You've got the smaller pulley on your waterpump drive don't you? And a fan clutch set-up? if so, who did you get it from? Does it operate on "speed" or a bi-metal temp actuator?

My current set-up just has direct drive with the smaller pulley - six blade fan - and the noise level is considerable at idle. So I can imagine where that will go when I get it going on the freeway...When I mentioned this to an engineer I work with, he sent me this link....

http://www.rossairworks.com/content/view/19/16/

...and told me that there are some pretty slick B-W fan drives on some of the diesel trucks these days. There is a "cross arm" rigid electrical lead that crosses in front of the fan and attaches to a small bearing on the nose of the fan blade/electric clutch assembly. When a separate thermocouple controller determines the need for the fan - a relay turns it on. Very clean - mechanical fan - electric "On-Off". Could be temp controlled on the street  - and switchd off at the track.  

I'm following this topic with interest. Where exactly did you place the restrictor? The bypass hose is the 5/8" hose from the water pump back towards the block?

regards,

When the engine is warm - thermostat open - water is still bypassing the radiator via this route. A very short hose - a size most of us have around the household for use in the yard - is directly connected to pump suction and running hot water back into the engine. Running this flow through the radiator instead can add cooling. Eddies car showed approximately a 10°F drop.

Using a partial block of the bypass can make this happen. I used a 3/8 brass pipe plug with a 3/16 hole drilled through it. To make sure the pump was not starting  up cold against a complete "deadhead" - some holes were drilled into the thermostat as well. The 3/16 plug hole was suggested by Ted as a way to insure that air bubbles trapped in the front cover of the engine when it is stopped - had a way back up to the intake manifold.

This is a "Robertshaw" style of thermostat and you can buy them - premodified by Stewart Components - or drill them yourself. There are 3 x 3/16" holes added into the poppet as shown here. If you have a restoration type car - no one will ever see the modification - but cooling will be enhanced.

Pete

http://www.stewartcomponents.net/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=Therm

When parts counter guys are confused about these thermostats - shift gears and ask for the part that fits a Chrysler 440 big block....

I do already have the Robert Shaw style thermostat, but find this intriguing. She always runs towards the high side of the gage & I would like to gain any margin I can.

Thanks. The knowledge I pick up here from this forum is truly appreciated.

Here’s a thread that touched on the subject of drilled thermostats and restricting the bypass hose.

http://www.y-blocksforever.com/forums/Topic35079-3-1.aspx

If you’re not having an overheating problem due to ambient conditions, then restricting the bypass is an item not needing to worry about.  This is obviously not a fix for other cooling problems that may be present.

Pete

I really like Duck's idea and think I might look into doing this myself. Is there a downside?

Cheers

Richard

My second thought is the adjustability of the bypass flow would be good with a shutoff tee, but the amount of restriction would be difficult (if not impossible) to measure.  However, a little trial and error might dial it right in to suit your current needs. 

I want to buy a smaller diameter water pump pulley like you have. You mentioned that you got it from Concours but I can't find it in their catalog. Do you have a part # ?

Pete

It proved impossible to find the smaller diameter, single V-groove pulley, with close to the proper "backspace" - except from Concours in steel - so I bought a less expensive, aluminum double groove from CVF (for a small block Ford) and had it modified. By cutting off the second (back) groove, reducing the outer diameter to 6.0 inches (down from 6.2), and opening the remaining V-groove to fit the earlier fan belt size - it works well. I had to move the pump pulley/fan mounting flange .1 inches toward the radiator (to align it with the crank pulley). CVF has reasonable pricing for their aluminum pulleys and they are American made. Try.....   cvfracing.com  

I heard that it is possible to make a double groove steel pulley (302 Windsor) into a short single, by chopping off the second groove and dressing everything smooth - I haven't tried this. There are pictures of the modification on the internet - so there must be some Windsor applications that need the short length single groove pulley. You probably will have to use a puller or press on the waterpump mounting flange to get everything back in line on a Y-block.