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Leaded vs unleaded gasoline


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Anonymous Poster
mike1238@earthlink.net

Feb 26, 2007, 6:06 PM

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Being new to the world of classic cars, I have a question regarding running unleaded gasoline in a 1970 AMC Rebel that was designed for leaded gasoline.

How will this affect engine performance, wear and tear, etc.

Thanks for responding


DanD
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Feb 26, 2007, 9:49 PM

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For performance I don’t think you’ll have a problem as long as you’re using a premium fuel of 98 or higher octane.
As for the lack of lead that all depends on whether this engine’s cylinder heads were or have seen a reconditioning and received hardened valves and valve guides? How to tell I’m not sure?
I can still remember; for example when GM started to put catalytic converters on their vehicles and had to use unleaded fuel.
They or not too many people didn't realized that the lead in the fuel also had a lubricating quality. Without the lead the valve stems were being chewed out at relatively low mileage of 30 to 50K.
Once the heads were reconditioned with the hardened valves the problem seemed to disappear.
I’m not an automotive machinist and I’m just going by what I remember but we had to have a lot of cylinder heads rebuilt back then and after they were reconditioned the problem didn’t return.
There are top end lubes that can be added to the fuel tank; some are just snake oil that will do squat; some are not bad, but anything that claims to add intake valve lubrication is better then nothing.
Dan.

Canadian "EH"






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mike1238@earthlink.net

Feb 27, 2007, 9:17 AM

Post #3 of 22 (22451 views)
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Thanks Dan. This is what I thought. I just wanted to hear it from someone smarter than me. The engine has never been re-built and is all original.

Mike


aggressivemale
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Feb 28, 2007, 12:29 AM

Post #4 of 22 (22445 views)
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The lead also helps seal the valves too! Maybe even cylinders. I think even if you do have hardend valve seats lead won't hurt and could still help. Just don't use lead at the same time you use an oxygen sensor. It will also clog up a catalytic converter if you use one. To avoid the snake oil brands of lead additive I would say make sure you get one that has real lead.


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busnuttwo@yahoo.com

Jan 12, 2008, 7:50 PM

Post #5 of 22 (22242 views)
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if you are going to use this car much have engine mods done diff valves andhead gasket and convert to photo cell ign easy to do hard for judge to tell if you go show for point pr just ad lead sub from parts store the ping you hear is is going to worse set back timing hurt permorence talk to engine machinist


Tom Greenleaf
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Jan 13, 2008, 3:56 AM

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Lead IMO was just a cheap way to boost octane rating. Otherwise it hurt everything. Before "unleaded" was mandated there was "white gas" used for marine (still automotive engines in many cases) and we would flock to buy it for off season storage as it didn't gell up like leaded did. It's hindsight now. I still maintain we were lied to about "tetra ethyl lead" being good for anything for the car itself,

T
_________________________________________
Long retired now


wildman
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Sep 20, 2008, 10:24 AM

Post #7 of 22 (21801 views)
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could damage the vales. you can buy the lead additive at the auto parts store to add to the gas.


Loserdave
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Nov 5, 2009, 4:05 AM

Post #8 of 22 (20949 views)
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in the 80's I had a friend who had an early 70's dodge colt, it ran on Leaded.
At the time i wasn't aware of that fact , and in a spirit of kindness i filled up her tank with Premium UNLEADED !
After a couple days she came to me and tells me that i messed up her car and that it was in the shop,, i really felt sick/bad about that.
so , it can mess up an older car i guess.


Tom Greenleaf
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Nov 5, 2009, 8:18 AM

Post #9 of 22 (20942 views)
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Bull!

Tetraethyl lead was just a cheap way in increase octane and did nothing to help an engine. Owned a 1970 Olds that never saw leaded fuel - 1/4 mil miles out of original engine!

