Technical "Rebuilt" Holley 94s leaking fuel, need advice

Hi everyone,
I've hit kind of a frustrating roadblock with my 51 Ford, and just thought I'd throw the situation out here on the HAMB and see what y'all thought. Here's the setup, kind of long but as short as I could make it:
Took possession in April of the car, with a freshly rebuilt Flathead 8 running dual Holley 94s (not Stromberg 97s as I previously thought). Probably has less than 500 miles on it since then.
Had some intermittent trouble with a rough idle early on, but was still drivable. A member here pointed out some fuel staining on the intake where it had dripped down from the carb, and recommended a rebuild. I checked with my father-in-law, from whom I got the car, and he says the carbs were installed as freshly rebuilt when the engine was installed (I don't know if his guys did the rebuild or they were purchased that way).
A few weeks ago, I came home from the longest drive so far and the leak had clearly gotten worse--visibly and with a much stronger gas smell after stopping--but it seemed to be running fine while on the road. The next time I started it, just to move it to the end of the driveway for a washing, the idle was so rough and sputtery and close to dying that I made it about 3 feet before just calling it off. Nothing had been changed or touched but something has gone seriously downhill.
I've had one of my trusted mobile mechanics pass on the job due to the age of the car, and the other isn't returning my calls/emails. A friend who owns a 54 or so Chevy rod seems to have no interest in helping/supervising me through a repair. I don't know enough about carburetors to diagnose or rebuild on my own. If I just have this thing towed to the local rod/custom shop every time something goes wrong then I am not going to learn a thing other than how to spend my money faster than I can make it. I knew I'd have a significant learning curve with this car, but I feel like this is kind of a bad omen.
I badly want to learn how to work on this thing myself and not just be some d-bag owner who just pays someone else to get me running every time something goes wrong, but how the hell am I supposed to learn without someone to help/guide? There's only so much you can learn from books, websites, etc, and I was not lucky enough to grow up around anyone who cared about cars or working on them. Perhaps I was delusional in taking the car in the first place.
Don't get me wrong, I don't want this to be another "God Help Me I'm So Lost" thread or to come across as a whiner and complainer, but I've had too many home improvement and OT car repair projects go downhill fast by getting in my head that "I can figure it out."
So, if anyone is still reading at this point, what do you think I should do? Just suck it up and pay the cost of a tow and the going rate at a shop? Pull the carbs off and try to rebuild on my own, even if they should still be good? Keep looking for a mobile guy who can be trusted with a HAMB car? I'm tired of feeling like a helpless fraud every time I walk past this car in the driveway.
In the end I guess this ended up more as a rant/bitchfest than a request for help, but really that's what I am after--helpful suggestions or advice for a guy who loves HAMB cars and lucked into owning one, but just doesn't have anywhere near the know-how of most of you on here. Thanks for reading and to anyone who takes the time to respond.

 

I don't have the answer because today I shipped my carb to a carb guy... but I can assure you that the hamb crowd will get you set back into the driver seat again. Owning these old cars isn't easy but all of this anxiety and effort is worth it brother.

 

Also check your fuel pressure.
Most newer pumps put out to much pressure for the older style carbs.

 

And also, new carb parts kits might have a bogus power valve included. Whatever the history of the carbs, if a power valve goes bad she's gonna run like crap cause fuel is getting dumped down the hole. These flatheads are new to me, but I've already learned the power valve problem first hand. Now I have a couple spares of the good ones.

 

@Pete Eastwood Has a good starting point. Knock down that fuel pressure to 2 to 3 psi. A Holley 12-804 regulator will take care if it if the pressure is above 4.

 

A picture of your setup would help us out immensely. A fuel pressure regulator as already mentioned.... depends on how the carbs are set up as you mention dual 94's - could be linkage bind, idle mixture, throttle position, power valves, accelerator pump linkage, etc. We can't help you if we don't have information. The more you can give, the better. Holley 94's are about as simple as it gets as far as a rebuild goes, so that's in your favor. You already got some heavy hitters on your thread, so that's in your favor also. Get some pics up here of your setup from a couple different angles, and let us know if you have means to check fuel pressure, vacuum, timing, etc.

