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383ci. Magnum vs. 400ci.

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  • Shorty Thompson
    started a topic 383ci. Magnum vs. 400ci.

    383ci. Magnum vs. 400ci.

    Okay, enough said . We know what the differences are huge " wabos" , tiny " wabos ". Here's my question. Since you can not find 383s readily available but you can still find a 400 here and there. Then why can't you build a 400 up to the samething as a 383 magnum ? What would it take ? Parts wise that is.

  • dodgeboy8
    replied
    400 is basically a 383 cast for 4.34 pistons vs the 383 at 4.25. mopar thought the extra 17 cubes would help make up for the lower compression for emissions in 1972? almost all 400's have cast cranks where until late 71 383's where all steel. cranks are the same otherwise. motor is OK got a bad rap. so a 383 crank and rods are the same if you want to go forged. they do make a nice 451 with a 440 crank and rods 440 crank mains have to be cut down. now while your at it if you cut rods to 2.20 chev size and offset grind you can get to 3.90 stroke to build a nice 474 cuber. 906 heads are good 516s won't flow shit even with the bigger valves because the intake bowl and ports are so small.

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  • Shorty Thompson
    replied
    Picked up 2 sets of heads tonight . A set of 906's and a set of 516's

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  • BK
    replied
    you can buy a sonic tester on ebay now days for less than $100

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  • Shorty Thompson
    replied
    Originally posted by Cranky View Post
    Any engine that you build for performance should be sonic tested. It' isn't that expensive and can save ya some money if the block has core shift. I like the 400 better since the bores are bigger which helps with less valve shrouding and creates better flow around the valves. Also, with a much larger bore vs the 383, your piston doesn't have to be so close to 0 deck for the same compression ratio. Go for it!! Too bad we're so far away from each other because I have one 400 block left that I had planned on using for my last build but it doesn't look like that is going to happen....unless I win the lottery lol
    Ya never know DJ you might ! Wished we closer as well , lol. I could use the tutoring.

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  • Cranky
    replied
    Any engine that you build for performance should be sonic tested. It' isn't that expensive and can save ya some money if the block has core shift. I like the 400 better since the bores are bigger which helps with less valve shrouding and creates better flow around the valves. Also, with a much larger bore vs the 383, your piston doesn't have to be so close to 0 deck for the same compression ratio. Go for it!! Too bad we're so far away from each other because I have one 400 block left that I had planned on using for my last build but it doesn't look like that is going to happen....unless I win the lottery lol

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  • Shorty Thompson
    replied
    Originally posted by BK View Post
    The debate has been more about the year rather than if car or truck on the 400s.

    If you're buying an engine, I'd pay more attention on the outward condition of the motor. You want one that was well cared for and lower moles if possible to tell. If a block, look for the least cylinder wall scoring and rust, measure to see if it was already bred for oversize, and buy or borrow a sonic tester to ensure you have good wall thickness left to bore. You really don't want to go more that .030 as the pistons are more readily available and you won't be in danger of too thin cylinder walls. remember the sleeves rust from the outside - where you can't see it.
    Good bit of information there as well as good advice I'm thinking. I got 1 call out replied to already. That 1 is sold. No biggie though. I still have a call out on 3 others( actually 5). I gave a shout out to a buddy of mine in Ohio. Asked him he if he knew of any better block than the other. He replied that he was told that " supposedly" the 230 block is suppose to be better than the rest. Did not matter if it were truck or not.

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  • BK
    replied
    The debate has been more about the year rather than if car or truck on the 400s.

    If you're buying an engine, I'd pay more attention on the outward condition of the motor. You want one that was well cared for and lower moles if possible to tell. If a block, look for the least cylinder wall scoring and rust, measure to see if it was already bred for oversize, and buy or borrow a sonic tester to ensure you have good wall thickness left to bore. You really don't want to go more that .030 as the pistons are more readily available and you won't be in danger of too thin cylinder walls. remember the sleeves rust from the outside - where you can't see it.

    Leave a comment:


  • Shorty Thompson
    replied
    Got to say , I love it . Right now I have the opportunity to buy probably 6 different 400ci motors. With that being said I believe I have an important question that needs answered before I buy. Is there a difference in block alloy//makeup/build in a car block as opposed to a truck block ? Is there a difference between the 2? More nickel than the other or what ?

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  • BK
    replied
    I was just getting into drag racing then, and if I'd put decent headers on the car, less slick for the under-powered engine, a decent carb, ran the valves, and new plugs.... that car might have gone 10.5 with that combo. I left way too much on the table back then. It was a garage built motor from used stock parts, not a precision engine. That said, I maybe put over 300 passes on motor, God knows how many Big Jim put on it (as it was in Big Red Ram wen I bought it) and when I yanked it to put a 540 in the car, I sold it to a guy in Norway. Consistant and dependable.

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  • BK
    replied
    It ran pretty good, considering it wasn't a precision built motor.

    The car was heavy with all metal and glass, 14" slicks, and a transbrake ar shifter - as it was a bracket car. The carb was a stock and old Holley 850 on a M1 intake. One night four passes were 10.97, 10.92, 10.94 and 10.97.

    Here's a video of it. Wasn't that fast in it as track was greasy.

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  • Shorty Thompson
    replied
    How'd run ?

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  • BK
    replied
    I did, but didn't build it. many have told me that the bare and stroke make for a near perfect geometery.

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  • Shorty Thompson
    replied
    Originally posted by BK View Post
    I've personally never been involved in having one built, but more a few engine builders have told me that it was an engine Mopar should have built, and it is the least expensive way to build a good race motor.
    Sorry boss , The 451 . Correct ? Kinda wished Damon had the time to chime in. Didn't you run a 451 in the black Coronet ?

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  • BK
    replied
    I've personally never been involved in having one built, but more a few engine builders have told me that it was an engine Mopar should have built, and it is the least expensive way to build a good race motor.

    Leave a comment:

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