Hello all, I'm hoping you can help me because I'm at wits end! About a year ago I bought a 1952 Chevy 2 door Styleline that has been slowly brought back to life with modern conveniences: 5 speed trans, 12 volt, modern brakes, ect, ect! The motor that came in the car is a 60-61 235 with new cam (I do have cam specks), 848 head with valve work, pistons (not sure of size), dual intake, and exhaust! I had done a bunch of reading about how the stock Rochester carb is rather unreliable and oversized for the aftermarket dual intake set up that came with the car. SO after a bit of research I decided to go with the Weber/Carter 2bbl (early 80s ford escort) dual carb set-up that Tom Langdon offers. The kit is pretty straight forward, reasonablly priced, and well reviewed. The problem is now that its installed on the car I can't get anything to work right!! The car will fire up and high idle fine, but the second I tap the gas to knock down the idle, gas comes puking and splashing up thru the vents and bowls. This causes the idle to drop very low making the motor chug and splash gas all over the place. After the motor is turned off, gas continues to puke out of the carbs filling the intake with gas. I contacted Tom and his suggestion was clean out the carbs--even though they had less then a half a hour run time of them. So I did..... and it's still happening!! What am I overlooking? Fuel pressure issue? Vacuum issue because of cam and bigger pistons? Timing issue? Any help and/or suggestions would be greatly appreciated!! Thanks JESSE!!
It sounds as though you may have a contamination problem that is recurring? Do you have a good inline fuel filter? How old is your fuel tank? If you are pulling contamination from your tank, it gets into the needle and seat and flooding will occur!!
The tank looks original to the car. I did clean it out a few months ago and I replaced the fuel line and filter. The carbs got pulled apart and cleaned this morning!
Brass floats or plastic? If they are plastic, they may be "heavy" and sinking. If they are syncronized then they have to be, syncronized. If its not an actual float, dirty needle/seat problem then it might have the ildle speed screws in too high making the carbs try to run on the mid range circuits. If screwing the mixture needles in or out has no affect, then that could be it.
They are plastic floats, and no I have not sycronized them. I read somewhere that the best way of matching them is to get one running the motor right then set the second one up the same way! I'm sure that is incorrect?
I would try a couple of things......remove the idle mixture screws and be sure the idle circuit is clear....a shot or two of compressed air should do. I would also tweak my float level down just a bit also. Dual carbs can be difficult to synchronize if your cam is producing a low vacumn signal. If you can start the the idle mixture screw precisely the same turns out....say, one and a half turns. Try to get two vacumn gauges hooked to each carb base with manifold vacumn ports....hook up a good tach and watch both that and your vacumn gauge on the carb you are adjusting.....enrich the mixture to achieve the highest rpm and vacumn reading possible with that carb....if you getting above 500 rpm...move the idle speed down slightly . It will take small adjustments from each carb two or three times ( or more)to achieve a close balance between the two. A 235 likes too idle around 450-500 rpm? Also ensure both throttle plates are starting with the same clearances....feeler gauges will do the trick.
Thank you very much! I will go pull apart the carbs and adjust the floats first so I'm not spilling gas all over! There is a TON of gas dripping into the secondary of the carb closest to the firewall and its causing the motor to run really rough. Washing the cylinders is making me nervous!
So This guy sells you new or rebuilt carbs and they flood out? You have a fuel filter and where careful no to get junk in the carb fuel line during installation? If so the seller might owe you two more carbs that don't act up right out of the box. Did the Rochesters act up?
They look brand new, but who knows? The gas that was in the car varnished over and the Rochester carbs leaked for months with out the car running, thats when I started looking into leaky Rochesters and all there problems.
The Rochester's did leak while the car ran, but I chalked that up to them being known for there leaking issues.
Leaky rochesters are traditional. But you can really cut down on the leaking by lowering the float level. The Carbs you are running now, I have no experiance with. But I'd check fuel pressure first. Just to see if that's your problem. Mechanical pump, or electric?
Mechanical, looks like I'm running to the hardware store for vacuum and file pressure gauges! It seems to me that the needles and seats are dirty and thats what is causing the fuel to come out the bowl vents, but I just pulled them back apart and there clean. While the car is running gas drips out of the secondary venturi's causing the motor to "chug" in turn making gas swell up and out of the bowl vents. when i shut off the motor a steady stream comes out of the secondary venturi.
I had some flooding issues with the Weber-Holley carbs from the same guy.This was 15 years ago,the supposed factory rebuilt carbs had grit inside,it appeared they has been "bead blasted" to clean them.Little pieces of grit would lodge in the float needle seat and cause flooding after shutdown. No matter how many times I cleaned the carbs,the grit always was there. Check you carb interiors for a similar problem,maybe my carb issue was rare but just saying.
That might explain whats happening here! What did you end up doing and what did he say about this problem?
Once I looked closely the grit was obvious,like it was semi embedded in the carb interior surfaces.Check your carbs carefully.I don't this is right place for me to bitch about what happened awhile back but new or rebuilt carbs should not have serious issues. Other guys claim to have decent performance from those carbs.As mentioned ,check all the variables like fuel pressure,float level,needle-seat etc.
Just came in from the garage and I wanted to give ya a heads up real quick as to what I found! The float in the carb closest to the firewall was pushed all the way up to the vent holes. This meant the fuel never even got a chance to slow down once the idle had been kicked down. SO I adjusted both carbs floats and tomorrow I will synchronize! Again, thanks for all the help!! I would like to commend everyone on the knowledgable tech support and the outstanding customer service!! VIVA LA HAMB!!
I hope you found the problem. I've had outstanding luck with this set up from Langton. If not, maybe my luck will change.
Hey bob my middle name is Murphy's law so let's hope this is an isolated issue and my bad luck doesn't rub off of everyone else!! The little instruction sheet Tom sent along with the carbs says that there looking for 8 to 14 psi and not to use a pressure regulator. I do plan on putting a gauge on the fuel line tonight to make sure I am within those ranges! Hopefully this is nothing more than a float issue!
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