Technical Shoebox intro and flathead rough idle

Hi everyone,

Some of you might remember my post from last July about the 1951 Ford that my father-in-law built up for me and my wife. After almost a year of shake-outs, changes, fixes and tweaks, the car finally made its way to Austin in April and now belongs to us. I hadn't gotten around to making a post with lots of nice pics to 'introduce' my car to the HAMB, so I thought I'd take a moment to do since it's kind of relevant to the rough idle that has developed.

It's a 1951 2 door, with virtually no body modifications (sharp-eyed Shoebox guys will notice at least one). I have some ideas about what I might do in that area at some point way down the road but right now it's too nice and I'm too green, and in any case it's the engine that's the problem right now. The flathead has been mildly modified in what my father-in-law described as mostly period-correct style, with some allowance for modernization in the name of reliability. I'll list as many details as I can remember off the top of my head: 239 ci flathead V8 (not the original block), Iskendarian cam, Fenton cast-iron headers, Offenhauser heads and intake with dual Ford carbs on a progressive linkage. It has been updated to a 12-volt alternator and the original mechanical distributor has been swapped for a modern electrical one, and I believe that's true for the fuel pump as well. Posting the only pics I have taken of it since we got it, but will post some more when I get home tonight or tomorrow--sorry they are not as nice as so many of the shots of amazing HAMB cars in incredible locations that I have seen here.

So, on to the idle...owing to some family health problems that have restricted my time to have fun in this thing, I've mostly just been taking it out for little short drives about every week or so just to get it running and moving; I think we have put a little over 300 miles on it, maybe, since April? Have not had any problems with it, until I went to drive it yesterday evening. It had been not quite two weeks since I last drove it, so it cranked for a few seconds, then started, but right off the bat it just didn't seem right: the idle was rough, like so rough it was shaking the car noticeably, and inconsistent as well. I'm not quite sure how to describe what I mean by that, other than it just wasn't smooth, not so much in the physical sense but more like it was sputtering, then ok, then sputtering, then ok...just felt like it wanted sputter itself out, but every time it seemed like it would it kicked back in and came back to life, briefly.
But it never died, so I started backing it out of the driveway, but then decided against going anywhere after 8pm on a weekday night with no one to save my bacon if things went downhill. So I know I don't have much to offer in the way of forensic details for a diagnosis, and probably "my carbureted engine is idling rough" is probably the equivalent of "check engine" in its vague unhelpfulness. But if you have any ideas for where I should start troubleshooting with a car that ran nice and smooth just a few weeks ago and now idles rough, poor, and inconsistent, please do share. Would a video of it idling help?
This is long enough already, so if you want to stop here and offer your 2 cents any advice is appreciated. But I also thought that I would just point out that, as I mentioned in my original post, I am not lucky enough to have spent my life working on or being around old cars (or even new ones). I am relatively new to the scene, having been pulled into a love of old cars and trucks by my father-in-law's passion for them, and this is obviously my first time owning one. Some might say I am in over my head and have no business owning a car like this until I have some more experience, and they would probably have a point. But what was I supposed to do, turn down a free Shoebox?
So I am and have been trying to, over the last few years, learn as much as possible and soak up some knowledge from any Shoebox or flathead thread that pops up, and I am trying to be an active member here so that I don't just show up when I need help.
All of which is to say, I highly appreciate anyone who has an idea about how I might address this problem without calling my shadetree guy or even worse, a mechanic. The only way I will be able to own this thing long-term is if I learn to wrench on it myself, so thanks for sharing your knowledge and experience with me. If I ask stupid, basic questions or come across as an ignoramus, I ask your forgiveness in advance.
Again, I will post more pics, and maybe even some video, when I get a chance tonight or this weekend. Thanks for reading if you made it this far!

 

Ok I’ll bite. Nice intro by the way.
What type of carbs are you running. What type of electronic distributor??Temporary Remove your filters and run the engine without them. Most filters are too restrictive. See a change?
No change....
Look for a vacuum leak, check hoses, intake and carburetor mountings by starting the engine and applying unburnt propane along every seam.
If the engine increases rpm during this, that will be a leak.
Try this and get back with us before we go on to a next step.

 

Great lookin' car! I really like the interior. Hopefully you get it figured out so you can better enjoy it.

 

Dunno if your willing to suggest this...BUT You seem sincere on wanting to learn about this car and there is a lot of smart and honest people here who would/could prolly stop by and take a look. If I was closer I would.

Sent from my SM-G900V using The H.A.M.B. mobile app

 

Love the car, I am just starting a 50 Coupe myself. Best thing in your pictures though is the dog, reminds me of my big guy that passed last year, great dog.

 

Nice lookin' car. I usually don't like white cars, but it works on yours. The first thing I'd do is pull the plugs. If any look the least bit funny, replace them. Cheap and easy. If the "electric distributor" is an aftermarket electronic unit, I'd go there next. Then check the carb and make sure it's clean inside. Good luck.

