Horrible gas mileage - Page 3 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Damien · 04-02-2009, 01:22 PM

[QUOTE=Rain City;3232573]Will the PCV Valve even help my gas mileage? /QUOTE]

No, the PCV will not affect your mileage, but it will make your enging last longer.

73chevyman · 04-02-2009, 01:31 PM

think that truck use to have the 3 port mechanical feul pump thats what that hose could be for. do you have a vacuum gauge. if so hook it up to your manifold vacuum if at idle your not in the range of 15 to 20 means your carb is out of wack. do you have any idea how to adjust your carb. if you don't i'll find something for ya to help you out. also check your timing, your truck should be set at 12 degrees advanced due to the fact you have a automatic trans. check the timing with the vacuum advanced off.

http://www.youtube.com/watch?v=6vKlA...eature=channel

watch this video it might help you

73chevyman · 04-02-2009, 01:42 PM

look on your radiator support it will tell you your gap rating for your plugs along with timing setting and so forth but you might not be so stock by looking at your motor. don't get frustrated just take your time and you'll get it right. sounds to me they didn't tune your carb right. read this too this should help out

http://www.centuryperformance.com/tu...e-spg-148.html

Damien · 04-03-2009, 04:56 PM

I just had a thought as long as we are talk spark plugs. What about the heat range?

UltraBlue71 · 04-06-2009, 02:29 PM

I wonder if the metering rods for that old Holley are the correct ones, where did the PO live? Ask him what kind of mileage it got. You didnt gain or loose alot of altitiude when you took it home did you? Everyone has opinions and this is mine, Get a Quadrajet, for your 350 have someone who knows what they are doing (not me, I never could figure a Q-jet out or make one work right) rebuild it and install it. They have little primaries and huge secondaries and are one of the finest carbs ever built as far a fuel efficiecy goes.

Adams74Chevy · 04-06-2009, 02:46 PM

Quote:

Originally Posted by UltraBlue71

I wonder if the metering rods for that old Holley are the correct ones, where did the PO live? Ask him what kind of mileage it got. You didnt gain or loose alot of altitiude when you took it home did you? Everyone has opinions and this is mine, Get a Quadrajet, for your 350 have someone who knows what they are doing (not me, I never could figure a Q-jet out or make one work right) rebuild it and install it. They have little primaries and huge secondaries and are one of the finest carbs ever built as far a fuel efficiecy goes.

Any recommendations on Q-jet gurus? I have one I'd like to get rebuilt right.

billnorman · 04-06-2009, 07:31 PM

Hey. Umm I would not route those plug wires so close to the headers, it will cause them to fail from the heat. That fuel filter unscrews, I fear them for that exact reason. If it unscrews while you are driving, good insurance will have been a smart investment. HOT ROD magazine had a good article about getting good gas mileage from Holley's. Something about putting a restrictor in the idle circuit. Your truck runs on the idle circuit unless you really stick your foot into it.

04-02-2009, 01:22 PM	#51
Damien Registered User Join Date: Mar 2007 Location: Farmington, MN Posts: 928	Re: Horrible gas mileage [QUOTE=Rain City;3232573]Will the PCV Valve even help my gas mileage? /QUOTE] No, the PCV will not affect your mileage, but it will make your enging last longer. __________________ I can still count my vehicles on two... wait three hands.

04-02-2009, 01:31 PM	#52
73chevyman Registered User Join Date: Nov 2008 Location: Lusby, MD Posts: 563	Re: Horrible gas mileage think that truck use to have the 3 port mechanical feul pump thats what that hose could be for. do you have a vacuum gauge. if so hook it up to your manifold vacuum if at idle your not in the range of 15 to 20 means your carb is out of wack. do you have any idea how to adjust your carb. if you don't i'll find something for ya to help you out. also check your timing, your truck should be set at 12 degrees advanced due to the fact you have a automatic trans. check the timing with the vacuum advanced off. http://www.youtube.com/watch?v=6vKlA...eature=channel watch this video it might help you __________________ http://67-72chevytrucks.com/vboard/group.php?groupid=37 73 C10 Fleetside If it ain't a Chevy it's foreign http://hotridesmag.com/

04-02-2009, 01:42 PM	#53
73chevyman Registered User Join Date: Nov 2008 Location: Lusby, MD Posts: 563	Re: Horrible gas mileage look on your radiator support it will tell you your gap rating for your plugs along with timing setting and so forth but you might not be so stock by looking at your motor. don't get frustrated just take your time and you'll get it right. sounds to me they didn't tune your carb right. read this too this should help out http://www.centuryperformance.com/tu...e-spg-148.html __________________ http://67-72chevytrucks.com/vboard/group.php?groupid=37 73 C10 Fleetside If it ain't a Chevy it's foreign http://hotridesmag.com/

04-03-2009, 04:56 PM	#54
Damien Registered User Join Date: Mar 2007 Location: Farmington, MN Posts: 928	Re: Horrible gas mileage I just had a thought as long as we are talk spark plugs. What about the heat range? __________________ I can still count my vehicles on two... wait three hands.

04-06-2009, 02:29 PM	#55
UltraBlue71 Registered User Join Date: Feb 2009 Location: OKC OK Posts: 489	Re: Horrible gas mileage I wonder if the metering rods for that old Holley are the correct ones, where did the PO live? Ask him what kind of mileage it got. You didnt gain or loose alot of altitiude when you took it home did you? Everyone has opinions and this is mine, Get a Quadrajet, for your 350 have someone who knows what they are doing (not me, I never could figure a Q-jet out or make one work right) rebuild it and install it. They have little primaries and huge secondaries and are one of the finest carbs ever built as far a fuel efficiecy goes. __________________ "You can put lipstick on a pig, sure it's pretty pig, but it's still just a PIG... 71 LWB

04-06-2009, 07:31 PM	#57
billnorman Registered User Join Date: Mar 2009 Location: glen burnie md Posts: 174	Re: Horrible gas mileage Hey. Umm I would not route those plug wires so close to the headers, it will cause them to fail from the heat. That fuel filter unscrews, I fear them for that exact reason. If it unscrews while you are driving, good insurance will have been a smart investment. HOT ROD magazine had a good article about getting good gas mileage from Holley's. Something about putting a restrictor in the idle circuit. Your truck runs on the idle circuit unless you really stick your foot into it.



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