Mpgp1999

Avgas in a Dodge

Recommended Posts

I have access to 100ll leaded gasoline for my dodge. Besides that it costs less then premium gasoline. It cost 4.75 San Francisco Bay Area. Is there any benefits in regards with storage and lubricity. 

Share this post


Link to post
Share on other sites

A friend of mine back in HS used to put that stuff in his 69 Chevelle SS 396.  Of course that was an 11:1 cr "built" engine that really benefited from it.
AFAIK (and I'm far from an expert) the only benefit you'd get would be the lead providing valve seat cushioning.  Oh, probably also the benefit of having no ethanol added but you can also get that benefit by carefully choosing your filling station (at least in PA you can).
The high octane rating will be totally lost on your engine since it has such a low cr.  Kind of like giving a wino a $1000 bottle of wine.  Pointless...
And there's also the fact that avgas doesn't have a road tax applied so getting caught doing what you're thinking about would probably get you a big fine.  Same as the risk the lifted diesel 4x4 truck guys take when they put dyed home heating oil in their trucks.  Cheaper fuel until you get busted.  Then expensive fuel.
Just my .02

Share this post


Link to post
Share on other sites

What year Dodge? Many 6-volt cars have trouble lighting high-octane gas and often don't run as well as they do with the cheap stuff. For example, the owner's manual for my 1941 Buick says to use 72 octane for best results. Even my 1993 Mustang 5.0 runs noticeably better on 89 than on 93. High-octane can be tough to light with those 6-volt electrical systems and low-compression engines. Avoiding ethanol is often good, but I don't really think avgas is a solution unless you're just going to use it for storage purposes and even then you might have trouble with it running correctly and if you're using avgas, you won't blame the gas. It can introduce a whole different set of variables to your engine if and when it starts to act up. As long as you keep the fuel moving through the car on a regular basis, I don't see much harm in regular unleaded in old cars. I have 110 old cars sitting here at any given moment and they've all got pump gas in them, nothing special. They all typically start and run, and if they don't, the most common issue is a stuck float which is easy enough to cure. Don't bother with premium, either--there's nothing in premium that's not in regular beyond a higher octane rating. It doesn't make more power, it doesn't clean the engine, and it isn't a special treat for the engine now and then. If your compression is less than 10:1, you probably don't need it.

 

Avgas is an expensive solution to a problem that isn't really a problem.

  • Like 2

Share this post


Link to post
Share on other sites

Higher octane fuel burns more slowly than lower octane fuel. You will find the exhaust side of the engine gets quite a bit hotter - it is may even be still burning as it goes into the exhaust. You may even have valve trouble.

 

Your car was made for, what, 53 octane? Or maybe 63 octane? Use the lowest octane you can find.

  • Like 2

Share this post


Link to post
Share on other sites

There are a number of restoration shops and museum collections using Avgas in their restorations because it will not evaporate like all the modern ethanol.  Maintains its characteristics for up to two years compared to pump gas beginning to deteriorate after 2 weeks.    And some auto repair shops will use it too - a local shop told me he does and explained how to get it at the airport.   The antique guys find no problem whatsoever in their low compression early engines.

 

It is indeed 100LL today meaning "low lead"  and there is minimum benefit from there being this little lead... but some.   Years ago, Avgas had much more lead - no more.   Under US law, you can not run Avgas on the street because it does not include your state or federal road taxes.   Avgas burns very clean, it is very pure, your car will start every time, your carburetor will love it,  it will not destroy any rubber hoses or diaphrams or carb parts.     100LL is rated as 100 octane "at altitude" so in reality it is somewhere around 95 octane at your ground level, depending on where you live. 

 

Fair amount of bother for me to get into my small regional airport and buy 100LL (credit card at their pump, must bring container, must enter the tail number of a prop plane) and they have gates.   But I do it when I need to and find it totally worthwhile and have never experienced any down side.

 

Try it.   I think you will really like it.

 

Share this post


Link to post
Share on other sites

My car is original 12v. Made December of 25. As for the octane I have heard of people using kerosene 1:4 or diesel. 

Share this post


Link to post
Share on other sites

I recently rebuilt my vacuum tank and now the fuel evaporated from the carb and vacuum tank in a day or so. In the past I have gone a month or two and there would still be some gas in the vacuum tank. The connections are tight and I see no signs of leaking fuel. 

Thats why I have a can of fuel to prime the carb. That extra fuel is avgas. The tank currently has 91 maybe with some marvel mystery oil. Since I am next to an airport I just walk over there with a jerry can and fill it at 4.75. For 100ll

Edited by Mpgp1999 (see edit history)
  • Like 1

Share this post


Link to post
Share on other sites

For the issue of road taxes. Couldn’t I keep track of the non taxed fuel that I used and pay the taxes at the end of the year. Is there any lawyers out there? I don’t see kerosene for sale with road taxes 

 

avgas is taxed federally and by california. I should not have any legal issues when using it on the road  To my knowledge clear kerosene is taxed and dyed is not. 

