400sbc or 402bbc?

[SShultz]

I am going to be swapping out the 6.2 diesel for a gas motor. I have two complete engines still in the trucks at my father in law's house and I can take my pick. One is a 400 small block and the other is a 402 big block. Both are completely stock. Their both runners but could use a rebuild. I really have no experiance with either engine so any insite would be much appreciated. The truck is going to be converted into a close relative of the ORD cousin willard (minus coils for now) so fuel economy isn't a huge concern. I'm primarily looking for good power and torque with the biggest concern for longevity and dependability. PLEASE HELP ME!
Thanks in advance
SShultz

 

[mnstrburbon]

I would do the bb 402 gobs of torque and the 400 small block are known for running hot unless you drill out the steam ports in the heads and such.
I had a small block in mine it let go i had a 454 sitting there same as you and went bb lots more torque at idle conditions when crawling around its a big block.

 

[b454rat]

Both are great engines. But the 402 will have little more grunt than the 400. Make sue you have all the accesories on the 402, trying to find factory stuff can be a pain...

 

[6.2Blazer]

I would do the bb 402 gobs of torque and the 400 small block are known for running hot unless you drill out the steam ports in the heads and such.
I had a small block in mine it let go i had a 454 sitting there same as you and went bb lots more torque at idle conditions when crawling around its a big block.

The factory heads already have steam holes, you only need to drill them out if you try to use a set of heads not originally from a 400.

The whole "400's will overheat" subject has been beat to death, but a lot of people who have actually had a stock or properly built 400 say it's a non-issue.

 

[pauly383]

I would use that .030 over 396 . Convert to full roller valvetrain and go climb out of a hottub in Moab while laying four rubber tracks

 

[SShultz]

Thanks!

Both of these motors are sitting in the origonal trucks in my father in law's back yard he said I could have either one. Both of these trucks ran well when parked so all of the accessories are there! It looks like I'll be going with the 402 now.
Thanks for the insite guys!
SShultz

 

[jtrux]

Both of these motors are sitting in the origonal trucks in my father in law's back yard he said I could have either one. Both of these trucks ran well when parked so all of the accessories are there! It looks like I'll be going with the 402 now.
Thanks for the insite guys!
SShultz

If it's being pulled from the truck, you should have all the bracketry so it shouldn't be an issue and it will probably be the short water pump setup which I prefer. I would probably start the engine while it's in the other truck first before going through all the trouble of swapping it over just in case.

 

[SShultz]

I have seen the engine run already. Just being the guy I am I'm gonna send it off and have it bored, have a head job done and get the crank machined just to be absolutely sure of everything. So the engine will be basicly new when it goes in the truck.
SShultz

 

[pauly383]

It will be a 406 or so after another .030 over. See how much taper it has , maybe your machine shop will leave bore as is so you can leave room for a future bore job .

 

[mnstrburbon]

The factory heads already have steam holes, you only need to drill them out if you try to use a set of heads not originally from a 400.

The whole "400's will overheat" subject has been beat to death, but a lot of people who have actually had a stock or properly built 400 say it's a non-issue.

quote quote and quote again well i guess if its been talked about it never happpens sorry,
all these replyies and a diesel guy throws the small block into the mix.

 

[abig84]

The whole "400's will overheat" subject has been beat to death, but a lot of people who have actually had a stock or properly built 400 say it's a non-issue.

yeah im one of those people. going on like 4 years with my 400, had it in the hottest conditions, offroading, towing, never came close to overheating

 

[sweetk30]

i would go big block any day.

and i had a built 400 sb in my last truck. ran 210 all day empty or pulling 6-7 k lbs at 65mph on highway.

even tryed fan shroud no shroud clutch fan non clutch fan. no big diffrence.

so 400 sb is warmer but all good.