36humpback Posted January 30 Share Posted January 30 I finally got my engine running. I put VP 110 racing gas in it as it is supposedly leaded gas. It has an octane rating of 107. Will it hurt my engine? Should I go to regular gas and add "lead additives"? Any help would be appreciated. Bob Link to comment Share on other sites More sharing options...
TerryB Posted January 30 Share Posted January 30 The higher the octane the more difficult it is to get the gasoline to ignite. If the rebuild included hardened valve seats and exhaust valves high octane should not needed or even leaded gas. You vehicle probably has a compression ratio of 7:1 or less and would be happier with lower octane fuel. 2 Link to comment Share on other sites More sharing options...
28 Chrysler Posted January 30 Share Posted January 30 Somewhere around 69 octane is what was used back in the day and i don't think you need to worry about no-lead gas. 1 Link to comment Share on other sites More sharing options...
ramair Posted January 31 Share Posted January 31 I do not know about the engine durability, but here in California our pump gas will go bad in less than a year, so I would say that in your state if you can get regular pump gas without the corn alcohol (think water) then stick with that as it will keep in your tank and it’s closer to the octane that your car burned when new. Here in California it is a challenge. 7 years ago I pulled the gas tank out of my 1968 olds Toronado to clean it and the inside of the tank looked like stainless steel. Last year my gas gauge stopped working so I dropped the tank and looked inside and the bottom of the gas sending unit was rusted off and the arm and float was at the bottom of the tank, I am not a engineer but……… 4 Link to comment Share on other sites More sharing options...
TTR Posted January 31 Share Posted January 31 (edited) 2 hours ago, ramair said: …. 7 years ago I pulled the gas tank out of my 1968 olds Toronado to clean it and the inside of the tank looked like stainless steel. Last year my gas gauge stopped working so I dropped the tank and looked inside and the bottom of the gas sending unit was rusted off and the arm and float was at the bottom of the tank, I am not a engineer but……… Sounds more like a problem caused by too long in storage between exercises/use. I have vintage cars I’ve owned and drive over 30 years here in California and their fuel tanks have been inspected every 10 or so years, last time in 2022 and none have exhibited problems like yours, but then again, I drive my cars fairly regularly, at least once a month and few thousand miles a year, on average. My 1932 Plymouth still has the OEM tank that came with it when I bought her almost 35 years ago and during its last inspection in summer of ‘22, inside look as clean as it did in 1989. Since that last inspection, I’ve driven her over 7000 miles and don’t expect the condition of inside the tank having changed much, if any at all. BTW, I use regular, non-leaded pump gas (+ MMO) in all of my & my clients vintage cars, including high compression 6 carb 4-cam V12 Ferraris, etc. Edited January 31 by TTR (see edit history) 1 Link to comment Share on other sites More sharing options...
ply33 Posted January 31 Share Posted January 31 6 hours ago, 36humpback said: I finally got my engine running. I put VP 110 racing gas in it as it is supposedly leaded gas. It has an octane rating of 107. Will it hurt my engine? Should I go to regular gas and add "lead additives"? Any help would be appreciated. Bob Having an higher octane than required should not damage the engine. The main thing it will do is lighten your wallet. The L-6 engines used in Chrysler product cars all had hardened exhaust valve inserts from the factory and do not need leaded gas. As a rule of thumb, the octane required is often the same as the compression ratio, so your pre-WW2 car the cheapest, lowest octane gas you can find at a normal gas station is more than good enough. If the rubber components in your fuel system are really, really old (like before 1990) then they may be damaged by some of the additives in modern gas. You can get rebuild kits compatible with modern gas for your fuel pump and you can replace the flex hose to the fuel pump. Some carburetor kits had rubber tips on the float valve, if your car had that then you will want to replace that too. But if the car has been driven at all regularly in the last 20 or 30 years these things have probably already been taken care of. Basically, buy the cheapest gas you can find and drive the car. 4 1 Link to comment Share on other sites More sharing options...
ramair Posted January 31 Share Posted January 31 True I have 7 antique vehicles and just like a favorite girlfriend sometimes we are with one more than the rest. Another issue is I would rather leave one parked for a couple of months than take it out and not be able to drive it for 30 miles to be sure to get all the condensation out. I am very religious about keeping my gas tanks topped off. Whenever I get down to 3/4 of a tank I fill up. My 93 Allante and my 68 Toro gets 500 miles a year each my Packards do about 300 , right now my 36 GMC has done close to 2000 miles since restored 2 years ago. My 1915 and 1928 Buick are used the least. I would like to drive every one of them more, but I work full time and I drive about 35,000 miles per year , would use my antique’s for work but I am a farmer 1 Link to comment Share on other sites More sharing options...
mercman from oz Posted January 31 Share Posted January 31 Link to comment Share on other sites More sharing options...
