Good Gas? Bad Gas? Need your thoughts...

[skrambler]

As I have explained in several prior posts, I recently (this past weekend) purchased a numbers matching 1970 Roadrunner.
The original engine has been re-built, 30 over and 20 over on the mains and rods. It now has a mild Competition Cam and Tappet package.
My question is What kind of fuel should I be running in it?
Obviously, gas is not even close to the same as it was 40+ years ago, so my choices, I suppose are Regular, Mid, or Premium Unleaded gas....Correct?
I am not racing the car, but simply enjoying it as an antique. Since all above are unleaded, is there going to be any difference in any fuels? Should I be adding any additives other than stabilizers if setting for a while?
Once again, thanks in advance for your replies.

 

[70rr-brian]

Do you know if when it was rebuilt if they put harded valve guides in it? If it does then premium unleaded should be fine unless you are in the 12 to 1 compression ratio or higher. If no hardened valve guides then maybe toss a bottle of lead additive in it about once every 4-5 fill ups.

 

[Propwash]

I run premium in my cars. As far as leaded/unleaded, the old gas (which was much better than today's as far as compatabilty), had Tetraethyl lead in it. Guys like yourself that don't have the hardened valve seats are forced to try and add an additive. Lotta backfire about the additives out there these days and even the availibilty can be an issue. I had a 72' Dart with a 340 that I use to run the STP lead additive. Not sure you can even get that in the states anymore, but back then I had no issues. Heard there is other additives on the market that perform, but haven't tried them. Another option you have is go to a small civil airport and pick up some AVGAS. 100 low lead (100LL) is the most common these days and is run in pistoned fired aircraft. Even though it is "low lead" it still has a higher concentrate of Tetraethyl lead than the old leaded gas used to have. Aviation Gas will run in your car with dilution and is actually a much more refined fuel. Down side....6 bucks a gallon right now.

There's a fella down the road that runs a Buick GS, he fill's a 30 gallon drum every year with the 100LL and dumps about 3 gallons in when he fills up or on the way to fill up. For me being a pilot, it's pretty easy to get, for him, he had to form a little bit of a relationship before they would let him on the flightline to fill up. Either way, most airports are municiple owned, thus you should have access to the fuel unless it is a restricted flightline. I couldn't see any small airport not letting you grab some fuel, the more they sell the lower their cost.

If you ever look into that option, here's a handy site were you can look at airport A/FD (Airport/Facility Directory). When you select a state and then an airport, it will indicate if and/or what fuels the airport has on site. Most of the lingo will look pretty foreign to you, but look under Airport Services, you'll find the info there.

http://www.airnav.com/airports/us

My 2cents...hope it helps

 

[bigmanjbmopar]

I have a 9.6:1 compression motor and run 91 oct. I would recommend it or 92 depending were in the USA you live.

 

[Sixer]

Do you know if when it was rebuilt if they put harded valve guides in it? If it does then premium unleaded should be fine unless you are in the 12 to 1 compression ratio or higher. If no hardened valve guides then maybe toss a bottle of lead additive in it about once every 4-5 fill ups.

It's the valve seats you have to be concerned with, not the guides. Unleaded engines have hardened seats in them (and all aluminum heads do of course) to keep the exhaust valve from receding into the head. Avgas is not that great for car engines, but is better than nothing. I get 5 gallons race gas (110 octane) and top the tank with unleaded premium. Works well, no detonation anyway-not sure of the lead content however, as even some race gas is unleaded now. Engines that are worked hard have the most to fear from valve recession, occasional spurts shouldn't be much of an issue. Just check exhaust valve clearance occasionally, if you note the exhausts tightening up, time to have the heads done and hardened seats installed.

 

[hunt2elk]

I use 91 octane premium. Stay away from anything with ethonal in it.

 

[tpodwdog]

since youre in Butler Pa...you can get 93 octane around these here parts...the higher the OCTANE ,,,the better. keeps the valves from knocking and pinging....and cures pre-ignition. i run 93 in my 1970 383 HP...i have no problems....of course i have timing and dwell set to where they're supposed to be!

 

[Deleted member 214]

If you are just cruising, run the lowest octane the car will take without knocking. Why waste money? If I am taking my 440 six pack 9.2-1 on a road trip (like from Fort Worth to Columbus for the Mopar Nats and back) I run regular and retard the timing a bit. If I want to stomp on it around town or take it to the strip, I use better gas.

 

[1969CoronetR/T]

I have tried Blue Torch 110 octane racing engine that is leaded in my 1971 Demon stroker. $8.00 a gallon was not worth it and the performance gain was marginal. Ifyou have hardened seats, I would use the highest octane you can afford. I use 93 octane in all my vehicles, old and new.

 

[RRcrazy]

I have a 383 bored 40 over 11.5:1 compression. This engine was built in 2005 most rebuilds have upgraded to unleaded gas but to be save you should find out who built the engine and ask them., you should also know what your compression ratio is. Once you know that you will know what your fuel should be I use unleaded 93 octane with no issues.

Hope this helps.

 

[Mesopic]

why don't you put a broquet fuel catalyst on it and run it on and use 93. i'm putting one on mine and it will run on 98 (fuel catalyst's are cheap and they add lead to fuel)

 

[Mesopic]

sorry they don't add lead but they mean you don't have to add lead.

 

[Ron 73]

The 318 in my 73 seems to run good on the low stuff ( i use lead sub in it), my Rams 318 pings when i use it and hate to start buying the pricey stuff but im afraid im going to have to change it..

 

[skrambler]

Update.
I was able to do a bit of talking with a fellow that owns a local fuel company in a near by town. He came up with this possible solution for me.
He has 89 octane, ethonal free, unleaded fuel. Plus, he stocks the Blue Torch, 110 octane leaded fuel too (close to $9.00 per gallon). I am going to try a mixture of 4 to 1 on my next fill-up, and see how things go. I have to assume that I do not have hardened seats, so I am hoping that the leaded fuel, even in the amount I will be using will benefit me. Plus, no ethonal will be a plus too.
Thanks for all your comments and suggestions. I'll post what I find out, if anything later.

 

[1969CoronetR/T]

I just put the VP Racing leaded 115 octane (I thought it was Blue Torch 110 octane) into my Coronet and it seemed to run better. It may be a placebo effect and at $8.00 a gallon it sure is not economical compared to 93 octane. A mixture may the best bet to negate some of the ethanol and extended cost of the racing fuel.

 

[Bigal75]

Run 93 -94 octane. As for the hardened seats do you drive it 10,000 miles a year? If not, I wouldn't even worry about it. Only use the octane that's required - any more is just a waste of money.

 

[Kern Dog]

I use 91 octane premium. Stay away from anything with ethonal in it.

Uhhh, good luck with that. Ethanol is everywhere. It will take legislation to get rid of it now.
Roadrunners, I mean Road Runners are great cars. Congrats on the purchase!

 

[1969CoronetR/T]

http://pure-gas.org/

No ethanol free gas in my area.

 

[skrambler]

Non Ethanol Gas

69Cornet44o, maybe, if you are able, this is the station were I found the gas I will be using.

Mars PA.UNBRANDED89 Purvis Fuels321 Mars-Valencia Rd.

 

[1969CoronetR/T]

Do they have it in any higher octane? I prefer 93, but 89 ethanol free would be great. Mars is about a 2 minute drive for me, so by the time I get home I would be turning back around for gas. I am going to the car show in Wexford tonight at Starlite (forget the churches name across from Sheetz).
Mark