2x4 carb.setup help!!
Thread Starter
Advanced
Joined: Dec 1999
Posts: 52
Likes: 0
From: grafton wv
2x4 carb.setup help!!
Just put the 2x4 setup on my 56. engine is the stock 265. Has been recent rebuild though. When i put my foot into it and at about 1/2 or more throttle seems like the car falls on its face. Can't tell if it is starving for fuel or loading up. Any suggestions would help. Do i need a hotter plug? Maybe change the metering rods? IS so to what metering rod? And where can i get the rods??
Todd
Todd
Melting Slicks
Joined: Oct 2001
Posts: 3,025
Likes: 12
From: Pleasant Grove AL
Re: 2x4 carb.setup help!! (todd99)
Do you see a cloud of black smoke from the exhaust? Are these stock 2X4 carbs, or two single carbs on a 2X4 manifold? Is the choke functioning? Does the front carb have a choke? Have you checked the performance of the accelerator pumps? What is the condition of the carbs? ie, used, rebuilt, professionally restored? I suspect that you are running too lean on acceleration. If you were too rich, you would probably have mentioned a black cloud. Also, how do you have the progressive linkage set up? Front rod should attach to the bottom hole (closest to pivot point). Give us a little more info and someone will try to assist.
Thread Starter
Advanced
Joined: Dec 1999
Posts: 52
Likes: 0
From: grafton wv
Re: 2x4 carb.setup help!! (todd99)
Both carbs has been completly rebuilt. They are 57 single 4 carbs. I had the single carb and single manifold and car ran like a top. never gave me a minutes trouble. The second carb. i purchased is same as the 1st. a 57 single 4. I also had it completly rebuilt. I have the original throttle linkage as well as gas line lines from corvette central for a 2x4 setup. I took off the choke from the front carb and sealed the choke rod holes in side of carb so i don't think i'm getting vacume leak? Also put on the original 2x4 mechinical advance distributor. I did put a pertronics electronic spark inside the dist. and took out the duel points? This should not have created any problems though? Everything else is stock on the engine. hope this gives more info to work with. I disconected linkage from frt.carb. this evening to see if this would make a difference and i think it actually was worse. Did not notice any black or white smoke comming from the exhaust. Took out a plug and they are dry and ash white not wet or black? Appears the plugs are firing fine?
Melting Slicks
Joined: Oct 2001
Posts: 3,025
Likes: 12
From: Pleasant Grove AL
Re: 2x4 carb.setup help!! (todd99)
If you were too rich, your plugs would definately be black and you would probably see black smoke from the exhaust if it were real rich. Actually, the white ash might indicate a bit too lean. Really should be a tan color. Can you visually see gas squirting in the venturi when the accelerator pump is actuated? As far as the pertronix, it should make no difference. You might want to insure that the advance is operating properly.
Drifting
Joined: Mar 2000
Posts: 1,958
Likes: 0
Cruise-In III Veteran
Re: 2x4 carb.setup help!! (todd99)
With a stock 265 and stock cam and heads but with dual fours there is a good chance you could be flooding the engine-- but as we've said, you'd see lots of black smoke.
With the 2x4 setup on my '58 neither carb is hooked to the vacuum advance. Both are tied-off. Vacuum leaks are generally more noticable under idle conditions and not WOT, though.
I wonder if you're having a similar problem with what I had on my '58 a while ago. My intake manifold was warped. That actually led to me.. not running rich as much as it was me having to floor it to keep it going since the gaps between the heads and the intake screwed up the mixture. It would idle and drive moderately fine, but I essentially lost a few cylinders and would have to open it up a lot to do a little bit of work (simple passing.) I knew there was an issue when a Ford Tarus beat me out of a stop light! :eek: The fix was a LOT of liquid gasket and a new set of gaskets. The right fix was to eventually get a new intake manifold.
I've also tuned the carbs using a... *thinks* vacuum tester. I forget what we tuned them for. It was well over a year ago and my memory is fuzzy :confused:
I wish you luck and await to hear other opinions on this one...
