How I lost 3 miles per gallon - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mikep · 11-03-2002, 08:53 PM

I pulled the 750 edelbrock off my boat the other day and replaced the quad on my 350 just to see what would happen. Gained about 20 HP in the process but my mileage went to hell in a handbasket. It may just be because I am enjoying the 20 horsepower a bit too much. After I get tired of full throttle 0-70 blasts I'll have to see what the real mileage difference is. The quadrajet was a good fresh carb but its amazing what a difference installing a different carb will make.

On a related note I pulled the 750 edelbrock off my brothers 390 powered 68 cougar and installed a new 600 cfm holley as it had backfired pretty bad once after sitting 4 years not running and it bent the throttle plates and choke plate ( also ballooned the valve covers and blew the air cleaner and breathers clean off the motor ). Runs great with the holley I must say.

GMC71k20 · 11-03-2002, 09:14 PM

horsepower is more fun the good gas mileage

tom hand · 11-03-2002, 09:20 PM

I would bet the MPG loss is due to the weight of your right foot. If tuned properly the Q-jet would give about the same horsepower.

mikep · 11-03-2002, 09:28 PM

The Q jet was tuned more for mileage . It was a 4MV I pulled off my boat with absolutely no throttle shaft bore wear or emissions controls . I regasketted it early this year and cleaned it up good as new . It ran great but it was a bit on the lean side which is great for mileage but doesn't help power much.

Longhorn Man · 11-03-2002, 11:22 PM

Quote:

Originally posted by mikep
I pulled the 750 edelbrock off my brothers 390 powered 68 cougar and installed a new 600 cfm holley as it had backfired pretty bad once after sitting 4 years not running and it bent the throttle plates and choke plate ( also ballooned the valve covers and blew the air cleaner and breathers clean off the motor ).

FRIKKEN YIKES!!!!!
What do you think of that old Cougar? This was my very first car, and i swear, one day I will have another. I got one of the hot wheels 68 cougar...sittin on the shelf right by the 69 step side one.

mikep · 11-04-2002, 01:55 AM

I like the cougars . My last "car" was a full otioned Q code 1970 cougar that I installed a 450+ HP 351 cleveland in . Heres a few pics. I sold it last year after a string of tickets. The cops would follow me from my house all the way to the ferry terminal that I go to to take a ferry to the island I work on. At 4AM ! If I pulled over at a store, they'd pull over and wait for me. It was horrible! That thing was LOUD ! 40 series flowmaster with 3 inch pipe and a comp cams 292H cam with closed chamber big port heads and 11:1 compression. 4.11 geared detroit locker 9 inch with currie axles and a 3000 stall C6. Ever seen the ports in a cleveland motor. Good God! It was my daily driver but it was pissing the wife off too much and the constant harrasment by the cops finally got me to sell it off. Some guy bought it for his 16 year old kid. That is the greatest dad in the world! ...next to mine!

Anyway I'd like to say that brothers motor "blowing up " scared the crap out of me. I mean I was standing next to the motor when it blew up and the breather flew right past me . Still havent found it a week later. The thing is it didnt even phase me. Spent too much time in the army in the back of howitzers I guess. Ive never seen valve covers blown out like that . That crankcase was full of vapor at just the right mixture when it lit off! FE motors are notorious about filling up with oil while they run so it was dumping oil all over the headers as we pulled it up into my garage. Made a God awful mess.

He's only got about 300 miles on the 390 since it was rebuilt . It was originally a 289 car so theres been a lot of parts swapping since he bought the car 10 years ago. Its got a fresh 390 with a decent lunati cam, weind intake , holley carb, mallory ignition, hooker headers, C6 tranny with 2800 stall converter and an 8.8 inch 3.73 geared rearend. He's also got a 69 camaro that used to belong to me that he and my dad are building up a 8-71 blown 454 for. Should be a hoot. He's bring that up here nxt year so i can paint it. Might have to milk that project!

mikep · 11-04-2002, 01:55 AM

heres my last "car"

Woody · 11-04-2002, 08:27 AM

Mikep,

My next door nieghbor has a 65 Shelby Cobra Replicia that has a Ford 351 W bored&stroked to a 392 with AFR heads, roller cam, a 750 or 850 holly, and he just added a 225 shot of NO2. He's pushing 400+ hp before the NO2. Told me yesterday that now that the weather has cooled , it will spin the tires at 100mph in 5th gear(has a 6 speed) when the no2 hits! It exhausts out of headers into sidepipes and really rumbles. He's been pulled over by most of the local State Police, but he's a Dr. so they let him go for one reason or another. I can here him coming over a mile away. A couple weeks ago he got into it out on the interstate and I could hear him at my house, and I was sitting in my truck with the doors closed at the time.
Of course we live just outside of a small town and there is a lot of Farm trucks and other loud cars and trucks but the cops don't pay any attention to it.
He's like a big kid, drives this thing as a daily driver unless it is raining.

I always liked Cougars, Nice Car!

lux hauler · 11-04-2002, 09:30 AM

Sweet Cougar!!

