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AeroAtom · 01-04-2008, 05:50 PM

Hello all, I just bought a 1985 (454 Chevy{Iron}, 75k mls) Winnabego Cheiftain and am a bit concerned about it's fuel economy. I have been getting about 5mls/gln most recently and am thinking this is probably kinda bad.
I already replaced the spak plugs, cables and put in a new air filter, I plan to do an oil change in a day or so. One of my specific questions is what the spark plugs should be gapped at. I was told .045, the ones I took out were gapped at .05. I assumed this was wear, but who knows. Another concern is that it seems to be idling kinda high, someone told me they thought the choke was too open and this was the cause, i adjusted what I could to minimize it's opening but this doesn't effect idle speed. The idle adjustment screw is far from touching the gas linkage. I was thinking the timeing may be a bit advanced, if this sounds reasonable or obsurd please let me know. I plan to verify the timing this weekend, 4 BTC, yes? Any suggestions would be great, I'll take anything at this point, I have had little luck finding things online, seems search engines are becomeing less and less effective, or possibly it's just me loosing my virtual mojo. Thanks in advance to any and all that reply.

AeroAtom · 01-04-2008, 05:50 PM

Hello all, I just bought a 1985 (454 Chevy{Iron}, 75k mls) Winnabego Cheiftain and am a bit concerned about it's fuel economy. I have been getting about 5mls/gln most recently and am thinking this is probably kinda bad.
I already replaced the spak plugs, cables and put in a new air filter, I plan to do an oil change in a day or so. One of my specific questions is what the spark plugs should be gapped at. I was told .045, the ones I took out were gapped at .05. I assumed this was wear, but who knows. Another concern is that it seems to be idling kinda high, someone told me they thought the choke was too open and this was the cause, i adjusted what I could to minimize it's opening but this doesn't effect idle speed. The idle adjustment screw is far from touching the gas linkage. I was thinking the timeing may be a bit advanced, if this sounds reasonable or obsurd please let me know. I plan to verify the timing this weekend, 4 BTC, yes? Any suggestions would be great, I'll take anything at this point, I have had little luck finding things online, seems search engines are becomeing less and less effective, or possibly it's just me loosing my virtual mojo. Thanks in advance to any and all that reply.

LVJ58 · 01-04-2008, 09:54 PM

With your engine warmed up to normal operating temperature, the choke butterfly should be wide open. If it's not, the cam on the choke linkage could cause a high idle. You'll need to adjust it accordingly. Your carburetor is most likely a Rochester Quadrajet. Also check for a loose vacuum line at the carb as that could affect the idle.

Here's a site that addresses ignition timing:
http://www.gmtrucks.org/showthread.php?t=365

If I recall I set the timing on my old 84 454 at 8 degree BTDC.

Good luck, Jim

Hillbilly2 · 01-05-2008, 03:28 AM

Be careful advancing the timing, motorhomes, unlike automobiles are pulling a load all of the time. If you advance the timming too much, you will have "pinging" (detonation) which will harm the engine. Thats probally why they had it set so low. Try a K&N air filter, they can help on gas mileage, They don't help as much on a normally asperated engine as your 454 gas burner, but on turbocharged engines I've gotten as much as two miles to the gallon better.

speed racer · 01-05-2008, 04:01 AM

The Qjet carb has alway had a problem with internal fuel leaks and the float geting fuel in it causing the float level to be to high. I would recamend a carb overhaul.

JerryForwood · 01-05-2008, 07:59 AM

Go to an Auto Parts store and get yourself a Chilton's manual on that year Chevy truck. If you plan to do your own servicing, you will need a reference manual for a lot of things.
PS, you probably can even find the manual at a public library if you don't want to buy one.
These forums are great but, you have a problem and post a question and wait. Then you finally get several answers that all conflict. A Real Manual at your fingertips will save a lot of time and give you answers on engines, transmissions, drive trains, brakes, and other chassis parts that you can rely on. JMHO!

AeroAtom · 01-05-2008, 02:59 PM

First off, I thank all that responded. What an awsome group of folks in here, tons of great info. I will be getting that chilton reference manual right quick. I have a couple of follow up questions regarding some of the replies.
Seth, could you tell me what you know about the computer in this thing? I take it it must have one, does it automatically adjust the timing?
LVJ - Thanks, great info, both yours and the link.
HillBilly - I was trying to say that I thought it was already advanced, and likely too much so, as it already pings up hill.

I think I will rebuild the carb after I very/ajust my timing. Again thank you all for the great advice, and happy RVing to you all.

**Petro** · 01-05-2008, 04:12 PM

AeroAtom;

Welcome to IRV2. You have found the friendliest site in the Internet. We have a wealth of information available to you just by asking. Post often and let us know how how you make out with your tuneup.

Don

NeilV · 01-05-2008, 05:41 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by AeroAtom:
First off, I thank all that responded. What an awsome group of folks in here, tons of great info. I will be getting that chilton reference manual right quick. I have a couple of follow up questions regarding some of the replies.
Seth, could you tell me what you know about the computer in this thing? I take it it must have one, does it automatically adjust the timing?
LVJ - Thanks, great info, both yours and the link.
HillBilly - I was trying to say that I thought it was already advanced, and likely too much so, as it already pings up hill.

I think I will rebuild the carb after I very/ajust my timing. Again thank you all for the great advice, and happy RVing to you all. </div></BLOCKQUOTE>

I would rebuild the QuadraJet first as you would probably have to fine tune the timing a bit after the rebuild.

The rebuild can be a bit tricky as you have to get the choke, choke unloader, float level, metering rod height and secondary unlock set just right or you will be sucking down gas like there is no tommorow.

AeroAtom · 01-05-2008, 10:06 PM

NeilV - I agree with the logic, but am short on time. I will retime now just t oget rid of the ping, in a week or two I will rebuid the carb if it is still idleing high. I need to be in IN in a week and have alot to do yet. I wanted to install a few high wattage solar panels, but time is killing me. Thanks for the advice though, i appreciate it.
Seeing how giving you folks seem to be, feel free to throw anything my way, I feel confident that this forum is going to make my life a whole lot easier. Thanks again.