 

Edit:
https://www.jalopyjournal.com/forum/threads/shoebox-intro-and-flathead-rough-idle.1111976

You already have a thread about this, in which we discovered the front carb had the choke shut... is that still a thing, or was that addressed? There's lots of pictures on that thread, with a fuel pressure regulator and a gauge...... what's the gauge say? It looks like your linkage is set up progressive, with most of the leakage coming from the rear carburetor that isn't getting a workout most of the time. What happens if you clean up the stained fuel and watch it run with both chokes open? What's it idle like? What's the fuel pressure? If it does indeed begin to leak again, when does it leak? At idle, or after shutdown? You gotta do some detective work here. A lot of the questions we're gonna ask you were already asked and answered on the previous thread. Help us out here!

 

It also appears the secondary carb has no idle mixture screws, and is possibly an after-market "secondary" base... is this the case? Easy way to tell - no idle mixture screws. Or the fact it's aluminum and not cast iron like the black one.

EDIT: I went back through the other thread and pulled some relevant pictures for this thread, putting them in my post above...

 

Wait a minute... hold the phone..... the more I look, the more I see.


First: The rear carb is a secondary. The base is an aftermarket aluminum one with no idle circuits. Therefore, it does no good to have your choke cable hooked up to that carb as that carb does not use its idle circuit.

Second, see that screw at the bottom left of the picture pointing towards the right? Make sure that thing is backed off the throttle cam entirely. As a secondary carburetor, you do not want the throttle plates open until the linkage pulls them open. If they are open at all, there's a vacuum leak. You'll want to use that screw to adjust idle speed on the primary carburetor (the front one), but on the secondary carburetor, that is not used.

Third, see your yellow circle there? That's showing you that your PRIMARY carb has the choke SHUT. If you're driving around like this, it's going to run like shit.

Fourth, the puddlage of fuel is coming out of the rear carb, and looks to be coming from both the throttle shaft area and power valve area, then running down. See where the "Ford" script is on the side? The power valve is is just below that. A small vacuum port gives the power valve a signal from direct manifold vacuum, but if the power valve has failed or is the incorrect type, it will leak fuel from the bowl down into the vacuum port and it will run like shit.

I feel like I could go on, but we need some input here.
1. Clean up the old fuel stains.
2. Back off that screw mentioned on the secondary baseplate. It should not touch the secondary throttle cam.
3. Address the choke situation. Secondary carb should either have choke removed or wire it open. Primary should be open at operating temp.
4. Start vehicle and observe. What is the fuel pressure? Adjust regulator until fuel pressure is ~ 2psi.
5. Observe some more. Is fuel seeping? Where? When does it happen?
6. THIS IS THE MOST IMPORTANT ONE. Report back. Don't let this thread die off like the last one, then start a new one a month later with the same questions.

 

How about a stock intake with just one of those carbs? Go back to duals after you know a little more.

 

After buying and running an old flathead, you’re quickly learning that it’s not a plug and play. Follow the directions these guys have suggested. Be prepared to spend weeks or longer learning about carburetors.
It part of the fun and challenge and satisfaction of doing it yourself.

 

Thanks to everyone who has chimed in so far. This response will be mostly directed to Tim's post since it's the most thorough.
1. Hard to believe but I actually did clean up the fuel stains after the last time I posted. What you see in the last pic in post #7 is the return of the stain, and one of the main reasons why I knew something was seriously off with these things. It went from as cleaned up as I could get it (second pic, same post) to that in just one afternoon of driving, about 75 miles.
2. The fuel pressure was holding steady at just over two when I checked it for the post about the rough idle. This last time, it ran so shitty I didn't even think it would keep running long enough for me to pop the hood and take a look.
3. The carbs are indeed sequential. I don't know much about them unfortunately; there is a build book with receipts, warranty info, and all related stuff that I have been hearing about but still haven't received. Love my FIL, he's a great guy, but he's kind of left me hanging here. He is a business owner and I get that he has other things to worry about but having that book would go a long way. I had thought I'd pick it up next time I visited but guess I'll have to get him to mail it asap instead.
4. I have to admit I am feeling more confused than ever about the choke at this point. The way it was explained to me was that I shouldn't really need to open it up except when the starting a cold engine in cold weather (and maybe when hot and suffering from vapor lock, IIRC?). But Tim, you are saying if the primary carb choke is shut, it will run like shit. The only vehicle I've driven before this with a choke was a riding lawnmower about 25 years ago.
5. It wasn't my intention to let my other thread "die off" and come back to ask the same questions a month later. You'll notice that one of my posts said "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.....If anything does come up, I'll update but for now I'll consider it problem solved." I did exactly that and thought I had responded to everyone's posts, so I'm not exactly sure what I did wrong here. I appreciate your efforts to help me solve this problem but unlike many here am not retired and have a lot going on outside work, so sometimes it takes me a week or two to carve out some time to spend on the car. Not ideal, but that's life. If that makes it seem like I abandoned the post then I apologize. If there is a
6. Seems obvious now but clearly I need to start it up and play around with it--do the detective work as suggested by Tim so I can provide some more information. Not sure I will be able to solve this problem myself but I don't guess I have to do anything drastic yet.
Leon, yours is a good idea but would require me buying a single intake. At that point it seems like it would make more sense to spend the money getting a mechanic to sort the duals out.
Petejoe, I will have to take your word for it on the fun and satisfaction because right now it's more frustration at my nearly complete lack of knowledge and ability! I never expected it to be problem free ownership but I also didn't expect to have a problem like this on my hands just a few months after getting a car that was supposedly sorted and thoroughly test driven. Thanks for taking the time to weigh in again.
I will do as much detective work as I can tonight and update this evening or tomorrow morning. Everyone's input is much appreciated.

