Those of you who are members of NAMGBR will have received the January/February 2026 issue of "The MG Driver", the Tech Issue, which contained an article written by HMGCC member Scott Hardy. The article discusses problems with MGA/MGB heater valves, and presents an alternative heater valve kit manufactured and sold by your humble HMGCC webmaster, Rob Ficolara. The article is reproduced below for the edification of those who either did not see the article or are not NAMGBR members...

New Heater Valve Kit for MGA/MGB That Solves OEM Deficiencies Now Available

While driving in an autocross last fall, the distributor in my 1972 MGB was doused by an unwelcome shower of coolant from a failed heater valve diaphragm. And judging from the high volume of online posts concerning failed heater valves, what happened to me is not an unusual occurrence. Thanks to the support of Houston MG Car Club members who came up with a blanking plate on site, I was able to complete the three-hour drive home. During that journey, I resolved to identify a more effective solution for controlling the heater.

The deficiencies of the available OEM style heater valve in MGAs and MGBs are well documented. If you have one, you already know. To summarize:

• When the diaphragm in the valve fails, the valve leaks directly onto the distributor.
• The valve design does not allow adequate coolant flow for optimum heat output.
• The valve resists opening and closing, making it difficult to operate with the cable controls.
• It is hard to either completely open or completely shut the valve, which results in heat being released when you don’t want it.
• The lifespan of the available replacement valves is not equal to the OEM valves. Mine failed after six years of use and I have heard of failures in much less time.
• The OEM design does not allow a socket wrench to fit onto the bolt heads, making it difficult to remove or install the valve, particularly the lower bolt.
• Failure of the valve has resulted in catastrophic engine failures due to overheating because the temperature gauge will not register when there is no coolant.

Numerous solutions to this issue have been shared on platforms like MG Experience, so I didn't have to start my search for a better valve from scratch. I resolved to use an automotive ball valve with the same push to open/pull to close action as the original valve, and I experimented with creating bases from failed heater valves. However, I found the castings to be poor quality, and the remaining base did not provide enough material to tap a large enough fitting to increase the coolant flow, so I needed a better answer. I designed a couple of trial heater valve bases that Texas MG guru Wayne Kube machined into reality.

Fortunately, I found out that fellow HMGCC member Rob Ficolara was pursuing the same goal of creating a better heater valve design, and he had the great idea of producing an easy to install kit for MGA and MGB owners. We tossed around some thoughts for procuring the valves and fittings, and he had the equipment to turn my heater base designs into beautiful, 6061 aluminum alloy pieces that allow more than twice the coolant flow of the original design. We also fixed the installation problem by using socket head screws for attachment to the block.

I installed a prototype design on my car, and the results were amazing. Installation was a breeze. I was able to use the original heater cable with a small modification. The valve was easy to move from completely shut to wide open and back again. The increased flow allowed the heater to put out more heat for the cold days (rare as they are here in TX!). It even looks proper. And that ball valve will never leak onto my distributor!

Rob has started producing the kit, which provides everything you need to replace the heater valve assembly from the engine block to the heater inlet. Rob is a fellow MG owner who takes pride in his work, and his kit provides a well-designed answer to all the problems created by the OEM design and currently available replacement parts.

The heater valve kit, which contains complete instructions, a pre-assembled valve assembly, and all mounting/hoses/clamps/gasket hardware, is available to MGA and MGB owners for $US 87.50 plus shipping. The ordering details can be found on his website, www.BritCarCraft.com. Don’t wait until your valve fails (again). Look into this upgrade today!

What’s in the box. (Not pictured are complete, easy to follow instructions).

Detailed view of the preassembled valve, fitting and base supplied with the kit.

The valve installed.