72 Chevy truck

Well as some of you guys may know im a big chevy fan and my family has all GM products. well im going to buy my grandpa 72 chevy that he bought brand new in 1972. it has a 400 small block farily clean except he used to live in nebraska so it has some rust that will need to be fixed but otyher wise farily clean.it will get completley re-done. my question is do you guys think if i put a a 5.3 or 6.0 vortex engine in it will it get better gas milage?? casue your still pushing around a brick? pics will come

The mileage on a 6.0 may not be much better, but it sure will run a whole lot better. Hp to HP the 6.0 will be alot more tame in a higher hp range, as in idle, and starting. You can make 600hp with a 6.0 and not really even have a rough idle. Your mileage will depend alot on trans choice, and gearing. You could probably get in the 16 mpg range, and still be peppy. We put a 6.0 in my cousins 70 chevelle, and used the 4L80e trans and rearend out of the donor pickup. It puts 625 hp to the rear wheels. It gets around 14 mpg on the highway, with 4.10 gears in the rearend. The 5.3 if built can also make about the same hp. Good luck

The question is will you recoup the cost of a motor swap in fuel savings?

I'm a fan of leaving things original provided they didn't come with an inline 250 or 292...I have a buddy that would argue that, but its besides the point.

A SB 400 would/could be just as fun...they make FI kits but they are pricey too, starting in the winter would be easier for sure.

Whatever you decide, 67-72s are b-e-a-utiful trucks. Good luck with the project.


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Well I would leave it with the 400SB but I'm looking for gas mileage but power the truck is going to be drove almost everyday. So I'm not sure what mpg a 5.3 would get in that truck??

And I think it's got 3.73

A 350 would be cheap and get good mileage. They are everywhere and there's a huge aftermarket for them too.


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You could get pretty good mpg with 400. Rebuild it, install an overdrive trans. A 4 barrel carb will get good mpg, if you can keep from getting into the secondarys very often. A 2 barrel will not get as good because of the size of the jets. Your primarys on a 4 barrel are smaller. There are just alot of optins out there.

Are you saying a naturally aspirated 6.0 is making 625rwhp on pump gas through and auto and 410 gears?

Yes, it is stroked to 6.7, different pistons, crank, rods, worked heads, bigger injectors, long tube headers and tuned computer, on 91 octane premium gas. The 4L80e trans was worked by tci, and we narrowed the rear end, and installed a limited slip diff.

Oh guy I was not thinking..... I forgot to tell you it's a 4 wheel drive... There went the mpg lol but if I were to keep the 400 or put in a 350 in it why not just make fuel injection???? And if I were to do a 5.3 or something I would put a 4l80e or 60e in it.

[QUOTE=djbrun;5380659]Are you saying a naturally aspirated 6.0 is making 625rwhp on pump gas through and auto and 410 gears?[/QUOTE]

The power of a Chevy ;)

[QUOTE=happymachinist;5380024]The question is will you recoup the cost of a motor swap in fuel savings?

I'm a fan of leaving things original provided they didn't come with an inline 250 or 292...I have a buddy that would argue that, but its besides the point.

A SB 400 would/could be just as fun...they make FI kits but they are pricey too, starting in the winter would be easier for sure.

Whatever you decide, 67-72s are b-e-a-utiful trucks. Good luck with the project.


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I had a 1966 Chevy c10 that was nice bought it for a good price with a rebuilt 327 SB needed a new 4barrel carb and 4speed tranny and exhaust but was new redone inside and outside. I was going to make my own bed rails for it oak wood or redwood. Nice truck your buying there too I almost bought a 72 before.

I am just curious what MPG are you trying to achieve exactly, because gas mileage in trucks hasn't really improved much if any at all over the last few decades. Power/Gallon has but again what exactly are you trying to build. If you just want economy a straight 6 with a one barrel is the way to go, lol!

IMO you cant go wrong sticking with the 400! It will give you more than enough power, I would only put money into fuel injection if you are worried about stalling on a incline or decline or have concerns with cold weather being a problem. You won't save enough fuel with EFI to justify converting it or make any more power over a properly sized carb.

