I have a 1972 454 elcy that is now overheating the heads only.

The car has been running fine til I noted rusted, dripping freezeplugs. Temp was a lways 210, 220 when pulling off freeway. I replaced the freezeplugs. The 2 in the bellhousing were left alone. The two at the rear side of motor replaced with brass. The four in the front side of engine, I could not reach so I used rubber plugs til I pull the motor. It is a weekend car. I also replaced waterpump (jegs),
themostat (180) and belts and hoses.

All was fine for the first 3 weeks (250 miles). Then the the temp started to slowly climb. First just in stop and go traffic, now idling in the driveway, it will peg 250 in minutes. thermometer placed in radiator though cap at that time shows 150 degrees.This is the stock gague in the driver side head. Must be sensor... replaced ..no effect. gague ? got aftermarket gague...same temp. Replaced clutchfan.. no effect. Pulled waterpump off and volume flushed motor though themostat hole.30 min both sides then blocked each side and flushed 30 min each side. 30 min reverse flush radiator. No effect. Oh, and I always fill motor via themostat opening as well as radiator. Jacked up front or car and tried to flush out all the air. No luck.

When wife gets home, I am off to get an infrared temp gague to see if it is just that one spot on the head or both heads.

Any thoughts? I assumed that I knocked some debre loose that clogged up the water passages into the head. I had hoped that back flushing would have done removed the obstruction. Do I really need to pull the heads to see whats going on? And I planned on going to Cruising the Coast in Mississippi thursday-saturday. If I need to pull the heads, I need to start tonight.

Thanks
Jeff

sounds like a bad new thermostat to me!

sounds like a bad new thermostat to me!
yup, absolutely.

The best thermostat is from Richardson. They are also sold by Mr.Gasket. They are very different looking from a stock type, hi-flow, and cannot fail closed.

New NAPA hi flow thermostat.... no difference. I will order that mr gasket one this week.

Infrared... 215 uniform on both heads when gague says 240-250. Must be a bad gauge and aftermarket gauge. Kinda hard to believe that... but.. if the head temp is only 215, I would think that is adequite.

Follow up...
I put in the becool thermostat. And new gauge. Went to cruising the coast in south mississippi. Temps in the mid 90's. Big traffic. Highest temp was 220. Went down by putting in neutral to raise idle speed. Temp 190 most of the time.

Thanks