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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 454Man on February 08, 2012, 09:33:37 pm

Title: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 08, 2012, 09:33:37 pm
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
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: bake74 on February 09, 2012, 07:14:00 am
     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.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 09, 2012, 07:51:22 am
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
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: bake74 on February 09, 2012, 09:01:23 am
     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.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: thirsty on February 09, 2012, 09:59:36 am
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!  ;D

I vote to keep the 454 in there. I always wanted to put a big block in a swb 4x4.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 09, 2012, 10:10:06 am
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
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: VileZambonie on February 09, 2012, 10:48:39 am
Just let the air out of the tires.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: choptop on February 09, 2012, 09:35:31 pm
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.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 09, 2012, 10:00:36 pm
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.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: bake74 on February 10, 2012, 01:03:03 am
Just let the air out of the tires.

     That's funny, not recommended but funny.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: choptop on February 10, 2012, 06:57:18 am
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.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 10, 2012, 01:01:52 pm
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?
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: choptop on February 10, 2012, 09:54:36 pm
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.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: bake74 on February 11, 2012, 07:32:17 am
if it runs good. Don't fix what's not broke.

      That right there should be the quote of the day. 
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 11, 2012, 01:55:59 pm
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

Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: choptop on February 11, 2012, 03:14:53 pm
I think the 366 heads are small oval port, but not 100% sure. Wont be a horsepower monster but should still have decent torque. Question is,  is it worth the price they're asking to you. You're gonna have to drop a bit more money on it before you'd have a trust worthy driver in my opinion
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 11, 2012, 03:38:44 pm
Yeah so far I'm looking at a spare rim 2 new tires gettin a qjet rebuilt. That's gonna be about 600 right there.  Oh and the eletric fans another hundred or 2. Ima try to talk em down on the price. Righ now its 8500 a bit high I think. I know they are gonna say I got over 14k in it.


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Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: choptop on February 11, 2012, 06:55:51 pm
$8500 is too steep for my blood. I have $5500 total in my red truck and that's new tires and wheels plus all I spent on swapping the rear axle.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: bake74 on February 11, 2012, 09:48:22 pm
Yeah so far I'm looking at a spare rim 2 new tires gettin a qjet rebuilt. That's gonna be about 600 right there.  Oh and the eletric fans another hundred or 2. Ima try to talk em down on the price. Righ now its 8500 a bit high I think. I know they are gonna say I got over 14k in it.


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      aarrgg, someone shoot the poor thing.  ;D  At $8500.00, that is what you call shooting for the moon but hoping for a piece of the desert.
     If it was me and I really liked it, I would add up what it is going to take (granted there is probably more you wont know about until you drive it awhile), and offer him less than that figure and add about $300.00 -$400.00 more for unexpected things. 
     When he comes back and Say's I put $14000.00 into it, I would just simply and politely say, I will be more than happy to pay you $8500.00 if these things did not need to be fixed, I have to fix them to be able to drive it. 
     He might not take it, but keep in touch with him, and in a week or so when he doesn't sell it, your offer will look more and more appealing to him.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 11, 2012, 10:01:43 pm
Hey man I really apreciate you being straight forward:)
I do like the truck, but I'm really stumped on why he's thinkin to ask for that price and the truck has issuses. I for got to shift into 4x4 to see if it works or has any weird sounds.  I checked into the 366 engine and heads on the net and they were mostly for tow/ heavy load applications. Like school busses and dump trucks. Oh the dng thing has a hole in the bed from the that big towin hitch folks use to tow dem big horse trailers:( so with the hole and the 366 tall port heads I now know what the engine may have been through
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 11, 2012, 10:03:10 pm
And sad thing is I actually like the dang truck. It doesn't smoke like I do lol

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Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: bake74 on February 11, 2012, 10:21:27 pm
Hey man I really apreciate you being straight forward:)
I do like the truck, but I'm really stumped on why he's thinkin to ask for that price and the truck has issuses. I for got to shift into 4x4 to see if it works or has any weird sounds.  I checked into the 366 engine and heads on the net and they were mostly for tow/ heavy load applications. Like school busses and dump trucks. Oh the dng thing has a hole in the bed from the that big towin hitch folks use to tow dem big horse trailers:( so with the hole and the 366 tall port heads I now know what the engine may have been through

     That is what I am here for.  It is not a total loss yet, I have taken tools and a compression checker with me on some of these truck purchases, if they are wanting to sell it they will let you check it out.  It just gives you more "canon fodder" as they say when talking final price.
     And besides, you don't want to overpay for a truck you will regret later.  Go back a second time and ask to test drive it again, that shows him you are interested, and he might trust you enough to check it out more.  Just my advice and what I have done over the years.  ( I am the guy who everyone around me wants to go with them when they buy used vehicles, and for good reason, I look at everything and not afraid one bit to ask the tough questions the seller might be willing to hide)
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 11, 2012, 10:48:59 pm
Thanks! I will go back a second time with a vac gauge and my timing light.  Id like to see if I can get him to fix the broken stuff or lower the price. Be nice if he lowered it to 5k,but idk
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 13, 2012, 05:33:24 pm
Ok, so taking yalls advice I'm gonna look at another chevy swb. This one has a 350 block, vortech heads, double roller t chain, 10 year old paint he says is clean, performer intake, holey carb, comp cams http://m.summitracing.com/parts/CCA-12-246-20
Has all the ac parts can be charged but says the compressor fron seal prob leakin. No prob I have an A4 I was gonna use for another ride that may work. New headliner, seat. Died door panels(idk) eaton posi, motive 3:42 gears:). Now to see how it runs, drives, looks in person
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 13, 2012, 05:43:51 pm
Oh is it possible to find a spread bore intake for the vortec heads so I can put a qjet on?
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: TexasRed on February 13, 2012, 05:51:42 pm
most of the intakes are spreadbore, the performer if it's base should be spreadbore.
Title: Re: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: 454Man on February 13, 2012, 06:09:11 pm
most of the intakes are spreadbore, the performer if it's base should be spreadbore.
Cool, thanks!
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: VileZambonie on February 13, 2012, 06:18:42 pm
Just let the air out of the tires.

     That's funny, not recommended but funny.

Why do you say that? We do it all the time on large trucks.
Title: Re: 1980 swb 454, 35s..... mpgs/ performance
Post by: bake74 on February 13, 2012, 08:18:45 pm
Just let the air out of the tires.

     That's funny, not recommended but funny.

Why do you say that? We do it all the time on large trucks.

     I did that once to change out a engine on a friends truck, I guess we let out to much and they were old tires, when we tried to inflate again, it split the sides on 2 tires.  :o