920cc Conversion
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Fast Eddie
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Any experience with Maney barrels Jim? Are they any better / worse than bored out stock barrels?comnoz said:
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Fast Eddie said:
I have not used a Maney 920 barrel. I have used them with 73mm 74mm, 78mm and 79mm bore plus the 1007 with wider bore spacing and they are pretty good.
I have heard [unconfirmed] that he was doing 920 barrels with Nikasil coating but was having trouble with keeping them round. I don't know the present status. Jim
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With 920cc liners you don't need the rod cutouts and then the cylinders won't crack.
But you need to use bore plates if you want to avoid distortion and get a good ring seal.
When using a copper Head gasket. Eliminate head gasket leaks by adding .005" copper wire around the pushrod tunnels and oil return holes. Add contact cement on both sides of the entire head gasket surface (something I learned from Ron Wood). I always send out the wire with my head gaskets now. I haven't had any leaks with this setup. Nothing else worked including silk string and every other sealer I tried.
Anyone have any feed back on the .005" copper wire?
But you need to use bore plates if you want to avoid distortion and get a good ring seal.
When using a copper Head gasket. Eliminate head gasket leaks by adding .005" copper wire around the pushrod tunnels and oil return holes. Add contact cement on both sides of the entire head gasket surface (something I learned from Ron Wood). I always send out the wire with my head gaskets now. I haven't had any leaks with this setup. Nothing else worked including silk string and every other sealer I tried.
Anyone have any feed back on the .005" copper wire?
lcrken
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As Jim pointed out, you really need to use torque plates for 920s, at least the ones using the iron cylinders with liners. I found back in the late '70s that using the torque plates shown below made a drastic improvement in ring seal for the 920 cylinders. Using them got rid of the black areas that used to appear adjacent to the through-bolt counterbores, and also eliminated the heavy blow-by experienced previous to their use. I also used copper O-rings around the bore, along with a copper head gasket, to keep the head sealed. I cut a groove .025" deep in the top of the liner, and used .032" copper wire. I never tried Jim's method with the smaller wire, but I don't see any reason it wouldn't work.
Ken
Ken
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No Norton stock 850 or larger needs the cylinder cutout for rod clearance. I always do away with them when I install a sleeve.
A 920 with short rods is still likely to break the liner at the bottom even without the cutout. If using a long rod I doubt that it would break as the thrust is moved up by 1/2 inch. You could even shorten the sleeve a bit.
I would suggest using a base torque plate on any 850 Norton barrel. The long through bolts will distort even a stock bore. If the barrels is sleeved then a top torque plate is mandatory. Jim
A 920 with short rods is still likely to break the liner at the bottom even without the cutout. If using a long rod I doubt that it would break as the thrust is moved up by 1/2 inch. You could even shorten the sleeve a bit.
I would suggest using a base torque plate on any 850 Norton barrel. The long through bolts will distort even a stock bore. If the barrels is sleeved then a top torque plate is mandatory. Jim
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comnoz said:No Norton stock 850 or larger needs the cylinder cutout for rod clearance. I always do away with them when I install a sleeve.
A 920 with short rods is still likely to break the liner at the bottom even without the cutout. If using a long rod I doubt that it would break as the thrust is moved up by 1/2 inch. You could even shorten the sleeve a bit.
I would suggest using a base torque plate on any 850 Norton barrel. The long through bolts will distort even a stock bore. If the barrels is sleeved then a top torque plate is mandatory. Jim
Thanks Jim, Jseng1 and Ircken but im wee bit lost. Are the torque plates for pressing the liner into an otherwise standard barrel? In other words this is in reference to converting an 850 to 920 rather than using Maney alloy 920 barrels? I was hoping that aManey barrel would avoid potential problems with cracking liners and poor head gasket sealing...
Matchless
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Torque plates are bolted to the top & bottom of the barrel during the boring & honing ops. This simulates the loads that bolting the barrel onto the crankcase & head puts on it. That way you end up with a perfectly round bore & better ring sealing.
Many years ago I spoke to a bloke at a local engine machining shop about this & he thought it was just another silly American idea.
Not agreeing with this I made up a pair of torque plates for a scrap Matchless twin barrel (separate barrels) & measured the effect. It was very noticeable. The flimsier the barrel the greater the effect. I believe the use of torque plates is standard practice when boring performance V8 blocks.
Martyn.
Many years ago I spoke to a bloke at a local engine machining shop about this & he thought it was just another silly American idea.
Not agreeing with this I made up a pair of torque plates for a scrap Matchless twin barrel (separate barrels) & measured the effect. It was very noticeable. The flimsier the barrel the greater the effect. I believe the use of torque plates is standard practice when boring performance V8 blocks.
Martyn.
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