im going to build a 406ci engine and all ive ever heard is theyll overheat.... well figure if i run a good thermostat i should be good. buy my question is can my factory radiator do the job? along with the factory water pump. can they?

 

it takes about 15mins per head with a drill.


you NEED the steam holes added.
you NEED head gaskets with the steam holes.

once there, its as easy to keep cool as any other small block chevy.

your stock waterpump, radiator, and even the single fan will keep it cool on the street and at the dragstrip.
upgrades arnt needed unless you plan on WOT operation for extended peroids of time.

 

I was wondering the same thing. I will be using a clutch fan. I have heard that the electrics might over heat. What I need to know is there different stock radiators that are better? Also make sure the heads have the steam holes.

 

the later cars with the alum radiators work better then the early copper/brass ones..


also, clutch fans SUCK for performance cars. heres the basic why:


you're in traffic. that fan has to move enough air to keep your car cool... so its either huge and moving alot of air, or its too small and you have to rev the car to cool it.



now you're on the open road trying to use your power.... you are now trying to turn this huge fan when you have plenty of airflow already... its costing you power. yes you ahve a clutch, or a flex fan... but its still costing you power.



so lets see... it costs power at speed, and it doesnt flow well when stopped.



now look at electric fans.
they kick on when you need them.
they stay off when you dont.
since they're closer to the radiator, they're more efficent at pulling air thru them.
also, since they're closer, it cleans up the engine bay, and gives you more room to work.


on a performance car, you almost ALWAYS want to swap out your mechanical fan for a flex fan.. only exception i could think off is for classic cars/resto-rods....

 

As Mr Dude says, plus, think about a new o.e. or better radiator and a good
long life, hi flowing electric fan. I've run a bunch of 400's, and as long as
you drill the steam holes/right head gaskets thay don't run any hotter than say
a 350......however.....if you ever seriously overheat one, it will never run the
same again.

 

I wasnt saying the clutch fans are better, just heard from some that they had problems with electric and went back to clutch. I ran electric pump and fan on my drag car so i could shut it all down for max power during the run and cool the car in between rounds. When i have electric fans i always have a bypass switch. I am going to get a griffin radiator from summit. I am not going to take the chance for the 160 bucks

 

mmk.

but just FYI, GM went to electric fans in cars in the 80s, and never went back.

 

what do you mean by steam holes? in the heads? please explain. does this mean i cant just go out and perchase any set of heads or do i have to have some work done on them?

 

400 heads have steam holes drilled into them,,,,non 400 heads dont,,,,,,,you can put any small block heads on a 400 but you just have to either drill these holes,,,or have a machine shop do it,,,,i had a set of old 2.02 heads i put on a 406 many years ago,,,just dropped them off at a machine shop and they drilled all of them for 40 bucks or so,,,,,,once thats done you need head gaskets for a sbc 400,,,,,,thats the only things needed,,,(the 400 head gaskets have the steam holes in them) never had overheating problems,,,my favorite small block.........i miss it..........

 

on a smaller SBC, theres room for coolant between the cylinders.

on a 400, there isnt any room.. because the area between the two cylinders is not connected, little air pockets of steam can form there, causing all kinds of cooling problems.

GMs solution was to put two TINY holes between each cyl... this let the steam escape.. or more accurately, let the coolant flow, so steam wouldnt form...



now these are NOT my pics, i grabbed them of a 30second google search to show you.

one side is the block so you can see the holes... the other is a normal aftermarket head that has had the holes drilled.

 

BTW, a 400 head gasket makes for a good pattern to show you where those
holes need to go.....

 

yes, it can be done at home with a hand drill.

but use a sharp bit.
and remember, while the exact angle isnt critical, the hole is NOT straight up and down, its angled.