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343 crank in a 360?
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Thread: 343 crank in a 360?

  1. #1
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    343 crank in a 360?

    I'm looking at building up a 343, is it better to stick the 343 crank in a 360 block since they have the bigger head bolts and the better flowing dogleg heads? Or is it better to keep the 343 block which supposedly have more "meat" for overbores, and possibly go with edelbrock aluminum heads?
    I'd like to stay on the budget side if possible, but i know the pre-dogleg heads don't flow well. And to fit the later heads on the 343 required stepdowels, and later machining for intakes i think.
    Also, i have no interest in stroking, i like and prefer the short stroke engines, the quick revs, and reduced wear they have.

  2. #2
    Thank you from BT ULTIMUS MAXIMUS STATUS tufcj's Avatar
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    The deck on the 360 block is .033" taller. If you use a 343 crank/rods, your pistons will be that much lower in the cylinder unless you use custom pistons. Big loss in compression. Some guys stuff a 360 crank/rods in the 343 blocks and shave the3 tops of the pistons for the increase in compression.

    You can run the Edelbrock heads on a 343 block. They will supply the stepped dowels to position the heads. I'm running 70-up heads on both of my 390s, using ARP 7/16" head bolts and stepped dowels. If you use an early intake/block with the late heads, you just need to slot the 2 center holes in the intake on each side, no other machining required. You can also drill/tap the later heads for the early intake if you don't want to slot it.

    No way to build a stroker on a budget.

    Bob
    tufcj
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    It's going in my CJ7 that i drive daily, looks like it may be the easiest to just go with the aluminum heads, especially for the weight savings even if it does hurt the wallet. My trans has no overdrive, which is one of the reasons i like the 3.28 stroke of the 343, as it stands now my old 258 is screaming to do 70mph turning 2500rpm. Any other tips that may help me it in my build? I'm shooting for something around 350-375hp.but, more is always better.

  4. #4
    Thank you from BT ULTIMUS MAXIMUS STATUS jeepsr4ever's Avatar
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    343 crank and custom pistons. You would have $690 into a set from us to your door.
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    Awesome ok, Are you saying $690 with a 343 crank and Pistons from you, or just the Pistons?

  6. #6
    Thank you from BT ULTIMUS MAXIMUS STATUS tufcj's Avatar
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    For off-road, I really prefer torque over HP. I had a mildly built 360 in my CJ7. It would sit and spin all 4 tires at idle if it couldn't find enough traction. I ran stock pistons (1974 block) with 1970 291C casting heads (gave me about 9:1 compression) a mild cam with about .488 lift and 112 lobe center, heads were polished/ported, and ran 1.6 ratio roller rockers. It had a Edelbrock performer and Howell fuel injection. Exhaust was stock free flow manifolds through a single 3" exhaust (due to local emissions laws). I ran 37" tires with 4.27 gears and Detroit lockers, had a T-18 trans and Dana 300 t-case for about a 70:1 low ratio.

    Bob
    tufcj
    1969 AMX
    1967 Rambler Rogue

    If you need a tool and don't buy it...
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    and not have it.
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  7. #7
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    Well, i figure the 343 has equal or more torque than the old 258. And everyone runs a 360, so im looking to do something different, and the 343's can be found for cheap. I have 3.54's with an Sm465 and 33" tires, with 35's, a dana 60, and 3.73's down the road. In low range and that granny first i can get out and walk faster than it crawls. My brother had a sbc 327 in his CJ, and man would that thing run.. Even with his 36" tires and 4.10 gears it would roast those tires all day. I understand torque is important, but these CJ's are so light that i think the short stroke engines are more fun in them. And will keep from breaking too many parts, i tend to use the skinny pedal to get over obstacles anyways.

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