I'm planning within the next few months to swap over to a corvette water pump. Why? I want to install an underdrive pulley system which requires the use of a water pump with the 3/4" shaft. The 84-91 year corvettes had the only reverese rotation water pump with the 3/4" shaft BUT.. its a short style water pump (but not for long). Doing a little 3rd grade math, I found theres a difference of 1.125" in height between our stock pump (6.983") and the corvette's pump (5.812") so I set out to use two 1" spacers along with a .125" pulley shim. A friend of mine recommended I go to a machine shop instead and have them make a custom set of 1.125" spacers to make the swap cleaner; thats probably what I'll do. Why not just buy a set of march, asp, or bbk underdrive pulleys already made for out stock pumps? I've read too many times on this board how 3rd genners feel little or no performance gains at all with UD pulleys. I was googling UD pulleys one night and came across these (click on the links to the right of the page): http://www.cantonracingproducts.com/...clongflat.html. What I liked about these particular pulleys is that they're specifically made for long water pump equipped vehicles. I already chose the pulley sizes based on the diameter of our stock ones and want to see what they will do for an L98. I'm probably going to get flamed for this but its my final answer and I'm 99.9% positive it will work so I am going for it . I'll keep you guys posted. Later, Phoenix

not flaming, just curious what your line of thinking is behind this....lets suppose you get this to work.... if you read posts about underdrive pulleys for thirdgens not giving any performance gains why would you think and underdrive pulley system with a corvette water pump do anything more than one designed for your car?

also if you still decide to do this, you need to get the machined washer/spacers for it, otherwise you will destory the water pump and possibly the belt and have a higher chance of the belt slipping off, because ordinary washers/spacers and not machined perfectly flat.

My main objective here is to install the pulleys for more HP & TQ. These are a little smaller in diameter than march pulleys so I think they'll make a noticable difference. As for the pump, not using it for performance gains rather I need it to install these pulleys since the water pump pulley fits only 3/4" shafts which this corvette pump has. I already know of a local machine shop that can make me these spacers so I'm set with that. Again I'm doing this for the proper installation of the pulleys themselves for performance gains.

Later,
Phoenix

to slow down the rotation of the accesories you want to reduce the size of the crank pulley or increase the size of the accesory pulley. so the smaller diameter pullies you are trying to use is defeating the purpose you have. i think you are better off just getting the correct pulley set for you vehicle. find a set with a smaller alternator pulley also so you don't lose charge capacity.

In my case wanting to reduce the diameter of the pulleys, doesn't smaller diameter mean faster rotation which also means more HP & TQ?: Check out this comparison in diameters:


Canton Pulleys Stock L98 Pulleys
Crank - 5" Dia. Crank - 8"

Water Pump - 4" Water Pump - 6.5"

Alternator - 2.5" Alternator - 2.5"

Power Steering - 6" Power Steering - 6.5" ( .5" larger dia. shouldn't affect steering much)

IMO I say they will add horses .

Later,
Phoenix

Still overdriving the water pump,so i don't think
there will be any noticeble difference-alternator is
turned quite a bit slower so there will be a slight
reduction of windage losses at very high engine rpm.
at idle the alternator output might drop off due to
the low rpm-you do not want to turn a CS130 alt.
too slow-it will overheat and probably blow a diode
or regulator.For a reduction in accesory power usage
at high rpm,the water pump should be underdriven.
Tried underdrive crank pulley on my car many years
ago,and though it had to increase h/p the difference
was not noticable at the rpm i was running
(5500 max)
I do think the '88-92 full serpentine belt system
is worth about 8-10 h.p. vs the early multiple v
-belt setup at high rpm.

the purpose of underdrive pulleys is to slow down the accessories. to slow them down the drive pulley needs to be smaller or the driven pulley needs to be larger, and vise versa. the ratio of the diameters you listed is only going to slow down the water pump slightly more, you will get more reduction with the correct pulleys for your car. get the march pulleys, power and amp series has the smaller alt pulley so it doesn't get reduced with the other accessories and you won't lose charge capacity and won't run the risk of electrical issues. the water pump, power steering, a/c will still be reduced but not so much you run into issues, and it will free up some power in the upper rpm's.

