Do I need to use fuel additives?

[jeryst]

Now that I am driving my Challenger around a little, I would like to know if I should use any fuel additives, like octane booster, or lead. I put 93 octane in it, and it seems to run fine. It is the original 1973 motor (340). Will the valves be damaged if I do not use a lead additive? If I need to use something, what is a good type to use that is readily available at someplace like Wal-Mart, or Advance Auto?

[426 pentastar]

No you do not need any additives to run on the street,sure fire way to tell is if it pings.That means one of two things,low octain or timing.

[jeryst]

It seems to run fine, without any pinging, even at load, do I agree that I probably don't need an octane booster (Although it would probably increase performance a little). I'm mostly worried about lead, because if the engine was made to use it, the valves can get damaged. I just can't remember when they reduced the lead, and if a 73 requires it.

[pink panther]

I run 93 octane and use octane booster in the chally.  Seems to be slugish when I don't and the timing is advanced enough that if i don't it deisels.

[MEK-Dangerfield]

It seems to run fine, without any pinging, even at load, do I agree that I probably don't need an octane booster (Although it would probably increase performance a little). I'm mostly worried about lead, because if the engine was made to use it, the valves can get damaged. I just can't remember when they reduced the lead, and if a 73 requires it.

From what you said here, be thankful you can get by with 93 octane.  Don't do ANYTHING else!! You are good to go. Lead was added to gas back in the day to prevent pinging. You will do NO harm running unleaded gas in your car.


  Mike

[Katfish]

I am curious about this as well.  My 340 is a 1970.  I have been putting in the lead additive.  I was under the impression the lead was needed as a lubricate in the older engines.  I thought you would do damage if the lead wasn't there?

 

[MEK-Dangerfield]

I am curious about this as well.  My 340 is a 1970.  I have been putting in the lead additive.  I was under the impression the lead was needed as a lubricate in the older engines.  I thought you would do damage if the lead wasn't there?

 

No,

  That is one of those old wive's tales. As long as you don't ping, there is no problem. The trouble is alot of the older engines are high compression, so that is why they need more octane. You can retard the timing a few degrees too to shut it up too. 

  Mike

[Katfish]

I was searching around and found this?

"A side effect of the lead additives was protection of the valve seats from erosion. Many classic cars' engines have needed modification to use lead-free fuels since leaded fuels became unavailable. However, "Lead substitute" products are also produced and can sometimes be found at auto parts stores."

[mopar-or-no-car]

It seems to run fine, without any pinging, even at load, do I agree that I probably don't need an octane booster (Although it would probably increase performance a little). I'm mostly worried about lead, because if the engine was made to use it, the valves can get damaged. I just can't remember when they reduced the lead, and if a 73 requires it.

according to the little owners manual I got with MY 73 it says that the engines were designed to run on leaded AND unleaded gasoline at 72 octane in 1973!! so don't worry about your 73 running on unleaded gas!! I don't know about 72's but I think 71's and 70's need the seats and valve guides changed in the heads to make them able to run unleaded gas!!

[JS27N0B]

I would not worry about no leaded fuel on a 1973 engine, they already have induction hardened valve seats to prevent valve damage.

lead does lubricate valves and earlier engine will have the valves and valve seats fail after many, many miles of unleaded use.

Hope this helps. No wives tale.

[jeryst]

Older engines really do need the lead. A friend of mine is a Hemi-addict (he has like 15 of them), and he said that up until somewhere in the 40's, all valve train components were hardened. Then, the  bean counters (no offense intended)  learned that since the lead acted as a lubricant, they could save a few bucks by not using the hardened components. It was that way, up until whenever they started using hardened components again. I knew it was sometime in the 70's, I just didn't know when. So if you run unleaded gas in an engine that was meant to use leaded gas, it will eventually fail.

[dimples]

Run a couple onces of marvel in your gas, just to be safe, wont hurt anything, just a little extra lube.
The owners manual on my 74 D300 advises the use of leaded gas for heavy towing. UNleaded is fine for normal driving, which would be what you guys do, right?
Still, running the marvel wont hurt anything, that is for sure.