other model?? seems like getting them hardwelded and reground adds weight to a reciprocating mass (bad) and will cost a bunch of money... (ebay probably has the rockers you're looking for for maybe $30)
 
i got the same rockers/shafts from the head that i got the cam out of.
they seem exactly the same as my original "fat cam" rockers. or very slightly different,
which is really confusing me

i feel like the added mass of a few mm of welding on valve end ofthe rocker would be so minuscule in comparison to the amount they already weigh...
 
Another trick is to a SL350 cam. It's also more aggressive. I used one on my motor build and it works great. Cam swap only.
 
good to know

does anyone know if i get the skinny cam's camcase, will it work then?
if i do that, it has to work!
 
woah woah woah. stop right now everyone.


the cam boxes are same no matter the model. If you are using the K0/K1 Cam, you need the k0/k1 rockers to go with it. that gap... hmm, you did remember to adjust the rocker height, RIGHT? ;)


sounds to me like you didnt adjust it. if it is in fact the right rockers to match the cam, it should work. dont weld anything.
 
i figured it out!
i thought it was weird, because my rockers/shafts came from the same engine as the cam.

it turns out, my exhaust valves are bent!
it was hard to tell until i took off the cam case this morning
thats why i couldnt close that gap.

im ordering new valves and guides
and im taking the head to a local machine shop to have it all cleaned up, milled a little, and have the new guides installed
 
where can i get some new valves and guides?
any good websites?
should i get them from a honda dealer?
 
honda dealer will rip you off. if your spending the money, you might as well get kibblewhite guides and black diamond valves...

http://www.bore-tech.com/CB.html


if you dont want to spend that much on valves, i have a set of valves that appear to be in great condition... give me an offer on them and ill ship them too you.
 
thanks for the link!
i ended up ordering a set of exhaust valves and and new guides for both intake and exhaust.
my intake valves look pretty good, and i dont want to throw down another $120 for a new set.

hopefully i dont have any more issues and i can get this engine back together soon!
 
so, just to update, i got all new valves and guides put in the head, and i have the type-1 cam. the rockers were messed up, so i found a set of K1 rockers. i ground a little bit of metal off the tops of the rockers, and then polished them this morning
so, now the engine is back together, i just need to torque it all down

hopefully i have it all back together next week
 
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