Stroked 340 vs Stroked 360

[70aarcuda]

Depends on the 340 block. If you can score a good deal on a 340 TransAm block, do so. This one has thicker webs to allow for 4-bolt mains.

One of the problems I have with the 360 vs 340 main discussion is that, at least in showroom trim, we never got to see a high compression 360 4 bbl with a forged crank. They also changed bore and stroke. So we have no good basis for comparison between the two in a factory HP configuration.

Over in the Chevy camp, the discussion is pretty much settled. The 327 was known as a high-winding runner. The bottom end was suspect. When Chevy came out with the 350 in 1967, it was essentially a stroked 327 with LARGER main journals. (FWIW: Chevy continued to use the 327 in 68-69 models but with a large journal crank.) This provided more power but also cleared up a lot of the bottom end problems.

Based on the Chevy experiences, I would think that a 360 would work better. However, the small journal LA does not have the gimpy bottom end reputation that the original mouse motor had, it may not be that big of a deal. Given that the upper end will be the same and cranks are the same except for main size, the ability to rev is going to be determined by the stroke and the balance that is necessary for the piston/rod combination that is used.

If you find a 340 TA block for a good deal...I would sell it to someone with a TA Challenger or AAR Cuda to fund the rest of the engine...

 

[70aarcuda]

I like my 340 with its super light Ross racing forged aluminum pistons.

340 4.070 3.310 6.123 -5.5 9.8 514 1.804 99625

360 4.030 4.000 6.123 -21.0 9.5 470 1.459 99787

Ross 408 pistons are 44 grams lighter then the Ross 340 piston with the same compression ratio, with the same manufacturer the stroker piston is always going to be lighter due the lower compression height...

1.804 vs 1.459....less aluminium...

 

[the wall]

you can buy a cast crank for the 340 mains also...only weight difference would be the bore size of the piston you choose....being that a 340 block has .040 larger bore from the get go.

this is true but remember the question was if you built them exactly the same so it would be a 40 over 360 or what ever it took to match

so the only thing that couldn't be matched would be the mains

 

[OldmanRick]

This question is really only for people building engines within specific class guidelines. You know who i mean, the guys running dyno's 25hrs a week looking for a 1hp gain. Yes there can be a minor gain in some circumstances, but for 99.9% of us it really doesn't matter. Ok. that's my final opinion.....

 

[dirty white boy]

If you find a 340 TA block for a good deal...I would sell it to someone with a TA Challenger or AAR Cuda to fund the rest of the engine...

had a 71 duster 340 A-883 4 speed car that had this same block in it from factory... X heads an 8 3/4 small bolt pattern too...