T
_________________________________________
Long retired now


Hammer Time
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Nov 5, 2009, 8:59 AM

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All this depends on the compression ratio of the engine. All manufacturers made major changes in the 1971 model year. They reduced the 10to11:1 ratios down to 8.5:1 or lower. These lower compression engines were built for unleaded. Any of the previous engines that had a compression ratio of 10:1 or higher did require leaded gas or they would at minimum ping and in extreme conditions, burn a hole in the valve or piston. That octane difference would be a major factor in a high compression engine.




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Tom Greenleaf
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Nov 5, 2009, 4:46 PM

Post #11 of 22 (20925 views)
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HT! Agree about the octane rating and compression ratios. The real McCoy was it was cheap to use lead to make junk fuel have higher octane ratings and that was the only reason. It takes more crude oil to make higher octane so it was just a cheap trick to make low grades behave as higher grades.

Oil companies have cut corners for ions. They care not for your wallet but watch theirs! Oil is a family biz and they ain't out to save you bucks - the companies that is. All retired from it now. Regulated up the butt now at least here and not in our best interest IMO,



T
_________________________________________
Long retired now


(This post was edited by Tom Greenleaf on Nov 5, 2009, 5:03 PM)


Loren Champlain Sr
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Nov 5, 2009, 9:06 PM

Post #12 of 22 (20916 views)
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Okay, you two...LOL. I was told, many years ago, that the lead was to lubricate the valve guides. So, the machine shops started putting in teflon coated guides. Another 'wive's tale'? To answer to orig. poster's question, no, one tank of unleaded fuel would have not caused the problem. If I remember correctly, it was a Dodge Omni? Your freind was lucky that it lasted THAT long. Those were destined for the scrap heap when they were new.
Loren
SW Washington


Hammer Time
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Nov 5, 2009, 10:09 PM

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Lead slows down combustion, just like octane does. Without lead or high octane, you get pre-ignition and then damage. You can still buy it at auto parts stores as a fuel additive and octane booster.




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Tom Greenleaf
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Nov 6, 2009, 10:12 AM

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I doubt an AMC Rebel needs anything but maybe? AMC made a couple super HP engines but never heard of it in a Rebel. Knew of a Hornet that was like a dragster and was OE!

T
_________________________________________
Long retired now


Hammer Time
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Nov 6, 2009, 10:14 AM

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I think they put the 390 in a bunch of those AMCs around that year. Remember the Scrambler?




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Tom Greenleaf
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Nov 6, 2009, 10:24 AM

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I don't recall 390 which sounds Ford but who knows what AMC did? One I owned (whole different car) had an International Harvester engine I think?? No slouch either! Long time ago now!

T
_________________________________________
Long retired now


Hammer Time
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Nov 6, 2009, 10:33 AM

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AMC was a big time performance car in those year using the 390. They were kicking ass on 390 Mustangs, 396 Chevelles and GTO's
The Rambler Scrambler and the 390 Javelin could run mid to low 13's off the assembly line.










1969 Rambler Scrambler / 390 Cross Ram 2X4 bbls Hurst 4 speed

There were 1,512 Hurst SC/Ramblers made of which, only 324 were the (B) paint scheme according to AMC records. Other reports say 500, either way not very many were made! They all came with the AMC 390 engine, 3:54 rear end gears, 4 speed trans and of course the Hurst shifter. The SC/Ramblers sold for $2,998.00, which was very little money for the long list of performance parts that came on the car. The SC/Rambler ran the quarter mile times of low 14's in stock form but with a few simple bolt on modifications, one of which was the cross-ram intake part # AM4486228 ( 300 made with AM# ) on them, these cars would now run low 12's. The SC/Ramblers were built for stock drag racing classes, in F-stock it was pretty much unbeatable, thanks to the SC/Ramblers horsepower to weight ratio. The stock SC/Rambler had 315 horsepower and 425 pounds of torque and weighed in at a fuzz more then 3000lbs. A slightly modifieded SC/Rambler would easily have over 400 horsepower. On the street this quick car was deadly to virtually any big three car as the front disk brakes stopped the little car in a hurry. This was a big advantage over most cars back in 1969. The SC/Rambler was a image maker car for AMC to say the least! We can play with the big boys of the performance car market and win! And it won a lot! The little Rambler became an instant legend among all muscle cars!




