Production Racer build

Been a bit busy recently working on a Proddy Racer which hasn't progressed much since I mocked it up last year.
Here's where I was up to:

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I was planning to race it, but that's on hold due to health issues. For now I'll make it roadworthy and see what happens in the future :|

The motor was already PR spec with a 3S cam, 40mm inlet valves and Dunstall pistons, but it was in a pretty sorry state, so I've gone right through it.
I got the crank ground and fitted it with new bolts, Superblends and R&R rods. The cam was scrap due to corrosion so I got a 4S from RGM
It's now got Dunstall 750 barrels & pistons, which were a pain because they need specific fasteners in BSF. I bought a set from a Famous Norton Specialist, but they were unusable, so I ended up getting some bar stock from Andy Molnar and I made my own, which was far more satisfying :wink:



The head had been ported (autographed 'MRO' inside the casting - anybody got any ideas?) and the inlets re-angled for the larger PR valves, but the guides were worn and the bronze seats had pocketed enough to warrant replacement.
Bannister Engines in Preston fitted new Iron seats, which I cut back and blended in - he also did the crank grind; one of the few guys round here who understands what a 90 thou radius means





There seems to be a bit of what may be evidence of pinking around the plug holes, but don't know what can be done about it, or if it will be an issue in future

I put new valves in with Jim's beehive springs and Ti collars, and I took some meat out of the rockers, especially around the extremities.
A pair of 34mm MkII Amals on Maney inlet manifolds rounds off the engine.
I got hold of an original PR headsteady which just needs a pair of spacers making up to bolt to the frame bosses.



I've always liked the high-level pipe look, and although they look great, I'm struggling to get sufficient clearance between the RH pipe and the downtube - need to think about that one :roll:
If I eventually do get it on the track I'll re-think what'll work best - Swarbricks are just a couple of miles up the road from me.

After shelling out obscene amounts of cash on a Quaife box, I didn't want to take any chances with my 'new investment', so I fitted a Maney outrigger and hacked out an old chaincase inner to accommodate it - love that natty welding 8)



So that's where I'm up to... more soon, I hope.

Well I was a little worried there when you started the thread with the mock up. Follow on pictures tell a nice story. Good looking build.

With the new seats did you check the valve to piston pocket clearances? Looks like you are going into it with some nice stuff. I always liked the up pipes.

Keep us posted and keep up the momentum.

I had the same Right side pipe issue on my 72 combat build. From the advice I got here; loosen the flange nut so the pipe is loose, place wooden wedges between the pipe and down tube and as in my case between the pipe and cyl fins on the left side. Tighten the nut as far as possible. At this point I put the muffler on and slipped a floor jack handle into the end to spring the pipe back into the dog leg bracket that secures the muffler. When everything is tight knock out the wooden wedges. Most of this took way more force than I felt comfortable with but the end result was successful.

Sounds Cool .

Remember , you can ' take it on a Race Track ' without haveing to attempt the Lap Record .
So chassis set up , or balance / integredy is the main thing .

They ran the 3.60 F & 4.10 R which should allow a bit of a drift , over on the side blocks .
Late suckers ran a 4.10 F & 4.25 18 rear . a chrome molley cheater framed'd be stiffer , for them .
The old KR 76 fronts were availiable for a while , a while ago . good Characteristics with the short
stiff sidealls , if you can find one . ( NOT in the Hard compound ) .
Means easing the brakes to lean it over , but way over the Trigonics have the rubber on the road .
and were narrow upright for less drag & thus Max Speed . So HARD brakeings near upright or
way over . Seeing thats what Williams Used , its how they had to ride em to go real quick .

A bit of ' bloended ' fuel ( methanol / nitro as additive ) if you become addicted is cheap horsepower .

Will look to see how the project progresses .

The old Reynolds Raceing Chain , was short life , as thinner metal so lighter , but higher tensile . but still stretched .
The Idea was it was LIGHTER & didnt Break. Unless you forget to button of airbourne .

It looks like you have the big valve conversion but the inlet valve angle has not been changed.
Check for "valve clash", especially when using a "non standard" cam.

Looking good! Love the Maney outrigger.

Will the burrs around the sparkplug hole cause hot spots?

johntickle said:

It looks like you have the big valve conversion but the inlet valve angle has not been changed.
Check for "valve clash", especially when using a "non standard" cam.

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Very well spotted, and you're right - I've got a pretty big problem!
The valve-piston clearance is fine - around 2mm on standard timing marks, but there is a valve clash (clearances set to zero for checking).
I haven't checked the cam with a degree disc yet, but it won't have any bearing on the clash problem.

I guess the only option is to get the inlets re-worked at the right angle and more new seats and guides ( and check the valve pockets again!) - God knows what the PO was thinking?

Happy times - not :cry:

Does anyone have the details of the engineering of the mod (angles, datum point etc.)?

swooshdave said:

Will the burrs around the sparkplug hole cause hot spots?

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I suspect they may under extreme duress, but I'm not claiming to be an expert here :?
If it looks to be a big issue I can get them filled and machined back - I'd just like to know if it's deemed necessary.

And to think I was worried about the exhaust routing... :roll:

B+Bogus said:

swooshdave said:

Will the burrs around the sparkplug hole cause hot spots?

Click to expand...

I suspect they may under extreme duress, but I'm not claiming to be an expert here :?
If it looks to be a big issue I can get them filled and machined back - I'd just like to know if it's deemed necessary.

And to think I was worried about the exhaust routing... :roll:

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I'd let an expert like connoz chime in, I'm just guessing.

swooshdave said:

I'd let an expert like connoz chime in, I'm just guessing.

Click to expand...

Very much what I'm hoping for :wink:

swooshdave said:

Will the burrs around the sparkplug hole cause hot spots?

Click to expand...

I'd let an expert like connoz chime in, I'm just guessing.

Click to expand...

It would be sensible to do it anyway - whether Jim chimes in or not....

B+Bogus said:

I haven't checked the cam with a degree disc yet, but it won't have any bearing on the clash problem.
:

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The cam used most definitely has a bearing on the clash problem !

But if they (valves) are that close, whatever cam you use looks like it has a problem...

I once fitted a Dunstall head on a 650ss .with a standard cam, the valves hit each other ..so guessing the stock cam timing was wrong for big valves

john robert bould said:

I once fitted a Dunstall head on a 650ss .with a standard cam, the valves hit each other ..so guessing the stock cam timing was wrong for big valves

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If that head had ever successfully worked on anything else, that would be very peculiar indeed.

Performance cams don't usually get milder timing with less lift. Quite the opposite, in fact...

Rohan said:

If that head had ever successfully worked on anything else, that would be very peculiar indeed.

Performance cams don't usually get milder timing with less lift. Quite the opposite, in fact...

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That's what's been baffling me - the head had clearly done a high mileage with the big valves, as the (bronze) seats were quite badly pocketed, and it had been running with a 3S cam - not vastly different to the 4S.
Pity I didn't photograph them together.
So the PO must have been running the engine with massive valve clearances, and I guess the pocketing would have helped too!
Not to be contemplated with alloy barrels - especially with steel pushrods :roll:

Oh well, as our Monarchy used to say; 'Off with his head!'
Or was that Alice in Wonderland?
Maybe I can use some of those 'funny' mushrooms to grow my valve seats :mrgreen:

Andy steer clear of""Funny Mushroom's" thats Steve Hobits domain!