MTFCA Forum

Like the Doc said, "You got it again son!"

My problem is with a 1920 engine.

The two different sized crankshaft pulleys are listed for 1920, one at the end and one at the beginning of years they fit.

I used the larger size pulley that should make the fan turn slightly faster!!

I'm wondering if a Gates 820 flat black belt was intended for use on the 1920 new size crankshaft pulley.

The Gates 819 belt that I installed is just long enough to let the fan hit the lower water outlet.

None of those belts are listed by length in any of the supplier catalogs for some reason!

The small crankshaft pulley is for the earlier small fan hub.

The large crankshaft pulley is for the later large fan hub.

Using the large crankshaft pulley with the small fan hub just makes the fan go too fast, it really doesn’t cool any better. It’s likely to create more problems.
-The fan bearings aren’t designed for the faster speed and wear faster.
-The fan isn’t balanced for the higher speed. The blades are riveted on and vibration is what cracks them. When an early fan blade breaks, it often significantly damages the radiator core.
-The fan really only needs to be effective from an idle speed up to maybe 10 mph. After that, your forward motion moves all the air thru the radiator, not your fan. Any higher fan speed over that is just wasted.

Also, I just looked and the Gates belts go from 25+7/8” to 27”. That’s it. Nothing in between. 25+7/8” is for black radiators with small cs pulley and small fan pulley. 27” is for large cs pulley and large fan pulley up to 1925 prior to the fan being part of the water outlet connection.

I checked the Gates site for Vintage Automotive belts. This is what I found:

I believe you are correct about the pan change Steve, but the pulley changes came later. The large crank pulley needs to run with the larger alloy fan pulley. The change was very likely made as a cost saving. The new fan blade is much simpler to manufacture.

All from down under.

Hi James, I run the poly grooved belts sometimes called serpentine they seem to last very long. Don't look write because of the grooves.
Common sizes are K0 then the # of grooves then 0 & the size in inches so a K060280 is a 6 groove & 28" long around the outside.
Craig.

I just ordered and 821 from Langs that might work OK.

I got an 813 for some reason!

That was an 816, not a 813 and now I know a Gates 816 is 28 7/8th inches long and will fit a 1916 to 1918 with a larger crankshaft pulley.

I run a small fan hub with a large crankshaft pulley on a c.1920 engine in our 1914. Have done so for about 25 years. Not my choice...the engine was built for a speedster and ended up in the 1914. I could not find the correct length belt for that combination. I ended up using an idler arm/bearing off of a distributor that John Stoltz sold, mounted to the timing gear cover. This allowed me to use a longer belt I could find. I put a modern sealed ball bearing pack in the fan, and have changed it once, just in case the bearings were going bad. They were sealed bearings and subject to the heat of the engine/radiator, so I figured it needed a change. Early original brass hub fans, which the 1914 should have, were not made so that you could install the ball bearing pack so I used a later small steel fan hub. I think these modern ball bearing packs are still available for the small hub fans...I have not checked lately. I threw a fan blade once with it. Probably more my fault for not checking on it, than it was a fault of the higher speed created with a large crank pulley. I run a cog belt and have had no problems with it. I cruise at about 35-38 mph and drive it quite a bit.