temp gauge reading different now

[72jimmy4x4]

I put in a 350 motor out of later 70's in my 72 jimmy. The 72 heads had what looked like 2 temp senders 1 on each head. The later heads only had one and a plug in the other. I tried to take the plug out but ended up breaking my 3/8 breaker bar so I left it. Now engine in truck and running good but when engine hot temp guage only reads just in to the normal range. It was a 180 thermostat which is new. Thought it my have the thermostat so it got another new one.Finally there is it because there is no second sending unit?
Thanks for any help

[1972C10]

Ive never heard of runnin two temp gauges Check and make sure the sender is good They are cheap if not.

If you need that other plug out heat the head up with a torch thats about the easiest way to get them out.

[72jimmy4x4]

The second sending unit was wired also.

[1972C10]

I belived you ..

On my 85 it has a bb with ac and it had a second sender for the ac Cooling fan I kinda doubt the 72 had something like this but never know. Im sure someone that knows more about it will chime in But ive never seen a second sender on a 72.

[Sweet72]

The temperature sending unit in the '72 heads was in the drivers side head. The temp. switch for the TCS (transmission controlled spark/temperature controlled spark) was in the passenger side head. This is a switch that closes when the temp. reaches 82 deg. F and enables vacuum advance.
As for the temp sender in the newer heads. I'd say it's not the correct one for your '72 gauge cluster, thus the incorrect indicated temp.