Any body happen to know the diameter of the water pump pulleys that come in the March kits for '88-'92 v8 engines? Either the three piece performance pulleys #4010 or the three piece power & amp #4410. If nobody knows the exact diameter, do you know if it is larger diameter than the stock water pump pulley or the same, or I don't know why it would be but maybe smaller?

There's some really bad info floating around reguarding pulley sizes.

While some people market smaller acessory pulleys, and report some HP gains, there are down sides. ie the water pump speed should be increased rather then decreased in order to reduce localized overheating with in the cylinger head. At WOT there are areas around the exhuast valves that the head temps go over 500dF, and in small pockets areas of steam form. This localized overheating is often what generates the cracking of heads around the valve seats.

The thermostat forms a restriction that helps to pressurize the coolant in the head, and the water pump speed sets what the actual pressure is.

Evans Cooling's web site has some interesting info about these issues.

I know this doesn't answer your guestion, but
HTH

I use to have the 3 pc billet march setup and the water pump pulley from march was the same size as he stock pulley. It just looked cool thats all.

Originally posted by Grumpy:
Actually the smaller accessory pulley will speed up the accessory and a larger accessory pulley will slow down the accessory, While a smaller crank pulley slows all the accessories, and a larger crank pulley speeds up all accessories.

Other than that I agree completely with you. Sometimes the quickest route to more power isn't the shortest path. Saving a few horses turning the water pump and alternator slower isn't worth the loss of ponies from vaper pockets, and lowsy alternator charging. I'm also not all about overheating or running the battery dead while idling in bumper to bumper traffic at night durring a rain storm with the headlights & wipers on and the AC blowing. Sometimes "high performance" means working nicely and performing as really needed not just maximum acceleration.

That's exactly why I asked this before buying.
I just want the billet water pump pulley to match the billet AC clutch & pulley cover I just got, but don't want to slow down the water pump any (actually I wouldn't mind speeding it up some), so I want the pump pulley to be the same size as stock or smaller. I won't be using the underdrive crank pulley in the kit because it won't fit behind my blower pulley anyway, besides the crank pulley's mostly hidden by it and I'n not all about the problems mentioned above.

I'll have to measure my stock crank pulley and check on the Alternator pulley size in the Power and Amp kit. I'd like to speed up the alternator by using a smaller alternator pulley with the stock crank pulley, but I don't want to over spin the alternater. It's got a 20,000 RPM limit so I can't safely go over 3.2:1 pulley ratio.


Originally posted by BOTTLEDZr28:
That's exactly what I needed to know, thanks.

Now the question is does March or anybody else make a matching billet idler/tensioner pulley, smog pump pulley & power steering pulley that is a direct fit. I know they make the older style power steering pulley with a keyway and bolt, but I'm not sure about the newer style press on pulley. I've also seen idlers and smog pump pulleys for the Mustangs but not for Camaros/firebirds I'll probably have to check with March on that one, Unless somebody here has already bought any from them or elsewhere.

Tracy

These are approximate sizes:

Factory
Crank: 7 1/2"
W.P.: 5 13/16"
Alt.: 2 1/8"

March Performance 3 pc. Set
Crank: 5 1/2"
W.P.: 5 1/2"
Alt.: 2 3/4" (The Power & Amp pulley is smaller)

I would suggest using the same manufacturer for all the pulleys and covers. There are some machining differences between the manufacturer's and mixing them could cause belt alignment problems. March makes the other pulleys and pulley covers too.

http://www.marchperf.com/

-Ozzy

Do these approximate diameters apply to the 350 L98 as well?

Thanks,
Phoenix

I'm not 100% sure, but I think that the 5.0 and 5.7 pulleys are the same diameter. I've also been running the march 3 piece underdrive pulleys on a basicly stock 5.7 with no problems...although the idle voltage will eventually drop to about 12.5 volts after a couple mins of idle.

Alright. How about the stock power steering pulley? to my knowledge stock L98s have a 6 5/8" ps pulley correct? I measured a crank pulley the other day off of a '90 caprice with what appeared to have the same serpentine setup as our L98s only it was TBI, It had a 7 3/4" dia.; I guess they vary on cetain cars huh?

Thanks,
Phoenix

As I said, not 100% certain, but they maybe diff, especially with other models. I do have pulleys in my shed that I can measure...were you asking about the shaft diam(5/8) on the power steering?I'll try to get the m as soon as i can.

My apologies I actually meant 5-5/8" dia. . I'd appreciate it bro. Are they the stock serpentine pulleys by any chance?

Thanks,
Phoenix

I measyred my stocl L98 pulleys, they are...alt=2-1/2, crank=7-3/4, waterpump=6-1/8, p/s=6-5/8. The March pulleys are...alt=3-3/8,crank=6-3/4, waterpump looks same as stock 6-1/8. I got the measurements for the march pulleys from the holes that they were in in the box, set is the 4010.

Hey thanks for that approximate info bgood . Our crank is exactly the same as the Caprice's pulley I measured at the JY and oddly enough I never knew they had the same serpentine setups as our's .

Later,
Phoenix