OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Tecumseh / Kirby Engines Tapping a Tecumseh flywheel for pully, what thread

Hi guys,

I'm trying to remove the flywheel from my TECUMSEH engine, but it won't budge. I found a puller in the shed, but need to get some bolts for it. One thing I noticed is the holes in the flywheel to screw the pulley into aren't tapped .. just wondering if anyone has tapped them before and can suggest a thread?



According to my Digital Calipers, I get a reading of,

- 5.7mm
- 0.22"

I grabbed a 15/64 drill bit and it seemed to fit into the hole (pretty snug fit).. and according to this website,

http://www.engineeringtoolbox.com/fractional-decimal-equivalents-d_1159.html

a 15/64 =

0.2344"
5.95mm

So should I tap the next size up?

Tap with M6 / M7 (course)

Tap with 1/4"

Because the hole looks to be an imperial size.. should I tick with imperial tap/bolt sizes ?

Thanks

Widget, 1/4 whit is best because it suits the hole size and it is a coarse thread suitable for alloy

Thanks heaps Norm .. quick question, how do BSW differ from UNC ? I see UNC has a thread angle of 60* whereas BSW has 55* .. does that make BSW sharper allowing for better/easier tapping ?

These are the BSW Im looking at ordering.. seem to be 1/4-20

http://www.ebay.com.au/itm/BSW-Tap-...te-Plug-from-1-8-1-55-deg-/401090400391?

Thanks again

UNC and BSW have the same thread per inch value, accept for the 1/2" size. Theoretical it would be possible to interchange them as they have the same amount of threads per inch. However due to the difference in thread angle, the connection would not be as strong as when using the proper combinations.

For the sake of pulling if you go with the BSW also use BSW bolts(screws) to ensure maximum strength.

As for which is better it more of a difference Imperial and SAE standards like SAE and Metric systems. Can drive you nuts on restores.

You can get this set
http://www.ebay.com.au/itm/252441187760?_t

Oh damn... placed an order already with the other link before I saw you post .. coulda saved a few bucks, ah well.. thanks anyways