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View Full Version : FYI: Short Belts and Under Drive Pullies


85_Capri_4v
05-16-2005, 08:22 PM
This is going down in the record books. I see so many questions here and on other forums about short belts. My problem is I have yet to find anyone running 86 and earlier 5.0's with A/C delete with under drives and also bypassing the smog pump.

Better Days bypassed his smog pump, but I believe he was running stock pullies.

There seems to be a ton of info on short belts with A/C especially 87+

So for what it is worth here is what worked for me.

Under drive pullies with A/C delete including routing around smog pump 835K6 belt. It is a tight squeeze but you can work it on and after a few miles if stretches enough to right in the upper normal range.

Under drive pullies with A/C delete bypassing smog pump~ 695K6 belt. This is extreemly tight and you have to really work it onto the water pump last. I had to bump the car while it was in reverse to roll it onto the water pump. When 1st installed it is VERY VERY TIGHT and actually outside the upper range on the tensioner. A 700K6 ( 70 inch ) belt would be easier to install but the tenstioner is now pushing the belt down towards itself as it runs from the waterpump to the alt to the tensioner. You do NOT want it to get to close. After about 20 miles of driving the belt stretches enough to ride in the upper range.

Hope this helps the early 5.0HO serp belt crowd. There will be pics on my website soon about this.

FYI: if you are not running under drives figure roughly 2.5 inches longer.

No Smog Pump No Under Drives Routing (courtesy BtrDays)
http://www.velocity.net/~lauriekay/beltroute.jpg

My Belt Routing Prior to Smog Bypass

http://www.velocity.net/~lauriekay/pullies56.JPG

PNY XPRS
05-16-2005, 08:37 PM
When I bypassed my smog pump, I used the shorter belt. I do have A/C and had an underdrive crank pulley so I had to use a longer belt than those listed. (sorry, I have no idea what size I used it's been too many years ago)
I had the same issue of the belt slightly stretching and rubbing as the tensioner pressed downward. What I did was remove the tensioner and re-drill the hole for the pin on the rear so that the tensioner was moved downward. I then located the tensioner between the belt path so it pressed downward on the return path from the alternator.
I don't have any pics unfortunately. :(

I might have the re-install the underdrive pully and find the correct belt :)

85_Capri_4v
05-16-2005, 08:43 PM
I have no rubbing issues, but it is very snug

BetterDays
05-16-2005, 10:09 PM
Whose motor is that in the first pic? (Hint, not mine!)

As far as belts, I ran no smog on mine, as well as bypassed the PS at the track.

I used the diagram and it was dead on for me on both occasions. And the car had UD pulleys on it...

:lol:

85_Capri_4v
05-16-2005, 11:03 PM
Kevin, if it wasn't your's I have no idea who owns that engine. I had wondered because it looked like they were using a Holley 1850 carb.

I can edit it so it does not defame you :? if you wish. :P

85_Capri_4v
05-26-2005, 08:36 PM
Bumped for the guys on this thread http://www.foureyedpride.com/phpBB2/viewtopic.php?t=17220