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What grade of fuel to you run

broncoP

Contributor
Sr. Member
Joined
Oct 22, 2001
Messages
890
Curious as to what grade of fuel guys are mostly using. Mine is a 72 302 that has been redone few years back with cam and stuff. I've tried all grades but have been using 89 octane lately
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
When it was original the "low-test" (regular in other words) stuff was fine. I ran Premium in my '71 for some reason for quite awhile. I think I just thought, without actually checking, that a '71 would have had higher compression and less likely to have hardened valve seats, so premium would have been a benefit.
Never did have any kind of a pinging problem at higher ignition advance levels, but premium made sense to me until I woke up one day and decided I should try to save a little money and went with regular from then on.

Your cam could certainly change that attitude. And the "and stuff" part could really change things.;D Especially if it includes higher compression and such.

But generally speaking, regular grade fuel is fine.

Paul
 

half cab

Contributor
Guru Bronco
Joined
Dec 8, 2010
Messages
16,306
I have an early 70's 351 and a close country store that sells ethanol free.
 

sprdv1

Contributor
REBEL
Joined
Mar 8, 2007
Messages
81,734
Reg Unleaded... whichever I get to first..

a tank of premium on occasion :)
 

sriha

Sr. Member
Joined
Jul 28, 2010
Messages
683
Non-Ox. Mine sits too long between runs and seems to work better with the carb not gumming up.
 

Eoth

Bronco Guru
Joined
Mar 10, 2004
Messages
1,677
Almost anything during the "driving season".. When the weather starts cooling off and I start thinking that it needs its winter sleep I switch to ethanol free.
 

Glass Pony

Contributor
Bronco Guru
Joined
Feb 13, 2012
Messages
1,817
Loc.
Sussex County Delaware
The politicians know better than anyone else in my state so we are forced to use E-10.:mad:
I thought I heard some pinging under load with 87 octane so I started using 89 and it seems good. I use Marine Stabil 360 during the last couple months before it gets put away for winter so it gets through the fuel system.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
11:1 compression, premium
In the winter I could sneak a little mid grade.

My low compression boat motor runs best on the lowest octane fuel I put in it. I have not found low octane leaded fuel since the 90s.
 

bmc69

Contributor
Bronco Guru
Joined
Jun 11, 2004
Messages
11,852
I run 89 in the 400 in my '78..so I can keep the timing bumped up like I want it.

I wish we could get ethanol free gas here but with one lonely exception clear the other side of the county, only marinas have it.
 

pcf_mark

Bronco Guru
Joined
Jun 11, 2010
Messages
3,574
87 is what I use but when I make a full throttle run at high rpm I get pinging. I plan to reduce my timing in the upper rpm in my engine tune to stop the ping. I do not need the extra little bit of power to justify running higher cost fuel!
 

ep67bro

Contributor
Bronco Junky
Joined
Aug 28, 2008
Messages
3,644
Loc.
Easton, MD
87 or 89 in my 67, and it is usually E10. I think it runs a little better on the 89. Ethanol free stuff is really hard to find and the price is crazy. I put marine Stabil in it toward the end of the summer when I know it sits more. Don't really have any experience with the 70 or 75 when it come s to fuel grades haven driven them enough.
 

56f100bbw

Contributor
Bronco Guru
Joined
Feb 3, 2008
Messages
2,286
Loc.
Tucson / lakeside AZ
Ethanol free is about 3.40 a gal I run it in the winter because of bronco sits for five months with a full tank of gas. Summertime i drive it every day gas cruise through so fast doesn’t matter
 
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