The Buda rods are a little on the weak side for that kind of stroke and they are to short for that stroke, they get kinked around to much. These rods have a straight cap and use a 2" diameter crankpin. With the straight cap, clearance isn't the best, you'll run out of room. They are 7.375" center to center.
Cockshutt, Herculees used a verry similar rod, a bit heavier and just a bit over 8" long. I do not rember if they were 8.0625 or 8.125 long. Either way though the bottom end is almost identical to the Buda rod.
I know some useing a Chrystler flathead rod. I don't know but I'm guessing same clearance issues for that much stroke. John Deere Dubuque series engines use a nice strong rod, but it's a little to bulky to fit much over a 5.5" stroke.
A Farmall H or 350 rod is nice, but the crankpin diameter is larger. I've used them out to 5.75" stroke but it's a lot of work to make them fit and clear out there. 8.000" length. One time I rember a fella telling me he built a 6" stroke engine with them in but would never do it again, lots of clearanceing work and sacrafice the strength to get them to clear out that far.
I've shortened and lengthened rods in the past by makeing a slug, tig welding it in the wrist pin bore and offset boreing a hole to the desired length.
If mill time is tight, just spend a few hours clearanceing a set of rods, a few more hours clearanceing the block, a few more hours figureing out where it's still hitting and more clearanceing..... then have some parts that you wonder if they are going to hold when done. That mill will soon have time to make a set of rods.
Your best bet is a billet rod, I have a local CNC shop make them for me, I start with 1" thick X 3" wide material cut with the grain structure running length ways. I don't use 4150 but I use a different material to start with. With the rod profile they clear at 6" stroke with no block clearanceing work, there's still about .080" room where the cap passes by the oil pan rails. I do have to turn the camshaft down between the lobes slightly, the cams are large to start with, and the rod will turn past but touch the cam, if I rotated the cap another 2 or 2.5 degrees or so they would clear with no cam clearanceing at all. I just use a 2" crankpin small block Chevy rod bearing. Clevite 745HN I think is the number, a hard or H series bearing.
I do have a sample rod made from mild steel that I could send you for a pattern, the cap on the sample rod is rotated 2.5 degrees from what I settled on for a final cap angle, but it's an easy change to make if you choose to make your own. I've got a set ready to go that are 8.000" center to center length also.
Edited by wi50 - 25 Sep 2013 at 2:23pm
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