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Discussion Starter · #1 ·
I have a 72 4x4 crew cab with a badly worn-out 360, I also have recently acquired a 72 camper special with a good 400bb. The question I have is it worth doing a motor swap? It seems that everyone going to a BB always goes to the 440 and I'm wondering how the 400 rates? I do pull a boat, & camper with my truck and the 360 currently comes up pretty short on the power scale. Thanks for any input.
 

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I would build it for what i want to use it for before i put it in, it's your choice though, the 400 isn't bad
 

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Discussion Starter · #3 ·
It's either rebuild the 360 or the 400, and I'm leaning towards the 400 (easier to adjust timing ;) but I was wondering if the 400 had any real problems and if I would really gain any hp or torque over a 360. Seeing how I have a complete truck parts are not an issue. But maybe the rebuild kit is.
 

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Go with the 400.. My only BB was a 400 in my 75 Fury, it also resided in my 69 Road Runner after some mode & then rebuilding.. But it has a LOT of potential.. even stock it will be an improvement. And just memories of the abuse that motor took makes me wish I'd never sold the car.
I agree on setting the timing.. the BB is much more user friendly. Don't forget oil filter location.. Can't get a much nicer spot for it.
Aaron Wyse
 

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Go with the 400, they are good motors, they got a bad rap from the lean burn systems in some applications. If yours is lean burn sh*t can the carb and distributor and go with the standard mopar electronic ignition. Due to using the same heads the 400 and 440 make the same amount of power, 440s just do it at a little lower rpm, the heads have always been the limiters on the bbs. Don't worry about which crank you have either, unless you intend to spend a large wad of money on the heads you won't hurt the stock crank in 400 or 440.
 

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400 is a good motor. And the 72 400 is the second of the best choices of the years. Was it a manual trans, because it might just have a forged crank. The best 400 blocks are in 71, with casting # ending in 230. Nice and thick. And pretty rare so dont bother looking for one. Yours is next best...thick with some extra ribbing for strength. If it runs good and your on a budget just through it in. You have all the other little things to worry about on the swap and you can always build it or a 440 or a 383 later if you need. More part selection (pistons ) for the 440 or 383. I have a 400 in mine and its fine. I want higher compression for a propane conversion and the highest I can get on a 400 is 9:1. I will be swapping in a 383 because of the pistons available. It is looking like 11:1 with the big 452 heads.
 

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Discussion Starter · #7 ·
It's a 72 400 with a 727, crank is not forged I did check and it seems to run well. No brakes so I didn't take it out on the road. Thanks for all the info, I also have a 67 413 but it has a frozen piston so I think I'll part it out.
 

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Use that 413 crank in the 400 block, make a 446 ci stroker.
 

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Bummo said:
400 is a good motor. And the 72 400 is the second of the best choices of the years. Was it a manual trans, because it might just have a forged crank. The best 400 blocks are in 71, with casting # ending in 230. Nice and thick. And pretty rare so dont bother looking for one. Yours is next best...thick with some extra ribbing for strength. If it runs good and your on a budget just through it in. You have all the other little things to worry about on the swap and you can always build it or a 440 or a 383 later if you need. More part selection (pistons ) for the 440 or 383. I have a 400 in mine and its fine. I want higher compression for a propane conversion and the highest I can get on a 400 is 9:1. I will be swapping in a 383 because of the pistons available. It is looking like 11:1 with the big 452 heads.
If you want higher compression from your 400, swap on a set of the closed chambered heads.. I can't recall the casting # off the top of my head; That made a major difference on mine, I had another set of closed chambered that were shaved; but I figured I didn't want to put the compression up any farther. I did end up ordering a forged 383 crank for it when I finally opened it up; at the time, the parts store couldn't find a listing for a forged 400 crank..

I would say that since it does run good already, throw a fresh chain & gears in it while it's readily accessable, along with checking to see if you have any oil leaks to tend to whiel it's out.
Aaron Wyse
 

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Discussion Starter · #11 ·
451 has a nice sound to it, I was told already to at least hang onto the 413 crank and I think I will, does it take alot of work to stoke out the 400?
 

