Reason I ask is that the long pump hd cooling/ac setup on my stage 1 puts the fan almost all the way into the shroud with the shortest fan clutch I could find. Running the clutch setup with the short pump on my 72 ragtop (455) would put the fan almost half in/half out of the shroud which I have read is the perfect placement. This would also allow me to run the single groove waterpump pulley which i would like to do with this car. Factory shows the short waterpump with the el cheapo fan ....but it does have an extension on it as well.... Just wondering if anyone has some real world experience?? This is a 72 car, I know the 70's run the short pump with the clutch but they also use different pulleys/shrouds and I have no ideas what they are like because I have never seen a 70 GS in real life!! Only 71 and 72's... Thanks later Tim
My 70 has the short pump with the clutch, no problems...in the last 34 years...Excuse the mess and the ugly parts I'm working on it!!!:laugh:
How do you know if you have a short vs long water pump? My 4-row radiator has pushed the shroud nearly all the way out past the fan, and if I have a long pump and can use a short one to get the fan back to half in/half out, that'd be sweet.
I have both...by accident My car does not have a/c, so I bought a new pump. Then later I found out that even though I did not have a/c, I need an a/c pump.ou: Yardley, I'd say there is about 1.5" difference, maybe a bit more.o No: I'll ship you mine for $25, already painted red.:Brow:
Short pumps came on non AC cars. If you want to run the short pump you would need the proper water pump pully also or your belts won't line up.
:af: :af: :af: Sigh. So I'll need to alter my alternator and AC compressor as well? What about the crank pulley and PS pulley??
Hey Tim, These fans are axial fans and build pressure at the blade tips thats why a shroud, (housing) is a big performance boost for the fan. Much better pressure capabilities getting air through the radiator, cfm Vs system resistance. On a typical axial fan the best placement is 2/3 into the shroud and 1/3 out.
The water pump pulley is the only pulley variable in setting up a short water pump vs. a long pump.I have a short pump on a 71 long pump AC GS.It works fine and the fan placement with the short pump does appear to be better with the '71 shroud. Rod
Got an Asm man Yardley? On my 71, the PS goes directly to the crank and not affected. You may need the crank pulley though, and you would have to fool with the alt & A/C. I don't think it is worth it....Maybe a different fan/clutch is the way to go.o No:
Yardley the pic that 70gsrick posted of his engine shows exactly which pulley you would need to run the short pump. As far as I know all you should need is this one single groove pulley.
Doh, forgot about the AC since I don't have any. I don't think its possible to run a 2 belt pulley on the short pumps. If it did fit it wouldn't line up with the rest of the pulleys.
Guys I have a bunch of info on my website about all this too. You can run the single groove short pump pulley on a short pump with or without the correct crank pulley, the hd cooling or ac crank pulley will drive it as well (and adds about 16% more speed over the 2 groove crank pulley). You cannot run the dual groove waterpump pulley with the short pump, it will hit the pump. This is 71 up info, I believe the 70's were the same length regardless. Here is the funny thing too, if you order the ac style waterpump, you almost always get the five bladed impeller since the pump actually ran faster with the ac crank pulley. So if you order the non ac version, check the impeller and make sure you get the five blades that go right to the edge of the casting, or you get the six blade impeller. NAPA is the only one I have seen locally with the six bladed impeller. And thanks for the info guys, I just wasn't sure how it would all fit...looked like it would be good but knowing you guys are already doing it eases my mind. Love this board!! later Tim
You lost me a bit there Tim I understand the diff in the impeller blades. Yes the non a/c got the 6 blades, but I assumed it was because the single g. pump pulley was larger in diameter (slowing the pump down).uzzled: I fear if you install the 6 blade on the a/c, you may push the water thru too fast. Am I wrong (as usual)?:laugh: o No:
Both waterpump pulleys (single and ac) on the 71 and 72's I have dealt with are exactly the same diameter. The CRANK pulleys have different diameters, the ac one being larger and thus driving the waterpump faster. I'm not sure about the water too fast thing, I hear it a lot but it seems to me the thermostat controls the temp and the flow.... Everything gets so complicated!! later Tim
