Modified flathead

[Ball Racing]

I used to race karts and we used a Briggs & Stratton 5hp flathead
12 Cubic inch the bore and valve sizes are almost exact of a Atomic.
But the Briggs had about 5/8" less stroke.
In full modified trim we turn 10,000++ RPMs on Methanol and sometimes Nitro Methane.
We ran a Tillotson chainsaw style carbs with bores from 1.000 to 1.125
We enlarged the intake valve to 1.440-sometime 1.500 inch and the exhaust valve up to 1.250
We had billet rods, billet cams billet lifters even billet flywheels.
We stressed the blocks severely and those would lift the jugs off.
We overbored them +.140 and had up to .500 stroker cranks

[Ball Racing]

Notice the twin sparkplugs .
That was a stock head I welded up the original hole and then relocated. The coil was from a twin cylinder 18HP Briggs
I also welded a intake on a angle for better flow.

Then there is the head I made myself with only a tablesaw, and a drill press and a dremel from a billet stock aluminum.
There is a billet rod with Wiseco Forged Piston.
We ran rods up to 4.600 long- stock was a mere 3.875 long
The engine with the red intake was a stock block that I welded the entire upper area, re cut the ports on a angle for better flow.

[Ball Racing]

I took one block and cut the cylinder out of it. added a taller deck, and angled the ports, then added back cooling fins.

[Ball Racing]

We placed a "girdle" on top of the engine down to the mounts to hold it together..
Look Close---- even a ...... *cough* PCV valve

[BadaBing]

The aluminum head made on a table saw. I would hav e that mounter and hung on a.wall as a peice of fine.art!

[Dave Neptune]

Daniel, nice ork! Certainly looks lke it could breath and use all of 1.25 @ 10K.

Did you do any "clean up" -4's breathing abilities?

Dave Neptune

[Ball Racing]

I worked the ports some but it's such a low-end power band I may have done more harm then good.

[sastanley]

Daniel, Looking good. Nice to have guys like you around to help us understand the details.

[romantic comedy]

Probably has more HP then the Atomic Four.


How about making an overhead valve head for the Atomic Four. (on the table saw?)

[Dave Neptune]

Daniel, has anyone tried a roller cam in Cart racing? I have seen some very impressive results in some Ford Flatties. I have seen some 32's pull the SB Chevy's and put back the flathead. Not quite as much power but being much lighter "almost" makes up for it. The guys that have done it say that it's just more fun to drive (better balanced) and the looks are truly nostalgic.

One of the 32's has a blower an Eaton Blower I think sitting under 3 Strombergs and it really looks great between the Eddlebrock polished copper heads! He claims the flathead to be 3tenths quicker than his 350 350 SB as he took another 500 pounds out of the car with the lighter flathead, aluminum front end, lighter rear end and trans.
His other 32 has a 600hp Ford Hemi that is also really tricked out. Its a crack up seeing the looks on faces when they realize it is a Ford and not a Mopar engine.

Dave Neptune

[Ball Racing]

Yes they have tried roller cams. But due to the smallness of our set-up they had to actually place the roller on the tip of the cam lobe. So you didn't get the full effect of a "roller" profile cam and lifter package.
They also broached the lifter boss square so the lifter couldn't rotate making a square shank shaft) and used a oval head lifter..
The lifters for the briggs look just like the valve, but upside down..

It was not uncommon to get a real 25hp from 14 cu in on methanol.
there was a sanctioned body that allowed up to 14.2 cu in in the "open" class so the aftermarket went with that.
Then guys would do stuff that was all out- outlaw (no rules) and make more HP

The have a class of drag racing for the kids called Jr. Dragsters.
They are a mini top fuel rail and they have gone over 90mph in the 1/8th mile with a single cylinder engine.
They have now made purpose cast blocks with up to 3.5 in bores (stock briggs was only 2- 9/16") on nitro
.500 lift cams
Some of those motors have been dynoed @50hp
Now the karting world is running OHV motors and they make way more torque per cu in.

If the Atomic only had more main bearings I could get a cam ground and am confident I could turn 8,000rpms with a set-up like I had on the briggs of course I would need the forged pistons, and different rods.

[Dave Neptune]

Daniel, FWIW the Palmer is a 3 bearing and very close to the same size. Anyone "waterski" in one of the "Bay's Wooden Boats"?

Dave Neptune

[Ball Racing]

There are some 40 ft Chesapeake Bay Deadrise Boats that will run 36 knots. Yeah they have pulled some skiers an tubers .https://youtu.be/I9_lBqxx85Y