I know this has been discussed ad nauseam all over the interwebs (especially the Pantera guys) but I wanted your all's input.
So....since getting my Mach I have seen it run pretty warm. Not to the point of overheating because I haven't really driven it for very long. So a few days ago I head out on a 30 mile trek, mostly back roads and a quick spin on highway. When I got off the exit ramp the thing was freakin' hot (needle almost the the H). Not boiling or maxed out but definitely warmer than I had seen running around the neighborhood. I flushed the system (it was really clean), checked the radiator for visible leaks, and made sure the water was flowing. Doing research I found out about the brass water restricter ring in the intake. I pulled my stat and verified it was there. Then it hit me. The T-Stat I bought was nothing like the ones I had seen from Robert Shaw, etc. with the brass shoulder and the flange. The one I took out of the car right when I bought it was like the new one as well. I cant seem to find a correct style except on ebay for $55.
So my question (finally) is: What are y'all using for stats or is everyone running the block off plate from WCC (which I ordered just in case) with a Windsor stat?
The thermostats that look like the older Robert Shaw pieces are now in the "high flow thermostat" category. I have used both Mr. Gasket and EMP Stewart brands. The EMP Stewart brand has worked better for me. This is what I use, http://www.summitracing.com/parts/emp-30.../make/ford It is a 160 degree model. I don't know if you have a different temp preference. I wouldn't use anything higher than 180 degree in these older cars.
What year Mach 1 do you have? A lot of things will cause hot running engines. Does it tend to run hot at low speeds or high speeds or both? What size radiator is in the car? Aluminum radiators make a significant improvement. Also, unrelated to the cooling system, if the ignition timing is too retarded the engine will run hot or a lean A/F mixture will cause a hot running engine (not too common).
There is a slight chance your gauge is inaccurate. But probably not, the stock gauge in my 69 Mach 1 is between the middle and 2/3 at about 180 degree. I guess at H you are probably about 210-215 degree.
I always doubt an old original temp gauge. If the engine was boiled at some time in the past, that often results in upsetting the calibration of the sender. Some makes will then read low, others will go way up for a minor change of temp. One of those i/r, no touch temp reading guns can br very useful.
Thanks man. I found the Mr. Gasket at my local parts store so I'll be trying this right after work. One more question: what ratio do you guys mix up for your coolant?
I use a 50/50 mix of anti freeze and distilled water. Distilled water is inexpensive in grocery stores and helps reduce corrosion. Or buy the premixed anti freeze.
Your description is indicative of insufficient coolant flow. It could be other things too, but that is common. The thermostat might fix it. Do you know what brand the radiator is? I've heard the China imported radiators of equivalent sizes have less coolant capacity. I don't know personally, just heard that information.
My first thought as I began reading this thread was/ is: What is the exact temperature? Idiot gauges really don't give allot of information.
The 351 C runs a Cleveland specific thermostat. Using the other will be a cause of eventual overheating.
Here is a list I pulled off the Internet of 351C specific thermostat numbers. In the attached photo the correct Cleveland thermostat is the one on the right.
I note in a subsequent post from the OP that the car always over heats unless it is just at tickover.
I would suggest it has a more fundimental problem, either serious (corroded waterpump impeller) or trivial (timing out, gauge sender too sensitive).
Some testing required on this one.
Steve Harris, will none of the high flow thermostats work in a Cleveland? I see the difference in your photo. I don't know why the Mr. Gasket thermostat also says it fits Clevelands. Napa also lists that Mr. Gasket thermostat for a Cleveland. It could be a misprint. I hope the OP reads your post (Steve Harris). I used to work with a guy that bracket raced a Fairlane with a Cleveland motor. He ran a restrictor and not a thermostat, how do those work on Clevelands?
M1FF, what is "tickover"? The OP said the temps are fine at idle per the gauge. I agree, it can be another issue, minor or serious. I suggested timing in hopes it would be checked. I have seen water impellers slip on GM products. Not Fords, at least not yet.