Rusty_OToole Posted January 31 Share Posted January 31 (edited) The rule of thumb is, your octane should look like your compression ratio. A 1938 Dodge came with 6.5:1 compression and at the time, regular gas was about 65 octane. Your car will run best and develop the most power on low octane regular gas. You could even toss in a little kerosene to lower the octane, if you have trouble with vapor lock in the hot weather. The go juice won't hurt anything but it isn't necessary. If you like, you can add some Marvel Mystery Oil to the gas for extra valve and ring lubrication. This will prevent valve sticking and give longer engine life. Edited January 31 by Rusty_OToole (see edit history) 1 Link to comment Share on other sites More sharing options...
Rusty_OToole Posted January 31 Share Posted January 31 (edited) I should have added that in 1938 most gas was low lead or no lead. Only the premium or hi test was sure to have lead in it, and then it was not very much. The heavily leaded high octane gas was a thing of the fifties. Your Dodge was made to run on low octane unleaded gas, with hardened valve seat inserts from the factory. Today's gas is higher octane, unleaded, and is also dry compared to the old gas. Gas used to be yellow and oily, if you got some on your hands it left an oily residue, today's gas is dry and leaves your hands dry with a white residue especially if it contains alcohol. For this reason, some say it is a good idea to add some Marvel Mystery Oil, Redex, Bardahl or your favorite upper cylinder lubricant. Even a shot of 2 stroke oil. This will help prevent wear of the rings and valves, and prevent sticking valves. Edited January 31 by Rusty_OToole (see edit history) Link to comment Share on other sites More sharing options...
TTR Posted January 31 Share Posted January 31 14 hours ago, ply33 said: If the rubber components in your fuel system are really, really old (like before 1990) then they may be damaged by some of the additives in modern gas. You can get rebuild kits compatible with modern gas for your fuel pump and you can replace the flex hose to the fuel pump. Some carburetor kits had rubber tips on the float valve, if your car had that then you will want to replace that too. But if the car has been driven at all regularly in the last 20 or 30 years these things have probably already been taken care of. All this ^^ along with every other operational (coolant/radiator hoses, etc) and safety (brakes, steering, suspension, etc) related rubber components should be replaced/serviced in any car due to their age related deterioration and especially in antique/classic/vintage cars for pride of ownership and respect for the car(s). IMO, no respectful owner drives/operates their beloved(?) car(s) with any of that being more than 10 years old. And tires even less so at 6 years from DOM at maximum. 14 hours ago, ramair said: True I have 7 antique vehicles and just like a favorite girlfriend sometimes we are with one more than the rest. Another issue is I would rather leave one parked for a couple of months than take it out and not be able to drive it for 30 miles to be sure to get all the condensation out. I am very religious about keeping my gas tanks topped off. Whenever I get down to 3/4 of a tank I fill up. My 93 Allante and my 68 Toro gets 500 miles a year each my Packards do about 300 , right now my 36 GMC has done close to 2000 miles since restored 2 years ago. My 1915 and 1928 Buick are used the least. I would like to drive every one of them more, but I work full time and I drive about 35,000 miles per year , would use my antique’s for work but I am a farmer With all due respect, I’m sorry to say/write it, but above sounds/reads like you have too many cars (or girlfriends ?) to adequately/respectfully (to each car or lady) maintain/date them all. OTOH, this is quite common among countless people buying/having more cars than they have time and money to properly maintain/own them. That, simply put, is the difference between a collecting and a hoarding. Most “car museums” are prime examples of this type of neglect, cars just sitting and deteriorating, due to lack of adequate maintenance and use. Most serious collectors with multitude of cars I know have dedicated individuals or even staff to keep their cars regularly exercised if they don’t have time to do it themselves. We all know having cars just sit long periods of time (including winter storage) between usage is far more destructive than shorter intervals, but many choose to ignore this and spend their hard earned money on quantity of cars rather than quality maintenance and respectful ownership of fewer. Also, keeping a tank full of modern/todays pump gasoline for extended periods (i.e. months) is not necessarily a very good idea either, as it (= todays gasoline) has much shorter “use before” lifespan than gasoline produced 2 decades ago and with ongoing introduction of larger quantities of ethanol and various other chemicals, it’s only getting worse, adding more urgencies to drive cars more frequently to prevent myriad of problems. Some of my aforementioned clients have their staff refill only enough to keep only fresh fuel in the tanks of the collector cars between driving exercises. 1 Link to comment Share on other sites More sharing options...
Leif in Calif Posted January 31 Share Posted January 31 16 hours ago, ramair said: True I have 7 antique vehicles and just like a favorite girlfriend sometimes we are with one more than the rest. Another issue is I would rather leave one parked for a couple of months than take it out and not be able to drive it for 30 miles to be sure to get all the condensation out. I am very religious about keeping my gas tanks topped off. Whenever I get down to 3/4 of a tank I fill up. My 93 Allante and my 68 Toro gets 500 miles a year each my Packards do about 300 , right now my 36 GMC has done close to 2000 miles since restored 2 years ago. My 1915 and 1928 Buick are used the least. I would like to drive every one of them more, but I work full time and I drive about 35,000 miles per year , would use my antique’s for work but I am a farmer I care for a '25 Chevy that is driven quarterly but only does about 50 miles a year. I've had a problem with old gas so I try to only keep about a gallon in the tank and add new when ever it's used. I did have a problem with a fuel line that was replaced in the 90's reacting to California gas, causing it to stop being hollow. The auto parts guy told me everything made in the last 25 years is resistant. Link to comment Share on other sites More sharing options...
