|01-05-2012 10:13 AM|
The rumor of 400's overheating is an old wive's tale.
The cylinders are siamezed, with no space between the cylinders. This was necessary to arrive at the very large 4.125" cylinder bore, but created a stall point where the cylinders intersect. When the factory built the motor, they found that the coolant would just sit there in the corners of the cylinders with no way to escape. They would make such a hot spot in the motor that they would contribute to early ignition (detonation) and maybe even help create a weak spot where the motor could spit out the head gasket. The engineers found that if they added a series of holes between the block deck and the cylinder heads, that coolant could flow through and eliminate the hot spots. Many racers have found out that the holes are not necessary if the motor is operated only as a race motor, because at elevated revs, there is so much flow in the water jacket that it washes out the hot spots and everything works well.
Problems arise when a hobbyist builds a 400 for all or some street duty, because the revs are not always high enough to wash out the hot spots, so the motor spits out the head gaskets at worst, or overheats at best. So, rodders not knowing to drill the heads for steam holes is what has lead to the rumor of overheating on 400's. Like all rumors, this one has been exagerated so that most rodders think all 400's just naturally overheat.
|01-03-2012 03:07 PM|
no 400ci i have a few 350, i was thinking about building a 400 until i was told they have heating issues, 2 cylinders firing side by side? i could be wrong. but for the $ i think i will stick with a 350 build. just want an everyday driver with good power, what do you think? im not a super mechanic either all advice is welcome thanx
|01-03-2012 09:58 AM|
|techinspector1||Do you have a 400 block?|
|01-02-2012 12:32 PM|
chevy small block rebuild
this is to all small block chevy fans, are all small blocks the same just bored out? how to cure the heat issues in a 400. trying to build the best small block with good power at a good price for a 74 chevy 4x4. 350? 406? any advice is welcome thanx
|12-31-2011 07:28 AM|
I would find another engine.
look for a COMPLETELY 350 votec engine 96 to 2000. These engines came with factory roller cams and vortec heads.
These engine came with 285hp stock but a set of headers and intake/carb can make over 300hp.
change the cam, modifiy the heads (bowl blending, spring pocket/valve stem mods) and the engine can make 350hp and still retain low rpm torque.
check with used engine salvage yards. Should be able to get one for less than 750.00 and may not even need a rebuild.
|12-31-2011 06:48 AM|
Hey bud.....I routinely build this engine that produces approx. 350 hp:
-Flat top pistons
-cam w/ .490 intake & exhaust lift (can be purchased at the Engine Parts Warehouse for $60)
-dual plane intake (summit brand is approx. $140)
-metal head gasket...the thin ones (can be purchased at the Engine Parts Warehouse for $18)
And you should definitely change your oil pump, seals, & gaskets during your build
|12-30-2011 06:53 PM|
|68NovaSS||Do a simple search here, there must be a thousand builds discussed.|
|12-30-2011 06:47 PM|
rebuilding small block chevy
im restoring my 74 chevy 4x4 starting with the engine. I have a small block 350 (good core) but dont really know the best set up for an everyday driver with decent power. could use some advice