Stroker question
- Thread starter jeffnoel
- Start date
Depends on the block and which stroke you want to use. Like on my 351w, I stroked it to 393ci, which is I think a 3.85" stroke. it didn't require any modifications to the block, but if you go any larger, you'll have to have the block notched to clear the crank.
i think that's the only modification that stroker kits would need to have done to the block. just notching it to clear the crank.
i think that's the only modification that stroker kits would need to have done to the block. just notching it to clear the crank.
78pinto
New Member
jeffnoel said:
my buddy did that, his needed the bottom of the cylinders notched and the block notched as well for clearance of the rods.
a 347 is a .030" overbored 302 block with a 3.4" stroke. so you'll have to have the cylinders bored out slightly, but if the block doesn't need it, don't bother. sometimes a honing will clean the bores enough, and with a 3.4" stroke, you'll get a 342 if memory serves me right. the extra cubes wont give you power.
i think clearancing the block differs with every setup. you'll have to get the kit, install it and check everything.
i think clearancing the block differs with every setup. you'll have to get the kit, install it and check everything.
Blue Thunder
15 Year Member
My early '70s block didnt require a lot of clearancing for the 3.25" stroke.
One reason I chose to build a 332" over a 347" was because I wanted a higher rod to stroke ratio. A stock 302 has a stroke of 3" and a rod length of 5.09" yielding a 1.69:1 r/s ratio. so I ordered up Eagle 5.5" H-beams, and with the 3.25" stroke, that also yields a 1.69:1 r/s ratio.
A 347" has a stroke of 3.4" and usually a rod length of 5.4",(some guys have used a stock length rod - a hideous combination) which gives a r/s ratio of only 1.58:1. Greater piston skirt/cylinder wall friction, less ring stability, and the usual power and efficiency losses associated with a low r/s ratio. NASCAR engine builders try to get the r/s ratio up over 2:1, because that's where the power and efficiency (and durability!) is.
I'd like to see a dyno comparison and engine longevity testing done on a 332" vs. 347", all other factors being identical. It would be interesting to compare them on paper.
One reason I chose to build a 332" over a 347" was because I wanted a higher rod to stroke ratio. A stock 302 has a stroke of 3" and a rod length of 5.09" yielding a 1.69:1 r/s ratio. so I ordered up Eagle 5.5" H-beams, and with the 3.25" stroke, that also yields a 1.69:1 r/s ratio.
A 347" has a stroke of 3.4" and usually a rod length of 5.4",(some guys have used a stock length rod - a hideous combination) which gives a r/s ratio of only 1.58:1. Greater piston skirt/cylinder wall friction, less ring stability, and the usual power and efficiency losses associated with a low r/s ratio. NASCAR engine builders try to get the r/s ratio up over 2:1, because that's where the power and efficiency (and durability!) is.
I'd like to see a dyno comparison and engine longevity testing done on a 332" vs. 347", all other factors being identical. It would be interesting to compare them on paper.
Blue Thunder
15 Year Member
A killer option would be to order up a Dart Iron Eagle 302 racing block, which can handle an overbore as large as 4.185" and will accept a crank with up to a 4" stroke!
http://www.strokerkits.com/ford_302.htm
With that 302 block, all sorts of cool combinations can be done:
4.185" x 3" = 330" SERIOUS high-rpm potential. (Reminds me of a baby version of the 427 FE side-oiler - similar characteristics and all)
4.185" x 3.25" = 358" (good for dirt racing rules)
4.185" x 3.4" = 374" (Pretty big, but still quick revving)
4.185" x 3.5" = 385"
4.185" x 4" = 440" (mopar would be jealous)
Along with having that cool huge bore to gain big displacement, you also have the side benefits of unshrouding the valves for increased Volumetric Efficiency.
http://www.strokerkits.com/ford_302.htm
With that 302 block, all sorts of cool combinations can be done:
4.185" x 3" = 330" SERIOUS high-rpm potential. (Reminds me of a baby version of the 427 FE side-oiler - similar characteristics and all)
4.185" x 3.25" = 358" (good for dirt racing rules)
4.185" x 3.4" = 374" (Pretty big, but still quick revving)
4.185" x 3.5" = 385"
4.185" x 4" = 440" (mopar would be jealous)
Along with having that cool huge bore to gain big displacement, you also have the side benefits of unshrouding the valves for increased Volumetric Efficiency.
Blue Thunder said:
I found a stroker kit (called the 302 Long Arm) that keeps the stock stroke but uses a longer rod and which gives it a 1.85 rod ratio while keeping the stock displacement. How would the power of the Long Arm kit compare to a similiarly built 332 (same cam, intake, carb, exhaust)?
302 Long Arm Stroker Kit
Blue Thunder
15 Year Member
jeffnoel said:
In race trim, the 332 would defeat it. 30 cubic inches means a lot of power, and the extra stroke gives torque. There's a point where higher r/s ratio doesnt yield as big an improvement. (diminishing returns)
In terms of fuel mileage, and hp per cubic inch however, that 302 kit would be the winner.
Ever heard people say that the old 289 motors "ran better" than the 302s? Even though everything is pretty much identical between the 289 and 302 except for stroke and rod length.
The 289 had the same length rods as a BOSS 302,(5.155") but with a shorter stroke, so it's r/s ratio was better than a 302, and the displacement difference wasnt enough to make up for that.
A 5.69" is the longest rod possible to squeeze into a 289 with the its 2.87" stroke. With a 4.030" bore, that's 293 cubes, and a r/s ratio of 1.98:1.
A setup like that would be incredibly efficient. If you were to use high swirl/high velocity iron heads, roller cam, ultra light pistons, free floating wrist pins, heat-reflective coating on the chambers and piston tops, performer intake, holley 490cfm double pumper, tuned 1 1/2" full length headers, and 9.75:1 compression, you would get phenomenally high fuel mileage and the torque would kick ass. You wouldnt need to rev the motor beyond 5000, and the short stroke and long rods would greatly reduce stresses. (reduce stresses doesnt just mean more durability, it also means more power and efficiency)
Drop that 293" into a Stang with a 5-speed, and 3.55:1 gears, and you have a great street cruiser. At least 25-28 mpg? Yes. Faster than a stock fox gt? Yes.
Blue Thunder said:
I read an article a few years ago about r/s ratios. It gave ideas of using modified chevy or chrysler rods and a special trw piston. I'll dig for it.
How available are 289 blocks and cranks anymore?
Would it be possible to put a 289 crank in a cutdown (decked 302 block) with the long rods and still have the same setup.
Blue Thunder
15 Year Member
The 289 and pre-'81 302 blocks are virtually identical. You can throw a 289 crank, rods and pistons in a 302, and you will have a 289.
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