Figure this out

Dragon · Post by **Dragon** » Fri Jul 18, 2008 1:12 am

My 71 F250 has a car 390 in it with factory high compression. When I got the exhaust leak fixed. I could hear bad pinging. I lowered the timing to 10 then 8. Was burning gas like crazy on regular. I found that I had ignored the air filter too long. Changing it the truck popped up from 6 mpg to 11.

I got brave one day a month ago. I tried premium. The truck then got a work out with a lot of little jobs coming in and no pinging. I did a full tank to full tank mileage check and highway is 15 now at 70 and town is 13 and the posi works so I don't wheel spin much but with the tools and stuff out it can smoke the rear tires. The 2 mile town mileage increase works out to be better than the extra cost offsets from the difference between regular and premium.

smclaren · Post by **smclaren** » Fri Jul 18, 2008 1:43 am

Premium is what that engine was designed to run on. Old engines LOVE that stuff.

In the old days we used to call it "Super" (in Australia anyway) ... when I had high octane AND lead.

As you quite correctly pointed out, it costs a bit more, but makes up for it in better milage, and general better running. I believe that its also better for engine life too, but don't quote me on that !

seattle67 · Post by **seattle67** » Fri Jul 18, 2008 8:51 am

Yup, mine has a 390 out of a 68 Cougar. It pings like mad with anything less then premium.

Steve, we called it "super" as well, some places still do. I can remember when I was a kid and my mom would tell the man with the star (Texaco) to fill it up with Ethyl. I think it was around 103 octane, now THAT was super!

binder56jd · Post by **binder56jd** » Sun Jul 20, 2008 9:21 pm

here's a little fun reading

http://www.oldgas.com/info/additive.htm

mrtleavitt · Post by **mrtleavitt** » Sun Jul 20, 2008 10:46 pm

Ya dude, if I run 87 octane in my stock 390 it pings on acceleration, but with 91 or higher it runs great! 111 octain is my favorite, but since gas prices are outrageous, my dad doesn't let me borrow it any more from his airport!

binder56jd · Post by **binder56jd** » Mon Jul 21, 2008 9:43 am

a MUST read re octane

http://www.europeancarweb.com/tech/0503 ... index.html

that pinging can be cured by proper timing--the oldtimers i knew called it "weaning"

Dragon · Post by **Dragon** » Mon Jul 21, 2008 9:58 am

You can get pinging with 10 Before or 10 after TDC if the engine has too much carbon or too high a compression for the fuel rating.

FLATBEDFORD · Post by **FLATBEDFORD** » Mon Jul 21, 2008 2:26 pm

I run premium in my 360. No pinging, seems to run nicer too. At $4.50/gal paying $.25 more for the premium is nothing. An extra $4.00 on a $70 fill up doesn't seem like much to me. It about 1.5% extra. Back in the days of $1.50 gas, that $.25 was a much bigger deal.

Dragon · Post by **Dragon** » Mon Jul 21, 2008 3:00 pm

I waited for 3 gas stations to stop changing their prices one day in a Gas war. They were all at the same intersection. I got premium for 13 cents a gallon for my 63 Falcon 170CID that spring day of 1970. In 71 I bought premium for my 67 Stang Racer for 21 to 24 cents in Denver.

FLATBEDFORD · Post by **FLATBEDFORD** » Mon Jul 21, 2008 4:05 pm

In 1998 filled my '96 F250 in Colorado for $.69. Nearly a $4.00 increase in 10 years. In the spring of '70 I was still in my mother's belly.

convincor · Post by **convincor** » Mon Jul 21, 2008 4:31 pm

i run premium in every old thing I own and aso started running lead additive. Make it smell like race fuel.

I only add 1 once per gallon which gives me a 3 point increase in octane to boot.

I calculates out to $.33 an once. So add that to the cost of the fuel.. It adds up, but I think having the lead with help the valves last that much longer. especially in a FE.
http://www.kemcooil.com/products.php?cId=4
http://www.hi-flow.com/HPOP4.htm

convincor · Post by **convincor** » Mon Jul 21, 2008 4:32 pm

double post..
while i'm here

binder56jd · Post by **binder56jd** » Mon Jul 21, 2008 10:57 pm

FLATBEDFORD wrote:In 1998 filled my '96 F250 in Colorado for $.69. Nearly a $4.00 increase in 10 years. In the spring of '70 I was still in my mother's belly.

it's a a matter of relativity--not relations--what u have lived thru

Steve - not meant as a put down to u or anyone else--it's just the things that one experiences are the things u measure by

spring of 70-- i was riding a tractor for 1.10 an hr--and rollin in the dough

gas was like 30 some cents a gallon

http://www.1970sflashback.com/1970/Economy.asp

FLATBEDFORD · Post by **FLATBEDFORD** » Mon Jul 21, 2008 11:14 pm

Why did this happen?

willowbilly3 · Post by **willowbilly3** » Tue Jul 22, 2008 9:32 am

I have a 70 car 2 bbl. 390 in mine. It is happy on regular but for the small difference in the price of super i use it fairly often. I have no idea if it will do a burn out and probably never will.
I can get low teens on the road but the most prudent city driving won't make much over half that.

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