RyanJB

I'm considering building a 400 for my firebird. Im just not sure if it would be worth it to build the 400 and stroke it or just build a 383. I also want to know from anyone who has already done the 400 swap: what did you do for engine mounts? How did you set up the pulleys? Could you keep AC?

adamemerson

A 400 will bolt right up where any other small block came from so you would not have to do anything to your motor mounts or your pullys

RyanJB

You can run standard SBC heads as well right? Meaning I could use my exhaust manifolds or headers?

TraviZ

iTrader: (2)

yes however make sure the heads you use have the steamhole provision.

RyanJB

Would any factory sbc heads have that provision?

mmadden55

No but you can drill them using the 400 head gasket as a template. I would build a 383 though. Better choices and greater selection in parts. You can get a complete rotating assembly from Tommy Johnson Motorsports recomend forged flatops and 6 inch rods.

900mile'92

it seems that the other members answered many of the pertinent questions. the engine displacement and internals depends really on intended use and the size of your budget. I prefer the 427 c.i. (4.00 stroke X 4.125 bore) alum SBC bowtie block route. however, the 383 crate motor from the general with alum heads and hot cam is a tough to beat value.

RyanJB

I'll take the bowtie option into consideration. I was planning on using a 70's iron block but that would most likely need to be bored and the Machine work might cost close to the se amount that block would cost. Thanks for the input everyone

900mile'92

we have done several 400 c.i. , 406c.i., 427 c.i., 434 c.i. motors over the years. the nice thing about a 70's block you referred to is that it is much lighter than a cast iron bowtie, dart, or world products block. however, 90% of the 70's 400 blocks you find are going to to have small cracks in the deck between the head bolt holes and the steam holes. and like you mentioned, you will be putting a lot of machine work money in the block including splayed steel 4-bolt main caps depending on your intended use. and even then, the block is going to be pushed to its original design limitation.

RyanJB

Sounds like I should abandon this idea before I get any money into it and just build a 350/383. Thanks for the help though.

ryan.1e

having just got my car running with a "factory" tbi system and a sb 400, the biggest pain i had was the flywheel. as you may or may not know depending upon your familiarity with the 400s in particular, as mentioned before, you will either have to drill the steam holes out or use the 400 heads, the factory exhaust manifolds will clear if the main tube drops below the exhaust ports as the early small block chevy block's oil dipstick will be blocked off with the f-body manifolds, (flowtech makes an awesome drop in header/y-pipe kit), and the 400s are externally balanced. the 3rd gen f-body cars transmission bellhousings will not clear a 168 tooth flywheel, manual or automatic. you have to use a 153 tooth flywheel/flexplate. a 400 balanced flywheel for a manual is about $350 as i found out. but summit racing carries a counterbalance weight that bolts on behind the flywheel for the 400 that costs about $45. if there is anything else you want to knw. send me a private message.

Regal105

the 168 tooth flexplate will fit inside the 700r4 bellhousing. 90's 454's and 6.2-6.5 diesels all had 168's and most had r4's, at least in light duty trucks.