Not sure if this has been mentioned yet, but a transmission swap would probably be very effective in increasing mpg.
The 5.3 vortec in my 2011 Yukon will get an average 18.7 mpg rating. When keeping a steady speed (on the highway, interstate, etc.) It will get 35 or more. (cylinder deactivation).

[QUOTE=1979chevy.;5381746]Not sure if this has been mentioned yet, but a transmission swap would probably be very effective in increasing mpg.
The 5.3 vortec in my 2011 Yukon will get an average 18.7 mpg rating. When keeping a steady speed (on the highway, interstate, etc.) It will get 35 or more. (cylinder deactivation).[/QUOTE]
Agreed the tranny swap would be a good idea something to reduce and add a better tranny. I know my cousin just installed a new tranny in his 69 camaro w/350 motor. He's getting 21-24 now hwy. Hes upgraded the engine so mpg would have been more if it wasn't for his upgrades and the carb he has on it. I know my Malibu if it had a 5speed instead of a 4 speed it would be getting near 38-40 mpg instead of 30-32 right now with v6. Get the carb and tranny on there.

Well.... That sound reasonable so are you guys thinking like a 4l80E or 4l60e???

[QUOTE=johnzillia54;5382737]Well.... That sound reasonable so are you guys thinking like a 4l80E or 4l60e???[/QUOTE]
4180e is the best by far but I just read there are limited aftermarket parts for this model.
Both are four speed as you may know.

Well I thought of something the 4l80e is electronic, I haven't looked in to stuff, but I would go with the 80 instead of the 60 because the 80 is 3/4 ton and 1 ton so idk I might go with the 700r4??

my cousin just got the 700R4 in his camero and hes getting good gas mileage now and runs smoother. He paid near 2K for it but worth it he said in the end.

Well I have decided what to do.... It's going to get a 6.0L Ls ( vortec ) but my problem and I need your guys help, but do I need a adapter plate to put my turbo 400 tranny behind it?? And if I do can you guys help me out finding one?? Thanks

for older trucks and cars i tend to go to: Summitracing.com they carry alot of stuff there and great info you can get free catalogs as well so you can have a catalog for reference.

Well I did a google search and couldn't really find anything??

Why not swap in the correct tranny as well, doesn't really make sense to put a new engine on that antiquated gear box. Especially if gas mileage is of concern. Aftermarket standalone controllers are available for the 4l60/80E trannys, that will work with any setup.

Back when I had my 79' Bronco, I just perchased an entire drive train (Including the dash and gas tank.) out of a 96' Bronco and just started with that. It made the job pretty easy and very few mods to make it work. (Motor mounts, Drive shafts, and a tranny crossmember, and instrument cluster bezel.)
So, buying a drive train from a parts yard with engine and tranny combo that you want is a good option.

You should not need an adapter, it should bolt right up. What year 6.0. 2007 and newer you will neef the power train control module, on top of the ecm.

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[QUOTE=westoakmech;5409353]You should not need an adapter, it should bolt right up. What year 6.0. 2007 and newer you will neef the power train control module, on top of the ecm.

sent from my not so smart, smart phone[/QUOTE]

Well I'm sure what year yet I would like to buy a low mile one or find a donor truck with low miles, but I do know its getting a 6.0 lol but I just missed a 5.3 with tranny that was in a 2010 and had 27,000 miles for 1700 bucks!! But if you guys happen to know of find a low mileage 6.0 with the ecu and wiring let me know please. Also if you guys know of headers that would fit in the truck I would like to know. Also any input or things you guys think I would want or need please let me know thanks! And you guys ( even the ford guys ;) have to admit the ls engines are sweet I mean over 300 hp stock and you get unthinkable power of them!

Anyone have a link or something??
Thanks

Well..... I found a 5.3 on Craigslist and it had the 6 speed auto tranny, and engine harness with 27,000 miles and it came home with me for 1700$.... I'm not sure what it will go in but the 72 is an option.. :)

[QUOTE=johnzillia54;5415251]Well..... I found a 5.3 on Craigslist and it had the 6 speed auto tranny, and engine harness with 27,000 miles and it came home with me for 1700$.... I'm not sure what it will go in but the 72 is an option.. :)[/QUOTE]
That sounds like a good way to go, be sure to post some progress of your project when you get it going.