dual water pump pulley?

[tdw6974]

In view of recent fan belt failure looking to upgrade to dual belt pulleys! Racing beat has the drive pulley and alternator in dual belt configuration but I haven't found a competition water pump pulley for 2 belts? any info appreciated. Thanks Tom Weaver:eclipsee_steering:

[lawtonglenn]

http://atkinsrotary.com/store/86-88-Rx7-Water-Pump-Pulley-N326-15-131.html

[tdw6974]

http://atkinsrotary.com/store/86-88-Rx7-Water-Pump-Pulley-N326-15-131.html

Glen, finally got to point ordered one and got it is about 3 3/4 " in Diameter vrs the single groove water pump pulley that was on before is about 5 1/8" so if I have theory correct the smaller dual pulley will turn the pimp faster?? We run a gutted thermostat with bypass plugged. I wonder if smaller pulley cause cavitation? Hope you and family are surviving the winter!

[chuck baader]

You are slowing the water pump. With the required racing radiator for the RX7 that should not be a problem. You may, however, research the need for a thermostat.

[Greg Amy]

If the water pump pulley is smaller, then it's making the pump turn faster.

Is that a pump pulley or an eccentric shaft pulley? And how does it use dual belts if they're not both replaced?

GA

[tdw6974]

If the water pump pulley is smaller, then it's making the pump turn faster.

Is that a pump pulley or an eccentric shaft pulley? And how does it use dual belts if they're not both replaced?

GA
Greg, that is the water pump pulley. The eccentric pulley and alternator pulley are both dual groove to enable use of 2 belts as a "fail safe" also installing a Water pressure warning light.

[lawtonglenn]

I had to remember why I sent you that link ... :shrug:

We use the LARGER (ie slower) single pulley ... I think
I just found a dual pulley since you wanted to belt and
suspenders yourself by using two identical belts at the same time

I didn't know then, nor does Atkins list, the diameter of their double pulley

sorry!

[chuck baader]

Went back and reread...my mistake. That is why various vendors sell a set...smaller crank, wp, and alt. BTW, pulleys are free, but it does not say you can change the number of belts:(

[Greg Amy]

Meh, I think they're OK. "Alternate" pulleys are allowed (with no subsequent restriction to their design) and "type" of drive (toothed, v-belt, etc) has to remain the same. It doesn't run afoul of the "prohibited function" clause...

"If it says you can..."

[chuck baader]

Greg, I disagree. It is not OEM stock and the "if it does not say you can..." rule does apply, just like not being able to change type of belt (expressly prohibited).

When I bought my RX7 I did extensive research on pulleys. The only thing I thought legal was the spherical bearing belt tension adjuster available. Remember, there is way more involved in changing the crank pulley than a simple bolt on!

[Greg Amy]

Greg, I disagree. It is not OEM stock and the "if it does not say you can..."
It actually does say you can. 9.1.3.D.n:

"Alternate water pump, alternator, power steering, and crankshaft pulleys of any diameter or material may be used. Type of accessory drive (e.g., V-belt, toothed belt, etc.) shall remain as stock."

There is no subsequent restriction to its "alternate" design. Ergo, the Roffe Corollary kicks in: "If it says you can, then you bloody well can!"

GA, reminding rules writers of Tip #3... (http://www.improvedtouring.com/forums/showthread.php?t=22779)


Edit: Just to clarify my point, Chuck, the following two sentences do not mean the same thing:

"Alternate water pump, alternator, power steering, and crankshaft pulleys of any diameter or material may be used."
"You may change the diameter and material of water pump, alternator, power steering, and crankshaft pulleys."

The first one allows alternate pulleys, adding (pointlessly) that the diameter and material may be changed (once you allow an alternate of something, it's open unless otherwise restricted.) The second one says you can use another pulley but you can change diameter and material only."

[chuck baader]

OK, you can change pulleys, but no where does it say you can add another belt:026:

[Greg Amy]

There is an implicit belt allowance with the pulley allowance, given that - by design - belt(s) will have to be changed with a change in diameter of pulleys. That is further clarified with the restriction that "type of accessory drive" must remain as stock.

Finally, within "Engine drive belts may be replaced with others of equivalent OEM specifications" so belts are implicitly "free" as long as they are equivalent to OEM (there's a wide open hole), and there's no subsequent restriction on the number of belts...

;)

GA

[Dano77]

OK, you can change pulleys, but no where does it say you can add another belt:026:

And, Mazda RX7s come with multiple belts to drive multiple accesaries( Alt,AC, PS AIR Pump,) both of which pass over and drive the waterpump.

That said, if it came with two belts why cant you run two belts of a different size. Your allowed to remove AC and PS and AIR. The result is you need a shorter belt to drive the water pump that is driven by said accessary drive.

What is so confusing??????? You not adding any belts. Pretty simple if you ask me.

[chuck baader]

Dano, good point. Mine came with one belt. I have never actually seen the stock configuration so that being the case, I would have to agree its legal.

[Andy Bettencourt]

Greg is correct. Follow the logic...if you can use any pulley, and you choose a dual pulley, you can then use dual belts even though it never says you can use dual belts...

They only way this would be illegal is if the ITCS specifically called out dual belts as illegal.