overheating problem

i have a 51 chevy sedan, 350,w/stock radiator new speedway short pump,160 deg thermostat,running 50/50 coolant and a 6 blade fan. runs for 5 mins,boils over. any help greatly appreciated im ready to hold it on the floor until it stops!

 

Ya gota go to the basics. Start with the rad. is it clogged up ? is the pump turning backwards ? Is the thermostat stuck closed. Try it with no thermostat. Look in the rad ansee if its circulating. Is it bubbling as if it has exhaust are compression in it ?

 

Air block? Head gasket?

 

True

Basics include history. Fresh everything or proven combo that just had a new water pump installed because of sudden overheating? When you say run for 5 minutes, do you mean idle in the driveway or running down the road?

Common causes-
Stuck thermostat
Wrong direction water pump
Facked up timing

Gotta give us more info dude, as it is you're about to get assaulted with irrelevant information when guys with 1/3 of a clue tell you how they fixed their own overheating.

good luck

 

Got vacuum advance?

 

sorry bout the lack of info. the rad has been flushed,the thermostat is functioning, and there is movement in the rad,i can see some tiny bubbles in the rad .

 

running in the driveway , timing is on ,va working,coolant is fresh pump is new,hoses new,all new except rad , my typing skills suck!

 

Feel rad core if you feel cold spots rad is plugged.Flushing does very little.

 

Note Shifty's comment about timing.

As well as my question about vacuum advance.

Do you or do you not have a vacuum advance distributor?

If so the fix may be as easy as selecting the vacuum advance cannister to manifold vacuum.

 

Bubbles in the radiator?? Check compression.