 The Ohio Crankshaft H beam rod on the special fixture that allows weighing one end of the rod at a time. |
Next up was the weight matching of the Ohio Crankshaft “H” beam connecting rods. My rods of choice are 5.400” inches long and use a .928” SBC size wrist pin and a 2.123” SBF journal size (although I see now on the Ohio Crankshaft website they have a SBC 2.100” journal). They are the typical “H” beam style construction rods similar to what are available from other companies BUT they come with the ARP 2000 cap screws, which are normally an upgrade from other companies that you have to pay extra for. Also, they are made from 4340 steel as opposed to other brands’ lesser materials. And, the Ohio rods only cost $359.00 a set! By far the best deal out there on quality connecting rods! The machine work and finish work is impressive.
I checked the big end of all of the rods for roundness and size and they were well within tolerance. Not the same can be said for a lot of other brands selling what appears to be the same product. The rods weighed in at 604 grams with a big end weight of 427 grams. The rods were pretty easy to weight match as the biggest variance was about 3 grams from the lightest to heaviest. The material removal is done with a belt sander and then I final polish the sanding marks with a Scotchbrite wheel mounted on a bench grinder. This polishes away any coarse marks and leaves it looking pretty. Each end of the rods is matched to the lightest sample. If done correctly the total weight of all the rods will be the same when done.
Now that we have the weight of the pistons, connecting rod totals and big end weight, rings, bearings, pin locks, pins, and a general oil weight allowance of 4 grams, we come up with a “bob weight” of 1723 grams. In the racing world that is pretty good (meaning light) for completely off the shelf parts. Some of the higher end lightweight assemblies will be in the low to mid 1600 gram range, but that is with much more expensive custom parts.
The bob weights are assembled and clamped onto the crankshaft in a specific orientation to precisely simulate the rotating assembly. The crankshaft is also made by Ohio Crankshaft and is a very nice piece. Part #43023400. It is made of 4340 steel and has a 3.400” stroke with standard 302 mains and rod journal sizes (once again I see the Ohio website now shows an SBC pin size). It has a nice rounded over leading edge to the counterweights and a unique black coloring. They are rated at up to 1500 hp so I think I’ll be okay! And, it only cost $450.00! What a bargain!
 This shows the placement of the bob weights on the crankshaft and everything ready to go for the first spin. Notice the lack of dampener and flex plate. I was trying to see if it would internally balance without a lot of fuss. Nope! |
 This is what the computer screen shows after a spin. All of the circles are where the computer wants me to add weight to internally balance the shaft. Maybe next time. |
I was initially thinking about trying to internally balance the crank even though it is designed as an external balance unit to be used with a dampener and flex plate that have weights attached to them. However, when I spun the crank without said dampener and flex plate the balancer told me that I needed to add 328.2 grams on the front and 315.5 at the rear in order to have a balanced assembly. That would take approximately nine slugs of “heavy metal” that cost around $60.00 each! I quickly did the math and decided I really didn’t need an internally balanced crank! So, I am using a TCI Rattler dampener and TCI SFI legal flex plate that are both made for a 28 oz. externally balanced crankshaft. I will finish up the balancing of the crank and go into more detail about the TCI Rattler harmonic absorber in the next article along with boring, honing, deck surfacing, etc.
As an update I did take ol’ Muscrate out to Cedar Falls Raceway two weekends ago for a day at the races and entered the Heartland Stock/Super Stock Association race and the Pro ET “no box” class. I was pretty pleased with the 2-year-old “crate motor” and ran a string of 11-teen ET’s and lost in the semi-finals of S/SS and the quarter-finals of Pro ET. Not bad for the first time out this year but unfortunately a couple rounds short of any decent money. Had fun though and it was the very first drag race Michael has ever attended! I’m sure it won’t be the last!
Until next time, always remember, there’s always hope and when in doubt. . .DO A WHEELIE!!
SOURCE BOX
| United Engine and Machine Company 4909 Goni Road Carson City, NV 89706 (800)648-7970 www.kb-silvolite.com |
Ohio Crankshaft 5453 ST RT 49 S Greenville, OH 45331 (800)333-7113 www.ohiocrank.com |
| TCI Automotive 151 Industrial Drive Ashland, MS 38603 (888)PRO-XTCI www.tciauto.com |
Moroso Performance Products 80 Carter Drive Guilford, CT 06437 (203)458-0542 www.moroso.com |
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