So our stock serpentine w/p pulleys (mine atleast) is 6.5" where as the UD w/p pulley is 4" and its still overdriven . To cure the low alternator output blues, I'm going to upgrade to a 140A CS144 alternator to replace my weak 105A unit. I already purchased an alternator bracket off of a 94 caprice which will allow me to install it cleanly since it bolts up to the exact same location as our stock units. Only difference is its for the slightly larger CS144 and btw theres plenty of hood clearance so thats set. I'm not trying to be 'different' here in wanting to do this or because no one else has done it (so I think) but like I had mentioned before, strictly for performance gains. I heard the more mods you have on an engine the better UD pulleys will work. I currently am running a flowmaster crossflow muffler (want to upgrade to 3" true dual), hedman shorties, perf. cam (not sure what duration), port and polished heads and plenum (want to upgrade to the mini ram) and 1.6 RR. I wonder what the guy who discovered for the first time that an LT1 intake can fit in an L98 with slight modification felt like when he saw is idea (which ended up working) bieng used alot as a popular mod? . Thanks for the info guys.

Take it ez,
Phoenix

you can't under drive ANY alternator, whether it be a 60amp or a 140amp. the powermasters 140amp alternator came with instructions that specifically explained to not underdrive this alternator, you need to speed the alternator back up if you are going to run an underdrive system.

If I was to install and run the UD system with my current CS130 105A alternator, I'm more than likely going to have under-charging issues which occur usually at idle (by what I've read on these boards). Wouldn't upgrading to a much larger 140A with the same 2.5" pulley (comes with UD set) fix this even at idle??

Thanks for the info QS later,
Phoenix

Bieng that I'm going to be underdriving the w/p as well, I'm possibly going to face overheating issues when sitting in traffic. I want to install this
pump:



Its from evans cooling and I've heard good things about them. As soon as I acquire the pump, I'm going to take it to the machine shop along with my stock long pump so the machinist can get an exact height as well as the correct shape of the spacers. I'll keep you posted. As for the alternator undercharging issues, I did a bit more research today and found that to correct this its best to upgrade to a bigger amp alternator which I plan to do as well as install the stock 2.5" pulley which the UD set comes with btw. I'll keep you guys posted on progress.

Later,
Phoenix

I have a Federal Mogul vette pump I was going to install on my car but it wouldn't fit obviously, if you get this to work that would make me happy.

I used a two-pulley underdrive kit from March (crank/alternator) and a Edelbrock victor water pump. Everything bolted right on, no issues, and now my car cruises about 20 degrees cooler thanks to the pump swap. I retained the stock alternator and have no charging issues at all. Did i notice any change in time's at the track from the underdrives? Nope, but the water pump swap was worth it.

Yeah, I just don't see why it would not work. I'm actually anxious to get this 'project' underway already.

I was going to go with an edelbrock short pump but decided on the Evans unit since its about the same price; looks just as good IMO.

Quick question on pump height. Are the gaskets going to affect fitment of the water pump? In other words are they going to add more inches on the reference height than what I already need?

Thanks,
Phoenix

The only issue I had installing mine was that the pump housing was a little thicker being aluminum and I had to grid the sides a little to clear my serp. belt bracket.

That would depend on gasket thickness. Have you considered using water pump spacers rather than shimming the pulley out? I would think that shimming the pulley out would cause added stress on the pump bearings and lead to premature failure. Water pump spacers are typically used for spacing the pump out when using an extra thick timing cover but would probably work in your application as well.. It sounds like you have a fairly stock setup execpt for the exhaust, if your goal here is performance your money could probably be spent better elsewhere. As far as the engine mods, did you do them or is that what the previous owner told you when selling the car? The reason I ask is because you don't seem to know what cam you have and the "port and polish" sounds like sales gibberish.

Yeah before my buddy recommended I get my 1.125" spacers machined, I set out to use a pair of 1" spacers which to my knowledge, only CSR performance makes them in that height. As for the .125" that are left, I have to use a 1/8"(.125") pulley shim to align it just right. The engine mods already came with the car when I bought it. No gibberish about the the port and polishing job, I saw it with my own eyes when I was getting my engine rebuilt. I didn't even know I had it done until the shop owner pointed out and showed me how the ports had been opened up some as well as the intake plenum. As for the cam, I know it was a crane cams since I had the sales invoice which I ended up misplacing and until this day, I don't know where I put it so I have no clue . I've had the car a little over a year now and the engine mods are there, trust me . I still have the seller's e-mail address so I'll ask him on the cam specs. Take it e z guys.

