Old bolted crank

wagel

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Aug 4, 2016
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Hi guys.. Just found out that one of the engines that I bought barely used and have not started myself has the old crank with bolted weights. Is it any good balance wise or should I just get a new solid block and balance that before putting the engine back together. Took it apart to change bearings.
 
those old bone-shaker motors were all we had for many years - they can be run OK, but will have a lot of vibration above about 25mph - they're good, serviceable, transportation if one keeps the speed down - run too fast, they tend to rip out the main bearings
 
Thats crap. Planned to tune it quite a bit. Anyway. Another totally unrelated question. The roofs of the transfer ports are tilted. I mean the transfer opens few mm earlier on intake side than exhaust. First jug I see with those ports. Does that give any benefit or should i just rise the port on exhaust side to have flat top? Otherwise its quite nice. Directed towards intake and so on.
 
transfer ports are on the sides, not front & back - the old H2 motors always had one transfer port a couple millimeters higher than other, which I guessed was to create a swirl effect to make mixture more uniform in chamber

personally, I would leave it alone
 
transfer ports are on the sides, not front & back - the old H2 motors always had one transfer port a couple millimeters higher than other, which I guessed was to create a swirl effect to make mixture more uniform in chamber

personally, I would leave it alone

Reread the post. ;) ;) ;)

I quite like the idea.. Not that I actually know whether it would work but it seems a cool idea to try. I would guess it does (or was intended to do) the same thing as directing the ports towards the intake side, clearing out the exhaust gases and losing as little of the fresh charge as possible.
Now I want one too!
Edit: oh, it turns out I have one. I thought it sounded familiar haha! :D
Mine is rough as **** though and nasty deep scratches on the cylinder wall, I'll be ordering a new one off eBay when I get around to it.
 
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Yes. You got it right the second time. But any ideas is should I leave it stock or make it "normal".
 
Anyway. About the crank balance. Connecting rod has Z - L markings on it. Piston with rings and wrist pin clips is 80g, bearing is 5g and wrist pin is 14g. Didn't have tools to take the crank apart and weigh that so I didn't have all data for Jaguars calculator. Has anyone got data for this crank model so I could get it close enough? I might be able to drill the wrist pin and get some grams off there and piston is totally stock so I might be able to make it a bit lighter.
 
the trapezoid shape is supposed to be an improvement - I'd leave it alone - no data on crank
 
I didn't even realise that it wasn't normal to have trapezoidal transfer ports. I have not split the cases on my engine but as far as I can see it looks like one piece solid type crank flywheels, I can't see any bolted on weights.
But the method we discussed for drilling balancing holes without splitting the cases (drilling into the outside edge, after sealing the crankcase with putty etc) should allow a trial and error approach. You can drill a bit and see if it helps, drill a bit deeper and see if it helps more, etc..
 
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