Edited by Mpgp1999 (see edit history)
  • Like 1

Share this post


Link to post
Share on other sites
8 hours ago, Mpgp1999 said:

For the issue of road taxes.

 

You are paying the road tax every time you mow the lawn or go for a boat ride.

Kinds offsets itself.

If and when I winterize I use 120 leaded race gas. Easy to find in most areas, just not at a gas station or airport.

As for evaporation, I keep one of those metal squirt cans full of gasoline with pressure over it. VERY handy.

 

https://www.ebay.com/itm/Liberty-Spot-Sprayer-Pressurized-Spray-Can-Steel-Red-1-qt-32oz/123815854893?hash=item1cd400032d&_trkparms=ispr%3D1&enc=AQAEAAADIKvsXIZtBqdkfsZsMtzFbFsbX3WcW5fmB%2Fx7ZbaZTyex5%2F5IBesqWURBxPsBx%2FTFyfde0VhS1ArmaoJQ8B9Vg%2FUHdH3sHIhYEGGgXkgTGo%2Baw3uMO%2FvjCvMy1ETzZLjVRft70Eoq4ejzEpAuuHH4Aozldfjks4h%2B7i5tqi3xHR4pjz%2FSO607oaL2zbPIL2MvMWe3erAWaM0LG6D39QxisTEY%2BwaWjzzIekHQo%2F88e4uVrAKbP0kkAwojmCMho%2B4JXYCWq%2BRws8E18ZszPKh43I1f%2BE1JIButODq6ny0n86FqsqUWlZOeYezq%2F2zzb5fBJnCHjY8ghAihLIt3XinAa9lCUpqXlqdtxVZsrkJXIWT5BOJmLaOi19vGQylYyWBwrTNNvQjC0h7o%2FoQ8iAhpFlvVogi9%2BySDm3OrUeim3J0%2BzFu8MbdBvxCIzWjoQDZDG2GDgTjb8dvOQTTIbIE2rbbwoWd5v3PFjWJ268oUwUfMxLzCkk8I%2B01n0qP5WzNYzW6JUmHwr5apL9Bi26e1HhXp9aWEw1vTMGAx4t%2BOV3ynqxu8bA3LGPo19ejIoq1xK%2BW9CB4mWW60G5nSsYg0uRxtg6iLxyNJdgZUEtf40%2B3rIrLRRtqFexxxNnIdfRRljv3UKbnfMDqzLOooA6H5u%2BnE3aMgJLyM7m07Dc9f1Gg%2FQ8gK0KUEFwfzyQ5jowLBX0XH5r9BvOKFaR8DD7KwUSbJNuXewUmIYlx6cGkwJWQ3Ery2DJj6Gi5scpVXIHB6HJ4BcbuKfk9n3qZr5zE6B4Ya5D%2FTJhmsh38HrVfrgBIvH3OJuGQdE8H%2BgNsba0GoqqlRisA7cfqqSqdF9Ym6%2B6HiVkO37JpwhVzndU6leRAkTq1OSFRyrUdqk80i1C8pw%2F8xuirpR9Q%2B1qv0jjd%2FMwO97xGbR0peY7nXFSO4e%2BBMl6JNw7bUfjg7m6l%2FD58tLRvZ153NHaXJX%2B5bZFV9OhO7Qa4wvkut4CJarJsKK3ejCE%2FQ%2BbytrNPtyoHFalocneejSv29ErYTOQBmtk2jFcZZvWbi%2FusLQ9iAUjUELk1g&checksum=1238158548932bcd69a8963b4c63b370390662f4be8b

Share this post


Link to post
Share on other sites

WOW !! that is one long link address.

Share this post


Link to post
Share on other sites

Many taxpayers may be overlooking the refund or credit available under IRC § 6421 for federal excise taxes paid for motor fuels and similar state provisions. The taxes are on fuels used to power vehicles and equipment on roads and highways. Taxes paid for fuel to power vehicles and equipment used off-road may qualify for the refund or credit. This includes farm equipment and certain boats, trains and airplanes.

 

https://www.journalofaccountancy.com/issues/2011/mar/20103438.html

  • Like 2

Share this post


Link to post
Share on other sites
23 hours ago, Spinneyhill said:

Higher octane fuel burns more slowly than lower octane fuel. You will find the exhaust side of the engine gets quite a bit hotter - it is may even be still burning as it goes into the exhaust. You may even have valve trouble.

 

Your car was made for, what, 53 octane? Or maybe 63 octane? Use the lowest octane you can find.

