The Ford Barn

Flathead Fever · 04-19-2026, 06:36 PM

Like has been said, a belt is designed to ride on the sides of it, not the bottom of it. It has twice the slipping force riding on the sides, the bottom of the belt is not supposed to be touching the pulleys. I see people make that mistake on flatheads all the time, a narrow belt on a wide flathead pulley, it will spin the parts, but it's not correct. All cars that use "V" belt are made to ride on the sloped sides of the belts.

If I remember correctly the '49 8BAs still had the wide belts and then Ford switched to the narrow belts in '50. I keep a bunch of old cut up belts for engine projects. I wrap the "correct width" belts around the pulleys and mark their lengths where I want them. Then I measure the cut belts and have the parts store get me knew ones the exact length I tell them I need. It works out really well. By the time I tighten it, it's in the middle of its travel. They'll stretch a little bit after they have been run awhile, so you always want to have extra adjustment for them.

04-19-2026, 06:36 PM	#22
Flathead Fever Senior Member Join Date: May 2010 Location: Yucaipa, CA Posts: 1,492	Re: 8BA Flathead fan belt widths Like has been said, a belt is designed to ride on the sides of it, not the bottom of it. It has twice the slipping force riding on the sides, the bottom of the belt is not supposed to be touching the pulleys. I see people make that mistake on flatheads all the time, a narrow belt on a wide flathead pulley, it will spin the parts, but it's not correct. All cars that use "V" belt are made to ride on the sloped sides of the belts. If I remember correctly the '49 8BAs still had the wide belts and then Ford switched to the narrow belts in '50. I keep a bunch of old cut up belts for engine projects. I wrap the "correct width" belts around the pulleys and mark their lengths where I want them. Then I measure the cut belts and have the parts store get me knew ones the exact length I tell them I need. It works out really well. By the time I tighten it, it's in the middle of its travel. They'll stretch a little bit after they have been run awhile, so you always want to have extra adjustment for them. Last edited by Flathead Fever; 04-19-2026 at 06:46 PM.