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Discussion Topic:
Starting Issue - 1941 original flathead
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Kpyto71 |
08-05-2025 @ 5:49 AM
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Member
Posts: 19
Joined: Jul 2025
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I posted recently about a 1941 Mercury Club Convertible I purchased. After purchasing, we've driven the car a bit - probably 5-6 times, at various speeds, always within a day or two of each other, and the car ran great - no issues (minus a known issue with it refusing to start hot - letting it sit for 15-20 minutes it started fine). To start the car cold, I would pull the choke about half way out, flip the switch to on, push the clutch in, and push the start button. A few cranks and the card would turn over, no issue. I would let the car warm up a bit, push the choke in, and it ran great. Last week we were busy, it rained a lot, and it was hotter than hot, so taking the car out was not an option... so it sat for a few days... the longest since we purchased it. Now, trying to start it several different ways, I'm not able to get it to stay running. A few things:
- The car is original... no modifications to the original engine (no electric fuel pump), single carb, 6 volt system
- When I say original, it's very clean (pristine), and has been restored - no corrosion, clean connections
- The gentleman that sold us the car said that he had added gas, but had not put lead additive in it - I purchased a lead substitute additive, and since adding we've driven about 30 miles.
What I've tried.. after the 1/2 choke and start button did not get it to fire (no response from the engine) I've tried:
- Full choke, start
- Full choke, 1-2 full pumps on the accelerator, start
- Half choke, accelerator pump to the floor, start
With no responses, I used starting fluid... took the top of the air cleaner off, sprayed into the carb, 1/2 or full choke, start... and the car would turnover (run) for about half a second, then stop. Adding more fluid most times will get it to fire, but it dies about as soon as it starts... or it'll stay running for a few seconds then stop.
With no changes and having put 30 or 40 miles on it since we've purchased, I can't imagine that there is an issue, but that perhaps I just haven't found the right combination to start. I have an old Chris Craft (1967) with twin 427's, and I know that they have their particular combination of pumps, and cranking to get them to fire, but if I do this correctly, they start without issue. I'm hoping I just haven't found the right combination on the Merc yet... Clearly I've got spark, and air... the fuel seems to be an issue (?), but the glass filter is full of fuel - and again, we were able to start and drive it with no issues all the way up until it sat for a longer period of time.
Related I supposed... we believe the carb needs to be rebuilt to potentially help with the hot start issue - or it's vapor lock perhaps (I've read about keeping heat from the fuel line by wrapping in tin foil, etc, but seeing a bit of moisture on the upper part of the carb, and the fact that it's been sitting a while... I'm thinking a rebuild is in order... but again, it's been running fine. I figured the carb was a good winter project.
I'm open to any ideas... as I think I've tried nearly everything - although I have not used the throttle on the dash at all... just the choke, and the gas pedal.
Thanks in advance for your help! Oh... I'll add a couple pictures of the engine...
Chris
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nelsb01 |
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08-05-2025 @ 6:14 AM
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Senior
Posts: 1095
Joined: Oct 2009
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Chris,
Welcome to the world of flatheads. Each with it's own characteristics and personality.
After looking at your photos, I would have a concern about the color of your fuel in the glass filter. You are supposed to be able to see through the fuel and your photo looks like your fuel is old, as in really old.
Since it does start on starting fluid spray, I would tend to agree with your dirty carb and fuel thoughts. Your carb could be gummed up and after sitting for a few days........and be causing your starting issues.
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Kpyto71 |
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08-05-2025 @ 6:24 AM
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Member
Posts: 19
Joined: Jul 2025
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Thanks Nelsb01....
The pictures are from a few years back... not recent. The fuel definitely looks better than that... but does have a slight brown tinge to it... I'll take a picture and post it later today... I just wanted something to put up to show the current set up...
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carcrazy |
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08-05-2025 @ 7:35 AM
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Senior
Posts: 1975
Joined: Oct 2009
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Be sure you have clean, fresh gasoline (10% ethanol is OK) without any additives and a brand new set of sparkplugs that are properly gapped. Once you have done this your starting and running problems should go away.
