what gas?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

PureChevy · 08-28-2003, 01:19 PM

my engine is a mild rebuilt 350. that is about all i know about it. It does have headers. I have been running 87 octane through it and it started to deisel every now and then. I filled up with 89 and it seems to have stopped. I was wandering what kind of gas should i be running through it everyday. Should i stay with 89 or just run it every now and then??

Thanks
Will

Ackattack · 08-28-2003, 03:58 PM

I'd say that 87 ought to be ok, but the timing may be off a little, or other "tune up" items.

*67Fleetsidedream* · 08-28-2003, 04:51 PM

simple fix what can you afford and do you like the engine deiseling?
Mine does the same thing. I use 89 octane when ever I can. But when the truck fund looks good I give her some 89 or 92 octane.
Runs like the wind on the 92 octane.

**COBALT** · 08-28-2003, 04:59 PM

I remember dealing with clogged fuel injectors in a mazda pickup I used to own. That was the last time I used 87 octane. Now that I work on these trucks I've rebuilt a few carburetors, and they're absolutely caked with garbage. With a new carburetor, and my wife's new Jetta I decided to use the cleanest fuel possible. To me the cleaner the fuel the better.

Nothing but 92.

FRENCHBLUE72 · 08-28-2003, 06:36 PM

I run water or close to it as gas is a 1:99 a gallon and my blazer is my driver... I would check the rest of you ignition stuff to make sure it is up to snuff first...

Longhorn Man · 08-28-2003, 10:49 PM

so 92 is cleaner than 87?
The octain rating is nothing but a chart of resistace to ignition. That is all it is. You can get clean 87 octain by going to better gas stations.
If the rest of your tune up is good, then you should run the 89 octain.
You are probably getting some pre-ignition that you don't hear, and when you shut it off, you get to see it instead of hear it.
Something like 75% of the pre-ignition is nonaudible anyways.
I say go with the 89. It's only a buck more per tank. (give or take a little)

PureChevy · 08-29-2003, 10:12 AM

I run nothing mut 92+ in my camaro.
I was just wandering about the older 350's. I figure i will just run 89 through it from now on.

cdowns · 08-29-2003, 11:05 AM

just wundering when was the last time you changed air/pvc/fuel and other maintenance items sparkplugs , ign wires , timing ?when did or have u ever perfomed routine maintenance on it ???

PureChevy · 08-29-2003, 11:56 AM

I havent performed any on it yet. I just bought i a month ago. I am headed to florida this weekend, when i get back I will probably go through and change everything out.

**smitty62** · 08-29-2003, 01:41 PM

Check idle speed and timing before you spend money on unnessary octane--87 should be fine unless the compression ratio has been drastically increased. 92 cleaner than 87 octane??--where in the hell did that come from?? IT'S ONLY AN ADDITIVE TO LOWER FLASH POINT!!!!

Longhorn Man · 08-29-2003, 10:32 PM

Quote:

Originally posted by smitty62
Check idle speed and timing before you spend money on unnessary octane--87 should be fine unless the compression ratio has been drastically increased. 92 cleaner than 87 octane??--where in the hell did that come from?? IT'S ONLY AN ADDITIVE TO LOWER FLASH POINT!!!!

That was my point too.

dwaite72lnghrn · 08-29-2003, 11:04 PM

Run what does not ping. The old heads were for lead and with out it you need to keep ping down as it drives the valves into the head further. Before I rebuilt the bb had to run 92 to keep it from pinging after I run 87 with no problems. If you have carbon fouling on the plugs it could have built up on the pistons and will cause this. Take it out on the highway for awhile and see if it gets better, tune it up, plugs, points, wires, timing, dwell.

