The road rocket racing sidecar project

[metalflake11]

Thanks for posting that, It has made me bog eyed reading it, but I understand what seems to be the crux of the matter. ie the angle of the shorter con rod altering the speed of the piston at different points in its travel. Good luck with it!

[Rocket Racer]

Thanks for posting that, It has made me bog eyed reading it, but I understand what seems to be the crux of the matter. ie the angle of the shorter con rod altering the speed of the piston at different points in its travel. Good luck with it!

a good synopsis, effectively the piston acceleration increases as does piston speed, not necessarily good things but within the realms of expected rpm ok. The A65 and Norton twins all run short rods, the norton on a longer stroke.
With quicker piston acceleration the motor should have an improved induction and exhaust cycle...in theory

[JulianM]

There are strong arguments for both short and long rods,
However, in general you use short rods in a fast circuit engine that runs at high speed for longer periods, and when engine service life is not such an issue.   Piston acceleration is increased and so is piston side load (greatly), in fact the piston side load is increased in proportion to any extra side thrust you may pick up from the rod angularity so be rather skeptical of that "plus point"   A longer rod "dwells" at tdc for longer allowing the flame to have more time to burn completely and have more effect exactly where it is needed, therefore also allowing more flexibility for spark timing inaccuracies etc, it generally gives a less fussy engine and also one that pulls off of the corners better.   Read any serious papers / books about NASCAR engine building and you will find more info on this subject than your head can handle!!

Good luck.
Julian.

[andy]

when i first noticed this page/post/headline this image automaticaly came to mind lol.

[Rocket Racer]

when i first noticed this page/post/headline this image automaticaly came to mind lol.

Brilliant, even looks like an A10 engine!

A good mate tells me the cartoon relates to Ogri borrowing his Grandmothers A10 to win 5 Pounds!
Sheer class

[andy]

yeh thats right his granny claims to have done "the ton" in/on it lol.

[metalflake11]

Looking at Rocket Racers signature (the script at the bottom of each post.) I thought it was a shame they didn't issue the same advice for the M series! ...........
https://www.youtube.com/watch?v=qumlsvxTof4
Gladly all was well! ....................... And good advice for us all at the end. Good ol' Sumpy!

[muskrat]

A mate of mine lost his front one on a Trihard. Wasn't as pretty as that!
Cheers

[Rocket Racer]

Latest plan is to fit line bored T140 rods with steel end caps. Price was right and the budget a bit tight.
Barrel shortening to progress over Christmas.

[Rocket Racer]

http://festival.nzcmrr.com/gallery/category/5-classic-festival-pukekohe-2012-the-engines?start=20

engine featured on the NZCMRR website! nice and shiny  

[muskrat]

 And the best looking too RR well done. The timing side of the G50 comes second.
Cheers

[Rocket Racer]

time for a bit of minor pre season fettling, first race of the season 7th & 8th September,

will be fitting the T140 rods and a shortened barrel, steel caps/alloy rods.
Pistons fly cut to clear the flywheels

my SR aka "rusty" in pieces in background and my ZB33 under the blue cover

[muskrat]

G'day RR.
How much difference in balance weight?
Yep that looks like a classic racers shed.
Cheers

[Rocket Racer]

apologies for the delay in responding, my wife's kitchen scales are giving me sufficient variation that I cannot effectively identify a weight difference between pistons or rods although it appear the rod saving in reciprocating weight is offset by the increase in rotational weight. Will try and source a decent scale but expect it'll be a suck it and see.
 Got the barrel (and pushrods) back on the way home from work, looks nice, but waiting for a fresh set of big end shells for the rod swap out.
Will be interesting to see if it goes back together with minor pain or shows up lots of butterfly effects 
The pistons actually look more modern fly cut, I'm quietly optimistic but we'll see.

[Rocket Racer]

barrel painted. still waiting for a fresh set of main bearing shells before I can swap out the rods, supposed to be racing it over weekend of sept 7th  at Taupo
so a bit of work to do, a wet weekend so spent quite a lot of it easing the gudgeon pins of the 9:1's which are going into it, which were a tight fit. a slow job.