Upgrades for milage - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chris mc bride · 08-19-2025, 05:55 PM

Quote:

Originally Posted by ullose272

find a donor 5.3/4l60e. tune and headers.

Thought about going LS. deal. When figure controller for trans and efi.cost to hop up bbc. It probably cheaper. Better mileage. Love sound of BBC with thumping cam singing thru 3" set of free flowing mufflers. Heck lil brother races turbo vr6 running 4.70 at 145 in 1/8 and we have talked bbc with turbo in Panel. If had LS it would have turbo or turbos and ungodly high price transmission and 9" rearend. I swear it is a disease and can not help ones self

ullose272 · 08-20-2025, 10:35 AM

Quote:

Originally Posted by chris mc bride

Thought about going LS. deal. When figure controller for trans and efi.cost to hop up bbc. It probably cheaper. Better mileage. Love sound of BBC with thumping cam singing thru 3" set of free flowing mufflers. Heck lil brother races turbo vr6 running 4.70 at 145 in 1/8 and we have talked bbc with turbo in Panel. If had LS it would have turbo or turbos and ungodly high price transmission and 9" rearend. I swear it is a disease and can not help ones self

find a 2wd 2500 with a 6.0 and a 4l80e, if you can find one wrecked, only few thousand bucks? 4l80e is very strong with just a HD2 shift kit. low compression LQ4 will make 600 hp with ease with a Turbo, or upgrade the rods/pistons and make 8-900? and be very drivable

**MikeB** · 08-22-2025, 04:39 PM

Depending on your carb, I'd lean out the primary jetting involved in steady state cruising. I've done that a few times with Edelbrock carbs using their handy dandy calibration charts. I've seen as much as 14mpg on the highway with a mild 350, TH350, and 3.08 axle. I wouldn't care to guess what around town MPG is!

With a Holley, you can keep reducing the primary main jet sizes until you start experiencing bogs, then go one step richer.

Also, make sure you have optimum ignition timing, and definitely make sure vacuum advance is working. It plays a role in increasing gas mileage at steady state speeds.

08-22-2025, 04:39 PM	#28
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 4,038	Re: Upgrades for milage Depending on your carb, I'd lean out the primary jetting involved in steady state cruising. I've done that a few times with Edelbrock carbs using their handy dandy calibration charts. I've seen as much as 14mpg on the highway with a mild 350, TH350, and 3.08 axle. I wouldn't care to guess what around town MPG is! With a Holley, you can keep reducing the primary main jet sizes until you start experiencing bogs, then go one step richer. Also, make sure you have optimum ignition timing, and definitely make sure vacuum advance is working. It plays a role in increasing gas mileage at steady state speeds. __________________ Mike 1969 Custom/10 LWB -- owned for 37 years. 350/TH350, 3.08 posi, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. Hedman stainless headers. Old Air installation in progress. 1982 Custom Deluxe 10 SWB -- converted from 250-six to roller cam 350 w/ Vortec heads -- sold 1981 C10 Silverado LWB, 305, TH350C -- sold, but wish I still had it! 1969 C10 (not the current one) which I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 26 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then! Last edited by MikeB; 08-22-2025 at 04:45 PM.



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