How much clearance stocker rotating assembly.

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cawcislo

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How much clearance is enough? Did some trial fitting of parts for for my 390 stroker. Nothing interferes, but rod bolts are awful close to bottoms of pistons. How much clearance does their need s to be? The crank counterweight is also close to the bottom on the block in one spot have maybe 0.040 clearance is that enough ? It’s a scat rotating assembly With cast crank and I beam rods.
 
Something like .080 and enough to and fro for the crank and rod side end play clearances stacked... .010+.006 example.
 
Seriously, I probably did the first or one of the first Mopar small block strokers around Macon in 1991. All I did was build a 408 using stock 340 rods, so I didn't have to worry about piston skirt clearance. I did have to relieve the block at the oil pan rails so the rod bolts could fling by. I ended up with around .060 to .080 clearance and it worked fine.

I said 408......but it was a 416. .070 over 360 with a 4" arm.
 
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It's the rod bolts interfering with the bore, not the pistons. Some rods clear fine ,h beams dont and the smaller bore 318 might change that to no rods clear without clearancing.
Now... if you use stroker postons based a narrower small end connecting rod like a later magnum uses..you can have rod contact to the piston.
 
cawcislo said:
How much clearance is enough? Did some trial fitting of parts for for my 390 stroker. Nothing interferes, but rod bolts are awful close to bottoms of pistons. How much clearance does their need s to be? The crank counterweight is also close to the bottom on the block in one spot have maybe 0.040 clearance is that enough ? It’s a scat rotating assembly With cast crank and I beam rods.
Click to expand...

I should have double checked my post. Rod bolts are very close to bottom of cylinders, like 0.030 but that’s a simple fix get to 0.060 or 0.080. The one crank counterweight is close to the bottom of the block. I’ll post a pic later. It’s scat rods and scat crank. Nothing interferes, but I want to ensure there’s enough clearance everywhere. It’s a 1977 LA 318 block.
 
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LOL. Like piston to valve clearance. Don't want to loose compression but you don't want a collision either. Lower end clearance is cheap. All it takes is a grinder and it doesn't hurt horsepower.
 
I believe the recommendations are .070 for steel rods and .100 for aluminum rods. That’s clearance between the rod bolts and bottom of cylinders.
 
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