Recently JH mentioned that he had a gaggle of 40 size engines to try in some upcoming projects.
"I have a couple of K&B .40's on the way plus I have two K&B DF 7.5cc motors and also 1 Rossi .40 and two OPS 40 pylon engines."
I know the OPS 40 pylon engines very well, in the 80's and early 90's I was an OPS works sponsored pylon race pilot, so know those engines like the back of my hand.
Which version of the OPS engine do you have? the engines up to the late steel front housing sit in a funny place on exhaust timing, they are timed at 170 degrees which is too much for running open face or on a mini pipe, I did run one of these on a mini pipe in F1 pylon at the 86 US Nats at Lake Charles but I struggled to stay on the led lap, where as in F3D I had fast time.
B.
Hi Barrie - not sure which it is:
Maybe you can tell me. I'll check the timing later.
J.
Hi Barrie - not sure which it is:
Maybe you can tell me. I'll check the timing later.
J.
J.
By the time that I started F3D pylon racing in 1982,the event had exclusively switched to rear exhaust engines, if your engines had been used in a pylon racer they would have been used seriously in the late 1970's.
I suspect that your engines will comprise of 3/8" crankshafts, maybe with a paxolin disk, (at some stage before 1982 they changed to a very nice cast steel disk), I think you will have moderate timing on the exhaust. The rear exhaust OPS pylon engine of 1980's had an exhaust timing of 170 degrees they also offered a sport timed liner with about 145 degrees exhaust, I have a hunch that is what you will have.
The last OPS pylon race engine had 193 degree ex timing and a team race style steel from housing.
What K&B's have you got? 40 S or 40 SR?
Regards
Barrie
This is whats in my treasure box so far - swapped for one of my smaller Gliders - Oldies but possibly Goldies!
Both of the newer K&B's are Clarence Lee custom DF units.
ST .40 is apparently a really fast Shadle (?) unit.
Now what could I cobble together for these lovelies?
Cheers,
J
For the 7.5 K&B's? - I have put the question to the Speed C'ttee, do they think it's worth instituting an additional class in the Open Speed category? For 7.5cc/0.46c.i. motors. There's a lot of motors of this capacity, but at the moment they only qualify for the 10cc/0.60c.i. category. This has appropriately thick lines and a 140lb. pull test, and such an entry would only make up the numbers, - no chance of winning.
I know we have "too many" classes already, but most of these 7.5cc motors have the same c/case as the 6.5cc motor from the same maker. So you wouldn't need an extra model, and the lines and pull test should be appropriately smaller.
Maybe SAM would also consider a similar class for Weathermen, in between 0.40 and 0.60.
I know a man who will be making suitable glass W'man fus's for these engines.
@rustler I don't think you will get a lot of traction for another class without at least a couple of folks with .45 models. The way forward is to enter in 60 light, the two line size is slightly thicker at .55mm over .50mm but I would think that a .45 class is likely to call for thicker than .50mm lines in any case for safety reasons. If you make a couple of competition runs and get some numbers on the board then there is an argument to have a pilots vote to add a .45 class. As a point of interest any speed that you or a.n. other posts in competition would be a record since it seems, by looking at the BMFA records that no nominal speed has been set for either 60 light or 60 heavy. I don't think that's right somehow, but it could be.. I would go for it, I know it means changing lines, but if you are screwing a .45 in your 40 model it's going to be in bits anyway...
