New setup- 340 based 416, 360 based 387, or 360 based 408?

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Lxiflyby

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Alright guys, my 381” 360 based stroker with a stock bore 4” piston and 3.790” stroker crank had issues and is out of the car and apart… I can rebuild what I have and go 4.030 bore and 3.790” stroke for 387” but I can’t seem to find any off the shelf pistons for the 3.790 stroker crank and custom forged Pistons might be a big up charge…. I could go 4” stroker kit in either a 340 block or 360 roller block that I have with an off the shelf piston by going to a 4” stoker crank… I have ported 53cc closed chamber w2 race heads and the goal is to go 10.5:1 to 11:1 compression as well as about 540hp so it’ll need 15-20cc ish dished pistons. Current 3.790 stroker setup is on reworked stock rods and Forged stroker crank.
 
408/416 are fundamentally the same from a power standpoint…….it’s whatever the 8 cubes are worth at a nominal 1.3hp/ci.

I’d use main bearing availability and general block condition as a guide for whether to use the 340 or 360 block.
 
W2s like rpm so the shorter stroke may be beneficial. And they like lots of duration and lift
7800 rpms is not uncommon . .
Solid roller is the way to go .
Get a custom grind from Jones or Bullet or research other successful combos. W2 facebook page will be a good resource .
A mild port job really wakes them up . If you have abilty get a set of Mopar templates . There is a guy that reproduces them out of thick plastic on W2/W5 Facebook page .
 
As parts parts supply’s dry up for these dated assemblies and builds, I believe it would be best to converse with folks that build engines as a business and inquire about their parts suppliers.
 
Lxiflyby said:
Alright guys, my 381” 360 based stroker with a stock bore 4” piston and 3.790” stroker crank had issues and is out of the car and apart… I can rebuild what I have and go 4.030 bore and 3.790” stroke for 387” but I can’t seem to find any off the shelf pistons for the 3.790 stroker crank and custom forged Pistons might be a big up charge…. I could go 4” stroker kit in either a 340 block or 360 roller block that I have with an off the shelf piston by going to a 4” stoker crank… I have ported 53cc closed chamber w2 race heads and the goal is to go 10.5:1 to 11:1 compression as well as about 540hp so it’ll need 15-20cc ish dished pistons. Current 3.790 stroker setup is on reworked stock rods and Forged stroker crank.
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Roller 360 block, 4" stroke will be all shelf parts. That's the route I'd go. Decent cam and basic home port job on the W2s and your goal is easily attainable
 
mbaird said:
W2s like rpm so the shorter stroke may be beneficial. And they like lots of duration and lift
7800 rpms is not uncommon . .
Solid roller is the way to go .
Get a custom grind from Jones or Bullet or research other successful combos. W2 facebook page will be a good resource .
A mild port job really wakes them up . If you have abilty get a set of Mopar templates . There is a guy that reproduces them out of thick plastic on W2/W5 Facebook page .
Click to expand...
Considering the tall deck height and piston pin height of a stock 340/360, a stroked engine with the lighter pistons and properly lightened rotating assembly(rods and crank) will rpm pretty much the same.
 
Duration @.050 of 260+
My 408 with same heads ported only makes 520ish hp with a 246/250 roller @ .648 lift
But I only have 9.8:1 compression .
Dynoed at 493 but I found I had 2 qts too much oil and #7 valves were way too loose .
Figure I picked up 25 hp correcting those items .
 
ch1ll said:
Considering the tall deck height and piston pin height of a stock 340/360, a stroked engine with the lighter pistons and properly lightened rotating assembly(rods and crank) will rpm pretty much the same.
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Possibly but my old 360 revved out much quicker and further
7800 vs 6300. Probably the bigger cam in the 360 but the difference is stunning ! That 360 was like a light switch over 3500 rpm . Had to set shift light low so I wouldn’t over rev. That needle just flew by the 7500 mark at mach speed . Lol
 
Can’t you use a Chevy rod with your 3.79” stroke and a 4.00” stroke piston? I think the Chevy rods are available in 0.050” increments?
 
273 said:
Wouldn't custom pistons be cheaper than a complete 408/416 rotating assembly ?
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I’m not sure yet, I have to make some phone calls to see if the custom pistons are in fact cheaper than a 4” stroker crank and off the shelf pistons… this is where I’m at with it…
 
mbaird said:
I believe you would have to turn journals down for chevy rods
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Correct, 2.100 for Chevy rod journals. Also nets the benefit of smaller lighter wrist pin. My k1 crank came with 2.1 rod journals.
 
I’d do a 4” build and sell the 3.79” crank. Another bonus of 2.100” or 2.000” rod journals is bearing selection in addition to a better selection of rods.
 
Lxiflyby said:
I’m not sure yet, I have to make some phone calls to see if the custom pistons are in fact cheaper than a 4” stroker crank and off the shelf pistons… this is where I’m at with it…
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You use a 3.79 crank, a 4 inch stroke piston and a 6.250 Chevy connecting rod.

You have to turn the crank down to 2.100 rod throws to use the Chevy rods.

It’s doable.
 
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