11-03-2002, 08:53 PM	#1
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	How I lost 3 miles per gallon I pulled the 750 edelbrock off my boat the other day and replaced the quad on my 350 just to see what would happen. Gained about 20 HP in the process but my mileage went to hell in a handbasket. It may just be because I am enjoying the 20 horsepower a bit too much. After I get tired of full throttle 0-70 blasts I'll have to see what the real mileage difference is. The quadrajet was a good fresh carb but its amazing what a difference installing a different carb will make. On a related note I pulled the 750 edelbrock off my brothers 390 powered 68 cougar and installed a new 600 cfm holley as it had backfired pretty bad once after sitting 4 years not running and it bent the throttle plates and choke plate ( also ballooned the valve covers and blew the air cleaner and breathers clean off the motor ). Runs great with the holley I must say. __________________ No truck :-(

11-03-2002, 09:20 PM	#3
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	I would bet the MPG loss is due to the weight of your right foot. If tuned properly the Q-jet would give about the same horsepower. __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

11-03-2002, 09:28 PM	#4
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	The Q jet was tuned more for mileage . It was a 4MV I pulled off my boat with absolutely no throttle shaft bore wear or emissions controls . I regasketted it early this year and cleaned it up good as new . It ran great but it was a bit on the lean side which is great for mileage but doesn't help power much. __________________ No truck :-(

11-04-2002, 01:55 AM	#6
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	I like the cougars . My last "car" was a full otioned Q code 1970 cougar that I installed a 450+ HP 351 cleveland in . Heres a few pics. I sold it last year after a string of tickets. The cops would follow me from my house all the way to the ferry terminal that I go to to take a ferry to the island I work on. At 4AM ! If I pulled over at a store, they'd pull over and wait for me. It was horrible! That thing was LOUD ! 40 series flowmaster with 3 inch pipe and a comp cams 292H cam with closed chamber big port heads and 11:1 compression. 4.11 geared detroit locker 9 inch with currie axles and a 3000 stall C6. Ever seen the ports in a cleveland motor. Good God! It was my daily driver but it was pissing the wife off too much and the constant harrasment by the cops finally got me to sell it off. Some guy bought it for his 16 year old kid. That is the greatest dad in the world! ...next to mine! Anyway I'd like to say that brothers motor "blowing up " scared the crap out of me. I mean I was standing next to the motor when it blew up and the breather flew right past me . Still havent found it a week later. The thing is it didnt even phase me. Spent too much time in the army in the back of howitzers I guess. Ive never seen valve covers blown out like that . That crankcase was full of vapor at just the right mixture when it lit off! FE motors are notorious about filling up with oil while they run so it was dumping oil all over the headers as we pulled it up into my garage. Made a God awful mess. He's only got about 300 miles on the 390 since it was rebuilt . It was originally a 289 car so theres been a lot of parts swapping since he bought the car 10 years ago. Its got a fresh 390 with a decent lunati cam, weind intake , holley carb, mallory ignition, hooker headers, C6 tranny with 2800 stall converter and an 8.8 inch 3.73 geared rearend. He's also got a 69 camaro that used to belong to me that he and my dad are building up a 8-71 blown 454 for. Should be a hoot. He's bring that up here nxt year so i can paint it. Might have to milk that project! Attached Images __________________ No truck :-( Last edited by mikep; 11-04-2002 at 02:05 AM.

11-04-2002, 01:55 AM	#7
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	heres my last "car" Attached Images __________________ No truck :-(

11-03-2002, 09:14 PM	#2
GMC71k20 Registered User Join Date: Aug 2002 Location: mass Posts: 1,277	horsepower is more fun the good gas mileage

11-04-2002, 08:27 AM	#8
Woody Registered User Join Date: Feb 2000 Location: Georgetown, KY, USA Posts: 631	Mikep, My next door nieghbor has a 65 Shelby Cobra Replicia that has a Ford 351 W bored&stroked to a 392 with AFR heads, roller cam, a 750 or 850 holly, and he just added a 225 shot of NO2. He's pushing 400+ hp before the NO2. Told me yesterday that now that the weather has cooled , it will spin the tires at 100mph in 5th gear(has a 6 speed) when the no2 hits! It exhausts out of headers into sidepipes and really rumbles. He's been pulled over by most of the local State Police, but he's a Dr. so they let him go for one reason or another. I can here him coming over a mile away. A couple weeks ago he got into it out on the interstate and I could hear him at my house, and I was sitting in my truck with the doors closed at the time. Of course we live just outside of a small town and there is a lot of Farm trucks and other loud cars and trucks but the cops don't pay any attention to it. He's like a big kid, drives this thing as a daily driver unless it is raining. I always liked Cougars, Nice Car!

11-04-2002, 09:30 AM	#9
lux hauler Psycho-billy Member Join Date: Jul 2001 Location: about 40 miles west of Cleveland, Ohio Posts: 2,591	Sweet Cougar!! __________________ '72 C-10 350 w/Lunati Voodoo cam (207/213, .437/.454), Performer intake, 625 Road Demon Jr. and Hooker headers. Support your community, support yourself. Buy local, buy American (or Canadian).



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.