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Should I Or Should I Not Keep The 454 Carbureted And Put In A 350 In A 83 Suburban C20 Dually?

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blackandgold51

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I got a 1983 Suburban C20 Dually(I'll send pictures in other post of it) Converted that has a 454 Carbureted wit a Turbo400, along with longtube headers and dual exuast.

I'm worried bout fuel mileage which I wonder about putting in a 350. Although today I took out the big air filter which was taller than a regular filter which been causing a problem with fuel mileage.

One thing I worry is that if I put in a 350 will it still come close to pulling heavy loads like the 454
 
No the 350 will not pull anywhere as good as a 454, plus the 350 isn't going to get that much better mileage, having a suburban and wanting good mileage don't really go together.
 
IMG_20180419_085811_zpsb9pej1vf.jpg
[/URL][/IMG] here's one photo of the suburban it's a 2 wheel drive

[URL=http://s1160.photobucket.com/user/oatisthesaint/media/IMG_20180419_085811_zpsb9pej1vf.jpg.html][/URL]
 
H20 Toie said:
No the 350 will not pull anywhere as good as a 454, plus the 350 isn't going to get that much better mileage, having a suburban and wanting good mileage don't really go together.
Click to expand...

I agree. I might as well just enjoy the 454.

Besides, I got a second vehicle which is a 1999 Crown Victoria
 
H20 Toie said:
No the 350 will not pull anywhere as good as a 454, plus the 350 isn't going to get that much better mileage, having a suburban and wanting good mileage don't really go together.
Click to expand...
Very true! And wanting it to tow a trailer is a big factor. And then having a dual wheel axle adds to it as well.
That would be like having a long hood KW with a huge sleeper, and taking out the 600 horse Cat to put in a little 11 liter engine to save fuel.
Not cool , or actually helpful.

:D

Nice suburban!
How about a front shot?
 
The 350 will get worse gas mileage most likely,it'll be straining to pull that big Burb around,the 454 will tow much better and make it cruise with less effort and your foot further away from the floor..

I've had 454's in 2 pickups and both got a tad better mpg than any of the small blocks I had in similar trucks..one was in a 3/4 ton 4x4,the other was in a '74 C10 2wd..the '74 got up to 15 mpg,it had a 3:08 diff in it,the 4x4 had 4:10s and got about 12 mpg,regardless of what type of use you were using it for..
 
6872xtc said:
Very true! And wanting it to tow a trailer is a big factor. And then having a dual wheel axle adds to it as well.
That would be like having a long hood KW with a huge sleeper, and taking out the 600 horse Cat to put in a little 11 liter engine to save fuel.
Not cool , or actually helpful.

:D

Nice suburban!
How about a front shot?
Click to expand...
Look down at front picture i posted.

And you're right. It's best to keep the 454 . Besides I got a small(although large) vehicle which is a crown Victoria(1999)
 
6872xtc said:
Very true! And wanting it to tow a trailer is a big factor. And then having a dual wheel axle adds to it as well.
That would be like having a long hood KW with a huge sleeper, and taking out the 600 horse Cat to put in a little 11 liter engine to save fuel.
Not cool , or actually helpful.

:D

Nice suburban!
How about a front shot?
Click to expand...
And like I said in my other post . I don't drive like a maniac. Im easy on the throttle and drive under the speed limit or 5mph below the speed limit. I wish I had a three speed transmission though
 
6872xtc said:
Very true! And wanting it to tow a trailer is a big factor. And then having a dual wheel axle adds to it as well.
That would be like having a long hood KW with a huge sleeper, and taking out the 600 horse Cat to put in a little 11 liter engine to save fuel.
Not cool , or actually helpful.

:D

Nice suburban!
How about a front shot?
Click to expand...
Lol a Kenworth with a 11 liter. I like Kenworth by the way
 
1) What will you be towing? How much weight?

2) How much driving will you do?

3) What's your rear axle ratio?

i am debating this very question myself---which engine to put in a 3/4 suburban? 383, 350, 6.2 diesel.........or even smaller?

IF you have the right gears, even a 305 could do it. But it will be SLOW.
 
I've got a 1976 k5 with 3.08's 31's and a 6.6 liter small block.
Passes anything on the road except a gas station.
Takes the 10% grade towing a 4,000 lb trailer in second gear at 60 mph.
Gets 5 mpg towing the grade.
10 mpg unloaded everywhere else.

Now my m1009 has a 6.2 diesel 3.73's 33's.
Gets 8 mpg towing the same trailer and grade but in 1st gear at 25 mph.
Everywhere else it gets 17 mpg unloaded.

I had swapped those axles between the trucks.
When the m1009 had 31's and 3.08's it got 19 mpg.
When the 76 k5 had 33's and 3.73's it still got 10 mpg.

That 400 sb does one thing well; makes torque.
The price is very poor fuel economy.

The 6.2 does one thing well; gets good mileage.
The price is aneamic torque production.
The 3.73's helped towing but it does not hold a candle to the 400.
Not even close.

If i were the op, i would enjoy that 454 sub for what it is.
It will never get good mileage and if it did, would be a stink bug for towing.
 
vandelay industries said:
1) What will you be towing? How much weight?

2) How much driving will you do?

3) What's your rear axle ratio?

i am debating this very question myself---which engine to put in a 3/4 suburban? 383, 350, 6.2 diesel.........or even smaller?

IF you have the right gears, even a 305 could do it. But it will be SLOW.
Click to expand...
I'm keeping the 454 in. Besides, I don't drive fast and like a maniac like everyone else do. Such as driving cautious and below the speed limit or under the speed limit.


I had one vehicle blow a horn from behind me while I was going under 35 mph in a 35 mph zone( i-10 service road)
 
K5wrench said:
I've got a 1976 k5 with 3.08's 31's and a 6.6 liter small block.
Passes anything on the road except a gas station.
Takes the 10% grade towing a 4,000 lb trailer in second gear at 60 mph.
Gets 5 mpg towing the grade.
10 mpg unloaded everywhere else.

Now my m1009 has a 6.2 diesel 3.73's 33's.
Gets 8 mpg towing the same trailer and grade but in 1st gear at 25 mph.
Everywhere else it gets 17 mpg unloaded.

I had swapped those axles between the trucks.
When the m1009 had 31's and 3.08's it got 19 mpg.
When the 76 k5 had 33's and 3.73's it still got 10 mpg.

That 400 sb does one thing well; makes torque.
The price is very poor fuel economy.

The 6.2 does one thing well; gets good mileage.
The price is aneamic torque production.
The 3.73's helped towing but it does not hold a candle to the 400.
Not even close.

If i were the op, i would enjoy that 454 sub for what it is.
It will never get good mileage and if it did, would be a stink bug for towing.
Click to expand...
Nice color of that blazer,That military color of that blazer which I might put on the suburban soon or later.
 
A 454 will get better mileage than a 350...that is a good one!

You are getting 8 mpg now, I assume. I assume because your post, as mentioned, is lacking in facts. A 350 will easily get 25% better mileage (10).

But, your 454 mileage will not drop off much, if at all while towing. Depending on what is hooked to your bumper, a 350 could get 8, and be a real dog.

How much do you tow? That trailer that is pictured could be towed w.my 2.4 Nissan, and a 4.3, and a 305. A 350 would be overkill.

So, what mpg are you getting now?
What do you tow?
What is ur axle ratio?....my guess is that you could use some gears.
What is ur RPM @ 60 mph?
 
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