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(This post was edited by Hammer Time on Nov 6, 2009, 10:35 AM)


Tom Greenleaf
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Nov 6, 2009, 11:30 AM

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The Hornet I recall was like this but a "Plain Jane" or what we called a "Sleeper" back when.

I just recall it would 'light' up both rear tires like nothing and a kid (high school days) could hold the care still (one hand on hood standing in front) with the wheels at some outrageous burn out speed where they really don't get traction till the catch new pavement.

I was shocked! Right at my school no less! I think I was driving a 63 Falcon at the time -144 six - laugh,

T
_________________________________________
Long retired now


Hammer Time
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Nov 6, 2009, 11:35 AM

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1971 AMC Hornet SST Pictures & Mods 1/4 mile data
12.488 seconds
109.650 MPH trap speed




1971 AMC Hornet SC/360
by the Auto Editors of Consumer Guide Cite This! Close Please copy/paste the following text to properly cite this HowStuffWorks article:

of Consumer Guide, the Auto Editors. "1971 AMC Hornet SC/360." 09 January 2007. HowStuffWorks.com. <http://musclecars.howstuffworks.com/classic-muscle-cars/1971-amc-hornet-sc-360.htm> 06 November 2009. Auto Videos
The 1971 AMC Hornet SC/360 was a muscle car that reflected changing times. Even a year earlier in 1970, when muscle cars were at their pinnacle, the signs were there for those who chose to look. Federal safety watchdogs, state and national emissions regulators, insurance companies -- even a changing social climate -- all took aim at the high-performance car.

For '71, the shots began to hit the target. Compression ratios retreated to accommodate regular-grade fuel, gross horsepower ratings began to fall to tamer-sounding net figures, and public relations-conscious automakers backpedaled. Into this upheaval stepped the 1971 AMC Hornet SC/360.

Muscle Car Image Gallery



©2007 Publications International, Ltd.
As the sun set on big-block intermediates, automakers turned to junior
muscle cars. One of the quickest -- and rarest -- was the 1971 AMC Hornet SC/360. See more muscle car pictures.


"Introducing a sensible alternative to the money-squeezing, insurance-strangling muscle cars of America," said its advertisement. "The Hornet SC/360." Hornet was the company's newest compact, and the two-door sedan was a reasonable basis for a low-profile muscle car. Original plans called for both an SC/360 and an SC/401, but when AMC discovered that a 401-cid Hornet probably wouldn't provide much of an insurance edge, the 360-cid V-8 alone was borrowed from the Javelin AMX.

©2007 Publications International, Ltd.
Based on the compact Hornet, the SC/360 offered a 360-cid V-8
in 245-bhp two-barrel form or, as shown here, a 285-bhp ram-air four-barrel.


In standard form, it had a two-barrel carb and a modest 245 bhp. The $199 "Go" package included a four-barrel and a ram air setup for a more satisfying 285 bhp. These were gross ratings. Optional in place of the standard three-speed was a Hurst-shifted four-speed or an automatic. Polyglas D70Xl4s were standard, with upgrades running to the handling package and the Twin-Grip diff with 3.54:1 or 3.90:1 gears.
An SC/360 couldn't stay with the big-cube holdovers, but it did combine respectable quickness with a taut suspension, big tires, and modest size for a package praised by Motor Trend as "just a plain gas to drive...it handles tike a dream."

©2007 Publications International, Ltd.
With the optional Hurst-shifted four-speed, an SC/360 like this
could turn high 14s. A sport suspension and efficient
dimensions made it a pleasing handler.


