LONG ROD 358M
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LONG ROD 358M
Yes I'm back after a long winter's nap. still kinda feel like Rumpelstilskein. Anyway time for another of my screwed up ideas.
Here sometime ago Hot Rod did a build up of a chevy 350 (i know, I know) using the 300 straight six rods. they were able to run 11:1 compression on 87 octane. it hadsomething to do with the crank-to- rod ratio. anyway according to their rag the longer rod allows the piston to dwell at top dead center for a longer period of time thus making the combustion process more efficient. they ended up making something like 450 horse and about the same on torque. the torque curve was pretty much flat as a pancake too.
Now on to the point of my rambling. With the deck height of the M block (10.297) and the stroke (3.5) you could use a 7.1 inch rod and a 1.425 piston and still have approxametly 0.022 deck clearance. All the parts are readily available and the only machining necessary would be the usual block work done for a rebuild and machining the rod journals down to 2.2 inches. And maybe narrowing the rods not sure yet, haven't been able to find the rod width yet. So with a crank-to-rod ratio of 2:1 you should be able to run the compression ratio of 10.7:1 it works out to. port the heads, add a decent cam, a set of headers, and a four barrel and it should prove to be a rowdy combo. i know the stroker could be built for about the same money but isn't nice to have options?
BTW. the heads can actually be ported beyond usefulness. i found a cracked set to work on and they can be really opened up to the point of high rpm only. For my next trick I'm gonna try to combine the H.E.I. system with the 351m distributor shaft to see if it will work. I'll let you know how my poor man's conversion work's out.
later........
Here sometime ago Hot Rod did a build up of a chevy 350 (i know, I know) using the 300 straight six rods. they were able to run 11:1 compression on 87 octane. it hadsomething to do with the crank-to- rod ratio. anyway according to their rag the longer rod allows the piston to dwell at top dead center for a longer period of time thus making the combustion process more efficient. they ended up making something like 450 horse and about the same on torque. the torque curve was pretty much flat as a pancake too.
Now on to the point of my rambling. With the deck height of the M block (10.297) and the stroke (3.5) you could use a 7.1 inch rod and a 1.425 piston and still have approxametly 0.022 deck clearance. All the parts are readily available and the only machining necessary would be the usual block work done for a rebuild and machining the rod journals down to 2.2 inches. And maybe narrowing the rods not sure yet, haven't been able to find the rod width yet. So with a crank-to-rod ratio of 2:1 you should be able to run the compression ratio of 10.7:1 it works out to. port the heads, add a decent cam, a set of headers, and a four barrel and it should prove to be a rowdy combo. i know the stroker could be built for about the same money but isn't nice to have options?
BTW. the heads can actually be ported beyond usefulness. i found a cracked set to work on and they can be really opened up to the point of high rpm only. For my next trick I'm gonna try to combine the H.E.I. system with the 351m distributor shaft to see if it will work. I'll let you know how my poor man's conversion work's out.
later........
