I'm putting a 4.3 in my Zuk. (please don't leave!) I bought an Edelbrock water pump and my pulley holes don't line up with the flange. My friend at the junk yard said only two pulley hole patterns are available, one pattern for "normal rotation" and one for "reverse rotation." I want to run a serpantine belt which would require a reverse rotation pump, right? The Edelbrock part says it is reverse rotation, but the smooth style pulley doesn't bolt up, and the bracketry won't fit around the water pump. Sounds to me like the wrong pump, but the "speedshop expert" says different. Please help before I strangle that little punk-ass down at the shop. Thanks, I'd call Edelbrock but it's Saturday, and I need to get this done this weekend.

Anyway, how many different pulley hole patterns exist?

Can the 350 and 4.3 use the same water pump?

Can the 350 and 4.3 use the same bracketry?

4.3 and 350 are basically the same block. Parts cross back and forth between the two all the time. I can't tell you about the bolt patterns on the pulley. I can tell you that the speed-shop punk is right about ratation. You have to be sure you get the right rotation pump, or you will have cooling problems.

I know about the rotation. The punk is saying the part he gave me is correct, but can't tell me why I can't find a single smooth pulley to bolt up.

THE PUNK IS CORRECT ABOUT THE ROTATION. THERE ARE 2 DIFFERENT BOLT PATERNS FOR THE PULLY MOST AFTERMAKET PUMPS COME WITH BOTH PATTERNS DRILLED INTO THEM, I WOULD SAY THAT HE HAS GIVEN YOU THE WRONG PUMP. AND YES A 350 PUMP WILL FILL ALONG WITH THE BRACKETS (PROVIDING THIS IS NOT A VORTEC AND IS TBI) THE TBI 4.3 IS IDENTICAL TO A 350 IT IS BASICALLY THE SAME BLOCK JUST SHORT 2 CYLINDERS, SAME BORE, STROKE, ECT. HAVE THE PUNK LOOK UP A PUMP FOR THE SAME YEAR OF 350 THAT THE SERPENTINE CAME OFF OF IT SHOULD WORK, THERE ARE VERY FEW VARIATIONS IN WATER PUMPS OVER THE YEARS BUT ENOUGH THAT IT CAN BE PROBLEMATIC GETTING THE RIGHT ONE I USED TO RUN A SHORT WATER PUMP ON A 72 CHEVY THAT WAS THE ORIGINAL SET UP FOR THE TRUCK BUT IF I ASKED FOR A PUMP FOR THAT TRUCK NOTHING FIT I HAD TO GET ONE FOR A 68 CORVETTE WITH A 327 TO GET THE CORRECT PUMP, STRANGLE HIM AND MAKE HIM LET YOU LOOK THROUGH THE DIFFERENT MODELS OF PUMPS UNTIL YOU FIND THE CORRECT ONE.

Are you sure you are routing the belt the right way?

I can't say for certain that I know the correct belt routing. Facing the front of the motor, the crankshaft rotates clockwise, correct? If that is true then the water pump will rotate counter clockwise, no matter which way the belt is routed. Remember, the back (smooth side) of the serpantine belt is what drives the water pump. Now another question, when I'm asking for a reverse rotation pump, which direction do they consider reverse? Is it reverse application for the year model or crankshaft rotation?

Thanks guys

I just got off of work, or I'd go look at the tag on my S10. I will go out to my truck tomorrow and look at the routing of the belt, and post back here for you.

Okay, I found out some info that might be usefull about reverse spinning water pumps. There is a long nose water pump and a short nose water pump. The long pump differs in a couple of ways. The spout angles down (clears bracketry), the water pump is spaced out from the block more and has a longer nose (aligns pulley with crank pulley), and the flange has only one hole pattern. The pump I had was a short nose pump. It fit the earlier Corvettes and not much else. The long nose fits most everything else. The newer style serpantine pullies will not fit early style pumps. However, early style reverse rotation pumps will align with v-belt pullies. So, be carefull!

1. only two types of reverse spinning pumps (long and short)
2. only two types of flange hole patterns for serpantine pullies (eventhough different pulley offsets are possible)

If anyone thinks this info is wrong, please correct me before I mis-lead some poor bastard!