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Discussion Starter #1
Hey guys n gals, I’m nearing completion of my CL350 engine build. For some insight if you haven’t seen my build thread or other post, my right cylinder exhaust cam lobe had some wear on it when I tore the engine apart and I sent the cam and rockers off to Delta Cam for a resurface and hardening. I received them back and kept them in the box until now, just giving them the cursory, wow they look new look over.
I admit this was my 1st build and I didn’t inspect the rockers too thoroughly at the time I tore the engine down or when I received them back. Now that I am to the point of installing them I notice I have 3 312 rockers and 1 non marked rocker. The other thing to mention is one of the 312 rockers has a wider spine on the underside and that rocker lobe contact looks different then the other 2 and different then the one with no marking. See below.

My CL350 is a 70 model. I believe this is what is called the skinny cam. I’ve seen pictures of the fat cam and it definitely appears fatter.

D073C922-2993-4420-87CE-B584B6AF2A56.jpg

Engine serial for reference

8CC54B1A-1427-47F8-B50A-CFC454403399.jpg

Cam when received back from Delta Cam

CCF2E315-7821-48DA-BBC7-11B57547B518.jpg

all 4 rockers, The one on the bottom has no marking. The 2nd from the top has lighter markings and a thicker underside.

D68A0C95-C0A1-44FD-B5F2-800020DB56AB.jpg

The underside of the rockers. The 2 on the left are the clearly identified 312 rockers. The third one is the one with faded 312 markings and the last one is the non 312, no markings. The 1st 2 (312’s) closely match. Lobes are nearly identical as I can tell and Center rocking points appear the same. The third with faded 312 markings has a slightly different shaped lobe face and the center rocker portion appears thicker. The last non marked rocker has a much different lobe face and the center rocker is nearly identical to the thickness of the faded 312.

I’m nearly 95% positive this means I need to replace 2 rockers. I’m bummed and slightly surprised this wasn’t caught at Delta Cam. I’ll be calling them Monday to inquire but I also know that it was my responsibility to look and inspect the rockers before, document better, and inspect after I received them.

Any insight would be great and if we agree that I need 2 312 rockers, anyone have some?
 

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Do you have a wood dowel the same diameter as a rocker pin? If so, slide them on and push the small end down. Measure the height of the wider end. If the same then you're fine
 

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Could be forgings from two different batches. Not necessarily identical but finished/machined to be functionally the same. I would do a trial assembly of the valve gear in the head and see if everything fits.
 

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In Delta Cam's defense, Delta Cam is in the business of resurfacing/grinding cams and rockers. They probably do thousands of them a year. I really doubt that they even know what most of them go in, let alone what goes with what. They open the box, repair the parts and send them back. When I worked as a machinist at a machine shop I would be given all kinds of parts to repair or reproduce and never knew what they came from, going into, or even did.
In your case, I would bet that the engine has been rebuilt in the past and the rockers were replaced. Working on these old bikes I have come across a lot of previous repairs, some good, some bad.
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Discussion Starter #5 (Edited)
In Delta Cam's defense, Delta Cam is in the business of resurfacing/grinding cams and rockers. They probably do thousands of them a year. I really doubt that they even know what most of them go in, let alone what goes with what. They open the box, repair the parts and send them back. When I worked as a machinist at a machine shop I would be given all kinds of parts to repair or reproduce and never knew what they came from, going into, or even did.
In your case, I would bet that the engine has been rebuilt in the past and the rockers were replaced. Working on these old bikes I have come across a lot of previous repairs, some good, some bad.
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I was hoping it didn’t come across as me throwing Delta under the bus as ultimately it was my responsibility to check the rockers initially. They were great to work with, great communication and quick turnaround with a great price. I’ve sent Delta some messages on it and I know they’re stand up guys. Still highly recommend them as the work they did on the cam was great and the rockers look good. Hoping it’s a solution as easy as Boomer states but looking at the lobes I would think there are degree differences with the contact points to the cam being different shapes.
 

