Z 2/8 Bypass Fitting...

[dutch]

   Can anyone give me the dimensions of a '68 variety water pump bypass fitting (elbow) that resides on top of the water pump. My car doesn't have one and probably had or should have been fitted with one originally.
I have a friend in the hydraulic fitting business who says he probably can source something real close after I showed him pictures of what one looks like - if I can provide him with some dimensions.
   I need NPT thread dimension into top of the water pump, the nipple dimension going out of the fitting to the rubber hose, and the NPT thread and nipple dimensions at the manifold side..
   If he can come up with something that is close I will order a hose and clamps so it appears semi-original and works for whatever reason it is there.
   By the way what was the real and/or intended purpose of the whole arrangement and did it work effectively?
Most other sbc cars didn't have such a deal and I wonder if it was in place because of the rpm range Z 2/8's were possible of and maybe the water pump cavitated due to the revs and the fitting and hose alleviated the problem somehow...

Any info is very much appreciated - Thanks, Randy

[rodent]

http://www.camaros.org/forum/index.php?topic=6942.0

http://www.camaros.org/forum/index.php?topic=6666.0

[tom]

To circulate water within the block when the thermostat is not open

[dutch]

To circulate water within the block when the thermostat is not open

Tom - then what happened in the many thousands (millions) of other sbc's that did not have such fittings? Did they have problems or not operate as efficientlt as Z 2/8's or few other models these were put on?
Don't get me wrong here , I appreciate you response - but the exact application logic escapes me so far...

[tom]

My mistake, thinking of thermostat bypass. Heater hose see UPC 1 M3 in 69 AIM 68 should be similar.

[JohnZ]

No need to custom-fabricate that elbow - all the Corvette parts houses have them. Paragon #2755 is an exact reproduction with the original repeating logo, #1059 without the logo.

[68Zproject]

So did the 68's get the one with the logo or plain?

[dutch]

John - can you tell me what the original intent of the elbow was?
 Most engines never had them - why the Z 2/8's and 375 hp 396's - was it something to do with the rpm limits they could achieve that made the application necessay or other reasons?

Thanks - Randy

[JohnZ]

John - can you tell me what the original intent of the elbow was?
 Most engines never had them - why the Z 2/8's and 375 hp 396's - was it something to do with the rpm limits they could achieve that made the application necessay or other reasons?

Thanks - Randy

It simply provided for additional bypass coolant flow before the thermostat opened, in addition to the flow provided by the bypass through the extra hole in the passenger side leg of the water pump and the bypass flow through the heater core.

[dutch]

There must be additional reasoning if it makes for much that better engine operation, why GM wouldn't have installed it on all of the sbc's at or after some point then - OR maybe it was deemed a better arrangement - but just not enough so that the cost to do it offset the benefits involved.....