 

Flame front propagation rate is a good analogy for the process. But it is not precisely accurate. 

 

Octane in the mid-'20s was in the mid 40s. 

 

I have a very important medical appointment. Must run. In the meantime, I will just reach into the grab bag and throw a little pulp at the wall. If it sticks, browse it in my absence. I need to establish my credibility before I distill this down. I spend quite some time on this issue.    -    Carl 

 

 

E91014E0-BFBA-4374-AA1B-A17CE2385F78.jpeg

DE614314-F4B0-4570-BC60-013F9CD27AA2.jpeg

E0B4800F-42FD-4BF7-AA40-D2327A67ACE6.jpeg

4D6CB667-FC18-4846-8BFF-ED653B20D0B7.jpeg

Share this post


Link to post
Share on other sites
58 minutes ago, C Carl said:

 

Flame front propagation rate is a good analogy for the process. But it is not precisely accurate. 

 

Octane in the mid-'20s was in the mid 40s. 

 

I have a very important medical appointment. Must run. In the meantime, I will just reach into the grab bag and throw a little pulp at the wall. If it sticks, browse it in my absence. I need to establish my credibility before I distill this down. I spend quite some time on this issue.    -    Carl 

 

 

E91014E0-BFBA-4374-AA1B-A17CE2385F78.jpeg

DE614314-F4B0-4570-BC60-013F9CD27AA2.jpeg

E0B4800F-42FD-4BF7-AA40-D2327A67ACE6.jpeg

4D6CB667-FC18-4846-8BFF-ED653B20D0B7.jpeg

This is very interesting. What is this book. 

Share this post


Link to post
Share on other sites

 A spare moment which gives an opportunity to the benefit of all. I will be back to clarify, but no matter what your background may be, you will derive something from all of this. Perhaps some of you could have written this, to others it is quite new. Most of us, myself included, will find ourselves somewhere in between. More :

 

 

 

 

420062D5-9EBC-4CC0-92DF-CB2C767A9E02.jpeg

3D896DA9-8E92-4C1F-939B-9D62B85611A1.jpeg

6B3DE9F3-2F86-4072-B33F-4A3EA78BAD45.jpeg

Share this post


Link to post
Share on other sites

Sure. The first book is : "Marks' Mechanical Engineers Handbook, 2nd edition, 1924". 

The first book of my second posting is : "Marks', 3rd edition, 1930".

All the rest come from a couple of the annual editions of : "Merck Index" from the late '50s, and the '60s.

 

For you, Mathew, I would recommend "Matks', 3rd". Fascinating read to understand aspects of the sophistication of engineering of the period. I am sure you know how to shop far better than I. Please let me know what these are selling for now. A "Merck Index" should be relatively inexpensive. I used to pick them up from University of Washington surplus. Could run from 50 cents to a buck or so. Let me see if I can find a page from the period I have referenced, which may be very automotive. Please standby.   -  Cadillac Carl 

Share this post


Link to post
Share on other sites

Octane in the 20s about 45octane? Ron mon or Ron+mon/2. What issues can occur with high octane in a low compression engine. My motor is about 50-55 psi. 

Share this post


Link to post
Share on other sites

I was able to find the 2nd edition online for under 35 with shipping. 

Share this post


Link to post
Share on other sites

As far as the lead goes, I think it's safe to say that the Dodge engines from 1914 through 1925 (at least) were not designed with the assumption that leaded fuel would help lubricate the valve contact surfaces.  Leaded fuel wasn't introduced until the early 20's although I can't seem to dig up a more specific date.  As for ethanol in fuel, my '25 seems to run fine on it (summer blend 87 octane) and I've never had any vapor lock problems on hot days in traffic (granted CT isn't the best climate to test this).  I also find that if I don't start the engine for 2 - 3 weeks, there is still enough fuel remaining in vacuum tank to start the car (I do shut the valve at vacuum tank fuel outlet between uses).  On the other hand, I've never driven the car with ethanol-free gas for comparison.

Edited by MikeC5 (see edit history)

Share this post


Link to post
Share on other sites
On 10/7/2019 at 1:55 PM, Mpgp1999 said:

I have access to 100ll leaded gasoline for my dodge. Besides that it costs less then premium gasoline. It cost 4.75 San Francisco Bay Area. Is there any benefits in regards with storage and lubricity. 

I've been flying with it for years. Last plane had an A65 Continental. Compression ratio was about 6. The Dodge is about 4. The good thing is AVgas doesn't have the crap in it. Put some auto gas in a saucer and Avgas in another. tomorrow the auto gas is gone, and the Avgas is still there.  Very stable. Also the Dodge was made for the lead to jube the valve guides, modern auto gas has none. 100LL(Low lead) does. the main reason for higher octane is so the fuel doesn't pre-ignite under the higher pressures of modern engines. The Dodge doesn't have that.  Bottom line, Avgas a lot better for the Dodge than modern auto gas.

