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390 Stroker
There's a guy in my area selling a 1974 390 truck block, as well as a 427 crank and both hi-po and standard 390 heads for $225. I admit I had settled on the 351W stroker route for my build, but this combination intrigues me. He hasn't returned my call yet so that's all the info I have. My question is: will that combo of block and crank make a nice stroker? Is the truck block better or just heavier than a car block? I know Mercury put a 428 crank in the 390 to get their 410 engine, but it seems I might run into an expensive balancing problem with the 427 crank. Any thoughts?
Bill Stradtner |
The 390 and 427 have the same stroke, so the way that motor sits now it's not "stroked". The 428 crank is the most common way to stroke it, and is externally balanced instead of internally like the 427 crank. Another alternative is the scat cranks that run about $500 which come in versions stroked further than even the 428's.
I don't know if there's any clearance issues to be concerned about in the 390's using longer stroke, so someone else can answer that. |
Stroker crank in the 390
The 4.125" or 4.250" Scat cranks physically fit fine in the 390 but be aware that they do so using BBC rods. The rod journals are smaller than the Fe which pulls in the rod overall dimension which in turn allows the rods to clear the camshaft.
The only issue I have with the Scat cranks for the stroker Fe's is having to add heavy metal to them using balancing bobweight numbers that would normally support having to remove metal. Just looking at the cranks, the end crankshaft counterweights appear to be slightly undersized compared to standard cranks although the Scat cranks have lightening holes in each of the rod journals. Of course, I'm internally balancing everything. I'd hate to see what the heavy metal bill would be using TRW/Federal Mogul slugs instead of the lightweight pistons I'm using. |
My thanks to Brent and Ted for the info. I went into one of my books (should have done that first) and saw that the stroke is the same for both cranks. The only advantage may be the possibility that the crank is forged and cross-drilled, but I can't tell that until the guy calls me. The weight issue still remains. This is not a "FT" block but a standard truck block and may or may not be heavier than the standard block. Also, were the truck blocks set up, like the 460, with thicker webs or 4-bolt mains? If so I may have to rethink my 351W decision. Thanks again.
Bill Stradtner |
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