 

Thanks for the ideas and compliments so far. Will start troubleshooting when I get home, and also update with more specifics about the distributor and carbs. I seem to recall my f-i-l saying the distributor was a Chevrolet unit (I know, heresy!) and the carbs are Ford-branded, but that is all I can remember at the moment. Sorry if what I threw out there was kind of vague; I wanted to get this posted early enough in the day that I had some ideas to play with by the time I got home.
Sorry to hear about your dog Hombre; ours just turned 10 and her hips are starting to go bad. She was a reclamation project worse than anything I have seen on the HAMB, snatched from the kill list at the last minute. It's going to really be a punch in the gut when she's gone. Just out of curiosity, do you know what kind of dog he was? We have always wondered about ours.
OK, back to the car! I will update and let everyone know how it goes when there is some news to report. The way car fixes usually go for me, it will probably be sometime Sunday evening....Not by any means opposed to AlwaysaMopar's suggestion but I wasn't sure if that was something I could actually ask on here. I would much helping and learning from someone on here than calling in a mechanic.

 

The distributor on your car is probably a converted SBC unit. They are a good conversion for later flatheads. It could be one of three basic types : a regular points type distributor, the same basic unit with an aftermarket (e.g. Pertronix) electronic unit, or maybe even a GM HEI unit (you can tell those because of their increased size). If you get far enough into it to suspect the distributor, at least remove the cap and determine if it is points or electronic.

 

Blakejr, Sent you a conversation about your dog check it.

 

Hi again folks, got a chance to do some troubleshooting and I think I may have gotten lucky. First, as you can see in the first pic, the distributor is a DUI (haha), and from tubman's description it sounds like an HEI--it's much bigger than the one in my OT late 90s GMC truck.
However, in poking around on the carbs I noticed that one, the back one and therefore the first of the two in the progressive linkage (is there a proper term for this?) was so loosely attached that I could pull it up and almost off completely, as you'll see in the 2nd pic where it's riding much higher up than the other one. The other carb is nice and tight.
This seems like a good place to start, right? Just tighten it up so no air is getting through and see if that takes care of it? Thanks again for the help, hoping that this is it

 

Your first picture in the last post shows fuel staining on the back carb that you mentioned in the post. Tighten it as you also said and it should fix it.

 

Nobody should say that you don’t deserve a car like that!!. In over your head, maybe, and a lot of us have been there. Great story, great car, and I hope that repair number one was a success.

 

might try separating the plug wires--could be cross-firing. looks like an hei to me. have one in my '50!

 

1952-54 headlight doors...

The fuel staining bothers me. That needs to be fixed. I know flatheads and leaky carburetors go together like peas and carrots but that one looks pretty serious.
Do you have a choke?
See if it smooths out after it warms up.
Is the gas tank dirty?
All the signs are there.... drove a lot, ran fine... parked for a while, runs rough and a carburetor is leaking.

 

Well Blakejr57 was that the problem? You have the capability to do this but please DO NOT leave everyone hanging that offered assistance never knowing the ultimate end fix. That will possibly get you les help the next time.

 

Don't worry warhorseracing! One thing I have picked up on the HAMB is people hate to be left hanging I just ran out of daylight yesterday.
So I tightened up the clamp holding the base of the air cleaner assembly, as mentioned in my last post. It started right up and ran beautifully and smoothly for several minutes so I am assuming that was the problem. Going to hold off on the test drive until the sun goes down as the heat index for today is 106 and we are without a/c and running the original radiator, unshrouded....If anything does come up, I'll update but for now I'll consider it problem solved.
A pretty easy deal altogether but I still appreciate everyone who took the time to read or chime in and help me get it figured out so quickly. Really nice to have a group like this to draw on and get encouragement from. I'm sure there will be more posts to come but hopefully not for a good long while.
F-One, on your rec I cleaned things up on the fuel staining as shown in the pic. It seemed pretty old and crusty, but at the very least now I should be able to tell if it is happening again in the future. Not to mention it looks 10x better.

 

You'll get good with those carbs and that engine in no time. They're dead simple. Glad you got it going again.

 

Damn, I just realized why tubman put "electrical" in quotes...because it was supposed to be electronic. Duh. I know it doesn't have points, is what I meant to say....

 

Great news but you still have problems. These can be taken care of later.
The fuel stains you cleaned up WILL return. Usually come from the throttle shaft area or the seams at the carb. This is caused by ill fitting or loose housing parts, worn throttle shaft holes or too high fuel pressure or residual pressure after the engine is shut off. You should rebuild your carbs soon.

 

OK Blakejr 57. Maybe I was in a hurry to find out what was really wrong and got in a fluster when I logged back in over 12 hours later with no response from you after you said you were going to look at it as soon as you got home. Well then you said you didn't deserve the car as you didn't know anything mechanical. I just guess I was hoping you didn't give up and go away. In the end, you; diagnosed the problem, or so you thought, and were correct, but asked for verification, then went and corrected that problem. BRAVO Sir. Don't ever overestimate yourself. You already know that the engine needs three things to run; air, fuel, and spark. Multiply that by eight and it can be a little daunting to the uninitiated but you apparently have the aptitude to figure out complex systems. Please accept my apology for jumping.

