So, off to Phil in Oz for a back-cut...
...and no more 1st gear ProStock launches!!!
Tim O'Mahony's 1978 900SD Darmah
"Back Cut refers to cutting the engagement dogs at an angle (in the case of this photo' 3 degrees) so that once they begin to engage, they stay that way. If they don't stay engaged, the end result is rounded dogs, like the photos above.
It is a very fine line between "hobby" and "mental illness"....
Going back together!
After 4 months of down time waiting for the heads and crank, I am finally reassembling the Darmah engine. The work that Guy Martin at Martin Brickwood Performance did on the heads and crank looks outstanding. On the heads, he installed hardened seats, new valves, new full length guides with standard seals, machined the closing rockers to clear the guides, Modified the rockers/rocker arms to allow valve adjustments without removing rocker shafts (ala Paso/F1), port matched the intakes and installed a set of MBP collets.
Last edited by tim61 on Fri Jul 07, 2006 10:07 am, edited 3 times in total.
It is a very fine line between "hobby" and "mental illness"....
Guy bead blasted the heads, adjusted the valves and set all the upper bevel shims in the process. Expensive??? YES! But worth it to me!
Last edited by tim61 on Fri Jul 07, 2006 10:19 am, edited 2 times in total.
It is a very fine line between "hobby" and "mental illness"....
The MBP "bulletproof" crank is pretty, but the fine work is not as apparent to the eye. Guy has the rods machined to accept a Stainless insert on the big end, and then uses a heavy duty bearing and a rod pin of his own design. I have heard of several vintage racers with more than 8 seasons on these cranks with no failures! Again, pricey, but a bargain compared to a crank failure!
Last edited by tim61 on Fri Jul 07, 2006 10:20 am, edited 2 times in total.
It is a very fine line between "hobby" and "mental illness"....
Saw your comments on the Heads list too; they look great Tim. I certainly will go that route should I need work on mine! I'm jealous of your dedication and willingness to tackle the engine rebuild yourself; getting access to the tools was helpful I'm sure - and the occasional look over the shoulders from the other Tim a blessing!
Cheers
Geoff
Cheers
Geoff
Geoff,
Thanks for the kind words of encouragement! I think I figured out the picture posting thing again. I post about once every 6 months, which is just about how long it takes me to forget how to do it!
As far as the rebuild, it was a lot easier than I thought it would be. It just takes a lot of time. I was actually quite entertained by the shimming process. Having only worked on Japanese bikes up to this point, I was well versed in the "assemble it and go" theory. The bevel requires a much more involved process which is really a lot of fun, once you get going
It becomes a game of seeing just how close to perfect you can get the clearance on all the shafts. Here are some pictures of that process.
Thanks for the kind words of encouragement! I think I figured out the picture posting thing again. I post about once every 6 months, which is just about how long it takes me to forget how to do it!
As far as the rebuild, it was a lot easier than I thought it would be. It just takes a lot of time. I was actually quite entertained by the shimming process. Having only worked on Japanese bikes up to this point, I was well versed in the "assemble it and go" theory. The bevel requires a much more involved process which is really a lot of fun, once you get going
It becomes a game of seeing just how close to perfect you can get the clearance on all the shafts. Here are some pictures of that process.
It is a very fine line between "hobby" and "mental illness"....