Hi, new to forum looking for some advice. I have a 78 everything thats in it was installed by previous owners dad and he passed away so i dont have much specifics. It has a 400 sbc that ive been told is a “421 stroker” any ideas on what it would it have been bored to? Has a mean sounding cam but i have no idea what lift and duration. Has a holley carb, edelbrock performer heads and team g intake.

my main question is cooling, it runs hot. Theres an aluminum radiator not sure what size, 1 electric fan and no thermostat but it had a flow restrictor in place of the tstat. Do you think id be better off the use a t-stat with a fan clutch and shroud set up for street use? Or a flex fan? The electric one thats in it is controlled by a temp sensor and seems to only have one speed and it doesnt kick on until its up to temp. i just dont think its enough. Any input is appreciated!

 

Yeah I'd go fan clutch,same thing a lot of big block guys run into with electrics.
The max over on a 400 is .030.
It's probably got this kit installed: https://www.scatcrankshafts.com/product/1-41568bi/

 

I would be tempted to get a double electric with shroud with the highest CFM I could. We used a restrictor on race car 400's to slow the flow down the coolant until we bought racing pump. At 6000 RPMs the coolant is moving so fast it will not absorb heat well. In a circle track engine you will run 6200-6700 for 10 minutes straight. For a street motor you want to keep it cool. Since you would normally only be at 6000 for short bursts I would try it without the restrictor. You should be able to fine a thermal switch that will turn on the fan at 165 degs.

How long has the car been sitting. Your aluminum rad will not rust out but it can plug or partially plug up. You can check the condition of the coolant with a voltmeter. Set the voltmeter to read at least 12V DC. Ground the black lead to the battery and put the positive lead in the coolant and see what you have. Over 4 volts you coolant needs attention. You can get a scanner style thermometer from Harbor freight for less then $20 on sale. Scan the radiator for cool spots not caused by the fan. If you have any you should send the rad out for flushing.

Keep stock 400's that are run hard cool can be tuff. You really want to keep it cool. Most SBC engine can recover from overheating 2 or 3 times that is not the same with the 400. They tend to blow head gaskets and warp heads like it was a ford escort. Yea I know my reference is dating me but I was around when circle track guys could still find 4 bolt main 400's in the junk yards for $250 dollars.