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Kpyto71 |
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08-05-2025 @ 10:53 AM
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Member
Posts: 19
Joined: Jul 2025
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Carcrazy...
So a question... for all I guess. I've heard that you shouldn't run ethanol (or need to prep the systems for it to eliminate the harm it can do), and that you should use a lead additive. I guess i've read the opposite as well... so... what's to believe?
Again, I'm new... prior to this the oldest car I've owned was my 1977 Olds with a 350. I've added the boat to that with the twin 427's, but those have electric choke and electronic ignition.... so having this car in my car is new to me... just want to be sure I'm caring for it the right way while I have it.
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carcrazy |
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08-05-2025 @ 11:55 AM
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Senior
Posts: 1975
Joined: Oct 2009
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Kpyto71,
If your 1941 Ford engine is original, it already has hardened intake and exhaust valve seats. The reason lead was in the gasolines of the past was to provide an octane booster. Modern gasolines have other additives included which provide more than enough octane. One side effect of lead was it reduced valve seat wear. Since your engine has hardened valve seats, lead is not required. When lead was used, spark plugs required cleaning every 10K or so miles. Now that our cars run on lead-free fuel, sparkplugs can go for more than 100K miles with no service being required.
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carcrazy |
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08-05-2025 @ 12:01 PM
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Senior
Posts: 1975
Joined: Oct 2009
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If you are interested in reading more about modern gasolines, hard starting, overheating and other issues with older cars, Fifth Avenue has some publications that you might find of interest.
https://www.fifthaveinternetgarage.com/technical_publications.php#modern_gasoline
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nelsb01 |
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08-05-2025 @ 7:14 PM
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Senior
Posts: 1095
Joined: Oct 2009
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BUT................
Make sure that your fuel pump and gas lines (from cowl to pump) are ethanol resistant, or you will have other problems with using ethanol. The older materials are not manufactured for todays fuels.
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40 Coupe |
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08-06-2025 @ 5:08 AM
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Senior
Posts: 1799
Joined: Oct 2009
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Is your ignition system producing good consistent spark to each cylinder. This is a very easy check.
If it is then the carb may be at fault. or fuel pump may be at fault. Charlie Schwindler is the man to rebuild 94 Carbs. Or do it yourself with a rebuilding kit from Daytona parts in Fla.
The Carb model number is embossed on the Carb body such as 91-99.
This message was edited by 40 Coupe on 8-6-25 @ 5:09 AM
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Kpyto71 |
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08-06-2025 @ 5:28 AM
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Member
Posts: 19
Joined: Jul 2025
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An update.... success!
Last night my wife and I tag teamed... she manned the starting fluid, and I manned the choke, starter, and gas pedal. After a little more coaxing we got her started. Looking in the glass filter, the fuel flow looked great and with the choke off after a very short time it idled with no issues. We took the car for a longer drive (longer for us right now was about 7 miles in the 40 - 50 mph range), enjoyed the evening air, and parked the car back in her spot. This morning, I went out pulled the choke a bit (1/4 out perhaps), and she fired right off after a fairly short push on the starter button.
I learned while playing with the choke, only pulling it out between 1/8 and 1/4 of the way was the sweet spot. Any more and the engine was unresponsive. It did take some time with the starting fluid though - nearly a full can of it. Again, a carb rebuild is probably in order. At least I feel I know the engine a bit better now.
The fuel looks much better than in the picture that I provided in my first post - again, that picture was a few years back prior to us becoming care takers of the car.
Thank you for the comments to help... the discussion points on lead additives is something I need to look into... I know the car has been restored, and while I have a LOT of documentation from the original owner (1941 - 1979), owners since did not provide documentation... so I don't know what's been replaced, or if the components of the engine will manage the ethanol or not.
CarCrazy - I believe the engine was last rebuilt in spring of 1972 with about 173,800 miles on it, and probably has only about 26,000 miles on it since... Lots of parts (I have a list) were replaced... original block, but not sure of the components used... I'd have to dig into that a bit more.
Thanks again, it was awesome to get her back out on the road last night!
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