The Fox .201 is not just a restamped .19.... The crank has a .003 longer throw... And, the crank is marked, but VERY subtly..... A dial indicator will show the diff in stroke....
Jim
Interesting. I would wonder if .003" stroke would make a Fox .19 into a .201...were the .19's that close to the .199 cu. in maximum for class A? I do have a 3 bolt Fox .19, but I don't know if its displacement calculates out to .199 or not. If I remember, I'll dig it out of the gun safe and measure it up.
Further, it would not surprise me if +.003" stroke might be a possible error on a .19 crank, given Fox QC and the fact that Rossi made a bunch of 2.5cc engines that were slightly over 2.5cc's and resulted in a World Championships F1C winner being DQ'd in 1979. My recollection (which may well be fubar) is that the stroke was +.005" long...and this being from a WORLD CLASS engine maker with many NATS and WC victories. I know Fox .35's have won the F2B WC, but I find it difficult to call Fox a WORLD CLASS engine manufacturer. NOT looking for an argument on this, Brett!
As a retired machinist (but only a wee bit of centerless and surface grinding and honing experience), I can imagine how the offset tooling for the crank throw might be done, and it would seem simple enough to design such that an error would be difficult...but you never know how somebody else would/could design the tooling. Then again, we're talking about Fox.
I don't recall seeing anything about a K&B .201 Greenhead, but saw many .23's, and then there was the 3.25cc version of the 3.5cc hotrod. Ditto for a Veco .201, which I suppose might have been a Series 200? Or a .201 version of the .19bb? From 1969, I mostly flew FF until the late '80's, and was a member of NFFS for two decades, so I can't understand why I wouldn't have read or seen those other .201's, but anything is possible. Maybe some California secret factory engines? That's certainly plausible.
By the way, when I worked in QC at Jorgenson Steel, one of my monthly tasks was to calibrate micrometers and dial indicators, both company and machinist owned. It turns out that for a typical 0-1" stroke dial indicator, .003" variation from nominal for a brand new one was about as good they got. Many "experienced" ones were .006" off nominal, which IIRC was acceptable. I saw some that were really beat and were more like .012" off nominal and those were labeled as unacceptable and supposed to be taken out of service. A 0-1" indicator would likely be used to measure a model engine's stroke, leading me to suggest that it's just not an appropriate tool for the job. There are 1/2" stroke indicators, but they're far and few between. I've seen a few of those, maybe 3 in 35+ years.
I looked online for a picture of the test device used, but no joy. It was a Mitutoyo, and sort of a vertical micrometer without the anvil end, and a column to mount the subject indicator on. The dial was probably 5" to 6" diameter, giving lots of hashmarks to eyeball. I seem to think it was marked in .0001" increments, but maybe .00001"...way less than required for the job. That instrument got sent out for calibration in a lab somewhere in Seattle.
The machinists whined that their rejected indicator worked fine to dial-in a round-ish part in a 4-jaw chuck, and I agreed completely, but Mil-Spec limits were law, so these were condemned if out of tolerance. Usually, they'd be tagged and sent in for repair at company expense, but if it wasn't adjustable by the lab to be in tolerance, the machinist had to buy a new one...and I'd get to check their brand new indicator. That's not adjust, but check and apply a stamp to show compliance to whatever the Mil-Spec is/was...which I'm vaguely remembering to be within .006" over the travel of the instrument, regardless of the travel. Kinda sloppy tolerance for a test indicator with only .010", .030" or .060" travel.
The WORST dial indicators were the back plunger .300" travel models, usually Starrett. They were crap, new or old. I don't think any of them passed. The 0-2" stroke indicators were not impressive either. Here's where Mil-Spec didn't mesh with reality. It really depends on how the indicator is being used. I'd trust a depth mike over a 1" travel indicator to measure an engine's stroke, anytime. Federals were my favorite real American brand, but they were already out of business by 1981.
Anybody know how to Google for Mil-Specs for inspection equipment? I tried, and gave it up.
Steve
Topic: Fox 201 engine (Read 3170 times)