This page shows the part numbers #304-306 fit the Ford (239) (256) and (272) - which also means they fit the 292 and 312 motors

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....

 
 Steve Metzger       Tucson, Arizona

I'm still unclear where this restrictor brass plug with the 3/16" hole in it is installed in the 5/8" bypass hose circuit. If this has already been explained, I apologize. I did a search & haven't yet found it.

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.

Brian - 56 T-Bird

Woodinville WA

what confused me is that the 304-306 thermostats are listed as being "non modified" which I imagine means no holes. Don't see any listed in that group that have the holes

Ditto

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

The restrictor simply goes anywhere within the 4” section of bypass hose that’s between the thermostat housing and the waterpump.  The primary reason for not blocking the bypass hose completely on the Y is to insure that air that is trapped in the water pump or timing cover will purge itself and subsequently eliminate an air lock which in turn prevents coolant flow.  I’ll add that completely blocking the passpass on racing engines is a common practice.

 

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.

Lorena, Texas (South of Waco)

How is the restrictor held inside the bypass hose?

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Machining the plug just a bit larger than the hose and pressing it into the hose middle is one way.  Putting an additional clamp around the middle of the hose so the restrictor is held tight is another.  As long as the restrictor is 5/8” diameter or larger, it’s not going to get past the hose nipples on each end of it if a clamp is not used.

Lorena, Texas (South of Waco)

Couldn't you just use a shutoff tee with a stub of hose on either side (instead of a drilled plug)? That way you could open or close it to suit the ambient temperature (?) Just my .02's worth- /Duck

BOO- YA!!!

Just ordered a thermostat from Stewart. I ordered a # 304 (160 degree) and they are going to drill the holes. So the answer to the question is there is no current part # for a modified thermostat for a Y block.

Pete

Couldn't you just use a shutoff tee with a stub of hose on either side (instead of a drilled plug)? That way you could open or close it to suit the ambient temperature (?)

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

Cheers

Richard