Thread: 401 Swap Out
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Old May 14th, 2017, 07:57 AM
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Ed Snyder Ed Snyder is offline
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Default Re: 401 Swap Out

Quote:
Originally Posted by bigblockv6 View Post
The 401 will for the most be a drop in provided it has the 6 bolt crank flange that will accept the 305 flywheel. The only other issue is in the placement of the water pump housing. If you choose to use the 401 water pump housing then you'll need to move the radiator up higher so the fan lines up. If you choose the 305 water pump housing then you need to eliminate the 3 piece timing gear and replace it with the 305 double roller and timing chain and sprocket, this also requires eliminating the center idler gear shaft which is bolted on. It needs to be capped off with a 1 1/8 expansion plug(freeze plug) in order to block the idlers oil passage or else the engine will loose oil pressure which feeds the front main bearings. It may sound a lot to you but it's not all that bad I did the same with my 478M conversion and it all worked out just fine
Another option is to simply remove the engine-driven fan from the 401 and use an electric fan instead. That way you don't have to do anything with the water pump housing or radiator. That's what I did on my '62 Suburban.
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Ed Snyder
Medford, Oregon
1962 1000 Pickup 401M & Muncie 318 with overdrive
1962 K1000 Suburban 401M & SM420
1965 2500 Suburban 351C & SM420 with Watson overdrive
1967 CM1500 pickup 351E & NP435
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