Increased MPG for carbs?

[clinebarger]

LS swap....

[76Charlie]

Originally Posted by clinebarger

LS swap....

All day

[OJ1988]

Originally Posted by clinebarger

LS swap....

How much driving would you have to do to save enough gas money to pay for the swap?

I'm all about saving gas, but spending $5000 or so to swap will take a long time to pay off.

Thats like the hybrids, I didn't understand why people were going out and spending $20-30k on a car to save gas money???

[tylervalo]

Originally Posted by OJ1988

How much driving would you have to do to save enough gas money to pay for the swap?

I'm all about saving gas, but spending $5000 or so to swap will take a long time to pay off.

Thats like the hybrids, I didn't understand why people were going out and spending $20-30k on a car to save gas money???

Me and a guy I used to work with did the math on financing a new hybrid vs keeping a paid for gas guzzler. I think the hybrid finally became cheaper to own around 9-10 years. Might have even been longer.

[Firebirdjones]

Originally Posted by OJ1988

How much driving would you have to do to save enough gas money to pay for the swap?

I'm all about saving gas, but spending $5000 or so to swap will take a long time to pay off.

Thats like the hybrids, I didn't understand why people were going out and spending $20-30k on a car to save gas money???

Originally Posted by tylervalo

Me and a guy I used to work with did the math on financing a new hybrid vs keeping a paid for gas guzzler. I think the hybrid finally became cheaper to own around 9-10 years. Might have even been longer.

And that's the catch. I've found it makes more sense money wise to make what you have more fuel efficient first before you consider spending money on engine swaps and new cars.

Don't know about you guys, but I hate $500 a month car payments, plus full coverage insurance, expensive tags every year that are based on car values (in AZ) etc... That $30,000+ sure would put alot of gas in the tank of the car I already have.

That's not to say I'm against the LS swap. I did a 6.0/4L60 swap in my blazer, but an ailing transmission let me to consider an overdrive which led to just swapping the whole thing. In order to make that cost effective though, you have to plan to keep the vehicle for several years. I drive mine daily and have no plans to sell so it works out for me. An LS swap is still alot cheaper than a new car, and I'm not driving a cookie cutter car around I think you get the best of both worlds in my opinion.

The cost of the swap never really waivered me in any one direction however, I just knew I would enjoy the 6.0 power and the drivability the overdrive provides.

I was in the same boat with my 79 454 pickup. I don't drive it daily, it's just used for towing and hauling stuff. Would have loved a brand new duramax, but I couldn't justify spending $50-$60k on a new truck for something I rarely drive, and only gain about 3-4 mpg. The rising cost of diesel fuel finally put a lid on that idea. Now 40-50 cents more per gallon,,,,no thanks. I'd have dug a deep hole with those truck payments and then the cost to put fuel in it......OUCH!

If diesel were cheaper than gas like it used to be (and should be still) I probably would have a new duramax sitting here.

[OJ1988]

Originally Posted by Firebirdjones

And that's the catch. I've found it makes more sense money wise to make what you have more fuel efficient first before you consider spending money on engine swaps and new cars.

Don't know about you guys, but I hate $500 a month car payments, plus full coverage insurance, expensive tags every year that are based on car values (in AZ) etc... That $30,000+ sure would put alot of gas in the tank of the car I already have.

That's not to say I'm against the LS swap. I did a 6.0/4L60 swap in my blazer, but an ailing transmission let me to consider an overdrive which led to just swapping the whole thing. In order to make that cost effective though, you have to plan to keep the vehicle for several years. I drive mine daily and have no plans to sell so it works out for me. An LS swap is still alot cheaper than a new car, and I'm not driving a cookie cutter car around I think you get the best of both worlds in my opinion.

I hear ya loud and clear! Thats why my daily driver is the 69. Even with the 14 mpg, I am spending less than a newer car payment! And looking a lot cooler

I have done a lot of little things to make my truck more effecient, but I really need to learn more about tuning the Quadrajet to really squeeze the miles out of it.

[Firebirdjones]

Originally Posted by OJ1988

I hear ya loud and clear! Thats why my daily driver is the 69. Even with the 14 mpg, I am spending less than a newer car payment! And looking a lot cooler

I have done a lot of little things to make my truck more effecient, but I really need to learn more about tuning the Quadrajet to really squeeze the miles out of it.

Quadrajets are good carbs that work very well. They have their querks like any carb, but if you are willing to dive in you'll find it's fairly easy.

Hopefully you aren't the sensitive type and are open to ideas and/or suggestions. If not, I'd highly recommend investing in a wideband air fuel meter. I've used the LM-1 for many years and it's the only way to tune a car properly. You can shoot for a lean idle 14.7-15.0 and a lean cruise of about the same AFR and that alone will probably get you another 2-3 mpg. It might require that you dive into the carb for a couple of jet changes, maybe metering rods and power piston spring changes.

If you run a lighter power piston spring that opens at a vacuum of say,,,,4-8 inches, it will gain you some mileage during throttle transition and light loads (climbing mild grades) when your vacuum is lower, the power piston isn't going to open as often unless you dive below those vacuum readings. So long as the leaner fuel isn't causing any pinging issues it won't hurt a thing. If you do any heavy hauling or towing, this may need to be tweaked more to stay on the safe side of things.

