Twin H carb question
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At idle and midrange my car seems to run fine, under a heavy load if is weak and lacking power. If I try to accelerate quickly it starts to take off then drops off quickly and acts doggy. I think one of the carbs isn't feeding on the high end. I think it's the front carb that isn't feeding. When I take the aircleaner off I can hear the back carb dumping fuel but not the front carb. Does any of this make sense to our carb experts?
Harry
Harry
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Comments
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Hmmm, sounds like maybe the power valve isn't working.
The power valve operates the metering rod, which is spring loaded up at rest, raising it off it's seat. This gives more gas when starting, and as soon as there is vacuum, the power valve lowers the metering rod into the seat, which gives the proper mixture for normal running.
When you open the throttle, the vacuum drops, thus releasing the power valve which lets the metering rod rise off the seat, dumping more gas in to match the increased air flow.
If you take the top cover off, you can watch the operation, and check it out.0 -
Okay, I checked the power rods and they are both openning up but after about half throttle the power falls off like it is starving for gas. It revs fine up to about half then no more. The top end just starts falling off, the back carb pops a little like it is giving too much gas but it isn't getting power. It's almost like a governor kicks in.
Harry0 -
IF you hear a pop out of any of carbs I would suspect a lack of fuel, is your fuel pump up to snuff? Also I would check any flexible hose in the system, as older hose is not compatable with todays fuels. Flex hose by pump may be bad cutting down on gas flow. You can check pump by connecting a vacuum gauge to inlet side of pump, I'm not sure what reading should be see your shop manual. Lou Cote0
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all of this is good, also, check the jets, I had a much similar problem, before i went to twin H, I also had a tiny clog in one of the little squirters... (lack of technical term...) and that was causing much issue...0
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Harry,what I'm going to post applies for so many different catagories of an old car.When repairing a car,it is assumed that you are driving it everyday and something happens and now it doesn't run or drive correct.When RESTORING a car,you have to assume that everything will need attention.If it doesn't after checking it out,the less the restoration cost.This is one of the reasons people always look for a low mileage or a very well maintained vehicle,the odds of needing a few less things that need restored are greater.After checking and/or restoring whatever it might be on your vehicle,you now know the integrety of this component or working system.Fuel and brake systems are a must to be restored from front to back,top to bottom.Sometimes you will find that people "advertise"new brakes or new carb.or new fuel pump and this is misenterpreted as the brakes are done or the fuel system is done.I don't know if you see my point here,but if you talk with someone that has an old car of some sort,you will usually find that they have had some kind of brake and fuel system problems. Intergrety of the working systems on your car will without a doubt make having your old car much more fun and enjoyable.I would plan on rebuilding the fuel tank,check,clean and blow the lines,install an inline filter[you can still get a bad tank of fuel-anywhere-]and rebuild the carb/carbs.I expect if it is starving for fuel on one carb.,you will find the float bowl will be completely full of real fine sediment.I have seen this sediment pile so high in the float bowl,it almost shuts the floats needle and seat off-thus causing it to stare for fuel.Standard Fuel filters are not a micron filter,and the fine particles will travel right thru the filter/filters and cause the carb/carbs to plug up.For some fuel system verification of problems,call a carb restoration company and ask what is the#1 problem they see with carb's?? I'm sure Ron at Daytona Parts company in Florida can tell you.I hope this info helps you and others.:)0
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I agree it's starving for fuel. Also agree on taking the top off those carbs and make sure the bowls are clean.
There is a screen inside the fuel pump that you need to make sure is clean also. Usually inside the one-bolt cover.
Then disconnect the inlet hose and replace it with a new hose stuck in a small can of gas to eliminate the tank/supply etc.
Then disconnect the fuel line before the carbs and crank it over and squirt into a coffee can. If you don't get a good healthy squirt every rev of the cam get a new fuel pump or put a new diaphragm in it.0 -
Ah, the joys of old car ownership. Here is what happened today. I drove to work and pulled up to the gate, went in to move the equipment I park in front of the gate to slow down the near-do-wells and the Hash died. No fuel, had to pull it into the yard. Checked the fuel filter and it looked to full of chocolate milk. Swapped the filter at lunch and took off for home. Got a mile and it quit again, the filter looks okay, and it started back up for another mile and died at the intersection, 100 uphill yards from home. Waited ten minutes, got her running and raced for home, got in the drive and rev'ed her up, running fine then starved out and the filter is empty. Either out of gas after 100 miles, or the local kids hit the midnight gas station aka the Hash and drained my tank, or the fuel pick up is plugging up. Anyway, I'll drop the tank while it's empty, get it flushed, a new sending unit and try again. Sure glad I have another set of wheels. While I'm at it I'll pull the top off the carb and see what the inside looks like. I figure all this driving after sitting for five years is washing down the sides of the tank and that was the sludge.
Harry0 -
Ayuh, you might be surprised what's in the tank. I cut a hole in the top of the Terraplane tank and actually peeled tar off the bottom with a putty knife.
Sounds now like you're right, there's probably some crud at the pickup.
On the 52 Hornet that had sat for 10 years, I plugged up 2 inline filters and am on the 3rd, and carry an extra. I should have dropped that one and cleaned it. You'll get it eventually.0 -
Yup, I thought I had dodged the varnish bullet because the previous owner had cut the fuel line to get gas for his tractor. So the tank was empty. What I had forgotten was in California we have a bug that builds nests in any tube it can find. So I'm thinking I had some bug nests in the filter, plus a dark brown sludge that looks like top soil, probably from the winds. Since I don't like being stranded I will drop the tank and have it flushed now, check the pump pressure while it's down and pull the tops off the carbs to see what got through. I think I'll run the steel lines while I'm at it as they had been by passed with rubber fuel line. At least I won't feel like I need to be driving it while the tank is out.
Harry0 -
I am not sure on a Hudson or a Hash for that matter but many fuel pickups in the tank have a screen/mesh on the end that corrodes gets dirty,plugs up over the years. I have run into this many times on other make cars. You can take compressed air and blow back through the line into the tank. A lot of the time you will get a loud pop and whalla fuel starts to flow like it should. Needless to say if you are going to drop the tank,you can't beat that.0
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While that tank is out is a good time to pull the pickup tube and check it, lots of old ones not in very good shape,especially when the tank has been empty a good while,allows the rust to get started.If one stores a car for a time,FILL ER UP,keep the air out of it.0
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I dropped the tank today, the inside is ugly. I'll take it to our radiator shop tomorrow for boiling then coating. The pick up tube is okay but no filter, just a tube into the tank. No float level assembly. I need to call Paul and order that tonight. Someone took this tank or at least the float assembly out and didn't put it back together. There were six completely different screws holding the assembly cover on the tank. As nice as this car is on the outside and inside there sure was a barnyard mechanic involved with it at sometime in it's life, I haven't found any bailing wire yet but it's only a matter of time. I want to thank everyone again for all the helpful suggestions I keep getting on getting this car going. This is a great group.
Harry0
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