High ratio B50 rocker arms

Here you can talk about all kind of TECH for the B50 B44 B25 And Other BSA unit Singles

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High ratio B50 rocker arms

Post by Momus »

Does, or has anyone produced alternative high ratio rockers, or rockers and rocker box, for the B50?
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Re: High ratio B50 rocker arms

Post by beat »

Momus wrote: Sat May 23, 2020 1:22 pm high ratio rockers,
was'nt it Stan doing something the like ? but I can't find it...
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Re: High ratio B50 rocker arms

Post by Momus »

Nothing came up in the search.

I thought someone may have had a line on a Jesel or T&D machined from solid production rather than cut and shut.
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Re: High ratio B50 rocker arms

Post by minetymenace »

Try Searching for "Rocker Arm Ratio", Stan mentions changing the ratio of the inlet in two topics and there is a fairly exhaustive topic under the same name...
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Re: High ratio B50 rocker arms

Post by Momus »

Thanks, I've read a few of the discussions Minty- more wondering if any of the vendors had something solid made rather than set up theories.

Looks like something else to make. Not to worry. It was my stated aim to replace every BSA made moving engine part.

I think that apart from the cam drive spur gear that aim has been accomplished, at least on paper.
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Re: High ratio B50 rocker arms

Post by SteveS »

Hi Momo

Some of the guys have done more than just theorise, but I don't think you will get anything off the shelf. If you check Stan Millard's Photobucket page here there are a few pics of the mods he did to B25 rockers to improve the ratio. I'm fairly certain he used the B25 rockerbox (eccentric adjustment) on some of his B50's. Stan also completed impressive (and successful) work on his B50 heads. You will need to scroll through his album to see all the detail - HPStan forever :thumb
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Re: High ratio B50 rocker arms

Post by Momus »

Thanks for the link.

I saw those photos some time ago when looking for something completely unrelated to BSA's. What does he do with that bike?
.
As Arthur would have said about the B25: "We've dragged a 1950's design kicking and screaming into the 1960's".
A lot of work. I wonder what the results were as far as increasing the torque?

We once brazed some thick iron washers to a 4 cylinder car head inlet side so we could port into the spring seat area. Long valves, mucking around with rocker arms, valve cover work.
It was a success in the broad sense but it probably failed to lift the specific torque although more power was made because revs.
I learnt that what happens further down the port, from around the valve guide and into the chamber is really important well after that.


I am doing something similar to that blokes B25 my experimental B50 head going on The Boris Johnson, straightening the port- the high ratio rockers are/were for my B50.
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Re: High ratio B50 rocker arms

Post by SteveS »

Hi Momu

That "bloke" is Stan Millard - HPStan, very well known and respected in the Flat Track community over in the US.

Did you see Stan's high port B50 head? May help with your head plans - see here.

If you get time it's worth checking out Stan's posts. If you use the advanced search and put his username 'HPStan' in the 'Search for author' box all of his posts will show up
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Re: High ratio B50 rocker arms

Post by koncretekid »

Ed Valiket makes them. You will then want to sand them down and polish them. You also have to open up the pushrod tunnel, as the pushrods now move at more extreme angles where they intersect the shorter ends of the rocker arms.
high ratio rocker arm
high ratio rocker arm
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P.S. Has anyone heard from Stan lately?
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Re: High ratio B50 rocker arms

Post by SteveS »

Hi Tom

Thanks for posting the details about E&V's rockers, I wasn't aware he was making them.

I was thinking the same as you about Stan
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Re: High ratio B50 rocker arms

Post by Barry Creary »

My thoughts to about Stan <1011
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Re: High ratio B50 rocker arms

Post by Momus »

SteveS wrote: Tue May 26, 2020 6:57 am Hi Momu

That "bloke" is Stan Millard - HPStan, very well known and respected in the Flat Track community over in the US.

Did you see Stan's high port B50 head? May help with your head plans - see here.

