Hi everyone i'm planning to swap a sbc 406 (400 .030'' over) (509 casting number ) 2 bolts main w/ stock 882 ported heads in my '89 Firebird wich is currently running a stock 305 TBI (LO3) , 700R4 trans and 10 bolts 2.73 rear end (recently rebuilded by myself) . The motor will surely develop at least 400hp with 10.5 :1 comp ratio when it's over . My question : will the stock trans and rear end will take the power on street 245/50r16 tires ? And do I absolutely need Frame connectors ?

 

The trans and rearend will hold up fine as long as your not racing it on sticky tires. With 400 HP,over time (depending how good/not good the trans is) the trans will take a crap...its nature of the beast. A 700 can be rebuilt to handle 400HP fine,as long as its done by someone who knows what their doing.

With a stout motor like that,I would say you need to put some 3.73 gears in it. Bottom end will be awesome b/c of the steep first gear ratio in the 700-R4 but it will turn 1900 RPM's at 60 mph. My old 87 had that combo so thats why I know.

Putting a trans cooler on it will help also,and I recommend you put one on it if you havent already. You can find them at your local parts store for like $20-$25.

 

I had a 87 formula with a 383 in it .The 700R will handle the power if build to . The rearend is the weak link here . I broke mine in just two weeks .I had a 9 inch build for it .Its still in the car today.Its fun combo in a 3 gen . It can handle the 1/4 mile and still turn at the end .

 

moving to 3rd gen.

 

with the stock 882 heads you are not going to make 400hp

 

Your asking a nearly 20 year old transmission to do an awful lot. It might hold for a while, or for a long time. I'd have it rebuilt before install with good parts at a reputable shop. The rear will be fine, hopefully it has a good posi. Subframe connectors should be the first mod to any thirdgen. Well before an engine swap.

 

Well Thanks a lot guys these tips should help ...

 

With the 406 (or the 409 in my case) the 882 heads are choking your engine to a point it will only put out about 285 rear wheel hp. The just do not flow enough air for this big of an engine.

I ran those heads on my 67 C-10 bracket racer for a couple years. It ran consistent 13.80's @ 98 mph with the 882 heads. I Changed the heads to a set of Sportsman II iron heads with 72 cc chambers & rejetted the carb and the truck dropped into the 12.90's @ 105 mph with no other changes. In my case this was a 70 hp increase by trap speed comparisons.

With the better heads I can also bump up the cam size in the future when I want to go faster. With the 882's you are stuck at the 285 hp mark due to the poor air flow.

You will destroy the 7-5/8" 10-bolt the first time you hook up. I originally had my 409 in an 83 Z/28 and even with the old heads the small ring gear couldn't handle the torque of the 409 and weight of the 83 with sticky tires. Your drivetain will be a ticking timebomb with the torque output you will have. The driveshaft was next with mine because it was a Super T-10 4-spd but the 700R4 in stock form will need some help to live reliably behind your 406.

Good luck.