I have a 86 monte carlo ss with the original 305 and I want to do an engine swap. I know a person selling a small 400 block for cheap ready to install. I plan to race the car every now and then but will mostly be used for a sunday car. How reliable is the engine and should I take this engine over a 350?

 

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I guess the only real questions are between a 350 and a 400 ..Which one has the 4 bolt mains?

Also model years/vehicles did they come from? How much mileage do they have on them?

Generally 400's were Pontiac and Buick motors.

350's however, were mainly Chevrolet Motors... with the exception of a few oldsmobile's.

The 4 bolt vs 2 bolt mains would be the decision maker for me.
The 4 bolt would be my likely choice.

 

It came out of a 72 chevy impala. i do not know the mileage on it or if its a 2 bolt or 4. I am going to check it out tommorrow.

 

A 400 is a good engine.Same basicly as a 350 just bigger bore an stroke.If your not planning on racing all the time a 2 bolt is "ok" 4 bolt being a lot stronger of a bottom end.You can get 500+hp out of a 2 bolt with out worry there's more power potentional in a 4 bolt.I have a 2 bolt that made around 400hp

 

From what I under stand... The 1972 turbofire 400 came stock with 225 HP...
That Motor/Block is actually getting rare. 2 bolt Main motors will hold some power torque...
But in the long run, My choice would always be a favorable
4 bolt main.... Power torque and reliability/buildability is why I would choose a 4 bolt main motor.

Its kinda hard to say which is the best way for you to go.... What vehicle did the 350 come out of? or what is it in?

also, if you take the numbers off the block (at the back lip of the motor at the trans mounting flange is where you find it.) Then call or go to a deale ror possibly look it up on line (the numbers) will be how will be able to tell if its 2 or 4 bolt mains without having to pull the pans off the motors.

 

You can always go with an LSX truck engine they have 6 bolt mains an a stock bottom end hold 600-700+HP.

 

With the 400 blocks, you need to consider that there isn't much meat in the main cap area for the 4-bolt caps. For the occasional racer, you might be better off with the 2-bolt block.

The 400 is a good powerplant to start with. I have a friend running 10s in his 78 El Camino with a 400 SBC.

 

Thanks Iceman!
That some really good info I had no idea!

 

Don't forget you can put a main girdle in the bottom end to strengthen it up too.
Good for higher powered 2 bolts