36humpback Posted February 1 Author Share Posted February 1 18 hours ago, ply33 said: Having an higher octane than required should not damage the engine. The main thing it will do is lighten your wallet. The L-6 engines used in Chrysler product cars all had hardened exhaust valve inserts from the factory and do not need leaded gas. As a rule of thumb, the octane required is often the same as the compression ratio, so your pre-WW2 car the cheapest, lowest octane gas you can find at a normal gas station is more than good enough. If the rubber components in your fuel system are really, really old (like before 1990) then they may be damaged by some of the additives in modern gas. You can get rebuild kits compatible with modern gas for your fuel pump and you can replace the flex hose to the fuel pump. Some carburetor kits had rubber tips on the float valve, if your car had that then you will want to replace that too. But if the car has been driven at all regularly in the last 20 or 30 years these things have probably already been taken care of. Basically, buy the cheapest gas you can find and drive the car. Thanks for the input. In rebuilding my panel I had the fuel tank cleaned and coated. All new fuel lines (steel and rubber). I don't know if the carb (bxov-2) and fuel pump are compatible with newer fuel, as the person I bought the rebuilt engine from passed away not long after I bought the engine (20+ years ago). After all the prep work on the engine it started right up after the fuel got up to the carb. No other feeling like starting it for the first time. Link to comment Share on other sites More sharing options...
36humpback Posted February 1 Author Share Posted February 1 Thank you everyone for the info. Regular gas Will be a lot cheaper. Bob Link to comment Share on other sites More sharing options...
Str8-8-Dave Posted February 1 Share Posted February 1 (edited) You can't buy pump gas with as low octane rating as the car was designed to run on. Running ultra high octane fuel is actually not good for these cars because the flash point of the fuel is very high which makes it harder to start the combustion cycle and the combustion cycle will not finish before the exhaust valve opens. Simply stated, you have the hottest gasses being discharged into past the head of the exhaust valve after it opens. The exhaust valve relies on contact with the cylinder head at the valve seat to keep the valve temperature within reasonable limits. When opens with high octane fuel it get heated to temperatures that can cause the valve stem to warp or literally burn the sealing edges off the head of the valve. Lead additive notwithstanding, it is the worst fuel to use in a low compression engine. Regular unleaded gas is around 97-98 octane these days which is much better than 107-110 octane leaded race fuel as far as completing the combustion cycle before the exhaust valve starts to open. The problem with regular unleaded is it contains ethanol which is hard on our old cars because it absorbs moisture. Modern cars use a sealed, unvented fuel system to slow this down but our cars have vented fuel systems where air is constantly changing in the fuel tank adding moisture to the fuel, which actually condenses as water droplets in the bottom of the fuel tank, then is mixed with fuel delivered to the carburetor. It's highly corrosive and can damage parts made of pot metal and raw iron. My 31 Buick has an archaic heat riser system consisting of an exhaust damper valve that sends hot exhaust thru a short piece of exhaust pipe to a double wall heat riser between the carburetor and intake manifold. I ran regular unleaded gas in my car exactly once. With a fresh tank of 87 octane unleaded gas I started the car and watched as big water droplets splattered out of the exhaust pipe joints leaving nice white spatters all over the shiny painted hood sills and front fender. I wound up switching to Sunoco 90 octane recreational fuel which has no ethanol as a compromise. It immediately eliminated the water discharge from the heat riser plumbing and it will store for longer periods of time in the car with a little Sta-Bil added because it does not absorb moisture. 1931 Buick 60 series straight 8 with factory original and fully functional heat riser system. A combination of heat control setting on the instrument panel and cam- operated linkage and butterfly valves in the diverter valve and heat riser that work off the throttle sends varying amounts of hot exhaust from the exhaust damper just above the header pipe thru a small inner tube (not visible) back to the heat riser above the carburetor, then returns the cooled exhaust back to the exhaust pipe thru a larger pipe (visible in picture below). I had a real mess with regular unleaded fuel because big water droplets blew out of the joints between the diverter valve, heat riser, and the horizontal exhaust pipe seen in the picture below. The rod in the background moves butterfly valves in the heat riser on the right and exhaust diverter valve on the left. The water droplets blew out near the 2 hose clamps that hold exhaust pipe seals where the pipe enters the castings. Edited February 1 by Str8-8-Dave (see edit history) Link to comment Share on other sites More sharing options...
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