Engine choice (gas mileage)

[GMCOneTon]

I just bought my dad's '67 C-10 Suburban (engine-less), and have several choices for an engine to put in it.

Vehicle info: C-10 w/most heavy duty options, originally a 220HP 327, NP435 4-speed, 3.73 gears.

Choice 1: An L-46 Corvette 350 - a 350HP, hyd. lifter engine with 11:1 compression and 492 code heads.

Choice 2: Undetermined-as-of-yet early-ish 4-bolt main truck 350 - not newer than late 70's-early 80's, and 95% stock.

Allowing that each engine would have a carburetor on it that would be optimum for that engine's best fuel economy, and all other factors are equal, how much difference in gas mileage difference could I expect between the two? (Best highway mileage.)

Thanks!

[SUBURBIAN]

Choice 2. You won't have much luck saving dough running hi-test and additives in an 11:1 engine on today's puke...I mean gasoline.

[GMCOneTon]

That's what I would have guessed. I'm more curious as to how much difference there will be between the two engines, as I'd like to take the Suburban on a trip over Halloween and need to find an engine fairly soon.

Also, I'll add a choice 3: A big block 366. How do these do on fuel economy, and how would it perform in a light truck as opposed to the dump trucks and school busses they were originally put in?

[kirk]

Also, I'll add a choice 3: A big block 366. How do these do on fuel economy, and how would it perform in a light truck as opposed to the dump trucks and school busses they were originally put in?

Big block and fuel economy should never be used in the same sentence :lol:

[GreaseDog]

gear ratio, tire size, trans? also is it 2wd or 4wd

[Jameslleary]

I just bought my dad's '67 C-10 Suburban (engine-less), and have several choices for an engine to put in it.

Vehicle info: C-10 w/most heavy duty options, originally a 220HP 327, NP435 4-speed, 3.73 gears.



3.73 is awful high(numerically) for a 2wd if you want gas mileage. If you have the $$$, I would just get an 87-95 replacement truck engine from GMPP. 200hp, 300 ft lbs.
That may differ a little either way with a carb.
A dual plane manifold, and a Quadrajet from SMI carbs, and nice exhaust with some kind of turbo muffler, or really long straight through muffler, and you should be good. Remember when choosing exhaust, Suburbans are an echo chamber, so choose carefully. Dont get caught up in the Horsepower and torque wars, its not a Corvette....200 hp is more than enough to keep her moving.
Or, you could find a wrecked trailblazer with an Inline 6....would be intresting restomod. And I dont want to hear about how the atlas I6 won`t move that truck, cause its a load of ****! My burb came from the factory with 165 hp, and 285ft lbs. and moved just fine.

[454cid]

That's what I would have guessed. I'm more curious as to how much difference there will be between the two engines, as I'd like to take the Suburban on a trip over Halloween and need to find an engine fairly soon.

Also, I'll add a choice 3: A big block 366. How do these do on fuel economy, and how would it perform in a light truck as opposed to the dump trucks and school busses they were originally put in?

I'd go for the 366 if I had it already......... I'd hope for 10mpg (optimistic guess), and be pleased with anything more. What's the 67 weigh?

[SUBURBIAN]

Still choice 2. It's a choked up smogger 350. It will run on 87 octane, easily make more torque than the original 327 ever did, and power the truck just fine. Everything's there for it, will all hook up & have billions of choices (price levels) for parts support, and will unquestionably match the remaining parts the truck was born with. Beyond that, will respond to upgrades and is an sb friggin c.

[ryan_thompson87]

:iamwithst

If he wants to play with it after you can easily do it and still run 87.

[Fast305]

I would run choice #1, except sale those 492 heads to a Corvette/Camaro purist and find some larger chamber aluminum heads to put on it. That would drop the compression down to 10:1. Swap out that cam and you will have a nice engine.

Or choice #4, find a L30 or L31 vortec engine, toss a carb on it, and get a modern set of fast burn heads and a roller cam out of the deal. The L30 305 Vortec put down more HP and nearly as much TQ as just about any 350 from 1973-1995.

[SUBURBIAN]

I would run choice #1, except sale those 492 heads to a Corvette/Camaro purist and find some larger chamber aluminum heads to put on it. That would drop the compression down to 10:1. Swap out that cam and you will have a nice engine.

Or choice #4, find a L30 or L31 vortec engine, toss a carb on it, and get a modern set of fast burn heads and a roller cam out of the deal. The L30 305 Vortec put down more HP and nearly as much TQ as just about any 350 from 1973-1995.

Sound, but pricey advice. Good luck finding someone that is dying for a set of 492's in questionable shape.

[GMCOneTon]

Thanks for all the replies, guys. I ruled out the 366 - a nice experiment, but it wasn't looking very practical. I'd love to buy a brand spanking new 350 from GM, but just don't have the $$$ for that. It's looking like I'm either going to wind up with the 350 that dad had intended to use in the Suburban but sold when he gave up on putting it in (I may be able to buy it back) or a local 327 or 350 that looks solid.

To answer one of the prior poster's questions, I'm not sure how much it weighs and it is a 2WD.

[vic_V8]

why not put a nv4500 in it and get OD, that is more gas mileage than anything

[GMCOneTon]

It'd be cool to experiment with different drivetrains components and see just what it could do, but right now I'm just looking for bolt-in pieces that'll do the job and will get better gas mileage than my 454.

[vic_V8]

the NV4500 is damn close to direct bolt in