My block is at the rebuilder's, getting the full treatment. In the meantime, I pulled the eight connecting rods I had hanging on the wall in order to select four that were suitable.
Was I in for a surprise! I have four of the older heavy rods, three "mid-weight" rods and one of the light rods from near the end of production. I remember pulling four of the rods from this engine and there was at least on heavy rod. I never bothered to look at the others.
Is there anything really "wrong" with using the heavier rods in an engine that will not be used in a speedster? Or should I start looking for three of the light rods and go from there? I'll be doing the babbitting/boring myself.
One of the best running Tís I have has never been touched and has the heavier rods. It wonít break any speed records but it idles beautifully and runs smoothly. I am sure there was a reason Ford made the switch but I donít know what it is.
Thanks Val........that's kind of the answer I was hoping for. I realize the lighter rods make for less reciprocating weight, etc. but considering the rpm of a "stock" T engine I just don't see a real problem.
While you can't send them in for cores, if you need new babbitt in them I know someone that can do it for you. Send me a PM and I will get you his name.
The heavier the rod and pistons, the harder it is on the crank.
4 pounds of a rod and piston, at a 1,000 RPM will cause a pressure of 200 pounds on the crank pin.
2,000 RPM's is 800 pounds.
3,000 RPM's are 1,800 pounds, on the crank pin.
This is in the Speed, and Sport book, on page 150,, in the right column, half the way down. Worth a read.
Herm, I have that book and will check it out. I forgot to mention that I'll be running aluminum pistons, so at least some of the weight is reduced.
Thanks everyone, George
It takes a lot of rods to make a matching set of t rods. Start checking with your friends for extra rods.
Make sure you weigh them with the Babbitt in them !
Here is what we did to balance the rods. We trimmed them all to make them lighter. Sorry for the poor exposure. It's a picture of a picture of a picture. Note the worn cylinder walls. This was a picture taken just before rebuilding the engine. We ran it this way on the dyno and I have posted the results here. The dyno only read torque starting at 1835 r.p.m. because it was calibrated for 351 Cleveland Pantera engines that day and son Bill snuck us in. We were still developing 100 foot pounds at 1835 r.p.m.at the start of the reading and were most likely developing a whole lot more at 900 r.p.m.
trimmed and Polished rod. Note the scored cylinder walls.
Torque and Horsepower dyno results. The sudden spike is when the triple gears failed and Bill shut it down. It had a lot more left in it at that time. We replaced the Reeder or Reader head (not sure of the spelling) with a Prus head and got even more power and speed.
1/4 mile times and speed
+++ jpeg +++ 824109 +++ 1/4 mile
The 1/4 mile speed showed on the test page but dropped off when I posted so here is the car's 1/4 mile speed and time along with a picture of it in action.
Fast Frank driving and Humble Howard hanging on. Note that the car is blue and that blue stuff keeps its crank up all day and night.
Any parts like Rods, and pistons out of balance, like the big ends all weigh the same, and all the small ends the same, will rob a lot of horse power, and R.P.M's.
It is no different then cutting a 1/2 inch off a two blade fan, on one side.
It also sets up a vibration in the mains as the crank stresses to rid it's self of harmonics.
Like throwing a brick in an old dryer !
The more out of balance, the more broken cranks!
All though Model T rods were not balanced, they were picked by weight, and not all that close.
But the Model A had balanced Rod sets, all done on automatic machines.
Well, after thinking about it for a couple of days it looks like I'd better start looking for three of the "light" rods before going any farther. I'll save the heavy ones to impress small children or someone who wants "authenticity" at any cost.
Thanks everyone! I'll post an ad in the classifieds for rods.