I've been chasing what I believe to be a fuel issues with the Holley 94 on top of my flathead. It's all bone stock. Here is my call for help. On first start up the motor idles smooth and easy. But once I drive for about 10 min and come to a stop the motor kicks sputters and dies and won't start again until I let it sit for 10 min or so. I open the hood and find fuel leaking from the bottom of the accelerator pump. So I replaced to plunger thinking the seal was bad. I set the float to 1 11/32 and 1 7/16 which seems to be a good starting point. But after driving again IT STILL LEAKS. The exhaust reeks of gas as if it was running too rich. Plugs are black. I am lost. I cannot for the life of me figure out why sometimes the motor runs like a top. And once I drive the car out of the blue it will die. Is the fuel level in the bowl too high? Is the idle mixture not right? Please help.
U may have fuel PSI to high,needs to be 3 psi. or less,also if your set up vibs it can make fuel bowel be to high,even with set right. Extra heat of carb can boil fuel too. But try this; http://www.jalopyjournal.com/forum/threads/links-to-holley-94-technical-info.286574/#post-3038526
Im using a stock replacement mechanical pump. I noticed too that sometime the idle screws don't change anything. Like if they I clogged. I blew them out and it just happened again Thanks for the link. I read through and might have a leaking power valve.
The two most common problems I have experienced with these carburetors are float problems and power valve problems. Both of these will result in a lot of gas being dumped into the intake. You can't adjust your idle when there is so much gas in there richening the mixture. They do have other issues, but these 2 are usually the culprit in my opinion. Look down the throat of the carb while the engine is idling and see if you can see gas dripping from the nozzles onto the throttle plates. If so, you should replace the power valve first. If you break the carb apart at the lower joint ( removing the base from the carb) without turning it upside down and look in the well where the power valve sits it should not be wet with gas. If it is then replace the power valve.. Also you can check the float valve by removing the top of the carb and holding it upright while you blow hard into the inlet. Move the float up and down while you blow and see if it completely cuts off the hiss of air when fully raised. If not, replace the float valve.. By the way, I set my float level lower than recommended....1 3/8". One last note......the power valves you get today in the rebuild kits often leak at the gasket where they seal to the underside of the carburetor. That is because the old original ones were flat on the bottom but the new ones seem to have a radius which binds before the gasket takes up. Test it for leaks after you install it in the carb but before you attach the base of the carb by filling the carb bowl with gas and letting it sit upright for a while. If it leaks then it needs some attention. Good luck.
You've got the wrong power valve , if you've rebuilt the carb the power valve in the rebuild kit has the wrong seat on it. There are two types one seals with a washer the other seals with a taper. Mine did the same thing ordered a correct one ( think from macs) all sorted
A few things can cause the problems. Fuel pressure too high. Float punctured. Needle valve not working correctly Power valve ruptured Power valve not seating properly Castings not flat allowing an air leak into the power valve chamber. I have had to contend with all the above before getting my 94s to run right. If the car runs great from cold without choke, it is too rich. (like as if the choke were on). How to address the issues. Fuel pressure and float problems. Use older steel tipped needle valves, not the ones in the kits. Make sure the float is not containing any fuel. Some new pumps deliver too high a pressure. try fitting the spring from the old pump to keep the pressure down. I have done all these things. Power valves. Make sure the valve doesn't leak. Probably not the wisest thing to do, but I **** on the valve and see if it holds the "****". If it seems ok, make sure it seats ok. Some don't. You can get correct valves from some vendors. You will find the recommended vendors if you look on FordBarn. Make sure upper and lower faces on the carb base and the lower face on the carb body are flat. If not the vacuum will not hold the power valve shut. I lap the faces on a piece of wet and dry on my drilling machine table (machined flat surface). You have to hang part of the body over the edge because there is a part that sticks out below the flat surface. Float level and things like jet size and power valve number are not relevant to this grossly over rich problem. They are the fine tuning side of it that can only be addressed after these fundamental issues have been dealt with. Mart.
