Oveheating issue resolved

[lalessi1]

A while back I posted about an overheating issue, my Custom with a standard 3 core radiator, stock 390, toploader and 3.89 rear seemed to overheat on the highway and would cool down with stop and go driving. I checked my gauge and sending unit all seemed OK. I recently put in SW 2 5/8" mechanical gauges and finally figured out what was happening. Originally I mounted the stock sending unit on the side of the block where a 1/4" plug was. It seems that the factory gauge was reading the coolant temperature close to the cylinder walls and that is where the engine is the hottest at constant speed. The new SW gauge was holding steady at 180 while the original gauge pegged. I simply moved the stock sending unit to the intake manifold and both gauges now track each other nicely. I thought I would share this, I never would have thought that would be the case and it makes sense to me.

[hiball3985]

Strange, I have never seen an FE temp sending unit in the block, they are always in the intake manifold..

[lalessi1]

The intake didn't have a 1/4" npt hole into the coolant system. I originally put it in the jacket drain hole (1/4" npt) on the side of the block. I wound up putting it into an 1/8 npt hole in the manifold with a nipple an adapter and a 90. Live and learn!

[hiball3985]

They make 1/8 npt sending units 

[lalessi1]

I always try to complicate things and then figure out why my stuff doesn't work!!! I bought the sending unit for a 57 and never looked back.... I tried to find where the original sending unit was installed, the manual says in the cylinder head. Now I have a Blue Thunder intake yet to be installed so I will cross THAT bridge a little later...The moral of this story is don't just go putting things in any ole hole just because they fit! 

[hiball3985]

"The moral of this story is don't just go putting things in any ole hole just because they fit!"
I hear that 
I'm sure the Blue Thunder will probably take the 1/8, so you just need one for an FE, I think the majority of FE's in the 60's use it and should work fine with the stock 57 gauge.

[lalessi1]

That is awesome to know....older and wiser!