With the 2x4 setup on my '58 neither carb is hooked to the vacuum advance. Both are tied-off. Vacuum leaks are generally more noticable under idle conditions and not WOT, though.
I wonder if you're having a similar problem with what I had on my '58 a while ago. My intake manifold was warped. That actually led to me.. not running rich as much as it was me having to floor it to keep it going since the gaps between the heads and the intake screwed up the mixture. It would idle and drive moderately fine, but I essentially lost a few cylinders and would have to open it up a lot to do a little bit of work (simple passing.) I knew there was an issue when a Ford Tarus beat me out of a stop light! :eek: The fix was a LOT of liquid gasket and a new set of gaskets. The right fix was to eventually get a new intake manifold.
I've also tuned the carbs using a... *thinks* vacuum tester. I forget what we tuned them for. It was well over a year ago and my memory is fuzzy :confused:
I wish you luck and await to hear other opinions on this one...
Thread Starter
Advanced
Joined: Dec 1999
Posts: 52
Likes: 0
From: grafton wv
Re: 2x4 carb.setup help!! (todd99)
thanks guys! I don't think the manifold is warped? When i bought it i had it boiled out and had checked at a machine shop? Hopefully the guy who rebuilt my carbs is going to check it out for me. At this point i have tried all the things i can think of to no avail? Tried putting on new fule pump? Setting timming etc? Seems to run pretty good at start up but when it gets warm than is when i notice the loss of power and the not wanting to stay running?
Will let you know what i come up with and please keep the suggtions comming>
Todd
Will let you know what i come up with and please keep the suggtions comming>
Todd
Thread Starter
Advanced
Joined: Dec 1999
Posts: 52
Likes: 0
From: grafton wv
Re: 2x4 carb.setup help!! (todd99)
Did a little more work! Set timming with light. No more pinging. Checked both carbs with air cleaners off and at idle and above, fuel dilevery is fine on both carbs. Put new set of ac 45 plugs in. The #1 plug did have black carbon but the rest were very clean. #1 may have foweled while i have been messing with the car? One interesting thing i have noticed is that fuel level in glass bowl just hovers around the fuel filter inside?? When i rev up engine and hold it there the fuel level drops even further? Could the car be starving for fuel and the stock fuel pump not able to keep up with "2" carbs? This would explain the car cutting out at full throttle going up hill? Is there a diff. fule pump for 2x4 cars? Also what about a high volume after market pump for edlerbrock or holley?? Please give some feed back!!
Todd
Todd
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
Re: 2x4 carb.setup help!! (todd99)
Todd -
2x4 cars use the same fuel pump as the 1x4's, and it's more than adequate for the job - with the outlet disconnected, it should deliver a pint of fuel in 30-40 seconds, and should maintain 3-1/2 - 5-1/2 psi to the filter. Have you checked the strainer screens just rearward of the fuel inlets on each carb? Remove the big hex nut, pull the mesh screens and make sure they aren't plugged up.
2x4 cars use the same fuel pump as the 1x4's, and it's more than adequate for the job - with the outlet disconnected, it should deliver a pint of fuel in 30-40 seconds, and should maintain 3-1/2 - 5-1/2 psi to the filter. Have you checked the strainer screens just rearward of the fuel inlets on each carb? Remove the big hex nut, pull the mesh screens and make sure they aren't plugged up.
Le Mans Master
Joined: Nov 2000
Posts: 7,246
Likes: 21
From: Going too fast over the hill. Iowa
Re: 2x4 carb.setup help!! (todd99)
Boogie check - disconnect the linkage to the front carb and try it (with a spring on the front carb to hold it closed). It won't be even at high revs, but you should be able to set the timing for no stumble. When one is set up, back off the accelerator pumps on both carbs - you don't need twice as much - and put the front carb back in business. You may need to add some advance to get it to swallow the gas.