Later,
Phoenix

CS144 might do the job(will have to try it and see,just
put a smaller pulley on if it drops off at idle)but i
would try to turn it about 3x crank speed for street use
too low alternator rpm will overwork the regulator as it
tries to provide enough voltage to keep the rotor
magnetism high enough to maintain the alternator
voltage,also the alternator's cooling fan won't be
providing the airflow needed to cool the diodes and
regulator,causing poor performance and possible failure
(underspeed is murder on CS130s)
Also be aware that many"high output"aftermarket
alternators provide the higher output by reducing
the number of winding turns in the stator in order
to fit in the thicker winding wire needed for the higher
output-output of those will drop way off if turned too
slow,will overheat too.

Thanks for the info 8t2 z-chev. I did some re on the CS144 alternator and liked the benefits of converting to one. Thanks to that, I luckily found the necessary bracket off a caprice at my local JY to install it properly without any modifications. I came across this 'heavy duty' version of the CS144 off this website: http://www.highampalternators.com/Ex...144%20type.htm. Would it be a much more reliable unit you think? I forgot to mention in my previous post that the Evans cooling corvette pump I'm going to acquire does not have a 5.812" reference height, rather its 5.795" so this means that my spacers are going to be 1.142" thick and not 1.125" sorry for the confusion if any. As for the spacers, I'm S.O.L. turns out that all the machine shops in my area don't have a large enough turning diameter on they're lathes. I found this company online which is probably my only choice: http://highprollc.com/products.html the spacers are second to the last from the bottom up.

Later,
Phoenix

BTW guys my vette pump is aluminum and weighs virtually nothing, that's why I want to do this swap. I picked up the pump brand new for 40 bucks so if this works I'll be smiling ear to ear.

Lol I was wondering if there were other possible reasons to do a swap like this. If your pump weighs virtually nothing you sure it has the internals?? j/k! Have you tried this swap before? Do you know if the 'vette pump flows more, less, or the same as our stock long pump? I've e-mailed highprollc.com on making my custom spacers and I'm anxiously waiting on a response lol. Keep you guys posted.

Later,
Phoenix

That would all depend on what pump you're using, stock for stock they're pretty much the same. It's odd but from my experience the vette pumps seem to be cheaper than the f-body pumps. For the past couple years I've been running a high flow aluminum pump made by flow cooler on my 86 vette, it was only about $80 new from summit. It's a great pump for the price, my car runs about 15 degrees cooler, it weighs less than the stocker and looks better too

Right on! I guess there are some benefits to having a corvette pump vs a long pump, that would explain the larger shaft>>>larger impeller>>>better flow.

Later,
Phoenix

I just got quoted $70 for the spacers and labor. Still waiting on total plus shipping to my area. I'll keep you guys tuned in.

Later,
Phoenix

The total plus shipping came out to $81.50 which is pricey IMO. I've contacted Canton Racing's custom parts dpt. to see if they can make a w/p pulley for 5/8" shafts like out stock units have as well as a p/s pulley for 1/8" keyed shaft. If not, I'll continue with the 'vette pump and spacers. I'll keep you guys posted.

Later,
Phoenix

What's wrong with the moroso short-to-long water pump spacers?

I've looked at the moroso spacers before and they are specifically for 5 5/8" short water pumps to convert them to 7" high long water pumps. The moroso 1.375" spacers would give the 5 13/16" high 'vette pump a total of 7.187" reference height; .25" more than our stock water pump height (6 15/16"). As for the custom pulley and mount, I was told that they only make them in batches of 20, not going to happen lol. I'm going to go on with the swap. A little on a side note, anyone know if a type II power steering pump can mount to an L98 with little or no modification?

Later,
Phoenix

FWIW, it would be cheaper to have the moroso ones cut down than to have new ones made from scratch. It's the setup time that makes them cost so much, and it would be very little time setting them up to cut them down. I'm a machinist by trade now, for the past 4 years.

Never thought of that before. I can just take them to my local machine shop and have them remove the excess material. Hey thanks alot 85TransAm406 I think I will go that route instead. Thanks very much for your input. I appreciate it.

Later,
Phoenix

That's what the boards are here for. If they try to charge you too much, u can mail them to me and i'll do it. I would definitely do a mock up with the new pulleys and uncut spacers to check alignment before having them cut though. u can manipulate thickness by leaving out the gaskets and using RTV only also.

Hopefully they won't overcharge me at the shop and as for mailing them to you, I'll definately keep that in mind as well. Thats true about the mock up, that way I can get idea on what the reference height will be more or less, hopefully to stock specifications if anything. Since I'm going the Moroso spacer route, they're 1.218" thick and to get them to a thickness of 1.142", the shop must remove .076" of material. Thanks again for the tips 85TransAm406.