 

No worries warhorse, no offense taken by your post and no apology necessary. You can probably tell as excited as I am to own a car like this it also makes me a little nervous to be the one responsible for keeping it in good running order. Even little successes like this adds to my confidence and knowledge base, and of course everyone here has been very encouraging, so that helps too.

 

My flathead had the stock single 94. With duals, they may be that sensitive to air flow through the air cleaners?

In my opinion they should not be that sensitive. If so, those air cleaners may be restricted or the filters dirty.

How does it run with both air cleaners off?

It also could be a coincidence and the problem either cleared up or will return.

They make brand new Stromberg 97s (English Made) and 94s (Edelbrock) 900 bucks later... leaky worn out carburetors are thing of the past.
Don't even cobsider the Chinese copies.... not with those 2 options available.

To repeat....A dirty gas tank will destroy carbs and fuel pumps. Filters don't help... the trash still gets through. Cleaning and sealing a tank is a waste of time.
Sometimes an original tank is in good condition... most of the time not. Check it out.... check the fuel filters for trash.

 

Thats a stupid thing to say. Do you think its a good idea to use a new tank that will immediately begin rusting? I dont think thats a good idea. I use POR15 sealer for every tank, new or old and have been sealing them for about 35 years with excellent results.

 

Good for you.
I'm sure there's model Ts running around with clean original tanks. On the other hand I'm sure there are some late model cars with varnished up or rusty gas tanks. Multiple factors come into play. Sometimes they rust.....sometimes they don't. Each car is different and has different needs. That's why I advised him to check and make sure that his tank is not contaminated.
You have had luck cleaning and sealing tanks, I have not.
Because I have experiences that differ from yours and a different opinion, does that mean it's stupid?
Maybe so..
Maybe here is something we both can agree....
If blakejr57 has a rusty or contaminated tank that is contributing to this problem.....
He needs to fix it.

 

F-One, I can't peg an exact date on it at the moment, but the tank is excellent shape, it at least looks new from the outside. Of course it is possible but I can't imagine it is original to the car, given the shape it is in. I just took it for a nice long test drive and simply tightening the clamp on the air cleaner assembly seems to have done the trick nicely. I will be watching closely for the return of fuel stains like petejoe mentioned, and I will follow up with the builder of the car to find out how new the tank is--always a good thing to know. Thanks again everyone

 

That's great!
The only reason mentioned the tank is sometimes it's overlooked in a restoration and ends up causing a lot of trouble for the owner.
You have a very special car you should be very proud. I had one a 50. I miss it.

 

My 51 has a new tank that was installed by the previous owner so they are out there if needed.

 

Perhaps it would be best to start a new post with this, but since it involves something that came up during the discussion of the rough idle--now seemingly fixed--I thought I'd continue the conversation here.
Yesterday I took the car on the longest drive yet, smack in the middle of the hottest day of the summer so far. My main concern was coolant temp, which ran kind of high but was mostly at about 75-85% on the gauge. I made it to my destination--only 28 miles, 46 min--okay. I lost my speedometer somewhere along the way too, but that is another thing.
When I went to leave a few hours later in early evening, the ambient air temp felt slightly cooler but the flathead seemed to get hot right right away. I was very nearly pegged to the top of the gauge on the stretch of 65mph highway before the Austin stoplights, and by the time pulled in the driveway I could hear the coolant boiling under the hood and see the first drops hitting the pavement underneath. I opened the hood help it cool faster, and sure enough, just as petejoe insisted earlier in the thread, the damn fuel stains had returned with a vengeance! You can compare the pics that I took here with those in my post #16 when I had just cleaned them up. I am almost certain the carbs are not brand new but they would definitely have been rebuilt with the engine.
So first, where do I start with the fuel leak? My first thought was the bolts that are holding the base of the carb to the intake, but on closer inspection it looks like it is possibly coming from higher up. I am especially suspicious of the spot shown in the last two photos, where the gasket is clearly deteriorated or overly tightened and has started to push out the side. To me that would seem to be the most obvious place to start.
And secondly, if anyone wants to weigh in as to whether they think a shroud is a good idea for dealing with the heat or if it makes more sense to invest in a new radiator--I have only briefly looked at one on Shoebox Central that sounds more capable--or whether overheating in a flathead on a stiflingly hot and humid day is just par for the course, I'd be glad to hear your thoughts. In the meantime I will be combing through past threads for as much info as I can about flatheads and cooling. Thanks to anyone who takes time out of their Sunday to help! It's much appreciated

 

Your carb definitely needs rebuilding with the last two pictures showing the probable cause. Does your car have the bottom sheet metal piece bolted on under the frame from the radiator back about a foot? This also definitely helps cooling on the shoebox and if it is missing I believe Shoebox Central has them also.

 

I would suggest you rebuild your carb if you want this madness to stop.
Looks as though your leaking at the throttle shaft, indicating the shaft has worn your holes over size causing leakage and your body gaskets are also leaking. I’d suggest you contact Dickster @ Dicks Hot rod carbs or Charlie Price @ Vintage carbs for rebuilding.
Heating problem??
Is your radiator holding pressure at all??
Your carb problem can wait until winter if you want to drive it now. Although that’s quite a bit of fuel pooling at the base.