hello Flat Ram,
Glad you could get in on this flathead talk! I wonder if you could ask your dad which rods gave problems, or if he had done the same oil port modifications to his engine?
I've seen our 230 hit 6000 with the single carb, but never held it any length of time to know if we could go that far and sustain it (for one reason the single carb wouldn't let us!). Right now somewhere around 5000 is all I want to hold, as our cam really isn't giving us anything beyond that. I really don't think the valve springs will take the 6000 as when dad hit it, it stuttered a little and began leaning out, the exhaust was very very hot.
I've spec'ed out the bigger series mopar flatties (3.438" bore), and like what I see! There is a 265 version out there, used in ag machinery and industrial versions. I think a few were used in very heavy dodge trucks during '56-'60 also. The cranks from these engines will drop into any of the 3.438" bore blocks without modifications. These bigger engines have 2.125 rod journals compared to the 2.00 journals of the smaller engines of 3.25 bore.
The stroke of the 265 is 4.750, .125 larger than the little 230. With an offset grind on the bigger crank to shave it down to the 2.00 journal, the stroke can be increased to 5.00" gaining a total cid of 279 for the cheap, stroked flatty. Of course, there is room for more, as this mod will leave the outer clearances of rod to crankcase the same as before. But, you've just gone from a $400 mod to a $1200 situation.
The rod lengths in these engines, both series, differs in length according to stroke. The longer the stroke, the shorter the rod. Its possible to increase your torque output at lower rpms by simply swapping rods with a shorter stroke engine and shaving off the piston head a smidge. A very good rod length/stroke ratio is around 1.75:1. If you check out the rod lengths vs. stroke in most flatties - you'll find something close to this number, that's why they seem to lug so smoothly at lower rpms than their bigger cid ohv cousins, who consequently run ratios around 1.55 with not much room to improve.
In the tractor world, Minneapolis Moline tractors built pre '55 all had stock rod ratios of 2:1, this is the ultimate rod ratio - my stock 40 hp Moline 4 cly. can show up a 66 hp IH 6 cly. on the pto any day of the week grinding corn @ 1000 rpm less at the flywheel.
I can hear those gears turning in your heads even now!
Hudson
[This message has been edited by Hudson (edited 08-23-2001).]
[This message has been edited by Hudson (edited 08-30-2001).]