DAMN!!! So many possible problems. I know I can rule out the float needle I tested that and it's good. I tired setting the float level a few different levels. The power valve is next. I'm ordering a few today. I'm gonna get a 7.5 and a 6.5.
I got my power valve to seat correctly in the hole using a copper washer under the Holley valve to make the tapered seat conform to the flat surface below. You can purchase from an aircraft supplier in Puyallup, Washington. I think it was Spencer Aircraft Supply. Glynn.
The car does start right up on a cold motor and with the choke full open and a few pump of the pedal. the carb was rebuilt but that was by someone else before I bought it. I send time a text last night to see if he remembers what jets and PV he put in this thing. still waiting on a response.
I think you should start with the power valve not seating properly I have seen this a lot with the new rebuild kits
Mart above is spot on! Only thing i will add is if you pull the power valve out it is really obvious as the different valves have a different diametre where the gasket seats,but there also over variations,They are a great carb once you getem dialed in. Johnny
It would be really nice if this fixes the problem. If anyone wants to check out my build. I've spent a long time trying to swap a t5. Re do the brake lines and do other **** to try and make this car drivable for this summer. And now the carb is raining on my parade. I just wanna cruise
If the power valve is incorrect,it will fill your cylinders with fuel gradually and thats what will make your engine stop,it will then start again once the fuel seeps past your piston rings into the sump. pull your dipstick and see if it smells of fuel! also the plunger, you need to soak it first,i use oil ,as a lot of them are leather...if you put it in dry it will burn the seal very quickly.johnny
Charlie Price from Vintage Speed sells the old style power valves, with the flat surface. Make sure your float is air tight, recently found one of mine half full of fuel, and that was a new float.
I know the needle is tight. I tried blowing through it with the needle closed and I got nothing. Asphalt demon. I'm pretty sure your right wit this. I didn't know a PV could leak like this. I only have headers in the motor right now and with the motor running I can't put my head under the hood for more than 5 seconds without my eyes feeling like they are gonna fall out.
I have two speedway Holley PV coming on Tuesday. 6.5 and 7.5. I hope that I can get these installed right so they don't leak
Another quick check which sometimes tells you straight up its the power valve. Is when you take the carb top off and the fuel bowl is empty it's usually a power valve constant leak,and the engines drawing fuel constantly. Good luck , let us know how you go! Johnny
The bowl has fuel in it when I take the top off. But I'm gonna replace the valve when they show on Tuesday. I'll keep you guy updated. Thanks for all the help
I'll add that in the last picture it's fuel comes from the tip of that br*** fitting. But it also comes from the base of it
There is a gasket that goes between the nozzle bar and the housing, so no fuel should be coming from that area.
Yep should have four gaskets under the four feet that sit on the carb body,and they should be sealed!which means no fuel .Also the br*** tubes are internal and run down inside the carb body and are linked too the jets and power valve.So you should never see fuel coming from them.Goodluck
Ok. And what I meant by fuel coming from the br*** tubes that is when I took them off I sprayed brake cleaner through them to make sure they where clear. And that's what I saw the fluid coming out. So I think I'm ok. I had to reorder a rebuild kit Because I f$&ing lost the one I got. I did get a chance to take the carb to work and use the parts washer on it. Sorta hoping that I had dirt stuck in one of the small ports. But I'm not Keeping my hopes up too high. Here's another small bit of info when I loosen the idle mixture screws they are wet with fuel. As for the PV. I installed the new one that came in the mail today the gasket is way too big to seal against the carb body. So I reinstalled the old one and don't see any leaks. I don't think the PV is my problem.
So is the carb fully apart now?Why don't you post a couple of pics of you carb now it's apart,and power valves,?most carb kits come with two power valves and a schematic drawing which shows gasket locations.you may still have the wrong pv
When cleaning your carb, hi pressure air hose with needle point is your friend. I know I will get a lot of backlash for saying that but it works very well to get crud and gunk out that the cleaner doesn't desolve, or just loosens.
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