Britbike forum Forums British motorcycles in general The competition forum Harmon & Collins 7242 cam

I have a set of Harmon & Collins Triumph cams,grind # 7242.Obviously for 650 or 750 twins,does anyone have any info on this grind ???

Here is something pulled from another forum on the Harman & Collins 7242 :

Here's the specs from the Webco catalog:

7242: Hard Faced Billet #6 and 9 combo
Valve Timing, In. OP. Cl: 40-68 Ex OP. Cl: 60-30
Valve Lift: .392, .364
Valve Clearance: .007, .005
Checking Clearance at cam: .020

David

Well,sometimes things just ain't what they are supposed to be.My partner dropped off the 750 flat track engine yesterday.This is the first time I took a good look at it.Mounted a dial indicator to measure valve lift,.314 push rod lift.....looks like standard late 60's stock cams.....Some people got fooled by an old cam timing card......
So..I'm looking for cams now at Megacycle...Anyone got a recommendation based on experience? The engine will be a 650 for class rules,we do have a set of standard bore 650 cylinders and MAP 10.5 tight quench forged pistons...

This is the 750 engine.Looks like a never used Routt 750 kit and spiffy aluminum clutch parts.The rest appears stock.

HB My co-worker has a set of H&C 7040 cams. Dont know the specs but they are quite radical looking and are currently available. PRT

I would be interested I. Purchasing those h&c 7040 camshafts

This info is from a website.............
Harmon&Collins 7054 Cam
A little more lift than the Q cam. For more mid-range torque.
Lift Center Lash Tappet Dur'n Open Close At
Intake .326 105 .002 R 267 31 56 .020
Intake .326 105 .002 R 246 20 46 .040
Exhaust .326 105 .004 R 267 61 26 .020
Exhaust .326 105 .004 R 246 50 16 .040

On my 67 tr6c it has a light crank r&r connecting rods a routt 10.5.1 800 kitt a flow bench ported tr6c head with oversized intake valves set up with 2 34 mm carbs 15/8tt pipes open and as of now a set of jomo 15 camshafts does anybody have a idea of what kind of power I can expect out of this combo and will it sound lumpy with those cams it has std radius tappets any help or ideas would be great thanks

A stock late 60's Triumph idles a bit lumpy for sure.The 800 cc kit will take some of the rough idle away but still expect it to idle with a lot of sound.Power? maybe 60 hp at 6500 rpm.

Now my engine.. I pulled the barrels to have a look inside...Brand new appearing cams,fully machined surfaces.Neatly etched on the intake is CD324/TTB, on the exhaust is TriCor CD330TTB63. So it's a a JOMO 15 "light" cam set. More duration with about the same lift as the so called 3134 cams.
My partner wants to save this engine for a flat track frame built for the street.
He's given the go for a fresh race engine build with hotter cams and MAP or similar rods....

R&r manufactures rods for map they are verry nice and have bullet proof arp 2000 rod bolts on them already the jomo 15 is identicle to the Kenny harmon 15 listed in the megacycle ads a set of h&c number 9 camshafts make great power I've ran those before in a 800

R&r manufactures rods for map they are verry nice and have bullet proof arp 2000 rod bolts on them already the jomo 15 is identicle to the Kenny harmon 15 listed in the megacycle ads a set of h&c number 9 camshafts make great power I've ran those before in a 800

Prt is your co worker still have those camshafts?

the TriCor TT cam is the same as the H&C scrambles cam, 280 duration with Rs and .313 cam lift
the TriCor 15 has 292 duration with .356 cam lift
the H&C 7040 has 300 duration with .416 cam lift
the 7040 is a roller tappet cam and requires the roller tappets, special lifter blocks, pushrod tubes and pushrods
If no one raises their hand I have all the stuff except the cams and would be interested in them
We like TriCor 15s and Sifton 390s in our 650s, Sifton 391s in the 750s
We run them on 1/2 mile and mile dirt tracks
Bill 817 403 7944
[email protected]

Hugoct that's useful information I'm also working on a t140 ally motor one of my many projects on my routt 800 what kind of power do u think it will make you have experience with the jomo or tricore15 where do you think the power curve will be ?

Thanks for the info hb and hugoct

there are a lot more factors involved in where an engine makes power than just the cams
We like 100 degree lobe centers for TT bikes and roll on power
We like 105 on the mile where you stay on the gas
We like somewhere around 102/103 for 1/2 mile
You can run R tappets on the intake and standards on the exhaust for a mellower motor
Stay away from big carbs, ports and pipes unless you are going to be reving it all the time

I'm using std radius tappets the bike is a street bike but I like to ride hard and like my stuff to be more on the aggressive side of things I also have a belt primary and a 5 speed conversion for this bike

I just want to get the most power out of this combo that is possible I want it to haul ass

I'm running a 20 tooth counter sprocket and a 16 in rear wheel

I want lotts of power out of the hole till around 7400 or so

Has anybody here heard of or used the superrod triumph aftermarket rods I'm assuming they haven't been made for several years are the any good what is the rod bolt torque to any info would be great

Stewart:
My greater family is noted for the Holiday meal. It is a celebration of a true blend of foods from a Celtic and Germanic traditions gone by. It has been a tradition to keep to simple pleasures. There is no better example of this than the basic apple pie that must be a part of all of our Holiday meals.

Why is it that some people can take flour, butter or lard, water, a bit of sugar, a pinch of salt, a "smidge" (yes, smidge it's in a Family recipe book) of cinnamon and nutmeg and just the right selection of apples, and have the adults and children alike, licking their plate. And why can some people take the exact same ingredients and have plates with half eaten pie being cleared from the table.

Come to understand this, and you will understand why a fast engine is more than the sum of its parts. It isn't the cam you use, or the brand or carburetor size that matters. It is the experience of putting them all together. Two equally qualified technicians can assemble an engine from the same pars and one builder's engines can be consistently faster than the other.

There are couple of basic "gimmies": More cubic inches, flat slide carburetors and higher compression. The later being problematic with available fuel. All of the rest are trial or error. The one thing I have come to learn the real increases are not where you think they are. And a lot of them are subtle. Simply put, It's all about getting more fuel and oxygen into the cylinder, creating an environment to allow maximum mixing of the two and getting it to burn quickly without any detonation. And like the humble apple pie, not all people will ever get the guidance, spend the time, and effort, to get it right.

There are people here that can, and will, spend the time to help you select the apples, and explain a smidge, but if you truly want a "hot Rod" please be aware that you might not get the results you want the first time. Many of us when we were first learning this trade had the experience of reading "The" tuning books on Triumph, and bought all of the "Right" parts and had a motorcycle that would E.T. slower in the 1/4 mile than a stock bike. It's humbling, just like the first time I tried to make an apple pie.
John Healy

Amen to that John!! I'm still trying to bake the kind of pie that everyone wants and agree with you wholeheartedly. PRT

none better than from the tree in your own yard that granddad planted !

and that you had to pick and peel!!!

John, at first I didn't know where you were going,but as usual,by the time you were done,all I could say was :Oh Yeah! Jack

That is a great way of explaining it nobody could do it better this isn't my first build I've been building triumph and riding them since I was ten thanks to my dad I was raised into them forever greatful of that especially at my age of 34 this bike was my dads and is the first one I ever rode at ten years old he sold and I found it by luck 3 years ago and have been restoring it cosmetically exactly as it was in my childhood internally hotter it's a centemental bike to me thanks everybody