FrontEngineDragsters.Org Forum
Technical => Matt Shaff's Engine Shop => Topic started by: Chuck466 on April 04, 2022, 06:02:39 AM
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So I have this LSM Cam in my application that I have had for 15 years really been a great piece, I called LSM last week and there saying it won't work with a blower set up, I'm sure they just want be to buy another camshaft from them, I would like to list the specs and get the opinion of other blown application racers.
Fire order 1-8-7-2-6-5-4-3
Intake lift at 50 470 Exhaust lift at 50 460
Intake duration 282. Exhaust duration 296
Intake opens 27 BTDC Exhaust opens 82 BBDC
Intake closed 75 ABDC Exhaust closes 34 ATDC
LCA 114
overlap 61
Running 1.5 Jessel rocker arms Intake lift 705 Exhaust lift 690
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Sounds like a very good cam to run in a small block using blower on alky to me. Make sure you have good springs and lifters. I have never run anything from LSM . My go to now is Mike Jones cams since Ultradyne is no longer around. Keep your comp. ratio at 10.50-11.00 :1 for easy on parts tune up. More compression will get more power but cost more in parts and be more razors edge on the tune up.
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Duration looks great. Taking lift is valve, if so I would say little low there. Agree give Mike a call. Just got a regrind from him. Might have issue getting cam core to grind, I know him and most everyone was having problem cpl months ago.
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Ok sounds good, I was hoping I could run this cam for now and get the bugs worked out, unfortunately my compression is 12.5 because of the small chambered head running a .070 head gasket to get it to 12.5, do new heads and cam will be next winters project change.
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Pistons are a lot cheaper than heads. Now if you are talking new heads that flow better and help with compression, it is hard to knock the new heads.
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Yes pistons are already flattops so can't do much there, heads I have now are 55cc so the new set I'm looking at will be 65cc or they have a 70cc and much better flow just new technology..
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The cam looks like a typical blown alcohol SBC cam that I have run maybe a little small on the lift from mine but everything else is in line. I have run up to 12.5-1 with a blower just have to be careful you have smalller tuning windows but it will work.
My current cam
Duration at .050 283 298
Lobe Lift .4800 .4600
Separation 113. OP CL OP CL
Timing Events @.050 32.5 70.5 86 32
Duration @.020 317 340
Gross Valve lift .720 .690
Rocker Ratio 1.5 1.5
Valve Lash .018 .029
Degree Intake Lobe to 109
50mm
But I am using 1.7 ratio
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Right on thanks Paul for the info.
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You can buy pistons for any compression ratio. Maybe not off the shelf. I buy them in 10 sets(2 spares because custom) specify stroke , custom rod length and compression deired with combustion chamber cc's in head.
Another option and cheapest,well in one way of looking at it. Any machine shop should be able to open chambers 10 cc's. Open around intake and exhuast valve to most you can or till get the desired cc's. Heck with some time and caution you can do it with die grinder and cc'ing equipment. As I have been called on another site,being a broke dyck I would do it myself. Will take cpl hours but trading sleep for performance is cheap.LOL
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Stupid question. Have you checked actual cc's in combo? Actual not advertised. They rarely are the same. Not trying to be insulting just know how much difference there can be.
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I ran into this in my sbc blown build.
Had to custom order pistons from je. Big part of my problem was
64cc heads and a 406 with aluminum rods. Apparently that’s a
Weird combo. But I didn’t know at the time.
PS if your gonna order, order fast. I been waiting 11 weeks
On lifters and still no update on an ETA.
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I've encountered problems with low compression that was caused by miss matched parts. customer bought a 454 chevy froma "race shop" that never at the level it should have.He did a compression check after water got into the motor 90psi there was miss match of parts could have been, crank, rods or pistions as the pistons didn't come to the top of the cylinder, I replaced the rods that worked with the crank stroke and pistons to get the proper deck height. the other was a 1947 Harley knucklehead el 61ci that a rebuilt was done and someone switch the cylinders with newer 74ci units, the 74 has a longer stroke resulting with pistons too low in cylinders had to have custom pistons made with a different compression height ( the distance from the top to the center of wrist pin,by JE
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Stupid question. Have you checked actual cc's in combo? Actual not advertised. They rarely are the same. Not trying to be insulting just know how much difference there can be.
Yes sir these heads have been fully CNCD and chambers fully softened, I ran this exact combination as a Max effort nitrous combination, running a .070 copper head gasket to help get the compression down some..