1980 swb 454, 35s..... mpgs/ performance

[454Man]

Hello all! I'm looking into gettin an 80 swb with a 454 block and 396 heads. The truck is fram off resto. Very nice and clean. It has 35s 4inch lift, and a 350 trans. I know this is a stupid question but what should I expect mpg wise? I plan to drive the truck daily to work.  Is there anything wrong with a 454 block with 396 heads? Thanks and any help is appreciated

[bake74]

     You should expect 9 - 12 or so depending on how it's tuned and your driving habit.  What year is the 454, the 396 was stopped being produced in 69 I believe (chevy bored out the 396 in 70 0.030" making it a 402, although they still labeled it under the 396 badge), the stopped producing the 396 in 72.
     If you really love the truck you could always swap out the 454 and sell it and put in a 350 or even a 305 if you want good gas mileage.  If you want to step on the pedal and have crazy power, leave the 454.

[454Man]

That's what I was thinking. I may keep it and get my qjet rebuilt from cliff ruggles or everyday performance. If that doent work I may look into a 350. But seein how its lifted wonder how hard ima have to work to get the engine out and a new one in

[bake74]

     If you do a engine swap, take the tires off, use several jack stands so it will not go anywhere and then swap engines, makes it easier if it is lower.

[thirsty]

You can pull the front clip off too. Then you don't have to pick the engine up as high to get it out if you swap engines.
Be careful doing this though because that's how frame offs start! 

I vote to keep the 454 in there. I always wanted to put a big block in a swb 4x4.

[454Man]

Good idea never thought to take the wheels off to swap engines. I'm one for runnin the 454 but if the mpgs are way too low after tuning then may have to down grade. I'm gonna go and check the 4x4 out this weekend hopefully

[VileZambonie]

Just let the air out of the tires.

[choptop]

I don't think putting a small block in the place of a bigblock is going to solve the mpg problem caused by the 35s. If anything else it seems to me that it will amplify the problem. Its gonna take torque to turn those babies and the bigblock has it at alot less throttle than the smallblock. My red 85 has 35s and 3:73 gears and I get maybe 13 mpg with a 350 and I know its tuned properly. I do have a heavy foot tho.

[454Man]

I don't think putting a small block in the place of a bigblock is going to solve the mpg problem caused by the 35s. If anything else it seems to me that it will amplify the problem. Its gonna take torque to turn those babies and the bigblock has it at alot less throttle than the smallblock. My red 85 has 35s and 3:73 gears and I get maybe 13 mpg with a 350 and I know its tuned properly. I do have a heavy foot tho.

Didn't think about the torque needed, but your right. I'm not quite sure what year the block and heads are, but what purpose would there be to putting 396 heads on a 454 block? More compression? That's all I can think of.

[bake74]

Just let the air out of the tires.

     That's funny, not recommended but funny.

[choptop]

The 396 heads could have been swapped for several reasons. They may be closed chambered for more compression, large valves or intake runners or just the only thing the previous owner could find. I think they even made a small oval port 396 head so it may make very little difference.  You wont know till you pull the heads and take a peek, but I wouldn't do that if it runs good. Don't fix what's not broke.

As far as letting air out of the tires to work on something, I've done it for years. If your running 20a inch rims, it wont do any good.

[454Man]

Ok so the 396 heads may have been a good idea great! The 35s are on 15 inch rims.
This is my first 4x4 guys. Is there anything y'all recomend not doing? Like shifting into 4x4 while moving, driving around corners at a certain speed, are bf goodrich alterain tires any good for the street? And last how fast can I drive responsiblely on the highway?

[choptop]

I've run BFG a/t's on several vehicles without any complaints.  I put 50,000+ on my last set but it was on my 08 work truck. As far as speed, I've driven 70-75 mph on my 35s without any issues,but it would probably do better once I get my front swaybar hooked up. The roads are pretty much straight and flat here. Alot of it is going to depend on how tight the front end and steering box are. Just use caution until you find out how your truck is going to handle.

[bake74]

if it runs good. Don't fix what's not broke.

      That right there should be the quote of the day. 

[454Man]

Well guys good news and bad...
I went to check out the truck and here's what I found
Bad...
Ac doesn't work
Blower doesn't work windsheild wipers don't function
Rear tires are crackin between the tread
Front diff is leaking
Passenger door power window or track needs to be worked on
Has a elda broke (lol) 600cfm on it
They don't know jack about settin the timing. I asked and he tried to find the base timing. With the vac advace hooked up.
No fan shroud??? And the radiator sits like four inches higher than the engine
The lift is a body lift. Hints the last line:(
So to drive it in texas heat id have to do eletric fans
May be more but ill start with the good
Good...
Two new procomp 35s up front
The engine runs good and has good oil pressure while driving
Oh I was wrong about the heads they are 366 heads. Can someone validate these are good please...
Excellent paint job like a pro did it.
New carpet, bench seat, headliner, dashpad, door panels look good.
New rear bumper and a custom front bumper.
It handles good
New rear brake lights
New front grill
Mabe more let me think