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Just ordered a VA kit but I don’t think the pulleys on my engine are correct to run the compressor, do I need to replace both the water pump and crank pulleys with the 3 belt type?
Also can I mount the transmission cooler on to the VA condenser?
Last edited by Dazaa Rafae Aman; 06-29-2020 at 06:34 AM.
The only thing you need to do is purchase a bolt-on third pulley to add on the damper (2-pulley) set. Just get one in the same diameter as the pulleys on that set and bolt it up. Then drive the A/C compressor directly from that pulley. The V-belt does not need to go around any other pulley.
I just needed 3 pulleys on the crank and 2 on the water pump when I added VA to my '73. I installed the bolt-on third pulley at the crank as Charley describes above. I replaced the power steering pump pulley with the correct one for an AC car and ran the PS pump belt only around the outside crank pulley. The AC compressor belt was routed around the middle crank pulley and the outside water pump pulley. The alternator belt was routed around the inside crank pulley and the inside water pump pulley. I derived this based on what I was told was the correct setup for a '73 with factory AC. The only pulley issue I ran into was for some reason the bracket VA sent me didn't align the AC compressor properly and it was also too close to the hood. They sent me a different bracket and all was well.
That said, I might do it different if I had to do it all again. Operationally, ever so often, I would throw the AC belt when running the engine hard at peak RPM. I always had to pull the power steering pump belt to re-install or replace the AC belt. Knowing that today, I would try to figure out a way to have the AC belt be on the outside for easy replacement. It no longer matters on my '73 as during my current engine/transmission swap project, I'm transitioning to a serpentine belt system which comes with a whole lot of other puzzles to solve.
Oh man this is more complicated than I thought. So are there any possible downsides to using a third bolt on pulley vs a billet 3 groove one? And do I need to swap the water pump one too? I know the water pump one just unbolts, does the crank need a puller?
There is downside to the billet 3-groove pulley.... $$$$$ You can find a GM bolt-on 3rd pulley for less than $50 on eBay. What is the billet job? $300?
No difference in performance; but you can't brag about the stamped GM pulley being "billet"....
Oh man now i'm more confused than before lol. So do I need to find the number on my current 2 belt pulley and then find out which add on will work with it? The car is a 71 but the motor is from a late 70's truck I think.
Oh man now i'm more confused than before lol. So do I need to find the number on my current 2 belt pulley and then find out which add on will work with it? The car is a 71 but the motor is from a late 70's truck I think.
If you have the Assembly Instruction Manual for your car, it should show the various pulleys (and part numbers) used along with belt routing diagrams. For example, my '73 AIM shows the 2 groove crankshaft pulley for a small block to be either part number 3858533 or 3911013. It shows the add on 3rd pulley to be part number 3751232. It shows the 2 groove water pump pulley to be either part number 3991423 or 3991424. It shows the water pump pulley to be a 3 groove pulley with the outside groove used for a smog pump. I can't tell if it's a 2 groove pulley with an add-on 3rd pulley like the crank or not. Maybe that's why they listed two part numbers for it?
I don't think it matters that your engine is not stock but you want to make sure you get the pulleys correct for your '71. Maybe Vintage Air could be of some assistance.
I don't think it matters that your engine is not stock but you want to make sure you get the pulleys correct for your '71. Maybe Vintage Air could be of some assistance.
DC
Why does it even matter if the pulleys are "correct for your 71" since the engine is not stock.
What really matters is that he gets all the pulleys to line up correctly. I think the addition of the 3rd pulley is a correct starting point.
He needs to start taking measurements and see how much everything aligns or not, and go from there.
Once he has the VA brackets and test mounts the compressor he can see if he needs to space out the 3rd pulley.
Do not get the 3-groove biller pulley at this point, that might throw off all the other belt alignments if I assume they are good now.
Dazaa Rafae Aman Dude, just get numbers off your water pump pulley (and your crankshaft pulley if you're going to use both) and I'll try to find the appropriate mating add-on pulley. I probably have it documented somewhere. Lemme know those numbers.
Why does it even matter if the pulleys are "correct for your 71" since the engine is not stock.
What really matters is that he gets all the pulleys to line up correctly. I think the addition of the 3rd pulley is a correct starting point.
It doesn't really matter. You are correct about what really matters. There are numerous ways to pull this off but the OP is already confused and one of the easier paths to success for him is to just source the correct pulleys for his car.
Ok I just pulled the water pump pulley and it's no 3991423, couldn't see any numbers on the front of the crank pulley so will remove it tomorrow, I assume the number is on the back. Interesting that the water pump pulley appears to be a correct Corvette part, I expected the whole engine to have been transplanted.
Edit, so I did a bit of googling and I think the confusion comes from the current belts being all wrong (no surprise considering how bubba'd this car was)
Looking at this picture, the second groove on the ps pump which is currently empty should be going to the alternator (but it doesn't line up so this wouldn't work anyway?) The add on pulley should go to the ps pump and the middle crank groove is what runs the ac. What a can of worms i've opened here. To simplify things, could I buy a 3 groove crank pulley and just use the 3rd belt to run the compressor? Leaving the current system in place?
Last edited by Dazaa Rafae Aman; 06-30-2020 at 04:42 PM.
Interesting that the water pump pulley appears to be a correct Corvette part, I expected the whole engine to have been transplanted.
Probably has to do with needing the correct Corvette specific water pump for clearance reasons. Can't remember the specifics but I think a standard long water pump put the mechanical fan too close to the radiator. Maybe others can confirm.
OTo simplify things, could I buy a 3 groove crank pulley and just use the 3rd belt to run the compressor? Leaving the current system in place?
That's what Charley recommended in post #2 and probably what I should have done originally. You'll have to mount the compressor with the VA bracket and see if it aligns with the outside groove on the crank. If it doesn't, maybe some spacers are in order or maybe VA has a different bracket. But, to get that 3rd groove on the crank, you really just need to source the bolt-on extra pulley. It was easy to install on mine.
OP: Why do you think there is a downside to using the 3rd bolt-on pulley?. I know of many SBC that have that configuration.
This is post #17 in this thread.
Just get a 3rd pulley and bolt it up.
Mount VA brackets.
Mount compressor and CHECK alignment.
Dazaa Rafae Aman
3991425 should be the add on 3rd pulley to mount forward of 3991423. You can check me on that below...... but it looks right. Saw one on ebay for 20 bucks. Looks fairly common. (NOTE: per gm it was superseded by part number 14023158 but that only for info).
here is a reference image.
Originally Posted by Dazaa Rafae Aman
Ok got it. Now to figure out which is the correct add on pulley
I added both a/c and PS to my 68. I ran the belt from the forwardmost (3rd) pulley. The easiest way to modify things was to change the Sanden A/C compressor bracket so that the belt aligns with that. Here's pic. I suggest modifying the a/c bracket and NOT spacing out any pulleys. https://www.corvetteforum.com/forums...post1595077786
My a/c belt runs around both the water pump and the crankshaft forwardmost pulleys. If you get the crankshaft pulley number we can search for the add-on pulley for the crank.
06-29-2020, 06:33 AM
Vintage Air - What Pulleys do I need?
