Serpentine Belt Length Without Smog

polaraman · Jul 28, 2015

I've seen about 100 threads about it but nothing clearly defined. Is there a part number I can use for a 5.0 serpentine belt without the smog pump? I have a 77.5 belt on it now and this is my 2nd belt. I'm thinking this belt is not the quite the right one because I'm getting belt shavings showing up on my airbox and after about 2 months or so, the belt breaks.

Thanks!

FoxMustangLvr · Jul 28, 2015

What I did for any time I needed belt length was to take the old belt and cut it and run it around my pullies without taking the tensioner in to account and mark where the belt over laps. Cut the belt and that mark and measure it. This is your belt length. You can also take the belt with you to the parts store to match it up. Some people also use a string. This is the best way to do it since what works for one person may not work for another so you must measure.

Have you checked for any misaligned or loose pullies? If your belt was loose you'd hear it slip and/or have possible high water temp and low battery voltage from the accessories not spinning fast enough.

FoxMustangLvr · Jul 28, 2015

polaraman said:
Is there a part number I can use for a 5.0 serpentine belt

Just ask for a 6 rib belt for your 5.0 at the specified length you need.

squeak93 · Jul 29, 2015

Check your routing. There are two ways to route it. One causes the issues you describe (usually from the tensioner moving under a load).

EDIT: I use a gates 85 length IIRC with the second pic on the left (down) routing.

A5literMan · Jul 29, 2015

squeak93 said:
Check your routing. There are two ways to route it. One causes the issues you describe (usually from the tensioner moving under a load).

EDIT: I use a gates 85 length IIRC with the second pic on the left (down) routing.

I was about to post that same pic lol.

90sickfox · Jul 29, 2015

So what if you're running AC and PS with no smog ?...that's how I run mine but belts been on for six years....numbers worn off belt. I'll try to take it off and measure tomorrow for you.

89oem · Jul 29, 2015

middle left diagram red loop 84.5"

90sickfox · Jul 30, 2015

Here's some pics of my belt routing. Its a 770k6 6pk1955...has been working well...no belt contact at tensioner.

TOOLOW91 · Jul 30, 2015

Always used a 84.5in with ac and p/s with no smog.. never had an issue

FoxMustangLvr · Jul 30, 2015

90sickfox said:
Here's some pics of my belt routing. Its a 770k6 6pk1955...has been working well...no belt contact at tensioner.

Shorten that belt! If that belt was to stretch just a little bit you'll be screwed.

90sickfox · Jul 30, 2015

The belt is already stretched....it started out with about a half an inch gap between the tensioner 6 yrs ago. The pick makes it look weird but its got about a quarter inch now. When running it opens up to about a half inch. I live in Maryland and this belt has carried me through several trips to myrtle beach, SC and into Alabama and Georgia. No problems at all.

squeak93 · Jul 30, 2015

Use the routing listed in the diagram. If you use what you have it will Not contact sitting still but I guarantee you each time the motor revs and torques it makes contact. Hence your belt shreddings you keep finding prior to breakage. Trust me I've wasted a LOT of belts routing the way you have pictured. Use the 84.5 belt (or a tad longer is ok, shorter will be extremely difficult to put on) and the pic on left side one down I listed above

90sickfox · Jul 30, 2015

I must admit squeak93 the diagram with 84.5 belt looks like a better routing. However, through trial and error my current belt routing hasn't had any issues. Under load the belt pulls the tensioner more widening the belt gap. There has been no contact of the belt. The pic is of my new 331... I ran the same belt on my previous 347...and the 302 before that. I may be just lucky. ;shrug Hopefully that spot where the belt would run past the smog pump will be occupied by something else....putting the belt right in the way.

squeak93 · Jul 30, 2015

I just realized you weren't the OP... I ran mine for about 10k each before they popped. At $35 a piece for belts (Poor college kid at the time) I had to find a way to keep a belt on longer.

mikestang63 · Jul 30, 2015

90sickfox said:
Here's some pics of my belt routing. Its a 770k6 6pk1955...has been working well...no belt contact at tensioner.

belt is one the wrong side of the H2O pump if it is a reverse rotation fox body pump. Belt should go from the alt down to the crank, then around the passenger side of the H2O pump, down around the PS pump, up around the A/C clutch, under the tensioner, then back around the alternator. 83 /12 to 84 1/2 inch belt.

02 281 GT · Jul 30, 2015

mikestang63 said:
belt is one the wrong side of the H2O pump if it is a reverse rotation fox body pump. Belt should go from the alt down to the crank, then around the passenger side of the H2O pump, down around the PS pump, up around the A/C clutch, under the tensioner, then back around the alternator. 83 /12 to 84 1/2 inch belt.

The water pump pulley should spin in the same reverse-rotation direction regardless of which way the belt it wrapped around the pulley so long as the non-ribbed side is against it.

But I will say that it would be better to run the belt as you describe. That's pretty much the same way I run the belt in my '95 with a deleted smog pump; the only difference being the location of the power steering pump and A/C compressor.

mikestang63 · Jul 30, 2015

02 281 GT said:
The water pump pulley should spin in the same reverse-rotation direction regardless of which way the belt it wrapped around the pulley so long as the non-ribbed side is against it.

But I will say that it would be better to run the belt as you describe. That's pretty much the same way I run the belt in my '95 with a deleted smog pump; the only difference being the location of the power steering pump and A/C compressor.

Look at his picture and tell me which side of the H2O pump pulley the ribbed side of the belt is pulling the pulley..

02 281 GT · Jul 30, 2015

mikestang63 said:
Look at his picture and tell me which side of the H2O pump pulley the ribbed side of the belt is pulling the pulley..

I could be wrong, but it looks like the smooth side is on the water pump pulley.

90sickfox · Jul 31, 2015

The smooth side is on the wp pulley. Like I said its been like this for 6yrs.... About 30,000 miles on different motor combos...on the street and the track...taking nitrous hits and all. No problems.

polaraman · Aug 5, 2015

Sorry guys.... I fixed my belt issues and forgot to follow up. I routed my belt just like 90sickfox's picture and went through 2 belts in a month. I bought the 84.5 belt and routed it that way and no more issues. Thanks everyone. I don't know how 90sickfox's setup works and mine obviously didn't.

Serpentine Belt Length Without Smog

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