Land speed record holder tear down

Randy Johnson's Land speed record holder (SCTA 750 pushrod production) during a teardown to switch to a different cam grind. This bike's been at Bonneville a couple times and has been ridden on the street for a few years (although it doesn’t look like it has more than a couple thousand miles on it).

Here’s the domed pistons. The carbon may have been cleaned off but I’m not sure as these photos were sent to me by the engine builder Steve Adkins at Preservation Cycle who is changing the cam.



You can see the machine marks on the skirt with a little bit of polishing in the upper middle area.


Randy’s bike on the salt.

Does the engine have the cam-change window or will they have to split the cases?

Danno said:

Does the engine have the cam-change window or will they have to split the cases?

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I don't think he has a quick change bearing so its the long hard way.
Here’s his cam. You can see that the lobes have a different color metal near the outside edges. That’s because a channel is cut into the cam lobe and then filled with hard weld before its ground.



The bronze blocks have oil supply holes that feed oil from the head onto the cam lobe as it turns into the lifter – an ideal oiling setup.

So its a Norton fitted with BSA cam followers..... Interesting mod to ensure a tad of lubrication for the cam and followers but why not bung a pressure fed supply to each lobe as per the Domirace motors or simply modify the crank cases to incorporate the cam shaft oil bath Mr Hopwood so very carefully designed into his 1940s Dominator engine to ensure the cam and followers were correctly lubricated at all times INCLUDING during the engine start period when premature cam failure often starts?

J. M. Leadbeater said:

So its a Norton fitted with BSA cam followers..... Interesting mod to ensure a tad of lubrication for the cam and followers but why not bung a pressure fed supply to each lobe as per the Domirace motors or simply modify the crank cases to incorporate the cam shaft oil bath Mr Hopwood so very carefully designed into his 1940s Dominator engine to ensure the cam and followers were correctly lubricated at all times INCLUDING during the engine start period when premature cam failure often starts?

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......."or simply modify the crank cases to incorporate"..........J.M. I know that you have had a bunch of experience with these bikes from way back & I respect that, but can't you acknowledge that this is a good set up. Okay the camshaft oil bath tray was/is a good idea for sure, but it's long gone from the castings, be it from the bean counters or poor engineering from Mr. Hopwood's successors or from whatever, but it is gone. Using these lifter blocks with the oil drain down passages seems like a sound solution for increased lubrication AND it provides for lighter reciprocating valve train componentry (freer revving & smoother / longer lasting cam and lifter) Come on brother, give credit where credit is due. Simply dropping in the modified lifter blocks and changing to a matching cam beats "simply" welding up a windage tray/camshaft oil bath ledge etc... IMHO

CJ, you sometimes show profound naivety sir…

You fail to realise the profound fountain of knowledge that Mr Browbeater, sorry Leadbetter, has / is.

Yes, some people try and ‘prove themselves’ by doing such trifling, petty little things as breaking land speed records and such.

Mr Browbeater, sorry, Leadbetter, is way above that, he doesn’t need to get involved in such trifling activities. He is confident in the knowledge he has, and happy to share it with us all minions… from his armchair.

Land speed records, pah! Anyone can do that.

Stories from half a century ago, unsubstantiated personal opinions and half-truths, recited from the armchair, are the mark of a true genius…

The cam and lifters look to be in great shape, the bike has a land speed record.
I'd say that it is oiling just fine. The proof is obviously in the pudding.
If it ain't broke.........

Jim,
Which cam did they run?
Which cam are they changing to?
And, why? What are their objectives from the cam change?

Fast Eddie said:

Jim,
Which cam did they run?
Which cam are they changing to?
And, why? What are their objectives from the cam change?

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They originally set the record with a JS2 cam (PW3 for radiused lifters) with a best one way speed of 129+ mph. We thought a bigger JS3 cam (D+ for radiused lifters) would give more HP but with the thin air (6000+ density altitude) the big cam didn't help. The rules also require a stock air cleaner box etc. So the jetting with the big cam had to go down to 260 when the air got thin whereas the jetting was up to 325 with the JS2 cam on a better day. It surprised me but that's the way it worked out. With the thin air you don't want to go too far with the cam (unless you are unrestricted and are allowed to make it breath the way you want). They're running Axtell ports copies but here again you have to be careful and not go to big on the ports in the thin air (keep up the velocity).

So the JS2 cam is going back in. Below is a quick change cam bearing which would make cam swapping a bit easier.


Regarding cam longevity and cam oiling - the hardface nickel base alloy welding on the lobes pretty much takes care of that problem.