  • Like 2

Share this post


Link to post
Share on other sites
4 hours ago, walt evans said:

Also the Dodge was made for the lead to jube the valve guides,

No Sir. Tetraethyl lead was introduced in the '20s as an anti-knock additive. It was found to be a suitable cheap additive by GM laboratories in 1921. It "acts by controlling the combustion or burning rate of the petrol when in the cylinders of the engine. In other words, it prevents undue rises of pressure over small crank angle movements - that is, when the piston is at, or about, top dead centre. Thus, spontaneous ignition of any part of the petrol-air charge is avoided..." from the Service Station and Motor Mechanics' Manual, by George George, 1940. It became available on 1 Feb 1923. Increases in compression ratios followed!

 

It was noticed in the early days of its use that it had a harmful effect upon the combustion chambers, pistons and valves of engines, due to the deposition of metallic lead. After considerable research, "ethyl fluid" was modified to be 61.69% TEL, 26.88% ethylene dibromide, 7.55% ethylene dichloride, 2.82% kerosene to dissolve 0.12% dye, plus some impurities. This was in 1940 of course. The kerosene had a slight lubricating effect too.

Edited by Spinneyhill (see edit history)
  • Like 1

Share this post


Link to post
Share on other sites
On 10/11/2019 at 12:00 PM, MikeC5 said:

I think it's safe to say that the Dodge engines from 1914 through 1925 (at least) were not designed with the assumption that leaded fuel would help lubricate the valve contact surfaces.

It is safe to say that NO ENGINES were designed assuming tetraethyl lead (TEL) would have any effect on valve lubrication. That is a myth. TEL was purely and only an anti-knock additive.

 

It was noticed, after ethylene dibromide and ethylene dichloride were added, that the carbon deposits in the combustion chamber are less than without "ethyl" being added. The carbon may be slightly harder than without "ethyl". In the cooler parts of the chamber, they are greyish in colour, while in the  hotter parts, such as the exhaust valves, they are reddish, but are easily brushed off with a stiff wire brush.

Share this post


Link to post
Share on other sites

Are you sure about that?  My own experience with a pre-unleaded gas engine was a '65 Plymouth Valiant with 225 slant 6.  I had done a valve job on the engine in '79 or so and did not install hardened valve seats.  I drove the car for another 80,000 miles when it began running poorly.  Plugs, points and carb rebuild didn't help much.  It turned out the valve clearances had closed up (solid lifters).  I finally pulled the head to find severe valve seat recession.  I thought this was due to running unleaded gas.  I also found out that these engines had induction hardened valve seats starting in 1972, which I assumed was in anticipation of mandated use of un-leaded fuel in the US.

 

This explains how I remember it...  https://oldschool.co.nz/index.php?/topic/20751-valve-seat-recession-explained/

 

I'm not a chemist or chemical engineer so I could be wrong... (just ask my wife)

 

Share this post


Link to post
Share on other sites

For what extra av-gas or lead additive will cost you, you'll likely be better off running the lowest-cost pump gasoline until valve recession becomes an issue and then doing a valve job with hardened seats.

  • Like 1

Share this post


Link to post
Share on other sites
37 minutes ago, MikeC5 said:

Are you sure about that?

My reading is that valve seat recession started in some engines after unleaded gas came into use. The octane boost of "ethel" prevented pre-ignition. When it was removed, the octane of fuel was reduced and flame front speed increased. This is what was hard on the valve seats.

 

As for a layer of lead, addition of ethylene dibromide and ethylene dichloride prevented the layer of lead being deposited - it was a serious problem before those chemicals were introduced. The byproducts, which come out in the exhaust, lead chloride and lead bromide, are highly toxic.

 

This is what wikipedia says about it, with references:

"Valve wear preventative

It is a common misconception that 'Tetraethyllead works as a buffer against microwelds forming between the hot exhaust valves and their seats.[14]' Once these valves reopen, the microwelds pull apart and leave the valves with a rough surface that would abrade the seats, leading to valve recession. When lead began to be phased out of motor fuel, the automotive industry began specifying hardened valve seats and upgraded exhaust valve materials to prevent valve recession without lead.[15]

Microwelding of the exhaust valve and valve seat is now thought to have occurred due to the increase of flame front speed when the switch to unleaded came about. The increased combustion pressures caused 'micro welding' in older style motors that had the valve seats machined into the cast iron head. Retarding the timing of the engines reduced the combustion pressures and proved to be an effective short term measure in the switch to unleaded fuel. The long term solution was hardened steel valve seats.[16] "

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now