Anyone successfully running a no air-pump setup with a 31.5" belt and stock pulleys? Can the alternator bracket be drilled out so much to accomodate the increased length of belt?

I've looked at the archives already and although it was suggested that 31.5" is doable, no one seems to have actually done it.

That's the shortest belt I'm able to find.

 

i would pick up a larger diameter wheel for the water pump, with the stock and no air pump the belt just barely makes contact. for ~$125 you can buy the greddy pulley kit and not worry about it.

 

29.5" 4 rib...this is what I found most of the guys here run. I haven't done it yet but will soon

 

I just installed a 305k4. My friend Jet7 and I used a grinding wheel to lengthen the adjustment range of the alternator bracket. We also had to cut two fins off the alternator so it would clear the efini Y-pipe after we raised it beyond the stock range. The belt is now reasonably tight, but there is no additional room to adjust for belt stretch.

 

I got a 290 K5 from Carquest. It was a tight fit but here is how I got it to fit.

Took the bolt out of the alternator mounting bracket and put the belt on. Put the bolt back in just the front part of the alternator (I couldn't get it to go all the way through and thread into the nut). Put the other belt on and ran the car for about 30 seconds while using my heat gun on the belt to stretch it out. Then I took the belt off and re-attached the alternator. The belt still wouldn't go on. I mounted the belt on the alternator and then turned the crank pulley until I got the belt started on the crank pulley as far as I could get it. I got in the car and turned the ignition to start the car (I didn't start it just turned the key for a second). The force of the starter turned the crank shaft enough and it popped the belt right on. It takes no adjustment but that it fine with me. I would rather have more contact with the water pump pulley with a 5 rib belt. The belt was made by Gates by the way. Just PM me if you need anymore help getting it on.

 

I got a 300k4 from a truck/heavy machinery parts store (one of those places that has all those in the back of the store and the store clerk goes and gets them for you).

I also got my asbestos DP wrap from them (that stuff works INCREDIBLY well).

 

Asbestos Wrap? Kewl!

 

This is a good idea, just to under drive the water pump, but its not required if you just want to eliminate the air pump.

If I remeber right when I did this, I used a 30" 4 rib (300K4) goodyear gatorback belt. Been running that for a few months now with no problems.

 

and I didn't have to grind or cut anything.

 

Jonski do you know what company makes the belt you have? Underdriving the alternator is one way of solving the problem but bear in mind what the trade off is. I do a lot of city driving and wasn't crazy about the idea of slowing down the coolant flow at low rpms.

 

Thanks for all your response. I tried on the 31.5" last night and there's no way in hell that could fit without a larger pully either on crank or alternator. Regarding the Greddy pulleys, another stupid question from me, I know better not to change these out on a piston engine as it takes out the harmonic balancer also. Is there any such concern with the rotary?

 

The Greddy pulley set only underdrives the alt and water pump.

 

Oh fair enough. Thanks for the advice.

 

i have seen anything from 29 to 31.5 inch belts used on stock fd's. I kinda had doubts about the 29incher but it apparently is possible.

 

CCarlisi,
I looked under the hood, but the the labels are too worn to tell.

 

I used the Greddy kit. Comes with New Tensioner, Alt Underdrive pully and Belt. Best way to go. If you get a belt thats too tight you can kiss the bearings in your Motor and accesories goodbye. A belt too tight on the crank pully will pull it hard against the Front main bearing and will ruin it. Also if you hear a drone that changes with your RPMS your BELT IS TOO TIGHT!! Make that Hum go away or your Bearings will.

 

DP

 

So are you using all the factory pulleys and the 300K4?

 

yup. at leats I'm pretty sure its a 300k4. I dont ahve the packaging or anything any more.

 

Have you had any cooling problems or does the car run any hotter than normal?

 

Nope. Since the pulleys dont change in size, then the water pump still spins at the same rate it always has. Assuming the belt doenst' slip (which it does'nt).

 

if i could do it again i'd use 30" plain and simple. 30.5 was too long and the water pump pulley wasn't turning. i also had the idea of drilling to make the hole in the alternator bracket bigger (so i could make the alternator sit higher & tighter) as seen in the pic circled in yellow



but i failed to realize until after was that the alternator itself was rubbing of the left side of the bracket (as seen in the red circle) restricting it from going any higher which made all that drilling useless.

i ended up using 29.5 (sold out of 30) and it was too short so i had to use a big *** screw driver to get under the belt and a breaker bar to turn the alternator pulley to get the darn belt on.

IMO stick to 30" and save yourself a pain in the ***

 

Yes, 300k4 rib (3 rib will work too)
Also, go to a Honda junk yard and grab the Alternator pulley off of one of them. Its the same size as an aftermarket FD one and will work perfect with the 300 belt with no drilling to the adjustment bracket.

 

3 rib really? i've only found 4 rib ($11 at kragen) what about everyone else? do we all have 4 ribs too? i couldn't find a 5 rib anywhere but i'd like to get one for the extra security. any one know where to find one?

 

I believe my Greddy Belt is a 5 Rib.