David,
Here is an article that I read a little while ago.
Duttweiler told me that the rod lenght can also effect
the amount of timing you can throw at a motor.
Your rods would probably work ok, if i had not just moved I would get you the prefered leght from my motor sports book. I dont think I can find it now.
Rod/Stroke Ratio
by George Klass of Accufab Performance Parts and Accessories
February 2005
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Much has been written about rod/stroke ratios in the past and it seems to be discussed on a regular basis on the hardcore50 message boards.
The consensus of some so-called experts is that when it comes to connecting rods, “longer is better”. Well, longer IS better with many things, connecting rods not necessarily being one of them. There are many “ratios” pertaining to engine design, including compression ratios, rocker arm ratios, bore to stroke ratios, horsepower to cubic inch ratios, and on and on. Exactly where rod to stroke ratios fit in to the equation depends on who you talk to and how smart they really are.
Much of the discussion over the last 20-years on the subject was centered around a theory first written about by Smokey Yunick, a more than reputable engine builder. Smokey wrote that a longer connecting rod length “FOR A GIVEN STROKE, MIGHT be an advantage under CERTAIN SPECIFIC applications.” Smokey never said, “a longer rod was always better”.
And yet, for years, some engine builders have decided (and shouted from the mountain tops) that a “better rod stroke ratio” was the most important aspect of a high horsepower engine, regardless of other, much more important factors of the engine design.
Even Smokey, in his later life, admitted that most of this “rod/stroke stuff” was either taken out of context or mostly malarkey.
But in the interest of malarkey, I have compiled a chart showing various American production V-8 engine specifications, and listing their bore, stroke, connecting rod length (center to center) and, their rod/stroke ratios.
Let us assume that we are looking to install a V-8 engine into our 1932 Ford 5-window coupe. We want both power and reliability, since we plan on doing a little drag racing and also some cruising. Those of you who think that the higher the rod/stroke ratio, the better, should ponder this question. For our coupe, would you rather select a 239 inch Ford flathead (1.86:1 rod/stroke ratio) or a 351 inch Cleveland (1.65:1 ratio)? Does anyone think that the “better” rod/stroke ratio of the flathead is going to outweigh the advantage of the better design and 112 cubic inch displacement increase of the Cleveland?
On the Ford V-8 side, the “best” rod/stroke ratio listed on the chart was on the very first overhead valve V-8 produced by Ford, in 1954. This was the 239 cubic inch Y-Block engine that replaced the flathead V-8, and had a 2.03:1 rod/stroke ratio. A “great” rod/stroke ratio, but a pretty crappy engine in every other respect.
Anyway, a very wise man once said, regarding the “rod/stroke ratio controversy”, that the optimal rod/stroke ratio for a V-8 engine is “8-rods to one crank”.
Have fun perusing this chart. Some of the engines listed may bring back some great memories for you older guys. And for some of you younger guys, you don’t know what you missed.
I mean, they are cheap to buy right?
