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MG MGB GT V8 Factory Originals Technical - Thermostat housing

Is there a thermostat neck available for the 215 that points to the left? All the ones I've seen go right which puts the inlet and outlet on the same side of the radiator and precludes the use of a crossflow unit. After reading up on surge tanks I'm beginning to think there is a significant advantage to be had by the location of the radiator cap on the suction side of the system, so has anybody seen one?

Jim
Jim Blackwood

Jim
The later rover motors and the RV8 used a thermostat housing that routed the upper hose over the dizzy to the drivers side of the radiator.
http://www.btinternet.com/~jon.wolfe/gallery/edelbrockperformer.jpg
Jake

The Buick 300 points the hose almost straight forward. It will let you route left or right.

The Rover housing mentioned above does not have the heater bypass outlet, & is not suitable unless you are using the later cover with gerator oil pump & serpentine drive.

Every conversion I have done routes the top hose to the driver side (US), bottom hose to the passenger side, except one which used a '66 Mustang style radiator with the top hose in the center of the top tank. The original factory V8 had a top hose that snaked around the dizzy & then to the left as seen from the driver's seat. That housing has a little less rh bias than the 215.
Jim Stuart

Jim,
I have the Buick front cover with a 4.2 engine, what therostat housing should I have to accomodate the heater bypass?
Regards
Tony
Tony Bates

If you mean the little aluminum fitting below the radiator hose end, its there in that picture, you just have to look for it. This housing will bolt right onto a buick manifold but not a rover manifold. the type Im running on my car is from an early P5B or something that has no bypass hose fitting, it is on the intake manifold.
http://www.et.byu.edu/~jmv/Cooling/thermostat1.jpg
Here is another pic of what I think youre looking for.
http://www.rpiv8.com/Gallery-2003/thermostat_housing_4wd.jpg
Jake

Well, I'm in a bit of a quandary. It seems that because my radiator is lower than the intake that I have an airspace in the intake manifold and the heads too and having the overflow connected to the top radiator hose doesn't eliminate it because of being on the high pressure side of the pump and in a high flow area. (Is it a coincidence that recovery bottles appeared about the same time that crossflow radiators became common?)

Anyway there look to be two routes to solving this. Probably the best from a performance standpoint would be an aluminum crossflow, which needs the top hose going left, and a surge tank located above the intake. The second , which is probably best in terms of cost, is the existing radiator which is probably just as efficient but is a downflow, and almost the same setup on the surge tank with the most important difference being the configuration of the bleed line(s).

I think I'll try the second one first, but I'm definitely on the lookout for a suitable thermostat neck. Jake, that one looked like a possibility. It sure sticks up though, doesn't it? I'll have to check for interference to the intercooler. Wonder what else might work?

Jim
Jim Blackwood

Tony-

(assuming I am the Jim you were addressing) Iused a Buick 300 on my 4.2 Rover with a Buick 215 front cover.

Jake-

Good pictures. The first is a Buick 300, the second appears to be a later Rover modified to includea heater bipass. The Buick has been modified by the addition of a fitting for either an air bleed, or as I did, a small hose to the overflow tank.

Jim Blackwood-

Almost all V8 conversions have the radiator lower than the intake. Some have no problems, others are driven crazy by steam pockets & air locks. Glen Towery's many conversions use the stock MGB overflow tank on the inner fender. I have used a tank-call it surge or overflow- mounted high on the fire wall shelf. This is usually a TR& or TR8 part that "t"'s into the heater line and the overflow tube on the radiator filler neck.
My new 300 uses a BeCool overflow tank including a radiator cap on a standoff mount high on the inner fender. I also use a crossflow radiator.

My experience is that filling the radiator is critical. I remove one end of the top hose to fill, attempting to exclude all possible air. Done this way, I have no problems. Filling via the overflow or surge tank almost always leads to air blocks.
Jim Stuart

Jim, your comments got me thinking and I came up with a rather ingenious solution I believe, but for it to work properly I have to make sure the fluid level of the surge tank can be maintained above the arch of the top radiator hose, and I think I can do that. The plan is to run a 1/4" OD tube inside the upper radiator hose up to the top of the bend. This tube exits via a fitting screwed into the bulge of the thermostat neck opposite the radiator hose connection. The fitting is a push-in type for connection of the bleed line to the surge tank and the internal tube is sized to be a snug fit in the threaded end and will be JB welded to the neck at the end of the fitting once the neck has been bead blasted. (have to get some glass beads first for my new christmas present)

There will be no more than an inch or two of elevation from the fitting up to the open end of the tube and the fitting is a 90 degree one so the volume of fluid that can be held in the tube will be small. So under statiic conditions coolant in the surge tank will cause an upward pressure in the hose by way of the heater return hose and the radiator, causing about a 4" slug of coolant to go up the bleed line followed by any air in the upper hose until the point where the fluid level in the bleed line equals the fluid level in the surge tank. I think. It probably really depends on how much above the hose the fluid level is.

When running, the upper hose and bleed line will be pressurized relative to the surge tank so there will be continuous flow through the bleed. This is a high flow area so it won't all be air, but since the fluid will have to make a 180 degree turn to flow up the bleed tube at least some of it will be air if there is any air going through. From the radiator it's a steep uphill path all the way so I'm not worried about air getting in the radiator and that only leaves the two small humps in the intake coolant ports. Finally, I'll drill an 1/8" hole in the thermostat and put that at the top, to bleed any air from the engine, and I think that should do it. Make sense?

Jim
Jim Blackwood

No.
Jim Stuart

Really? I wonder what I left out?
Jim Blackwood

This thread was discussed between 04/01/2005 and 09/01/2005

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