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Author Topic: The worlds fastest Weslake.....well maybe!  (Read 48152 times)
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Briz
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« Reply #60 on: October 05, 2011, 02:11:47 PM »

'Bout time I updated things.

Thu Aug 18, 2011
Thought a good deal about the intake system for this. The supplied manifolds on the engine were lifted straight from the 500 singles. The front one was at a silly angle especially for the carburation that the engine would have been expected to have.
Even with injection, the throttle body would have been going thru my chest! Not ideal.
So something more appropriate was in order. Originally I envisaged using TL1000 throttle bodies, but they're huge and incorporate the injectors, whereas I wanted the injectors downstream of the TBs and pointing in a straight shot at the valves.
Then another idea occured. Why not have a single throttle body feeding a plenum, which would then feed a manifold/ injector housing which would extend the 2 ports to each valve back several inches? A long ram effect with a smooth flow.
Now individual throttle bodys are well known to give a snappier throttle response compared with a plenum, but thinking about it, on a long straight run on the salt snappy throttle response isn't needed or wanted - I imagine you could quite easily induce wheelspin on each gearchange.
So a more damped response is a good thing in this application.
Of course, its easy to forget that airflow needs to be considered holistically (!) Its no good having a perfect port layout if the atmosphere its drawing upon is going the other way at 150mph!
Laminarity of flow is what I'm after. And if its easily convertable to turbocharging, so much the better.
Heres the pics. You can see that the throttle body (off a volvo) will point forwards and the plenum is a curved tube affair to keep it all moving in the right direction. Ducting is deliberately kept on the large side to provide the plenum area right up to the manifolds.




Gas tank. This is the dumpiest tank I ever made! Function before form here.
It needed to be tall enough to house the fuel pump:

But short so I can hunker down behind it out of the airstream. Took a day & a half sandbagging & wheeling - my arm hurts! but its done:



Sat Sep 10, 2011
Got loads more done now. Almost ready to blow it all apart & look inside the engine.
Mostly brackets etc of course.
Exhausts, according to Julian Cranfield, should be 54" long. Thats why they have to snake up the inside of the footpegs. I know the rules say the exhausts cant point at either the salt or the rider!:

RH footpeg setup:

LH footpeg & shift linkage:

HD boxes were never made to have rearsets!

Wed Oct 05, 2011
With the fabrication done, the frame etc off for paint and some customer stuff done, I'm tearing into the engine.
In order to get the cam timing right on reassembly, I fished out my old Hagon 'dural' timing disc. Probably a collectors item now!


I have to figure it all out myself with this - no manuals. Dismantling the cam drive was a puzzle, but got there in the end.


Dealing with a lot of 25 year old silicone seal doesn't help. All stuck fast. Being a low production lump, some things weren't well sorted - like how do you get a socket on this bolt? A bit of machining needed here.


Finally got the head & barrel off. Dished pistons and small volume chambers. Tomorrow I'm going to have to take a burette to it all to measure the compression.



Relieved that the cylinder bore looks in good condition (dont know about the front one yet) I had fears of rust from all those years in storage.
« Last Edit: October 05, 2011, 02:21:27 PM by Briz » Logged

Briz
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« Reply #61 on: October 07, 2011, 02:26:30 PM »

I've just about figured out all I need to know about the engine now.
The pistons have a Cosworth part number which I noted down. It looks a lot like the dish in the piston top is added later. I suspect they were flat-tops as supplied.
I called Cosworth and they confirmed that it was made for the Weslake. Its not lifted from another application.
The one in their catalog which looked close turned out to be about 5mm taller. So thats no good.
Cosworth dont have any of the weslake pistons in stock. Minimum orders apply, so thats out.
The trouble is, the (perfect for the street) 10:1 ones I have are a bit too high for turbo use and not high enough for NA
I'm gonna contact Ross pistons, who according to ol' Sumo have a reasonable minimum order of 4. They apparently were willing to do Sumos as 2 pairs with slightly different diameters so he could have spares for any reboring.
I'm wondering if they'll do 2 pairs of different compression ratios. One pair at 9:1 and one at 13:1 would be great. I'll call them Monday.
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wobblywalrus
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« Reply #62 on: October 07, 2011, 05:23:54 PM »

My oldest son's Triumph had a backfire and it blew up his airbox.  My Triumph backfires occasionally and sometimes it pops off an air filter, or one time, both carbs.  Now I clamp the carbs to the manifolds and the cleaners to the carbs with just enough pressure to make a seal and no more.  I want things to come apart without breaking anything.  So far, it works.  Just an idea.  I was looking at all of that fancy intake plumbing.
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Briz
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« Reply #63 on: October 09, 2011, 06:29:11 AM »

Thats a good point. I was going to have a blow-off valve in the plumbing before the throttle body for the turbo.
Might be a good idea to have one after it too for those reasons.
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peterdallan
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« Reply #64 on: October 10, 2011, 01:21:14 PM »

Has your engine ever been used? It looks brand new!

