Rear End Gear?

[Ross F-1]

... So the check the tach idea is a simple one but I really doubt that's it. No way it is idling at 1000rpm.

No, it appears to be reading 2X actual RPM, so it could be idling at 250. Or it could just be a crappy tach that reads whatever it likes. If you know someone with an old "Engine Analyzer" dwell/tach, or the local shops have one (almost certainly will), it's a 10-second check.

 

[mustang8]

I get numbers similar to Martin for that combination.

Edit: Well, we may have both been using the same calculator! I think you may be getting the correct reading. I will do some more checking, but this chart seems to have the numbers you are seeing (hard to read, but has 28" tires with 3.73 comes out 2909 rpm).

I am going to calculate it by hand and not use the online calculators! and see what I get.

So I might be right? I asked my dad again what he remembers from years ago and he just says it had stump pulling gears.

 

[mustang8]

No, it appears to be reading 2X actual RPM, so it could be idling at 250. Or it could just be a crappy tach that reads whatever it likes. If you know someone with an old "Engine Analyzer" dwell/tach, or the local shops have one (almost certainly will), it's a 10-second check.

I have one of those. Small hand held device, I use on snowmobiles works on 2 and 4 stroke motors. Just got truck home 2 days ago from my buddies shop where we did all the upgrades and now with iola this weekend I wont have time til next week.

 

[mustang8]

I just cant believe it would actually idle at 250.

 

[George/Maine]

2200 rpm in a flathead sounds fast. you may have 4.11 gears.
2900 rpm you would have no more problem= 64 mph. 3.73 gears.
Count the turns on drive shaft or are you to fat.

 

[mustang8]

Na I should fit. Only 32 so If I don't fit I might have to call Jenny Craig.

 

[scooder]

I wouldn't be surprised if it could idle at 250 ish rpm.
You said "it's barely idling there" a stock flathead will idle very comfortable at 400rpm, so barely idle at 250 rpm makes sence?
Just make sure your hand held meter is set for 8 cylinders or your reading on the 8 cylinder scale.
Martin.