Phoenix

Not sure, I was refering to replacing a factory cast vette pump with a cheap aftermarket aluminum pump.

I just won't know until I complete the setup. Worst case scenario, the pump will flow the same as the stock one. I really don't think theres a possibility of the pump not working TTYTT. Best case scenario, the pump will flow better than stock as well as allow me to install the pulleys. Progress will be updated as necessary.

Later,
Phoenix

i run a vette pump on my engine you will need to delete the smog pump and lower serp bracket i used a water pump pulley spacer instead of useing the waterpump spacers i wanted the clean look the short pump has

the issue with underdrive pulleys is you kill the alt votage so much i can only use the crank pulley the alt pulley the engine needs to me at 1500 to not dim the lights at night useing the stock alt pulley and only the crank underdrive it needs to be at 850 rpm to keep the lights bright at night

if your never gonna drive at night this may not be a problem but i think i gained 3 hp from the underdrive pulley not what i call worth the cost

Edit i think thouse pulleys are step back there like V-belts but use flat belts instead

Whoa! Its actually been done already . Good job . I actually want the short pump to sit just as my long style stock unit does so I'm going to go for the pump spacers. In doing this, I can keep my smog pump and the lower serpentine bracket. As for the pulleys, they are flat belt. I'm still going along with this swap but having the car back in the shop due to mechanic's error is not helping . I'll keep you guys posted.

Later,
Phoenix

Azrael, where did you get your pulley spacer, how thick was it, and how much did it run you?

i got the water pump spacer off ebay 1 1/4 inch
its designed as a fan spacer

Phoenix the angle of the vette pump will force you to cut out the smog bracket and delete the pump even if you use the water pump spacers

http://cgi.ebay.com/ebaymotors/Alumi...spagenameZWDVW pump spacer i used i just used it behind the pulley
but you can get the aluminum long water pump from Gm performance parts it has both bolt patterns

So the whole pump is angled differently compared to my stock long pump? Now I'm wondering if theres a way around this as I don't want to delete anything if possible. As for the GMPP water pump, is it a reverse rotation pump?

Thanks,
Phoenix

My federal Mogul vette pump says reverse rotation right on it. I already broke the bottom of my bracket off as well so this is going to be a no brainer for me! I'm excited about this swap, I've had that pump laying there for ages.

Phoenix the kit you linked to for pulleys looks more like a v belt set up replacment anyway you would be deleteing smog and ac aswell
it puts the alt where the ac is normaly on serpintine cars
or if your only buying the pulleys it looks like it has the dual bolt water pump pattern already im sure it comes with a spacer for the shaft

sure it mite make more power just remove you serpentine belt at the track for a run to see the differance but im sure its not worth the extra cost of those pulley sets

id tell you just go with the normal underdrive pulleys
i picked up mine for 25 on the summit clearance rack but like i said couldnt use the alt pulley cause you cannot drive at night as soon as you hit a red light the lights get so deem even with a brand new battery and alt

so i only run the crank pulley

and yes the gmpp water pump is reverse rotation

so the flat belt pulleys are designed to replace v-belt pulleys?.
I've already got the voltage issue covered as I'm going to upgrade to a CS-144 140A alternator using a bracket from a 94-96 caprice. I think I know what you mean about the pump bieng angled differently, did you mean the spout where the hose connects to? As for the GMPP water pump, do you have the model no.? I'd like to check it out.

Thanks,
Phoenix

http://store.summitracing.com/partde...5&autoview=sku

GM Performance 12497986 is the part number from summit

if you have both pumps sitting next to each other you can really tell

maybe you can tell the differance from these to pic's but i really didnt take a good front shot of the long pump on the car :/

also i had to modify the outlet hose as the short pumps outlet is much smaller i had to cut a smaller hose then slip the stock one over it

really all this sounds much harder then it is to do the mod

i think the water pump looks better all tucked in and it also gave me a cheap 25 dollar pump i can take to autozone if i need a replacment

also i had cash issues so i couldnt afford the Gmpp one at the time and i got a vette pump off ebay for 6 bucks shipped

Thanks for the link. All I can say is . I'd really like to leave all the serpentine brackets in place and not cut anything but I don't think I can avoid that. This isn't turning out as planned at all anymore which sux cuz I really wanted to get this going. Both pumps seemed almost identical but I guess not . I'm still trying to find a way around this though. I'll keep you posted.

Later,
Phoenix