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awyseguy said:
Bummo said:
400 is a good motor. And the 72 400 is the second of the best choices of the years. Was it a manual trans, because it might just have a forged crank. The best 400 blocks are in 71, with casting # ending in 230. Nice and thick. And pretty rare so dont bother looking for one. Yours is next best...thick with some extra ribbing for strength. If it runs good and your on a budget just through it in. You have all the other little things to worry about on the swap and you can always build it or a 440 or a 383 later if you need. More part selection (pistons ) for the 440 or 383. I have a 400 in mine and its fine. I want higher compression for a propane conversion and the highest I can get on a 400 is 9:1. I will be swapping in a 383 because of the pistons available. It is looking like 11:1 with the big 452 heads.
If you want higher compression from your 400, swap on a set of the closed chambered heads.. I can't recall the casting # off the top of my head; That made a major difference on mine, I had another set of closed chambered that were shaved; but I figured I didn't want to put the compression up any farther. I did end up ordering a forged 383 crank for it when I finally opened it up; at the time, the parts store couldn't find a listing for a forged 400 crank..

I would say that since it does run good already, throw a fresh chain & gears in it while it's readily accessable, along with checking to see if you have any oil leaks to tend to whiel it's out.
Aaron Wyse
I have a set of closed chamber...they are 516's but 915's are the best ones. Anyway you can only count on about a half point increase with the smaller chambers...those older engines used thin metal head gaskets and you will gain about .02 with a composite. Not cheap with the closed chamber head because it would need the larger valves and hard seat inserts on the exhaust side so prepare to drop about 500 US plus easy to get the heads done while the 452 are true induction hardend already. Also the 383 is the more recognised engine for resale purposes. But if I had the froze 413 thats the one I would rebuild. Short wheel base RC's dont need to have the biggest engine (440) and the 413 has great torque numbers at like 2000 rpm. I think that long stroke down the smaller chamber seems to work great.
 

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the problem with 413s is piston availability, even 440 crank 400 pistons are easier to find.
 

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The 400 is better option than your 360 just plan old stock you should be able to notice a change. It seem to be the concensus of the site that the 400 is the best option. To me the 451 sounds like a sweet idea beacause you got the crank might as well us it but it all depends on what you want out of the truck
 

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I dont know enough to know if this could be made to work but could std 383 sized pistons (4.25) be used in a 413? It would require a bore of just over .060 but with all the rods that are used for stroker combos is there anything that will allow a B piston to be used in a RB block?
 

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Bummo, kb makes off the shelf pistons for 440-413 crank in 400 block, I believe for either b or rb rod length, I like the rb length, leaves a very light piston, some prefer the shorter b rod with taller compression height on the piston. You have to have the counter weights on the crank turned down (any competant machinist can do this) and you either need to turn down the rb mains to b size or have the block line bored to rb main size. Either way will work, again opinions will differ which is best.
 

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Sig you would be lucky if you found a 400 that had an actual 8 to 1 comp and not more like 7.8 or so, there is no way a factory 400 had 12 to 1.

If you are going to go to a stroker you need to make the heads flow, use the shorter rod and good heads, if not using good heads use the longer rod
 

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txs said:
Bummo, kb makes off the shelf pistons for 440-413 crank in 400 block, I believe for either b or rb rod length, I like the rb length, leaves a very light piston, some prefer the shorter b rod with taller compression height on the piston. You have to have the counter weights on the crank turned down (any competant machinist can do this) and you either need to turn down the rb mains to b size or have the block line bored to rb main size. Either way will work, again opinions will differ which is best.
I know there are lots of pistons and combo's for a RB crank in a B block. What I dont know is can you use a B piston (4.25) in a RB block with RB crank if the bore width is not a problem. Its the deck and compression measurements and that stuff that I dont know about making fit.
 

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You have to use a piston made for the motor, a B motor piston won't work in a RB motor
 
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