The Copperhead 820

[Tom Smith]

Red SAE Kart.jpg

(114.57 KiB) Downloaded 31 times

The first Copperhead I know of that ran on a kart was on a kart I modified for a Margay Gearbox set-up. This required lengthening the frame and adding a double shear mount for the gearbox torque arm. After running one event it was determined that the chrome bore wasn't somehow done correctly due to the chrome flaking around the ports which caused a compression loss. That block was switched for another one with the chrome process corrected and it is still running fine. They like to consume a lot of methanol just like the old 820s do. 2 new style large throat double pump Hl Tillotsons don't seem to deliver quite enough fuel to be able to run nice and fat on the top end on this one. Adding a 3rd smaller carb on the stuffer would be something I'd try on one without a pipe.
Is Ed running stuffed nikasil blocks, pipes, and fullcircle cranks? That's how I'm going to build a pair if I find a suitable kart for them and it's also why I've been interested in how well they run stock and for how long.

[mcbob]

Tom some time ago i purchased two sets of Tillertin HL and two sets of Gem V12 reed blocks plus a bottom stuffer manifold to mount on the Copperhead the stuffer manifold is for a single carb as i thought turning up with six carb's might be the odd couple to many but i'm waiting to hear back from Dave Bonbright about the availability of getting another Tillereton HR and reed block to sling under the Copperhead two carbs would be easier to tune than 5 or 6.

Mc Bob.

[Dick Teal]

Mc Bob,

I have a pair of the Vintage 820's that Dave put together for me. The Copperhead and the Vintage are similar but the Copperhead has a different head and bigger shroud over the head. The head on the Vintage is like the old Hortsman heavy duty head. The blocks are the same.

Literature is available that shows the two engines side by side and I beleive that only the Vintage version can run in the VKA events and neither can run at the REAR event.

My Vintage engines have HR 196 alcohol carbs (the large hard to get ones) and are easy to tune. The engines use a V-6 reed that is similar to the V-12 in area. They run strong and idle great; the mid range is impressive also. Dave does a great job on alcohol carbs.

I've only run them at Brodhead (Suger River Raceway) where the long straight is short but I haven't noticed a fuel problem at high RPM. When Earl Larson (GEM) did the HR plate for the V-12 a long time ago I did run a bottom HL carb with the HR on top. I can't remember too much from then but you can always add the bottom carb if you want to.

I also have two 820's that I built like I did in the mid 60's. They have three small bore HL 232 carbs that Dave modified for alcohol. The top manifolds are Big J and the bottom manifolds are GEM; they use the West Bend reeds. One has the porting, piston, rod and crank from the Vintage engine and the other has an old modified block with a Weisco piston and polished crank like we did in the mid 60's. I built the second one for show but I'm sure it will run strong. Vince found me some NOS rings for the Weisco piston.

I have run the first three carb engine for a few laps at Brodhead and it seems strong but I didn't take the time to fine tune it. I never had too much trouble tuning three carbs a long time ago and I expect that it would be the same today. I've discussed the three small HL's VS the one large HR with Dave and he seemed to agree that the three carbs have a slight advantage but we both agree that it may not be worth the effort and complexity.

I will have all of this stuff at the Brodhead Vintage event, the REAR event and the delayed Quincy event.

Hope this helps answer your questions,

Dick Teal

[Roger Mulkey]

Toms post about the flaking chrome was in an earlier engine. I got one of the first prototype blocks from Dave. It was put into Chrysler Power Bee 82026 with Wisco thin ring piston. I ran this engine at Adams in 07. Being alerted to the flaking problem, US Motor redid all the chrome on the production engines, one of the many production delays. I have two US Motor "West Bends", they have run perfectly for over a year. The only problem is the motor on the SAE keeps breaking the ears off on the fan shroud. Dave says stronger fan shrouds are in the works. Roger

[Tom Smith]

Two other minor items with the Copperhead/Vintage 820 block is a Big-J box muffler hits the larger fins on the side of the block and the PTO bosses are wider which moves the chain guard location closer to the clutch. Not a big deal unless it's an inboard clutch on a STINKING SIDEWINDER KART then it's a pain to get the chain on the thing.

[mcbob]

Thanks Dick Rodger and Tom or is it Tom Dick and Harry ? Great fellas for your imput it makes for good enlightenment .......... so has the chrome problem been completely overcome as i have very little time on my engine actually mine is the Vintage version as i thought the only differences where the physical size of the head in area and maybe the cylinder fins where of a larger size and the shroud which would have to be bigger to cover these features. I picked the Vintage version because my engine only runs for short bursts less that 30 seconds with the power being on for less in the cuts so extended hot running isn't i feel a problem.

If in the future i need more from the Vintage engine it will be returned to him for further mods.
Sometime back a Karter gave me a stroker kit a Horstman 2.0 but the crank is marked and after a heck of a lot of phone calls to some pretty smart people i canned the idea of getting it repared so i am in need of another crank and if i can beg borrow or steal one na i'd gladly buy one then i'd ship the bits back to Dave along with my engine so he could set it up for me.

Mc Bob.