Need help finding a 400 balancer
Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
Originally Posted by dutchlincoln79
The 351M uses a different harmonic balancer than the 400
NOT NECESSARILY TRUE ~ 1977/79...IT DEPENDS ON THE APPLICATION / 1980/82: 351M'S USE A DIFFERENT BALANCER THAN A 400 USES.
NOT NECESSARILY TRUE ~ 1977/79...IT DEPENDS ON THE APPLICATION / 1980/82: 351M'S USE A DIFFERENT BALANCER THAN A 400 USES.
MY info comes straight from the: 1973/79 & 1980/89 FORD TRUCK PARTS CATALOGS. The same parts catalogs Ford dealers use.
Posting Guru
Joined: Jul 2007
Posts: 1,355
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hmmm but both can be used on any of them, although it really doesnt make any sense due to the fact that one crank weighs more than the other one.... sooo.... damn I have to use the same balancer my 351m has due to availability where I live...
Junior User
Joined: Nov 2007
Posts: 72
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Wow, this has really turned into a mess...
351M and 400 (and really most pre '81, externally balanced Ford SB engines for that matter) used the same weight balancer, with the same bolt pattern. 28oz. imbalance. Sometimes the overall depth of the balancer was different, meaning if you try to interchange them, you have a crank pulley that might not line up properly.
In 1981, it all changed when Ford went to the heavier imbalance. Those won't interchange with earlier (pre 1981) applications.
As an aside, the weight of the crank doesn't make a difference in the imbalance. As long as the crank is counterweighted properly, you could have two cranks with the identical imbalance, but have one weigh 50 times as much as the other.
351M and 400 balancers are cheap and plentiful. If you can't find the exact replacement, go to Professional Products and pick up one of their universal application units. They come with different spacers to properly set your crank pulley. Read this and see.
http://www.professional-products.com/dampersProductSBford.php
351M and 400 (and really most pre '81, externally balanced Ford SB engines for that matter) used the same weight balancer, with the same bolt pattern. 28oz. imbalance. Sometimes the overall depth of the balancer was different, meaning if you try to interchange them, you have a crank pulley that might not line up properly.
In 1981, it all changed when Ford went to the heavier imbalance. Those won't interchange with earlier (pre 1981) applications.
As an aside, the weight of the crank doesn't make a difference in the imbalance. As long as the crank is counterweighted properly, you could have two cranks with the identical imbalance, but have one weigh 50 times as much as the other.
351M and 400 balancers are cheap and plentiful. If you can't find the exact replacement, go to Professional Products and pick up one of their universal application units. They come with different spacers to properly set your crank pulley. Read this and see.
http://www.professional-products.com/dampersProductSBford.php
Laughing Gas
Joined: Jan 2006
Posts: 883
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From: New-brunswick,Canada
i bought a bare 351m400 block from 77 truck who need .030,install a rebuilt 400 crank 10 under used my 2 351m parts and buy silvolite 30 over pistons with aussie heads. I install the pistons,connecting rods, crank, camshaft xe-256 and double row timing set from comp cams without balancing. Can i inspect "shaky" problem ? or should i
disassemble to get this rotating assembly balance with damper and flex plate...?
disassemble to get this rotating assembly balance with damper and flex plate...?
Posting Guru
Joined: Jul 2007
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Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
Originally Posted by hollenjoe
JAJAJA thanx man..... just that everybody has a diferent opinion, I will try the 351m one on the 400 if i get trouble ill go with the universal one....
Posting Guru
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Oh i know your right dummynumbers, im just stating why the mess started inthe first place...
yeah its actually done with the balancer and the engine assembled, dont really know the procedure I just read it somewere..call Tim for more info on it... i will inquire with a local shop..
yeah its actually done with the balancer and the engine assembled, dont really know the procedure I just read it somewere..call Tim for more info on it... i will inquire with a local shop..
Junior User
Joined: Nov 2007
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To balance an engine, you need an engine balancer (not a cheap instrument, or one most shops have). You get the total of each of your balanced reciprocating assemblies (bearings, rods, pistons, wrist pins, rings), and bobweights of the same weight are clamped to the crankshaft. For externally balanced engines (most Ford), you must have the flexplate/flywheel and damper attached to the crank, and the entire assembly is balanced. Internally balanced engines (like the SBC), do the same, but are not required to have the flexplate/flywheel or damper attached prior to balancing the rotating assembly.
You can't balance the engine with it assembled.
You can't balance the engine with it assembled.
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