 

Why is the choke hooked up to the secondary carb? Shouldn't be on the front carb?

Bones

 

I don't know about the choke situation, but it seems to me the float is to high on whichever one is leaking. My 3x2 did the same thing. If it's been like that a while, it's probably fouled some plugs would be my guess. My vote is to - recheck fuel pressure, maybe with a different gauge to be sure, lower the float or floats if they're both doing it, figure out what these guys are talking about with your choke setup (could always get rid of it altogether and just work the throttle until it warms up), check the plugs. Then go for a drive. and have fun!!

 

Update: as several people have pointed out, the choke cable is indeed hooked up to the secondary carburetor. I don't even know what to say about that...it's about the dumbest thing I could imagine doing and I don't know how that got past anyone with two cents' worth of mechanical knowledge before the car got to me. But the fact that I didn't notice it yet should give some idea of just how much I have to learn about cars of this era. Looks like I will need to buy a new choke cable in order to reach the primary. In the meantime...
I uploaded two videos to youtube: the fuel pressure gauge during idle holding steady right at 3 and the idle as I played around with the choke on the primary (ignore the blue masking tape on the air cleaner; just there to help me remember which is which). I'll spare y'all the amateur hour commentary and analysis and just let you watch and tell me what you see.
Now, back to Tim's posts. I double checked that the screw is backed off of the throttle cam (I think it was fine before, but definitely is now). You said it should not be touching--how close should it be? You also said the choke should be open at operating temp, but how much? A small adjustment smooths out the idle and makes it run like it should, but if I go much further than that then it sounds like it's idling too high. It this a sort of personal preference thing or is there a more specific setting than "when it sounds right?"
Last, fully agree with Tim--the fuel leak is my biggest concern right now. I couldn't get the leak to replicate running in the driveway, even when goosing the throttle. If I go out for a drive I could probably get it to leak again, but of course then I wouldn't be able to observe where the leak was originating. Consensus seems to be the float is the main suspect but it appears I'd have to at least halfway dismantle the thing to get to the float, and I'm concerned I wouldn't be able to get the thing back together correctly.
Thanks everyone, feeling ever so slightly more optimistic that I can get this problem licked on my own.

 

Chased one for weeks. Since the top gasket was always wet, I naturally assumed the top casting was warped from over tightening. I straightened it our and even tried two gaskets to no avail. I finally noticed it only leaked when the pump was on. Pressure was about 2 1/2 lbs and float level was right... that's ok. Long story short....the fuel fitting was not seating properly at the inside taper and there causing an almost indistinguishable drip underneath the fitting.

 

Go to Vintage Speed web site. Charlie Price has informational tutorials on Stromberg and Holley 94 carbs. You need to familiarize yourself with the workings of the carburetor. I also do not like progressive linkage on a 2 x 2 setup.

 

I just wanted to clarify I'm not bagging on you for starting a new thread, but when you ask the same questions, many of which were addressed previously, you waste a lot of time to get back to where you were a month ago with the other thread - our time and yours both.

Good on you to go out and take a look at what's going on. That's how you learn. The reason I suggested the fuel cleanup is so you can see when new fuel appears. If it doesn't show up while running, then monitor it a few minutes after you shut the car off. If it shows up then, it's a different problem than if it shows up while running. Make sense?

The screw on the secondary throttle cam has zero effect on operation. How far the screw is backed off the cam makes no difference. It was originally there to set idle speed, and since that carburetor has been modified to eliminate the idle mixture screws, it is no longer necessary to adjust idle speed on the carb that has no idle circuit. Make sense?

