MFI Thermostat Rod Extension Dimensions

[bobmagyar]

I searched for some data on this but could not find anything with my search parameters.

The rod that extends out of the MFI thermostat from my pump has the following dimensions.

When cold: Datum to end of rod = 14.3mm
Free play when cold: Rod can be pulled by hand to 17.1mm (this is not against any spring force what so ever aka. rattles)
When hot: Datum to end of rod = ~19mm using heat gun.

Would anyone have any data showing nominal values for these states of the thermostat?

My car seems to be running rich due to popping in the exhaust. I also checked to see if the thermostat was moving the linkage in the pump far enough which I believe it is.
Id like to just confirm that my thermostat is operating properly to rule this variable out.

If anyone has data to share that would be great.

Thanks in advance.

[2.5MFI]

Your measurement for cold seems to be correct. Ranges from 14.25 to 14.75 are normal. The free play when cold is also normal. But your 19mm seems long. The 6mm OD rod itself has a step down to 3.95mm OD at the end where you are taking your measurements. That 3.95mm OD section is 27.50mm long. That step between the two prevents the rod for extending out any feather than 17.50 to 17.75mm. There is also a small cir-clip on the rod just before the step-down. If the cir-clip is missing that might let it stick feather out, but that would cause some problems with the disc measurements. This is the same rod used on the 1970 pump on up. The 69 pump may be a different length, I'll have to check.

[rvdv]

So if that's the case where rod is coming out to far, wouldn't the engine be running to lean then, I am assuming the further the rod extends the leaner it gets.

[2.5MFI]

The rod extending out will not make the MFI pump run leaner. The rod when extended can only move the warm up compensator spring guide so far and it bottoms out. The length 19mm on Bob's thermostat tells me there might be a problem inside his thermostat.

[bobmagyar]

Thanks Mark!

Well I am happy to say that my numbers match yours and that I am not sure how I got 19 for my warm length. The thermostat rod cannot extend any farther then the the spring clip allows which results in the same 17.5-17.75 number you mention. I am not sure how I got a 19mm reading before. Must be getting old eyes already.

[304065]

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