Where does the extra serpentine belt length come from when you have a Leece-Neville?

Looking at serpentine belts AGAIN................Rock Auto shows several lengths for our trucks. The standard is 110", a couple more sizes in the middle, and the 114" for leece-neville equipped trucks. Serpentine belt routing diagrams show identical belt routings for standard trucks and ambulance prep trucks, so my question is where does the extra 4 inches come from? The diameter of the alternator pulley?
I'm switching over to the updated alt/PS/vac pump bracket and dampened tensioner and was wondering if i need to run a different size belt.
I google searched for engine pics of ford diesel ambulances, but came up with nothing. Seems to be a couple of guys here have the ambulance prep trucks and could maybe shed some light on this.................

alt case is larger so there is more offset

On the subject of serpentine belts. I would like to convert/update one of my trucks to that arrangement. What years will interchange with 92 F350/ 7.3 engine?

Thanks...

G. Mann.... Any 92, 93 or 94 idi serpentine belt setup will bolt directly to any idi 6.9 or 7.3 engine... they are all drilled the same. The vacuum pump is the only reall issue going from v belt to serpentine... You have to drill out the v belt vacuum pump mounting housing for it to work on a serpentine system...

AC pump and hoses are unique to the serp system too.

I have trucks/engines with both, 8-rib serpentines and all V-belts, my personal Ford/Cummins even has BOTH a serpentine AND a V-belt.

I don't see the serpentine system as being superior to the V-belts.

The serpentine was designed purely to speed up things on an assembly-line.

It really complicates any future add-ons.

Most manufacturers offer limited choices in serpentine belt lengths, often making big incremental jumps, meaning a belt of maybe an inch longer is probably not available, but one four inches longer may be the next available size.

The only real advantage of the serpentine belt is it's ease and quickness of installation/removal, making any chore that requires belt removal much simpler.

A little fore-thought in bracketry, such as implementing integral adjusters, would make V-belt work a lot simpler, instead of the more often case of poke a crow-bar under something and take up the slack.

I know as fact that a good properly adjusted B-series V-belt will out-hold and outlast any serpentine set-up.


That being said, I like my system on the Cummins that has the main engine accessories = fan, water-pump, and Leece-Neville, all on a single 8-rib serpentine and the A/C compressor and trailer-vacuum on a B-series V-belt.

My diesel ranger came factory with a serpentine belt running just the power steering pump. And a single V-belt running the water pump and alternator and another belt from the alternator to the vacuum pump. I like V-belt setups more as they are more forgiving and when everything is adjusted right they seem to last longer for me.

I do not know about v belts lasting longer. I have customers with over 300k on their serpentine belts and that millage could never be done on v belts. I have been in the Trade since I was 16 and can remember with great fondness v belts coming off in high heat due to streaching and taking every other belt with it and turning all of them into a big knot. A serpentine belt installed on avehicle properly puts less tension on bearing of waterpumps, alternators and such. Now a serpentine belt system not installed properly. IE brackets with wrong bolts spacers were they are not required bad or wrong idler pulleys or a worn tensioner. will spit/eat beltsn like a child and candy. IMHO. and who has the proper guage to tension v belts????? I have one but have you or ever seen a mechanic use one ? No just get out the prybar and pull.

Fair enough, I will say when everything is as it should be serpentine belts will last longer. At least V-belts you can install with out tools

The alternator pulley on a Leece Neville equipped truck is larger so that would be the reason for the bigger belt. Personally I like a V belt system because if the alternator belt breaks you can keep driving as the power steering belt also drives the water pump in addition to the alternator belt. I personally drove my truck about 150 miles when the alternator belt broke. A serpentine belt breaking will leave you dead on the side of the road.

Doc.... This is why one carrys a spare serpentine belt.... Behind the rear seat... Actually I have two back there.... Ya never know when you may need them....

I have a full set of belts in my toolbox, just in case. Also, I can swap belts between the york and the alt, so that also helps. That said, I've never had to replace a belt due to it flying apart on me. Then again, I replace all belts once a year, whether they actually need it or not - belts are cheap, a tow ain't.

icanfixall said:

Doc.... This is why one carrys a spare serpentine belt.... Behind the rear seat... Actually I have two back there.... Ya never know when you may need them....

Click to expand...

How could you find them ??

another thing you need to remember is who adjusts the belts when they are supposed to? thats where ser. belt setup is better, you dont adjust it. its a more user friendly system that one doesnt have to think about until there is a problem. also there would be a lot less ser. belt failures if the person changing the oil would do there job, anytime anyone changes your oil they need to inspect belts and hoses, and ck all fluids. lot less break downs would happen if people did that. also people need to know how to read fluid levels, brake fluid for one, if the master cylinder is low, ck your brake pads, easy enough. but then again, who does all that when changing there oil?

Ican and Me carry spare serpentine belts just in case someone is broke down with a broken belt. I'm sure we will never need one.