Peter
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Briz
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« Reply #65 on: October 10, 2011, 04:49:07 PM »

It is Peter. Never run at all as far as I can see.
Just sat on somebodys shelf for 25 years. huh Must have been an expensive purchase back then. Go figure.
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Briz
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« Reply #66 on: January 20, 2012, 05:56:39 PM »

Right then! I've worked off all the customer-work for awhile so I can devote my whole attention to finishing the bike.
Got a package thru from Ross Pistons today.
First I gotta dry-assemble one cylinder to check valve clearances. A real pain on this DOHC lump where everything has to be done with degree wheels & dial gauges. rolleyes
Heres one of the new ones (left) next to one of the old Cosworth ones (right)
Nice bit of workmanship.
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saltwheels262
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« Reply #67 on: January 20, 2012, 07:50:42 PM »

looks like you're pumping the compression.

what is the difference between the 2?

bf
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bub '07 - 140.293 a/pg   120" crate street mill  
bub '10 - 158.100  sweetooth gear
lta  7/11 -163.389  7/17/11; 3 run avg.-162.450
ohio -    - 185.076 w/#684      
lta 8/14  - 169.xxx. w/sw2           
'16 -- 0 runs ; 0 events -- made a 2 state change in ZIP codes

" it's not as easy as it looks. "
                            - franey  8/2007
Briz
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« Reply #68 on: January 21, 2012, 09:17:36 AM »

Just the compression. The new ones have a 4cc dome whereas the old ones had a 6cc dish. Bumps the compression from 10:1 to 14:1.
Definitely not pump gas friendly!
Wonder if the starter will get a hernia lumping that over!
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kiwi belly tank
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« Reply #69 on: January 21, 2012, 02:51:45 PM »

I just checked out your build from the start, neat stuff. Interesting to see the head bolt setup is like the 59 ESO I have here, presumably to free up the head for ports. These old hand crafted engines are so cool to work on, you can feel the history in your hands.
  Sid.
ps  SP250 in the blue bike looks like fun. 
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Briz
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« Reply #70 on: January 23, 2012, 02:50:14 PM »

Thanks Sid, yeah the V8 bike worked out well. Very rideable.

Saturday, I made some tools to help set cam timing including one which locks the cam at max lift. Makes the job a breeze! The cam sprockets have vernier adjustment; once the correct sequence of work is figured out, its not the nightmare job I had feared. Phew!

Did the modelling clay test today to check valve-to-piston clearance.
0.040" - 0.050"
Hmmmmm....
Normally .060" is the rule-of-thumb minimum, so I'm in a bit of a quandary now.
I know the valvetrain on this motor is safe to 14,000 rpm (!) - far more than the bottom end will take which is about 10,500. So valve float or bounce isn't likely to be a factor.
And the tall crankcase will likely expand with heat more than the steel con-rods so clearance might widen when its up to temperature.
Setting up the pistons to take .020" off the valve notches is going to be a pain.
This test was done with the cams set at 103.5 degrees which is what Julian Cranfield recommended. Dave Perry on the other hand reckoned about 105-106 degrees. This might well make a big difference to clearances and the later intake closing point may favour high RPM power.
I'll try it again tomorrow at 105 degrees. If it makes no difference I'll be back to the same decision.

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Nortonist 592
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« Reply #71 on: January 23, 2012, 03:09:25 PM »

Briz.  David is right.  I have both my Weslakes at 106 degrees.  Mine don't like anything beyond that.  Also I have been running VP C10 and ERC 110 race gas with no issues for years now.  I've never tried pump gas.
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Get off the stove Grandad.  You're too old to be riding the range.
Briz
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« Reply #72 on: January 23, 2012, 05:58:13 PM »

Ah! thanks Bill, I'll see what the clay says tomorrow!
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wobblywalrus
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« Reply #73 on: January 24, 2012, 01:58:54 AM »

Briz, what about using a thicker base or head gasket?  You will lose more compression than relieving the pistons but it is much easier to do.
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Briz
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« Reply #74 on: January 24, 2012, 06:28:08 AM »

Yeah, that'd work, but I dont want to lose the 'quench' relationship between the head & piston. Its already .050" (head gasket thickness) I'd like it better if it was .040"
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