08-28-2003, 01:19 PM	#1
PureChevy Registered User Join Date: Jun 2003 Location: Hickory, North Carolina Posts: 340	what gas?? my engine is a mild rebuilt 350. that is about all i know about it. It does have headers. I have been running 87 octane through it and it started to deisel every now and then. I filled up with 89 and it seems to have stopped. I was wandering what kind of gas should i be running through it everyday. Should i stay with 89 or just run it every now and then?? Thanks Will __________________ 1972 k10 4x4 LWB (Sold in 2005)

08-28-2003, 03:58 PM	#2
Ackattack Senior Member Join Date: Aug 2002 Location: Valley Center KS Posts: 3,525	I'd say that 87 ought to be ok, but the timing may be off a little, or other "tune up" items. __________________ Project Bruiser: 68 Pro-Touring C-10 5.3L / 4L60E Project Ironhide: 97 GMC Crew Cab 4x4 Cummins SOLD: '69 GMC 1/2T SWB TBI'd: Project No Buck Assembly Manual Index Sign up Thread!!! Factory Service Manual Index

08-28-2003, 04:59 PM	#4
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	I remember dealing with clogged fuel injectors in a mazda pickup I used to own. That was the last time I used 87 octane. Now that I work on these trucks I've rebuilt a few carburetors, and they're absolutely caked with garbage. With a new carburetor, and my wife's new Jetta I decided to use the cleanest fuel possible. To me the cleaner the fuel the better. Nothing but 92. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

08-28-2003, 06:36 PM	#5
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,606	I run water or close to it as gas is a 1:99 a gallon and my blazer is my driver... I would check the rest of you ignition stuff to make sure it is up to snuff first... __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

08-29-2003, 10:12 AM	#7
PureChevy Registered User Join Date: Jun 2003 Location: Hickory, North Carolina Posts: 340	I run nothing mut 92+ in my camaro. I was just wandering about the older 350's. I figure i will just run 89 through it from now on. __________________ 1972 k10 4x4 LWB (Sold in 2005)

08-28-2003, 04:51 PM	#3
67Fleetsidedream Wiseass secured himself a BAN Join Date: Nov 2000 Location: MOON!!! Posts: 2,282	simple fix what can you afford and do you like the engine deiseling? Mine does the same thing. I use 89 octane when ever I can. But when the truck fund looks good I give her some 89 or 92 octane. Runs like the wind on the 92 octane.

08-28-2003, 10:49 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	so 92 is cleaner than 87? The octain rating is nothing but a chart of resistace to ignition. That is all it is. You can get clean 87 octain by going to better gas stations. If the rest of your tune up is good, then you should run the 89 octain. You are probably getting some pre-ignition that you don't hear, and when you shut it off, you get to see it instead of hear it. Something like 75% of the pre-ignition is nonaudible anyways. I say go with the 89. It's only a buck more per tank. (give or take a little)

08-29-2003, 11:05 AM	#8
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	just wundering when was the last time you changed air/pvc/fuel and other maintenance items sparkplugs , ign wires , timing ?when did or have u ever perfomed routine maintenance on it ??? __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

08-29-2003, 11:56 AM	#9
PureChevy Registered User Join Date: Jun 2003 Location: Hickory, North Carolina Posts: 340	I havent performed any on it yet. I just bought i a month ago. I am headed to florida this weekend, when i get back I will probably go through and change everything out. __________________ 1972 k10 4x4 LWB (Sold in 2005)

08-29-2003, 01:41 PM	#10
smitty62 Registered User Join Date: May 2002 Location: North Carolina Posts: 1,234	Check idle speed and timing before you spend money on unnessary octane--87 should be fine unless the compression ratio has been drastically increased. 92 cleaner than 87 octane??--where in the hell did that come from?? IT'S ONLY AN ADDITIVE TO LOWER FLASH POINT!!!! __________________ Stepsides look like real trucks! Smitty

08-29-2003, 11:04 PM	#12
dwaite72lnghrn Registered User Join Date: Jun 2002 Location: central pa Posts: 1,525	Run what does not ping. The old heads were for lead and with out it you need to keep ping down as it drives the valves into the head further. Before I rebuilt the bb had to run 92 to keep it from pinging after I run 87 with no problems. If you have carbon fouling on the plugs it could have built up on the pistons and will cause this. Take it out on the highway for awhile and see if it gets better, tune it up, plugs, points, wires, timing, dwell. __________________ 72 longhorn c30 502BB/th400/fact air/4.11rear/ custom camper 72 bug(the better half's) under reconstruction 2009 HHR aqua blue 71 GMC k20 350/sm465 2009 Chevy hd3500 6.6 Victory Red crew cab dually Dave & Jeanne



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