[77LTneedswork]

I noticed the other day that my 77 Lt 305 seems to run too cool at idle and only reaches a good operating temp when I'm wide open on the road. Then I noticed while I was adjusting the carb that when I goose it the upper hose will collapse and restrict flow. What will cause this? I've never seen this before. Thanks

[BlackoutSteve]

Do you know if your thermostat was open or closed?

If it were closed, it's possible that it was the restriction causing the upper hose to collapse.

Also, do you have the bypass hose fitted between the pump and intake? If it's been removed, this would put additional vacuum against the thermostat when it's closed. Many people remove the bypass hose and block it off. It really should be left in place. (Just checking.)

[dawg]

incorrect thermostat. ( no bypass hole in the body of the thermostat)
replace with a high flow thermostat.
or you could have a bad radiator hose (rotting from the inside out).
time to change upper and lower hose and heater hoses aswell.

[l1tech]

Your radiator cap is bad and not allowing coolant to be drawn back in from the overflow resorvoir which is causing the vacum on your system and collapsing you upper rad hose

[BAMiller]

I agree, try a new rad. cap first.

[Camaro Dave]

I would start with the thermostat, it sounds to me like it might be stuck in the open position, since it takes your engine so long to reach operating temperature. Also it wouldn't hurt to replace the upper hose, since it might be too soft.