If you get time it's worth checking out Stan's posts. If you use the advanced search and put his username 'HPStan' in the 'Search for author' box all of his posts will show up
Stan probably wouldn't have heard of me either ;-)

I've seen the photos of the head and some other stuff that he has modified. He is another keen back yarder willing to have a go.
He seems to be able to make his engines get along ok and hold together.

It is a shame, or disappointing, and/or a commercial reality that no one has had a go at making a decent replacement top end for the B50's- CCM/Weslake's semi successful effort excluded. It's been done for various other old Pommy beasts like the Norton and Triumph twins, Manx's and probably others I don't know about.

It's just my opinion but ditching the BSA's standard pent roof 45 degree valve angle for the same sort of layout used in racing pushrod V8's with near vertical valves, very compact heart or kidney shaped combustion chambers and flat top pistons would be the go. The valves are going down rather than across so can be easily lifted a long way like 15 or 16 mm on the inlet and the compression ratio can be made a respectable 13 or 14:1.

Time and tide and so on but I am trying to find a dead cylinder head of a particular type used on 5 litre Ford V8 racing engine to cut up and graft onto a Beezer. I sold a damaged head of the right type a few years ago and haven't stopped kicking myself. These sit over a larger bore than the BSA B50 can have but otherwise service a similarly sized cylinder- 625 cc- that the bike engine can have. These have very nice ports and are making up to 130 to 135 hp per litre at around 7100 rpm. Now that doesn't translate directly of course but it does give you a 80 hp 625 or a 65 hp 500 at very low rpm.

The photo is the type of commercially available car rocker that has a high ratio.

In the BSA B50's case the fulcrum would have to be moved toward the bore center, but the pushrod alignment would be maintained although the forces increased.
B50 rocker.JPG
B50 rocker.JPG (9.73 KiB) Viewed 1751 times
Last edited by Momus on Wed May 27, 2020 9:10 pm, edited 1 time in total.
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Re: High ratio B50 rocker arms

Post by Momus »

koncretekid wrote: Tue May 26, 2020 12:20 pm Ed Valiket makes them. You will then want to sand them down and polish them. You also have to open up the pushrod tunnel, as the pushrods now move at more extreme angles where they intersect the shorter ends of the rocker arms.

B50 hr rocker arms.jpg

Tom

P.S. Has anyone heard from Stan lately?
Thanks for that.

How were the standard rockers made?

Investment cast?
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Re: High ratio B50 rocker arms

Post by minetymenace »

Now if you are looking for a different head, one of Stan' s posts shows a Porch head on B50 a barrel....

Stan is still alive, I had a very brief reply when I messaged him on fb just now.
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Re: High ratio B50 rocker arms

Post by Momus »

minetymenace wrote: Wed May 27, 2020 7:26 pm Now if you are looking for a different head, one of Stan' s posts shows a Porch head on B50 a barrel....

Stan is still alive, I had a very brief reply when I messaged him on fb just now.
Apparently the Porsche head has the same or similar stud positions. Wouldn't be worth the trouble other than the novelty I'd opine. I've got air cooled Porker stuff and had it on the flow bench. The cylinder head porting is not much better than the Beezer and other aspects are worse.

Good ones were making 110 hp per litre with the factories best efforts.
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Re: High ratio B50 rocker arms

Post by koncretekid »

I think the included valve angle on the B50 is about 67 degrees, so better than earlier 90 degrees. Here's one you could copy:
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Re: High ratio B50 rocker arms

Post by koncretekid »

B50 revised head
B50 revised head
B50 revised head.jpg (24.29 KiB) Viewed 1723 times
B50 revised head
B50 revised head
B50 revised head.jpg (24.29 KiB) Viewed 1723 times
I think the included valve angle on the B50 is about 67 degrees, so better than earlier 90 degrees. Here's one you could copy:

Also, you do need to open up the intake a bit:
My head by Ed V.
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Re: High ratio B50 rocker arms

Post by Momus »

You're correct, the B50 valve angle is a lot less than 90 degrees. I often wonder why the production engineers didn't make their chambers more compact - and pistons lighter.

That head has large diameter valve seat inserts?Possibly the fettler (yourself?) has dug the original seats out and remade the throats and seats?
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