That wideband will be your friend, and can be used on any car, just weld a bung in the exhaust and plug it in to the cig lighter, (also runs off a 9 volt battery) you're set to go.

[clinebarger]

Originally Posted by OJ1988

How much driving would you have to do to save enough gas money to pay for the swap?

I'm all about saving gas, but spending $5000 or so to swap will take a long time to pay off.

Thats like the hybrids, I didn't understand why people were going out and spending $20-30k on a car to save gas money???

The OP was talking about an $8K 383....

I look at it this way....Have more power, Better drivability, OBD II dianostics & I havnt done anything to it other than maintenance (oil changes, trans service) in 8 years....Its an overall improvement, Fuel milage was just a bonus.

My 350 was getting worn out, With dual smog pumps it was a nightmare to work on & I still had to smog test at the time.

The old Burb doesnt owe me anything, I dont see how in the world me doing an engine swap is in the same league as buying an expensive hybrid $hit box??

[OJ1988]

Originally Posted by clinebarger

The OP was talking about an $8K 383....

I look at it this way....Have more power, Better drivability, OBD II dianostics & I havnt done anything to it other than maintenance (oil changes, trans service) in 8 years....Its an overall improvement, Fuel milage was just a bonus.

My 350 was getting worn out, With dual smog pumps it was a nightmare to work on & I still had to smog test at the time.

The old Burb doesnt owe me anything, I dont see how in the world me doing an engine swap is in the same league as buying an expensive hybrid $hit box??

I didn't mean to offend you.

What I was getting at, was when someone has a good running combo and asks for better mpg advice, and people say "Swap an LSX". That seems silly to me.

I understand if you are starting from scratch the LS is a killer engine and a great swap. But to tell someone to spend thousands to swap one to improve their milage is silly.

[Firebirdjones]

Originally Posted by OJ1988

I didn't mean to offend you.

What I was getting at, was when someone has a good running combo and asks for better mpg advice, and people say "Swap an LSX". That seems silly to me.

I understand if you are starting from scratch the LS is a killer engine and a great swap. But to tell someone to spend thousands to swap one to improve their milage is silly.

I can completely understand that which is why I didn't suggest it. You can get respectable mileage out of a carb if tuned properly and driven reasonable.

I actually was happy with the carbed 350 in my 72 4x4 blazer. A mild 355 with a small Crane cam, RPM edelbrock intake and a 750 holley. Long tube headers, 33" tires and 3.07 gears, and the original 350 turbo.

I would get 13 mpg around town and 16 mpg highway. Drove it like this for years and was very pleased considering what it was. It never let me down and started every day, very reliable driver.

I only swapped in the 6.0 because the original 350 turbo was dying, and figured now is the time for an overdrive, and that led to the LS swap. I already have the software for tuning since we own a couple other LS cars so that expense was out of the way.

I'm still a carb guy at heart as several other cars I have are all carbed. You can't beat the simplicity and cheap parts/easy repair. When tuned properly they run and drive just as well as anything else out there. As a matter of fact the LS retro swaps that are converted to carbs are still very popular. Edelbrock makes the intakes, and MSD makes the ignition controller so you still get the benefit of coil-on-plug ignition, cam and crank sensors still used etc....

The only real big advantage the LS engine has over the gen 1 sbc is it's 15 degree heads vs the gen 1 23 degree head, that's why they run so well. Fuel injection is nice, but it's spendy, then you need software to tune and diagnose it which is another added expense. Technically speaking, you could put a nice FAST/Edelbrock fuel injection setup on a Gen1 sbc cheaper than swapping an entire LS engine, and have your multi port fuel injection and easy drivability that way.

The 14 mpg you are getting with your current combo is decent. I'm sure you'll find more without spending a ton of cash.

[clinebarger]

Originally Posted by OJ1988

I didn't mean to offend you.

What I was getting at, was when someone has a good running combo and asks for better mpg advice, and people say "Swap an LSX". That seems silly to me.

I understand if you are starting from scratch the LS is a killer engine and a great swap. But to tell someone to spend thousands to swap one to improve their milage is silly.

You didnt offend me.....I do agree with you on swaping soley for milage is not financially sound.

[86swb]

Originally Posted by OJ1988

How much driving would you have to do to save enough gas money to pay for the swap?

I'm all about saving gas, but spending $5000 or so to swap will take a long time to pay off.

Thats like the hybrids, I didn't understand why people were going out and spending $20-30k on a car to save gas money???

The wife was wanting a new car and the Toyota hybird was about the same price and gets much better mpg so that is why she went with the Toyota. We get about 46-48 mpg and very happy with it. We traded in our 2004 Jeep Liberty 4 wheel drive. But I would not sell my truck and put that kind of money out for the milliage.

[C-10 simplex]

It's getting a little late night for me to get into it whole-hog. But here is what i DON'T believe in:

The whole notion about cold air intakes increases mpg. Why? Because warmer air=less dense air= less fuel. Leave the stock air cleaner assembly completely hooked up the way it came from the factory for best mpg results. Also, what many people may not realize is at full throttle---when vacuum is low, the stock air cleaner lets nothing BUT cold air to the carb.

Discuss.