fox 35x vs 36x

Hello friends,- I wonder if anybody could tell me the difference power and performance wise between these two moters. I already know the 35x had a weaker crank! Lets talk about the ones made from 1962-1965. Thanks Paul

Paul,

Try this link:

http://www.clcombat.info/foxhistory.html

Some of the 35x had two bearings in the same case as the 36X.
(One piece case))
Quite a few of the ones marked "35" are now 36!!... if they were really used in the hot days for Fox. easy to tell from outside. the 36 jug has a taller deck, above the case by about 40thou+-, maybe more.The head is a lot farther from the block. than the 35..same piston/rod.(same case bore as a stunt 35)
36x piston/sleeves are now extinct!! I bought all that Fox had two years ago(4) all sold for more than the engines are worth, 38$
Both run about the same, 14to 15k with a 9x5 on 15%. A lot more with the period wood 8x8 or 8x6.
I have a few of each.(Sale!!) You can twist the sleeve a little off to slow them down for speedlimit, Thirsty tho, 5oz/5min. Only a little better with the insert. IMHO. MM

Hey guys, Thanks for the info Paul

>Some of the 35x had two bearings in the same case as the
>36X.
> (One piece case))
> Quite a few of the ones marked "35" are now 36!!... if
>they were really used in the hot days for Fox. easy to tell
>from outside. the 36 jug has a taller deck, above the case
>by about 40thou+-, maybe more.The head is a lot farther from
>the block. than the 35..same piston/rod.(same case bore as a
>stunt 35)
> 36x piston/sleeves are now extinct!! I bought all that Fox
>had two years ago(4) all sold for more than the engines are
>worth, 38$
> Both run about the same, 14to 15k with a 9x5 on 15%. A lot
>more with the period wood 8x8 or 8x6.
> I have a few of each.(Sale!!) You can twist the sleeve a
>little off to slow them down for speedlimit, Thirsty tho,
>5oz/5min. Only a little better with the insert. IMHO. MM

Yup, the 36X is simply a "stroked" 35X. Although the shaft was improved over the years. Bill Ives (good guy!) lists this as a '64 development, but some friends and I had prototypes in '63. I lost the match for 3rd place in Open Combat at the '63 Nats to Bill James, who was then Sales Manager for Fox. The consolation was that Bill gave my pit crew and I prototypes of the 36X and thus began a period of several years where I had a "Fox Contest Team" in Minnesota with some factory support.

Fox was ecstatic with our 3rd & 4th place finishes because Johnsons had been sweeping the event for several years, but an interesting point is that I was using the Fox 29X (as I had for much of the period '59 - '63) ... If you recall, the Fox 29X dominated Proto Speed for several years even after the "imports" blew them away in Class B Speed. I reasoned that the brute torque of the Fox at lower speeds (remember, Proto is timed from a standing start) must say something about that particular engine and its "numbers" - i.e., bore/stroke ratio and timing, etc.

Any engine is only as good as the way you use it. I generally used smallish, light airplanes set up for big turns and a hit-and-run approach. I can't tell you how many of my "victims" swore I must have a .40 motor marked as a .29!

In view of my approach, I generally ran a Grish (Tornado) yellow nylon 8x8. When I ran wood props, I'd never go under a 7" pitch. The Rev-Up 9x7 or 9-7-1/2s were great.

I don't believe the Foxes were made to run a zillion rpm with a "nuttin by nuttin" prop - you're just not using the engine at the best point in its power curve. But they aren't slow... I related in the thread on the Fox 15X how Phil Cartier bad-mouthed the Foxes I ran in the '60s and '70s against Phil until friend Dale Mendenhall pulled out a tachometer to show that my Fox 36X was turning an 8x8 800 rpm faster than Phil's G.31/.35 turned a "nuttin by nuttin"...

These were great engines. My fuel was 23% synthetic oil, 30% nitro, and the only time I ever "blew" an engine in many years of (winning) competition was in a practice session at the contest site.

Free the engine completely, put a small oil hole in the con rod, make sure the wrist pin clips are securely in place, and you've got a real winner on your hands.

I love those motors!

Dennis Leonhardi