The choke needs to be wide open or eliminated on the secondary carb. On the primary carb, it needs to be wide open once the engine is warmed up. All the choke does is aid cold starts. In Texas, you probably won't need it much. The choke cuts the air going into the engine. Driving around with the choke on is like trying to run a mile breathing through a straw. Make sense?

If the engine idles too high with the choke wide open, then the idle speed screw on the primary carb can be backed off the throttle cam slightly. What that screw does is it pushes the throttle plates open to allow air past them at idle. Ideally they should be open only enough for the engine to idle smoothly, so in other words, that screw is forced into the cam just enough to make it sound "right". Make sense?

The normal procedure to adjust these things is something along these lines: set timing, set fuel pressure, adjust idle mixture screws to achieve highest level of engine vacuum possible, back off curb idle speed until engine idles at an acceptable rpm. We are assuming your timing is already set and correct. We are assuming your fuel pressure is set and correct. We are assuming your idle mixture screws are set and correct. That doesn't mean they are. Make sense? You gotta check these things and mark them off the list as you go.

The idle mixture screws are the small screws on the base at the rear of the carburetor. They control how much fuel mixes into the air traveling through the carburetor. You can give these a "baseline" by GENTLY seating them and backing them out 1.5 turns. When I say gently seating, I mean with the engine off, you twist them clockwise inwards with your fingers until they stop. Do not gorilla tighten them in with all your strength. GENTLY. These are precision tipped screws, and it is easy to damage them. After lightly seating both screws, back them both out 1.5 turns each. Start engine, listen to it run. Turn screws (most likely clockwise, i.e. in) 1/8 turn at a time. The engine speed should go up. Repeat this until engine speed drops, then back them out 1/8 turn to the previous setting. This is your engine's highest operating vacuum. In other words, engine is running: turn L screw in 1/8 turn, turn R screw in 1/8 turn. Engine speed increases: turn L screw in 1/8 turn, turn R screw in 1/8 turn. Repeat. Engine speed DECREASES: turn L screw back out 1/8 turn, turn R screw back out 1/8 turn. Now your mixture is set. If engine is idling too high, back off the screw on the throttle cam until it idles smoothly at an acceptable speed. All of this information is available in just about every carburetor thread on here, and on the internet. Do some reading, look at some YouTube videos, look at some diagrams, and familiarize yourself with your car. This is back in the day when your car talked to you, and you better listen!

 

I run triple 94's on my car and have had the same issues . You have the same regulator as I do and I cant see what type of gauge that is. Yes there good quality gauges and some not so. That said I moved my gauge from the fuel block up to my first carb and got totally different readings. Fuel pressure and fittings into the carb play a big part on these carbs. I would take my car out for a run, get back home and overnight the intake gully was full of gas, even nearly hydraulic my motor. I'm only suggesting this because you say the carbs were running great. Not sure if Dreddybear is still on here but he had some great threads on the 94. Hope this helps

 

No worries on my end Tim, I hope I didn't come off too salty. One of the first things I picked up on around here is how much people hate taking the time to help others only to have them disappear and not share their experience/solutions for the benefit of others. It's supposed to be a community, not a free help line and I try to respect that, so apologies if it seems like I am being wasteful of anyone's time. I always start with a search and reading through any relevant posts I can find, but again--since I am building up a knowledge base basically from scratch it's not always easy to go from words on a post to understanding what is going on with the actual car. Same for the Charlie Price videos, which I have already watched more than once--they are good and helpful to a certain degree, but seem to assume a certain level of familiarity or experience with carburetors that I don't necessarily have.

The reappearance of the fuel leak after I cleaned it was after ~35 miles at highway speed, so it's not surprising that I couldn't replicate it in the driveway. It rained most of the evening yesterday so I didn't get it out on the street. Think I will check the fuel fittings tonight as Phil Coopy and deadbeat mentioned, then take it out and see if I can get it to leak again under actual driving conditions.

I very much appreciate the time you are taking to write such detailed posts and even to grab photos from my previous thread. Yes, pretty much everything you wrote makes sense. Like y'all I was also under the assumption that pretty much all of this--timing, fuel pressure, idle mix--is or was correct when I got the car, which is why it's so frustrating to have to deal with this just a few months in. I am listening to my car but right now it feels like it is yelling at me in some foreign language.

I know I keep saying it but thanks again to everyone for the input--everything helps and I will update again when I get a chance to check fuel fittings and take a drive to try to replicate the leak.