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Did not think you were dishing on Delta Cam, just clarifying a little. A different contact area should not make any difference as long as the valve adjustment is correct and nothing is hitting anything. The cam is a constant dimension and will move the rocker the same amount wherever the rocker makes contact.
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Those look like the variations I have seen in rockers for the skinny cam.

The fat cam rockers will not have any clearance when fitted to a skinny cam, one engine I took apart someone had taken a grinder to the rocker end to get it to fit. Three were correct but one was for a fat cam, not in the FSM to do that.

You could do an assembly of the top end on the bench and slip the one rocker that doesn't show the 312 marking in to see if there is clearance between the rocker and the cam.

My bet is on there being no issues.
 

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Discussion Starter #8
Thanks for the replies guys. I was under the impression from reading previous posts that the cam and rockers should be matched. 312 being the skinny cam rockers and no markings being the fat cam rocker and these should not be interchangeable . Am I incorrect on that? The face of the fat end of the non numbered rocker is definitely straighter and a little longer then the other three.
 

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Discussion Starter #9
The "312" rocker arms are for all cams (Cb,CL,SL)EXCEPT the fat base circle cams that came in the KO Cb350 and KOSL350. All four rocker arms must be the same with each cam ie: four 312's with the small base circle cam and four "non-312's" with the fat base circle. The fat base circle has the same lift but 10 more degree's of duration than the small base circle cams.

The early rocker cam for the fat base rocker should be more "square or blocky" than the 312....there is also a number associated with early stuff, 281 I think, but its not on the rockers, so I look at the pad.I
So doing a bunch of web searching I came up with this Quote above from the 13x forums along with some Qoutes from Outobie that state the same. It looks like someone mixed in at least the one early model cam rocker and I should replace that one. The non marked rocker is definitely more square then the 312’s and my machinist who worked on my head had me replace one single valve for it being out of spec and slightly bent. I didn’t take down which rockers came from which position so this may of been the root cause (speculation).

I’m not taking a chance. Anyone have a 312 rocker they would trade for my older non marked rocker or have a good source on a 312 rocker? My cam gear also has 312 marked on it for reference.
 

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I've been resisting this since the original post appeared. At least it was filmed in Japan, that's something right?

There's only one way to rock.
 

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I never saw VanHagar live and I had no idea they actually did any of Sammy's solo stuff... that would have been great, love Sammy ever since he left Montrose
 

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Well, I have about 8-10 random spare rockers in my spare parts bin. Just did a quick search through them which yielded 3 possible rockers for your consideration. Two clearly marked 312's and one faintly stamped 312 like the odd one that you have. Plus the rest were all the fat cam style.

The 3 possible "good" rockers all have excessive wear on the face that contacts the cam lobes, unfortunately, so they would definitely have to be sent to Delta to have the surfaces built back up, ground to spec and hardened.

I have a few things to get done on my bike today so I am going to pop them all into my ultrasonic bath and clean them up as good as possible to get a better look at their condition. Will post the after-cleaning pics up here once they're done.

If you're interested, they're yours. Just pay for the shipping and I'll get them out the door. I also have two spare cam gears, one for each of the spare camshafts in my parts bin, one skinny, one fat.

Hope this helps, if not then I hope someone else on here will have what you are looking for.

Good luck with the rebuild!

Sent from my SAMSUNG-SGH-I537 using Tapatalk
 

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Well, after cleaning and closer inspection it appears that I actually have one clearly stamped 312 and two of the faintly stamped 312's. Here are photos for consideration.

The top one in the pics is the clearly stamped one. Reads "92" on the valve end, and "312" on the camshaft end.


Edit: what appear in the photos to be dimples/divots in the valve faces of the top two rockers are actually just polished smooth spots from contacting the valve stem. Running a fingertip over the spot feels glass smooth, with no height variation relative to the rest of the valve-side face.

Sent from my SAMSUNG-SGH-I537 using Tapatalk
 

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Since those four rockers and the cam you sent off to be resurfaced are from the same engine it seems they would work together just as well as they did originally. Why pay out good money to have a part reconditioned, then toss it to replace it with a used part from some other engine?
 
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