Radiator 250 or 305/350

I swapped a straight 6 engine from my 82 GMC Sierra for a 86 Chevy 305 from a G10 Van. Without swapping the radiator. Would this cause my temp gauge to act retarded and have my engine run hot?
Thanks Guys & Gals:dunno:

Putting a bigger engine in there might be causing overheating, your probably going to need to put a more heavy duty radiator in there, this could be why your temp gauge is going all over the place and your engine running hot.

- Kevin

yes you need a larger radiator. Get one to fit your truck but appropriate for a V-8 engine. You should be able to get one of these at autozone or just about any parts store. You'll need the correct fan, fan shroud and fan clutch also.