[erikgto]

Hi,

I've got an '81 Turbo T/A WS6 with TH350,3.08 posi rear and the current 400 needs some work, it has 6X8's and a Torquer II with Holley 750 which is a really bad combo for this engine

What would you do?

* redo my 400 mildly with 6X-4 heads and Summit 2801 cam (no boring, honing etc)

* Have my 455 block bored, honed etc. and build it with the 6X-4 heads and Crower 60916 cam (this will be more $$$ to build)

I am not gonna race this thing, it will be a cruiser.
I like torque and I don't rev my engines wildly. Maybe a little wheelspin now and then.

Would there be a big difference in fuel economy between the two (given I drive both the same relaxed manner)?

BOTTOM LINE; WHAT WOULD YOU DO?!?!?

[2manyT/A'S]

Personally,I'd go with the 400/6x4's with an 068 Pontiac grind & Edeltork Performer/Q-jet.

It's a proven combination.

You'll have TONS of good streetable bottom end & the 400 should yield some better fuel economy than the 55,depending on your driving habits,of course)

[Transam Stripper]

455 that way you won't regret you didn't build it bigger & badder. Losing sucks.

[form74]

I have the the same combo but with a crower 60919.

[Ben M.]

I have the almost exact same 400 combo in a '73 Grand Am with 3.23 gears and the car is a beast to drive. Lots of fun without being too much effort and hassle in the maintainability\drivability part. Putting a 455 is fun and I'd do mine too, but if it needs to be bored and honed, that is just extra cash that may not be available at the moment (especially if you need a sleeve or two like mine =P ).

I'd put a 301 turbo back in just for fun though ;-)

[Don 79 TA]

i don't think either one you can go wrong with
but it's always better to use the bigger cubes if you can

besides, the heavy second gens and the 455 torque make it a nice setup

i am in the same situation
i want to redo the 400, but also have the 455 in the garage. i know my 400 tune well, and know what i am after, with the 455 i'll have to rethink a few things, minor though

[triathlonx13]

No Replacement for Displacement! Go with the 455 if you can.

.

[bonneville Joe]

My 400 in my '78 4spd is a beast.

400 with 6X-4s, factory intake, q-jet and summit 2802 cam. 3:42 posi. Anyone that says 70s cars are slow, i make believers with this thing. It's a blast, makes tons of streetable power and runs like a mofo.

[BAD455TA]

NICE LOOKIN CAR MAN! If it were me and the 400 is original, then rebuild you can have a rowdy setup still...but if it's not...455!...Leave the 400 sticker on it and it will kinda be a sleeper!

[GREATGTO]

I would go with the 400 block with an aftermarket 4.25 stroker crank

[78savette]

Can't go wrong with either motor, I put a 455 in my 81 with the Crower 60919 and it runs great, not missing the 301 at all.

[Father&Son73T/A]

You can't beat the torque of a 455,I own a W72 and an L75 car,........455 all the way baby.......

[erikgto]

Thanks for your replies so far!!!

As it stands right now the choice is almost certain going to be the 455.

I'm waiting on Ken from PPR to get me some shipping info on the 5140 I-beams.
Got a lead on a nice set of 6X-4 heads.
Will use the Crower 60916 cam with matching valvesprings
I'll leave the TH350 as is (the way it shifts I suspect it has a shiftkit fitted) with the stock converter.
Keep the headers (unknow brand) that are already on the car, just need quality gaskets to prevent leaks.

I'll also ditch the Holley 3310 I got right now.
Looking into getting a Q-jet done by preferrably Cliff R.
A quality Q-jet might win back some mileage (providing I can keep my foot out of it!)

However I do think I'll need to save up for subframe connectors...I don't wanna risk any thing with the body and all that 455 terror-torque

.