Temp gauge question

[75sierraclassic]

I've got a 75 Sierra Classic that i rebuilt the 350 engine. By suggestion from the machine shop I put a set of 305 heads on the engine to raise compression since one of my heads was cracked. The 305 heads use a different temp sender than the 350 heads, so I bought a temp sender for a later model truck. Do you guys know if the guage in my truck and the newer sender are compatable? The guage only registers a little bit over the cold mark. It seems to be registering a temperature, but it is like the scale is off. I used a temp gun to measure the outlet temp on the intake manifold and it was your normal 220 F. With it registering so cold I really don't know where the engine may be overheating.

[Slonaker]

When I used an early sender in my '86 after swapping the engine, it read much hotter than the engine actually was. I used an adapter to allow me to run the old sender, and it reads normally now.

Slonaker

[1972C10]

Sounds Like He Has The Smaller Hole Heads And The Old Sender is The 1/2 His New Setup Is More Than Likley 3/8 I think as long as the parts man that gave it to you was competent.. You should be ok But im sure if you dont have the proper one it will read in error.

[75sierraclassic]

Thanks for the input
It sounds like I need to get a later model temp gauge from the same year truck that I got the sender for.
Slonaker,
Where did you get the adapter to convert the signal, sounds like I did the reverse of what you did and they may have a converter for that too.
Thanks Again

[Slonaker]

I got it from the plumbing section at Lowes. It was less than $2.00.

Slonaker