i have a 1974 Chevy 400 2bolt out of a truck i wanna put in my IROC the only specs on the motor i could find are 150hp 295torque STOCK. after finding out the motor only had 150hp compared to my 190hp im alittle worried this motor swap might just be a waste of time and money the plans are to get the heads redone and cam it. also i am debating on keeping my TPI intake or swaping to Carb i know with carb i will gain more power. so i was wondering if this motor swap is worth the time and money and how much power i could expect outta this 400 with a limited budget

 

400s were built for tq, not hp. they went in heavy trucks and cars. you can build a high hp 400, the same you can build a high hp 350. theyre basically the same block with only a few differences. building the 400 will cost a lil more than an equal 350 since you cant interchange all of the parts with the 350s (like the crank and pistons).

 

The lousy heads are going to be the limiting factor here.

 

If you buy a set of heads for it the motor will make great power. Look into a set of vortec heads bring them to a machine shop let them drill the steam holes and put them on! Get a nice mild cam and you will have a strong motor with gobs of torque. Look into the lunati 60201 or the comp xe262h.

 

very misinformed. a 400 built with the same money as a 350 will make more hp than a 350 and ALOT more torque. heads, boost the compression up and cam it, the nodular 400 crank has been known to take 450 hp no problem

 

This is what i found when i got the casting numbers off the block

3951509 400 73-76 Pass 2 bolt main, 2 freeze plugs per side
3951509 400 75-80 Truck 2 bolt main, 2 freeze plugs per side

 

All the casting # tells you, is it's a 400.

As it sits, it's .... a turd. But, a turd with PLENTY of potential. Just don't hallucinate that you're going to drop it in as-is and set the world on fire.

Good heads, a decent cam, good exhaust, .... it becomes a whole other matter.

Yes it costs a bit more to build a 400 bottom end than a 350, but not a whole lot more. Might be a 20% premium or so, not too much considering that you get more in exchange for spending more. But if the short block is OK as-is, run it; just don't take it past 5500 RPM or so very many times and expect it to survive. The crank will most likely break, that's how they usually fail. Build it to make good power below that, and it will last as long as any other SBC.

Any idiot can drill the steam holes, even me. If I can do it then surely somebody with some actual brains can handle it.

 

Found these heads on craigslist for $250 casting number 3973487 would they be any better than the stock 400 heads?

 

Yes, they would be better. Probably not as good as Vortecs, though.