Adjustable timing set for 250?
- Thread starter 80Stang
- Start date
We're maybe four weeks from our sample motor arriving at the Adelaide factory. Add up to eight weeks for R&D/prototyping/production of the first batch (factory would like to halve that time). Then return shipping kicks in.
I'd like it to be sooner, but that's pretty much where I'm at.
I'd like it to be sooner, but that's pretty much where I'm at.
The factory are still in R&D. They're trying all the existing programmed stock sizes of sprockets, to see if a combination will bring the slack within tolerance. Failing that, the next stage is to prototype some, and see if they'll fit inside the cover.
Stan did raise with me, the modest possibility that it may not be feasible with the double roller chainset.
Stan did raise with me, the modest possibility that it may not be feasible with the double roller chainset.
OK, here is where it's at (updated today):
Stan says that the IWIS chains cannot be made to work with the centreline distance of the US250. Bummer.
They are apparently coming up too tight with one set (unfittable), and too loose with another (unreliable).
Fallback "maybe" option, is to get complete single roller timing sets delivered, and re-slot them to nine keyways with CNC. This relies on crank gears not being nitrided, but hardened on the teeth only.
The company are mid-acquisition of another firm so it will be a couple of weeks (realistically IMO middle January) before this one could be test-run. Looking for input on this proposal!
Thanks, Adam.
Stan says that the IWIS chains cannot be made to work with the centreline distance of the US250. Bummer.
They are apparently coming up too tight with one set (unfittable), and too loose with another (unreliable).Fallback "maybe" option, is to get complete single roller timing sets delivered, and re-slot them to nine keyways with CNC. This relies on crank gears not being nitrided, but hardened on the teeth only.
The company are mid-acquisition of another firm so it will be a couple of weeks (realistically IMO middle January) before this one could be test-run. Looking for input on this proposal!
Thanks, Adam.
JP billeted new gear pairs, to try the 52-link chain, and a 54-link chain.
The "pitch" or roller centreline of the chains (quite different on the IWIS to Ford OEM), determines feasible limits for sprocket radiuses by tooth count; else the chain sits too high on the sprocket tooth, or nestles in the root and remains slack.
While the "slack" version would be highly unlikely to skip a link, Stan was not willing to use it, as he considered it too risky, and says it would appear worn out when new, from a consumer viewpoint.
Sprocket tooth profile is cut with a specialised cutter that alone costs thousands; that's why they didn't rush out to buy a cutter for single-roller chains.
The "pitch" or roller centreline of the chains (quite different on the IWIS to Ford OEM), determines feasible limits for sprocket radiuses by tooth count; else the chain sits too high on the sprocket tooth, or nestles in the root and remains slack.
While the "slack" version would be highly unlikely to skip a link, Stan was not willing to use it, as he considered it too risky, and says it would appear worn out when new, from a consumer viewpoint.
Sprocket tooth profile is cut with a specialised cutter that alone costs thousands; that's why they didn't rush out to buy a cutter for single-roller chains.
I did raise that issue - vernier adjustable gear drives.
Similar problem! The tooth pitch is likely going to require a new cutter profile, which is outsourced and hellishly expensive. You have less meshing tolerance with gears than chain.
I reckon we need a new block. Alloy, with cast-in siamesed steel bores that can be punched 120 over. SBF bellhousing flange and the Australian cam position. And, of course, a "skunk works" FoMoCo part number backed by some credible story about fifty of them being found in a NE barn...
Similar problem! The tooth pitch is likely going to require a new cutter profile, which is outsourced and hellishly expensive. You have less meshing tolerance with gears than chain.
I reckon we need a new block. Alloy, with cast-in siamesed steel bores that can be punched 120 over. SBF bellhousing flange and the Australian cam position. And, of course, a "skunk works" FoMoCo part number backed by some credible story about fifty of them being found in a NE barn...
