Cylinder Head and Cross flow Cooling system

[Dadandson]

I am rebuilding a head for my 1275 motor and I need to verify an opinion. I was told by a fellow to plug the coolant port on the water pump that runs vertically in to head. I do not have a heater and the outlet is currently bypassed. I realize I would also have to plug that spiffy TEE lower radiator hose as well. Are there two coolant jackets running through the head? I know you guys love the "Opinion" part on this forum, Have fun.

 

[58Custom]

That is the coolant bypass for when the T-stat is closed.

What was the reason given for plugging it?

 

[Dadandson]

I was told that the motor will run better if the head is a little warmer.

 

[jlaird]

Ha, ran just fine for 50 years with that open. I would be darned if I would plug it up.

 

[Dadandson]

I will leave it open. Does anyone know the O.D. of the outlet on the head? The one in the head is damaged and I need to press a new one in. Thanks

 

[jlaird]

Boy, that's a new question for sure.

 

[Trevor Jessie]

Nope, it is not a new question. It has been discussed here before and I think dklawson had the answer.

 

[58Custom]

I was told that the motor will run better if the head is a little warmer.

The head will be warmer if the water does not circulate when the T-stat is closed. Not sure steam pockets is the way to go. Also, the cylinder walls are likely to be cooler, and thus wear more rapidly. But, maybe it would not be that bad.

 

[58Custom]

Nope, it is not a new question. It has been discussed here before and I think dklawson had the answer.

I found this thread. Some non-bypass stuff there, too.

 

[jlaird]

Now that I reread that I do remember it a bit. Was no answer though.

 

[Trevor Jessie]

That was the thread I was thinking about. Sorry, I thought a size was discussed.

 

[GrahamP]

I beleive the stud in the head is actually screwed in and you can buy replacements. Apparently it's a real swine to get out :frown:
Late A series engines had the by pass hose removed at the factory, IIRC it was done to remove the weak spot caused by that hose, if removed then you need a stat with bypass holes drilled in it, but I have no idea of the size required.

If you don't need a heater then maybe you don't need a stat, you could fit one of the restrictors used in racing engines instead.
Graham

 

[Dadandson]

I removed the old fitting by milling it out and discovered it was threaded in. I damaged the existing threads so I tapped it out to a 3/8" NPT and I will make a custom fitting or use a brass pipe plug. I live in Arizona and don't have a heater. I am also not sure I have a thermostat installed on my current head. I will find out when I am ready to install the new head. Something else I am going to do is remove the four tubes in the exhaust ports, press in little pieces of brass into the tube and braze them in for good measure. I will then put the tubes back in, back them up with setscrews and grin them flush to the exhaust port when I port and polish the head. My car is emission exempt. The head will go to boil and magnaflux on Monday.