 

Hang in there. You don't gotta conquer Rome in a day. On those fuel fittings- that's a snug kind of fitting, not a gorilla strength type fitting. If the leak is happening at cruise, I would think it's either a needle and seat, float adjustment, or power valve. It's gonna take some investigating. Try to get pictures of the source of the fuel leak. We know it's the secondary carb, but where on the carb? Also as mentioned when? Good luck


Sent from my iPhone using H.A.M.B.

 

Keep in mind I don't have a dinosaur's lifetime worth of experience like some of these folks on here, but I have rebuilt a few Holley 94's. Been awhile though!


Sent from my iPhone using H.A.M.B.

 

Are the power valves fitting (seating) correctly?
I read somewhere that some rebuild kits have improperly made power valves.

 

Contact Charlie NY on The Ford Barn. Charlie, 1-716-662-9159, is IMHO the best for 94 type carburetors. He will supply the correct power valve modification to solve that problem. Charlie will rebuild your carburetor, test it, and explain to you what the problem was. Your carburetors seem to be a mish-mash of some-ones idea of what to do, or what not to do.

 

Sort-of update: I can't believe it's been more than two weeks but I FINALLY got my father-in-law on the phone this past weekend, so I wanted to update this post just b/c I kind of left it hanging. Don't want to be that guy.

As it turns out, the quotes on rebuilt in the title were unnecessary--the Holleys were purchased rebuilt by a shop in South Carolina, though I didn't get the name. At some point during the install, I think when they were trying to get the progressive linkage set up, they got Charlie Price on the phone, who provided the linkage itself, the aftermarket no-idle screw base for the secondary, advice on the install, and also a new set of the correct power valves. So theoretically--I still have not torn into the carbs--they should be seating right and working correctly.

In the handful of trips I've taken in the time since, I haven't been able to make it leak as bad as it did when I made the original post--there's been almost no leak at all, in fact, and very little gas smell as there was before. I'm thinking it must have had something to do with trying to keep up with the person who was leading the way to our destination, on a 75mph toll road in a new car--essentially WOT for a good 30 minutes on a hot afternoon. Thankfully the heat has broken somewhat and I generally avoid highway driving, for the current lack of seatbelts if not the C4 trans with no O/D.

I got the choke set correctly on the primary as well, and I believe I have a much better understanding of how it works and when to use it.

In the meantime, I am gonna drive the damn thing as much as possible and keep watching for that leak, and make a careful note of how or when it reoccurs. Hopefully this won't end with me stranded somewhere but I figure that's got to happen at some point. There is a chance that f-i-l will be visiting this weekend and if so I will have him tool around with me and see if we can get somewhere; if not, then after the first of the month ($$$) I will most likely disconnect the carbs and send them off to one of the guys who has been recommended here.

Really appreciate the help and support from everyone. I will make a final update when I have something to report.

 

Hey everyone,
Sorry to resurrect a long-dead thread, but I want to be true to my word and the HAMB and update this post since I have some new information.

Can't believe it's been almost a year, but I think I finally discovered the source of this carburetor leak. I don't know if it's gotten worse or I was just too dense to figure out where the leak was coming from a year ago, but the other day as I was redoing some wiring terminals under the hood, I noticed that when the key was turned to the on position so that the fuel pump is running but the engine is not, gas was badly leaking from what I believe is the throttle body on the secondary carb.

You can see the drop at the end of the arrow in the attached picture, and I made a short video that you can see here if you are so inclined. So, now that I know that, what steps do I need to take to fix it? Given the location, seems pretty likely I am going to need to remove and perhaps rebuild? Just a reminder: I am still pretty dang new to carbs and old cars in general so I have a lot to learn--don't take it for granted that I already anything! Appreciate anything constructive or helpful that anyone has to offer and anyone who took the time to read--thanks!

 

Check your pump pressure.
Should be no more than 2-1/2 lbs.

 

Pressure holds steady right at 3....And, strangely the primary doesn't seem to leak

 

The Holleys are designed to withstand 2-1/2.
I wouldn’t look elsewhere until I got to that number.

You are leaking at the throttle shaft hole. That’s a normal wear area.
The fix (if needed) would be to ream out the hole and install a next size shaft to replace it. These can be obtained.
But........
Get the pressure corrected beforehand by installing a regulator.
It just may not leak at the correct pressure.

 

Yes definitely as above mentioned. BTW for what its worth, I bought a cheap Chinese carb from an Asian web site over a year ago and heaps of miles on it and that thing runs like a champ. No leaks ,touch wood, yet. Much to the disgust from some on here that say poor tooling would lead to future problems. Cheers