You are absolutely correct. The only thing to be gained from shorter rods (actually a stock rod is 5.7) or longer stroke to rod ratio is port velocity and you loose everything you gained by a steeper rod angle which robs torque.
The 406 SBC is the 400 bored 0.030". Can be done with the short 400 rod, but better with a 5.7" or 6.0" rod. Keeps the 3.75" 400 stroke. I have had a number of high winding 301s and 377s, but at realistic rpms for street driving I like the torque of the 406. I also admit that I have slowed down as I have gotten older.
If that "Ford's flat plane V8" you are referencing is the new Coyote engine, both those SBC engines/camshafts don't have a snowballs chance in hell of keeping up with it....and I'm a die hard Chevy guy admitting that. Again rod length changes DO NOT change piston speed. The DZ302 got it's overinflated high rpm reputation in an age when the production heads on it were a restriction on any thing with more cubic inch like the 350.....if the heads had been big enough back then the 350 would have had no trouble turning the same rpm, the DZ would be nothing more than an afterthought today, cause it ain't no big powerhouse. Stroke has almost nothing to do with RPM capability, especially when talking about domestic V8 engines. As long as the heads can provide enough airflow, valvetrain becomes the first limiter of rpm, requiring more exotic parts to stay together(Roller rockers, girdles, ***anium parts, valvesprings then shaft rockers) followed next in line by material strengths in piston and rod/crank design. A current 410" 3.8" stroke Sprint car engine will run the balls right off any DZ302, and make it look pitifully sad in the process. The dual overhead cam Coyote is just no comparison to a DZ302....their not even in the same ballpark, the DZ302 is still out at the far end of the parking lot hoping to get in the game.
I'd have to dig out the article from Hot Rod or Car Craft, where I first learned about the stroker 305. I have it somewhere, and it'll probably drive me nuts now until I find it. I bought the "kit" from California Discount Warehouse, and it took forever for them to find a 400 crank; not like the aftermarket ones we have now, as then it was strictly cores. I'll find the article, the edition, and what magazine it was in. I am Butch/56sedandelivery. It was in the December 1993 issue of Car Craft, and the article was ***led, "Inching Up". The company doing the engine was RHS Performance Engines out of Memphis, Tn.It talks about using post 80 305's as they came in virtually all cars/trucks for emission and fuel economy reasons., and some difficulty finding 350 blocks (???) at the time. Then, "Swapping a 350 for a 305 may also be technically illegal in certain areas subject to stringent emission control requirements (California). The engine displacement is cast into late-production blocks, making it increasingly difficult to subs***ute a 350 for a 305 without "getting caught". Keeping the engine's external appearance "stock" looking solves the swap legality problem.", by using the stroker kit The "mirror" trick must have been something I read elsewhere, like in the advice columns of Hot Rod/Car Craft. I do specifically remember that being done in California, although I never lived there. The article says they were also limiting the intake valves to 1.94 in the World Products S/R 305 heads. So, the heads I sold wound not have cleared the 305 bores. I am Butch/56sedandelivery.
5.6 rod either puts the piston way down in the hole with 3.48 350 stroke, or pushes it up with a 400 stroke. Not talking custom pistons with proper pin height here. Could be for a goofy offset ground crank cheater combo, when you get into high end race engines all combos are fair game and may be track dependent. Original 383 stroker combos used 400 rods. As they became more popular, pistons with 5.7 or 6.0 rod pin ht are readily available and cost effective. I guess the same carries over for 334 /305 strokers. If you guys have ever torn down and measured a 400 sbc, all Ive found are beat on the outboard piston wall, egged, from the side loading of the shorter rod. Dont see that same wear pattern in a 350. Thats enough for me to stick with 5.7 or 6.0 rods.
All of our 3.48” stroke engines ran a 6.125” rod with off the shelf pistons and our 3.875” stroke engines run 6”. I’ve got a set of Elgin 6.125” stock “appearing” rods ready for an engine some day. Should sell them. As rod lengths for a comparison the GMC 6 engines come with a 7” rod and I have 8” now all my racing ones using a 4” stroke.
On y tube there is a guy Richard Holdener He dyno everything and builds many different engines. He built 302,327 and 350 SBC with 5.7 and 6 inch rods all the same block and there no performance difference on the same dyno same block,not just chevy stuff.
you have it backwords the longer stroke has more angle puts more wear on the bores and has more piston speed the shorter rod and stroke motors have less stress over all
ERicnova spells it out correctly get a beer an pencil an paper an draw few crank an rod throws an think of them turning the same rpm then have another beer think some more you will figure it out um it's not rocket science short stroke generally makes longer lasting motor while stroker motors are stressed have higher piston speeds and wear on everything given being run at the same rpm
oops ericnova is wrong about rod length an piston speed the longer the rod the higher the speed you can't really say anything specific unless your looking at an actual build an look at dome height crank throw rod length ect. sorta waste of time really cause there are so many combos
I think a couple (maybe) of new guys with less than a hundred posts are just having a little fun. Pete
I am gobsmacked no one has mentioned Smokey Yunik, who wrote extensively on the Chevy small block and goes into detail, in his book on Power Secrets, on the why and wherefore of connecting rod lengths. Rather than attempt to join the fray allow me instead to offer the suggestion that OP find a copy of his book and add a master racer's knowledge to his quiver?
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