Topic: It's running, kinda.... need some help please?

[MCRider]

Ok, so with no specs on the cam, not knowing what the valves are suppose to  open and close at.
Just lining the marks up and running it like that, is it possible even with the marks and notch dead on, that the cam is marked wrong, and that it needs to be advanced a bit to make the valves close sooner, so the piston is not making contact on it's way up?

I'm guessing finding the lobe centers, and just making it the same degree each way for intake and exhaust is my only option?

This is new ground for me, but I've been reading every thread there has been on degreeing cams in the last 2.5 years. I think theoretically, we should be able to time up a cam like a stocker and run it. In fact I would wager that the vast majority of hotter cams were installed just that way.

But due to production tolerances I don't quite understand, this often yields less result than the cam can produce, and so we have to degree them to get closer. But... since we are running both intake and exhaust off of one cam the best we can hope for is some sort of compromise, splitting the difference between the ideal intake and the ideal exhaust setting.

Within the far limits of the compromise in either direction, one can experiement and see if one likes slightly advanced or retarded from the 50/50 compromise, for the power curve of choice. Welcome the neighborhood dyno. Many good engine builders I'm sure could tell you from the seat of their experienced pants that such and such a cam should be slightly this way or that. Hence the slotted sprockets, and the Gordon frame kit. Or in my case the APE frame kit.

Having stuck my foot in it, I would enjoy reading what those who know have to say.

[scottly]

When I found that the valves had been been kissing my pistons, I milled away the witness marks, and then a bit more for good measure. I wasn't very scientific about it, but I didn't know what I do now. (That was over 30 years ago) In any case, clearance is clearance. If I were you, I would mill the piston valve reliefs about .050" past the marks.

[BrianAdair]

When I found that the valves had been been kissing my pistons, I milled away the witness marks, and then a bit more for good measure. I wasn't very scientific about it, but I didn't know what I do now. (That was over 30 years ago) In any case, clearance is clearance. If I were you, I would mill the piston valve reliefs about .050" past the marks.

  I don't know if I would have much of a piston left.....
I may go a little more than I have already just for peace of mind, in a way, looks like I'll be claying it again.... yay.

[scottly]

Welcome to the world of high performance! It comes with a price, and it comes with rewards....

[mlinder]

I find 104 degree lobe center listed for the RC315. Is this correct? I dunno. But if people are telling you the cam looks like an RC315, start with 104.

[BrianAdair]

I emailed Dynoman about a thicker head gasket, and valve guides.
They do have a .059" thick CFM-20 head gasket, and guides, the guides are pre-honed, the local guy is saying he wouldn't want pre-honed guides, that he would prefer to hone them to fit the vales...

Options on the pre-honed guides....?   

Also the guy from Dynoman said this,

As little food for thought. The Rocky S12 kits were a bore in for the stock motors and worked well with the stock cam, as they were low compression, however when you add a cam to the mix you drop the static compression and the low and mid-range power can suffer greatly. As it is easy to sell, you might want to move up to an 836cc kit that has more compression and larger valve pockets. You would then have more power throughout the RPM range and a much better dynamic power curve. You would also have 30 year newer technology forged pistons with a better ring pack as well.

We do not know what task you would like your end product to perform, but this is the best bang for the buck that is out there and more reliable as well. Just let us know what you think.

Cheers,

Buzz

I almost feel that everything I have done has been a waste of time and money....!

I understand that the Rocky pistons are almost flat and probably have around the stock compression of the K1-K6, and that with a bigger cam, letting more in and out, that the compression that these pistons provide, may not be enough, and it will run sluggish in the low and mid range, as Buzz stated.
That is not what I want, but I also do not have the funds to bore the jugs again and also buy another set of pistons!

Opinions on this also?

I can get it going like this, and always bore it to the 836 later...

[mick7504]

Just a thought mate.

Without going to the added expense of another piston kit and boring, it might be worth considering this cam that Ken at Cyclex has available.
http://www.cyclexchange.net/Engine%20Parts%20Valve%20Trane.htm

#EN-617 (The first one) and an adjustable cam sprocket.
Or you might be able to get away with using #EN-618.
Ken would be able to advise you on the best one to choose.

Mick

[BrianAdair]

Just a thought mate.

Without going to the added expense of another piston kit and boring, it might be worth considering this cam that Ken at Cyclex has available.
http://www.cyclexchange.net/Engine%20Parts%20Valve%20Trane.htm

#EN-617 (The first one) and an adjustable cam sprocket.
Or you might be able to get away with using #EN-618.
Ken would be able to advise you on the best one to choose.

Mick

Yea, I have an email in too them, on my situation also. Talked with Jake over the phone today to check on the status of a previous order, he said to email all my specs to them and he would get it to Ken.

In my own (amateur un-experienced mind ) I was thinking of a couple options.

1. run my stock cam for the time being until I'm able to get the 836 kit.

2. remove the pistons, mill the edge in the 2mm that would make the pistons fit in the chamber on the head, cut the valve pockets deeper. I have a .020 base gasket now, go down to like a .005 or .010 base gasket, run a thinner head gasket, standard .043 or maybe even a .030 copper.with a squish band of around .045 to .050. A lot of clay-ing, checking, and measuring, but I feel it would raise the compression.

[mlinder]

It would raise compression. I'd prolly do that.