The SC/360 turned out to be a sleeper in more ways than one. Even with a base price of just $2,663 (about $40 below the '71 Duster 340), it made up only a fraction of the 75,000 Hornets built for '71. The SC/360 died after just one year as one of the muscle car era's better-kept secrets.
The 1971 AMC Hornet SC/360 Specifications
Wheelbase, inches: 108.0
Weight, lbs: 3,,057
Number built: 784
Base price: $2,663

Top Available Engine
Type: ohv V-8
Displacement, cid: 360
Fuel system: 1 x 4bbl.
Compression ratio: 8.5:1
Horsepower @ rpm: 285 @ 4800
Torque @ rpm: 390 @ 3200

Representative Performance
0-60 mph, sec: 6.7
1/4 mile, sec. @ mph: 14.9 @ 95








A Brief History of the AMC Hornet
The year 1970 was an important turning point in the History of the American Motors Corporation. Since the 1954 merger between the Hudson and Nash companies that gave birth to the company, American Motors had been manufacturing and marketing their products under the Rambler brand name. Although the Rambler line of cars did very well early on, the cars and the name began to take a beating in the marketplace during the mid to late sixties. During this time, the Rambler name was irreversibly harmed. In an effort to create a new company image the Rambler name was dropped forever. The Kenosha, Wisconsin Independent would now become known as AMC.
As 1970 rolled around American Motors introduced their new AMC cars into the market. They replaced the Rambler American vehicle line with a completely new car, the Hornet. The AMC Hornet was an attempt to meld the frugal image of the Rambler with an image of luxury into a new type of compact car.
The new Hornet was designed by designer Dick Teague and was to be the basis of a whole new group of car lines. As was seen later that year on April Fool's Day. The company introduced the first American subcompact car, the AMC Gremlin, its chassis was a shortened Hornet chassis, cut down by one foot.
Built on a 108-inch wheelbase, the new Hornet sedans had a long hood/short rear deck styling theme that was in line with the public tastes at the time. These basic elements had been used in 1969 for the new Ford Maverick compact car, which had proven to be immensely popular. The AMC Hornet would compete directly with the Maverick offering a longer wheelbase, which gave the car more interior room that it's rival.
The Hornet showed AMC's turn back to niche politics. Not only was it available as a stripped and cheap base model, but also a long list of options was offered, and that's what made a difference from the competitors. Everything from its base 232 cubic inch six cylinder, vinyl seats and rubber floor mats to a luxurious top model with a 360 cubic inch V8, cloth interior and carpeting. Even automatic transmission, disc brakes, air conditioning, reclining bucket seats and vinyl roof could be ordered.
The Hornet also brought back the strategy of parts sharing. The two and four seater versions were identical up to the roof, and even front and rear bumpers interchanged. Hornets were produced from 1970 through 1977 when the line was moved upscale a bit and dressed up as the AMC Concord, which later wore a new body with four-wheel-drive and was called the AMC Eagle.
The Hornet did especially well in drag racing modified by the privateer Wally Booth who took the crown from the deep pocketed "big guys" one year. Maskin and Kanners also drag raced the Hornet with good success. (see Booth's Killer Kelvinators Tribute Page)
While the high option cars are most valued by current AMC collectors, the low option Hornets make good hot rods by merit of their relatively simple lightweight all steel unibody and very good interchangeability of factory performance parts, making an AMC 401 V8 engine basically a bolt in modification.
The AMC Hornet as a collector car is supported with active, loyal AMC enthusiast clubs for part sourcing and information. Aftermarket high performance parts are not commonly found in mainstream medias but quality hot rod parts are indeed currently available.




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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Nov 6, 2009, 11:37 AM)


Loren Champlain Sr
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Nov 6, 2009, 3:55 PM

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AMC 390's were, as I remember, small blocks. The AMX (two seat Javelin) were very quick.
Loren
SW Washington


Hammer Time
Ultimate Carjunky / Moderator


Nov 6, 2009, 6:33 PM

Post #21 of 22 (20862 views)
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They were like the Mustangs................ 400HP stuffed into a 10 cent car.




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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator


Nov 7, 2009, 8:05 PM

Post #22 of 22 (20846 views)
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AMC was coined "All Most Complete" as a slur against the company. As said - owned two and both were great. Others were just trouble from new! Wonder why they don't exist anymore?

T
_________________________________________
Long retired now




Leaded vs unleaded gasoline


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