580 West Bend Questions

[Mike Reller]

I'm guessing that the average age of anyone who actually built a 580 for racing, would be deceased, but here goes. Long ago, I saw 580 West Bend 3 port engines converted to 5 ports with the use of two sections of bent tubing running from the crankcase, to the cylinder. I thought this would be cool to try, considering the scarcity of 5 port blocks. It struck me that the downside of this would be that it may have the effect of increasing the crankcase volume, any thoughts about this. We ran a 5 port in 1963 in a sportsman class. With a Wiseco piston, some porting, and dual carbs, it ran pretty well, and was ultra reliable. Also, has anybody ever heard of replacing the caged bearings with lose Mac needle bearings? We did, it worked. Any help would be appreciated. Mike

[Terry D Bentley]

If you are worried about too much volume just add a super stuffer and/or full circle crank. Dont think the added volume is going to hinder the gains. Not in the rpm range these motorss run. Nothing wrong with just loose needles instead of cages. Both work fine. Have you ever removed a Power Products rod? It has twice as many loose needles that are half the length. A real pain to assemble.

[Bill Hermsted]

Terry- I've installed many sets of the 56 short needles until they would haunt me in my sleep! I only once was lucky enough to find a set with the beeswax still intact. Tecumseh made the change in the late 1960's probably to lessen the pinch effect on the needles when the rod rocked a bit.
Macs don't need the double row since their rods can't rock, right?
bill

[Andy Symons]

Mike,
Converting the 3 to the 5 port 580 was done way before the factory released their version and there exists a number of articles about the process. One is in "Racing Karts" magazine, August '61 (used to be "Karting Sport" up to April '61).

Once the 580v5 came out, I doubt anyone did it by hand any longer, since it was a pain to do. There was discussion about the placement of the ports and whether the factory had placed them in the best spots but I doubt anyone ever did an in depth analysis which actually showed a significant difference. If you already had a 3 port and didn't want to buy a whole new engine you could buy West Bend's conversion kit #5191-1 which came with the new 5 port cylinder, redesigned high compression piston, rings and gaskets for $22.00. Whether you had a 510, 645, 580 or even a 700, you could make a 580v5 out of it.

By the way, as a teenager I was hacking and filing on 580s for years until the 610/820s arrived in early '62 and I ain't dead yet!! In fact, I'm in the process of building two 580v5s for an old Percival right now. They're pricy but still available and show up fairly regularly on forums and eBay.
Andy

[Terry Bentley]

As long as you as in the process of building those West Bends, could you measure a piston pin length and diameter? Doest have to be exact, just wanting to know if they use a 1/2" diameter pin and a rough length.

[Terry Bentley]

The reason I wanted the pin size is to purchase a bunch that were available. The pin is 1/2" and just short of being 1 5/8" in length. The pin also has a blind hole to keep from feeding exhaust back thru the intake when piston is in position to do such. Anyway the pin is long enough to use on Power Products, and shortened will work on Macs. Being a blind hole, I dont have to worry if the Power Products has booster ports added. Just thought I would follow up in case this info is useful to anyone.

[louie figone]

West Bend Service Manual for the 510-580-700 shows the wrist pin to be 1.88 long x .50015 / .50000 dia.

[Terry Bentley]

Well that confirms the info sent to me from the seller. His dimension is a little short on length, but does not hamper the reason for my inquiry.

[Andy Symons]

Sorry, I haven't been on lately but thought I'd add another 2 cents.

The 0.5" diameter is correct but I'm confused by the 1.88" length Louie gave. The original pins and the replacement #7017s I bought both measure around 1.62" which confirms the length given by Terry's seller. The available distance between the clip grooves in a 580 piston is significantly shorter than 1.88. The part number for the wrist pin for the 700 engines is 31017 and I wonder if the 1.88" applies to that part - after all, it's going into a 2.25" bore rather than a 2.0625. You can get away with using the shorter 7017 pins in the 700s but I wouldn't.

West Bend designed the closed end of the pin on the intake side to prevent filling with intake charge. Any exhaust accumulating in the hollow pin really has nowhere to go since the pin doesn't get below the bottom of the cylinder wall at bdc, unless you count the clearance between the skirt and the wall.

Starting to get excited seeing these old 5 ports comin' along! Andy

[Terry Bentley]

Andy you must be right about the pins. I now have a dozen for the 580's that measure 1.620 in length. I dont have the 700 torn down to confirm length, but looking thru the exhaust port noticed circlip groove is not cut in any deeper than on a 580. With difference in piston diameter, then pin is obviously longer. Anyway, these pins I got worked out perfect for my Power Products AH-61's, Clintons A400-E-65, obviously Westbend 580 and cutting to length all the Macs.