Author Topic: RC240 cam and K/H D grind info, also how to tell non stock valve springs (Read 3574 times)

hellbilly1932 · « **on:** May 23, 2011, 08:19:27 AM »

I've been running the RC240 in my stock motor for several years but I can find no info on it what so ever. From what I can tell the motor is stock but I did notice some slight port work was maybe done at some point in its life and there are some stamped numbers under the valve cover near the valves that looks like a machine shop code of some sort, there is nothing like it on either of my other heads I have. Also is there any way to check a valve spring to see if its stock?

I have a K/H D grind cam that I got years ago and never put in a motor because I don't know what it's specs are and if it would be happy in an otherwise stock motor. Any info on this?

Thanks.

754 · « **Reply #1 on:** May 23, 2011, 08:41:08 AM »

RC 240 is a regrind cam..mild.
int timing 30deg-65deg
exh timing 65deg-30 deg
int and exh lift .330
running clearance cold .014
RC 240 Street Torque-- for smaller bore lower compression motors. Good for road riding and touring. The only cam that can be bolted in a stock motor without piston valve pocket machining.

Some may not like the valve clearance, I run 12 thou on a RC 327, and its not real noisy, got another RC list somewhere will check clearance in that 240.

I think the KH D is a very hot one, are the lobes huge and big duration?? if so you are gonna need a lot of motor work.

hellbilly1932 · « **Reply #2 on:** May 23, 2011, 08:48:03 AM »

I'm saving the D grind for a big motor build somewhere down the line.

So with the RC240 i've had the valve/rockers set at stock clearances for years is that a no no? I have the motor apart now putting in new studs and gaskets and there is no evidence of any piston valve contact.

Hinomaru · « **Reply #3 on:** May 23, 2011, 08:49:30 AM »

Here's some specs on the Kenny Harmon D grind.

http://www.satanicmechanic.org/megacyclecam.shtml

Scroll down to part number: 125-D

MRieck · « **Reply #4 on:** May 23, 2011, 02:45:27 PM »

Those Harmon grinds are based on Ducati patterns. I just got a "SuperF" for a customer. It looks like a Chevy small block roller cam.

MCRider · « **Reply #5 on:** May 23, 2011, 06:08:18 PM »

As to the valve springs, stockers look like they should be heavy duty. They are more tightly wound with thicker wire.

(Modern) HD are thinner wire not so tightly wound. The wire is a stronger issue. The less frequent winds reduces chance of coil bind on high lift cams. To me, the looks are counterintuitive.

A spring is a lever all coiled up. If you straightened it out, its harder to bend a short lever than a long one.

A spring gauge would tell you for sure. I have such a gauge and would do some measurements if there was a urgent need. Otherwise it can wait.

I'm not an engineer or such. These are amateur ramblings and observations. I defer to anyone who knows better.

turboguzzi · « **Reply #6 on:** May 24, 2011, 12:55:25 AM »

Quote from: MCRider on May 23, 2011, 06:08:18 PM

As to the valve springs, stockers look like they should be heavy duty. They are more tightly wound with thicker wire.

(Modern) HD are thinner wire not so tightly wound. The wire is a stronger issue. The less frequent winds reduces chance of coil bind on high lift cams. To me, the looks are counterintuitive.

A spring is a lever all coiled up. If you straightened it out, its harder to bend a short lever than a long one.

A spring gauge would tell you for sure. I have such a gauge and would do some measurements if there was a urgent need. Otherwise it can wait.

I'm not an engineer or such. These are amateur ramblings and observations. I defer to anyone who knows better.

more winds (stock) = lower spring K = lower natural resonance frequency = valve float at lower revs.

less winds = higher nat. freq. = less valve float,

Big Jay · « **Reply #7 on:** May 26, 2011, 12:08:00 AM »

On stock springs, the inners are not interference fit and will slip right through the outers.

hellbilly1932 · « **Reply #8 on:** May 26, 2011, 09:23:04 AM »

Any more info on what is best to set the vale to rocker clearance at for this RC 240?

MCRider · « **Reply #9 on:** May 26, 2011, 11:27:26 AM »

Quote from: Big Jay on May 26, 2011, 12:08:00 AM

On stock springs, the inners are not interference fit and will slip right through the outers.

That's good to know. Will make sorting my box of springs easier. Don't know where I got so many springs from over the years. Most are probably stockers, but you never know.

I got my APE TDC finder today, quick service, thanks!

NitroHunter · « **Reply #10 on:** May 26, 2011, 08:42:48 PM »

Back in the day I had that RC 240 cam in an RC 836 cast piston motor, (the old RC 30/30 kit) it was a really good combination. Very nice for everyday around town riding, and I didn't have to wind the daylights out of it to enjoy the ride. Put many highway miles on that one with 52+mpg.

Frank do you have those valve clearance specs handy?

754 · « **Reply #11 on:** May 26, 2011, 09:27:06 PM »

Yes, but I forget to check in my other catalog.

754 · « **Reply #12 on:** May 27, 2011, 10:12:14 PM »

Checked my other catalog, got new info . (think there was a misprint on early catalog)
RC 240
296 degrees duration
Lobe centers 118 degrees
. 327 intake lift, .330 exhaust
valve clearance intake and exhaust .004
That sounds more like it!

MRieck · « **Reply #13 on:** May 28, 2011, 06:59:05 AM »

Quote from: 754 on May 27, 2011, 10:12:14 PM

Checked my other catalog, got new info . (think there was a misprint on early catalog)
RC 240
296 degrees duration
Lobe centers 118 degrees
. 327 intake lift, .330 exhaust
valve clearance intake and exhaust .004
That sounds more like it!

Really??

754 · « **Reply #14 on:** May 28, 2011, 09:02:48 AM »

That Is what it said, will look at what it listed for the other grinds.
The 240 cam was used in the 30-30 kit.. they claimed 30 % more power and 30 % increase in gas mileage, they used 10-1 cast 836cc pistons, header, and the 240 cam.

hellbilly1932 · « **Reply #15 on:** May 31, 2011, 01:04:29 PM »

Thanks for all the info guys! just got my head back from the shop today so its all going back together today.

754 · « **Reply #16 on:** May 31, 2011, 08:00:12 PM »

That 118 degrees center may have been a typo? in the catalog?
The other Honda cams were 104 and 105 degrees.
The Kawi and Suzuki cam were 108 or 110 degrees on the streetable cams, the top fuel cams wwere 115 degree centers..

dhb53 · « **Reply #17 on:** June 07, 2011, 01:57:30 PM »

754 if you ever decide to sell your KH D grind cam let me know

MRieck · « **Reply #18 on:** June 07, 2011, 02:23:13 PM »

Quote from: dhb53 on June 07, 2011, 01:57:30 PM

754 if you ever decide to sell your KH D grind cam let me know

You can still get that grind in hardweld from Megacycle. I recently purchased a KH "SuperF" cam for a customer.

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Author Topic: RC240 cam and K/H D grind info, also how to tell non stock valve springs (Read 3574 times)

Hinomaru