Holley 1050 3-circuit - vapor lock or tuning? - Chevelle Tech
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post #1 of 17 (permalink) Old Feb 11th, 17, 10:54 PM Thread Starter
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Todd
 
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Holley 1050 3-circuit - vapor lock or tuning?

I just got the car back together a couple of weeks ago, so I'm still working out the bugs. The last couple of times I drove it the weather was in the 30's, today it was in the 60's and I started noticing a new issue.

Cruising on the highway it seems fine, great actually. What I've noticed is when I'm idling for a while, at a light or whatever, and try to accelerate it's almost like it's not getting fuel and sputters out. If I crank on it for 10-15 seconds it will finally fire back up, runs a bit rough and then I'm off again. This happened probably 5-6 times last night as I was driving in some mild traffic.

I'm going to see if I can find a manual for this carb to possibly do some tuning, but I'm also thinking it's possibly vapor lock.

Any thoughts here or things to help troubleshoot?

Thanks,
Todd
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post #2 of 17 (permalink) Old Feb 11th, 17, 10:58 PM
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Re: Holley 1050 3-circuit - vapor lock or tuning?

Did you touch the fuel line or carb to see how hot they were?

Steve R
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post #3 of 17 (permalink) Old Feb 11th, 17, 11:06 PM
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Eric
 
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Re: Holley 1050 3-circuit - vapor lock or tuning?

Sounds like it might be flooding over. Have you checked the float levels?
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post #4 of 17 (permalink) Old Feb 12th, 17, 1:56 AM Thread Starter
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Todd
 
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Re: Holley 1050 3-circuit - vapor lock or tuning?

Quote:
Originally Posted by Steve R View Post
Did you touch the fuel line or carb to see how hot they were?

Steve R
I did, but it's kind of hard to say if they were 'hot'. Also, I'm not running a return, just a holley mech pump with a regulator. I've seen in the past sometimes with an elec pump and return the fuel has a better chance of getting hot resulting in vapor lock.
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post #5 of 17 (permalink) Old Feb 12th, 17, 2:01 AM Thread Starter
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Todd
 
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Re: Holley 1050 3-circuit - vapor lock or tuning?

Quote:
Originally Posted by Gulf Coast Chevy View Post
Sounds like it might be flooding over. Have you checked the float levels?
I will check that in the morning - thanks for the advice. I would have to agree, it does kind of seem like a flooding could be the issue. It's almost like cranking it cleans up the plugs and it eventually fires.
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post #6 of 17 (permalink) Old Feb 12th, 17, 2:13 AM
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Re: Holley 1050 3-circuit - vapor lock or tuning?

Don't disregard a potential ignition issue.

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post #7 of 17 (permalink) Old Feb 12th, 17, 3:14 AM
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Gary
 
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Re: Holley 1050 3-circuit - vapor lock or tuning?

if it runs fine everywhere else its probably flooding like allready said. look down the carb while its running and check to see if the primary or secondary venturis are dripping. check your float levels. its common to get a piece of debris in the needle and seat
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post #8 of 17 (permalink) Old Feb 12th, 17, 3:48 AM
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Re: Holley 1050 3-circuit - vapor lock or tuning?

Agree it is most likely flooding. If that checks out ok, then vapour lock is possible. Wrap alum foil around the fuel lines as a temp measure & see if it helps.
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post #9 of 17 (permalink) Old Feb 12th, 17, 8:48 AM
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Re: Holley 1050 3-circuit - vapor lock or tuning?

IMO, not likely to be vapor lock this time of year.

see if you can get it to malfunction, hop out, pull the air filter lid, look down the carb with a flashlight, see if anything is dripping. could be a POS in a needle/seat ass'y.

3-ckts are not more prone for vapor lock or anything else than regular 4-bbls.

how old is the fuel in the tank?

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post #10 of 17 (permalink) Old Feb 12th, 17, 9:08 AM
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Jim
 
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Re: Holley 1050 3-circuit - vapor lock or tuning?

Another thing you can check, when it malfunctions, after removing the air filter and you looking down the carb, open and close the throttle and see if there is any fuel squirting from the accelerator pump nozzels. If there is no fuel that might indicate a vapor lock.
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post #11 of 17 (permalink) Old Feb 13th, 17, 1:42 AM
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Re: Holley 1050 3-circuit - vapor lock or tuning?

Percolation.. Fuel boiling in the bowls.
Next time it happens, remove the air cleaner and see if the boosters are wet from fuel.
I'll bet your restart has plenty of black, over-rich exhaust, yeah?

Post pictures.. -or it never happened!
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post #12 of 17 (permalink) Old Feb 13th, 17, 11:18 AM
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Re: Holley 1050 3-circuit - vapor lock or tuning?

Several possibilities, but running a 3 circuit on the street is a bad idea, as well as for a lot of race engines. And the calibration you need with 30 degree ambient temps will be different than at 60. That is why factory cars had heat controlled chokes and exhaust heated tubes to the air cleaner. It's possible you have something else going on, but you probably just need to tune it correctly for the weather. And read up on converting it to 2 circuit.

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post #13 of 17 (permalink) Old Feb 13th, 17, 11:30 AM
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Re: Holley 1050 3-circuit - vapor lock or tuning?

Whats wrong with a 3 circuit? I have run 3 that were 3 circuit carbs and never had an issue with any of them going clean on the transbrake and running down track.
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post #14 of 17 (permalink) Old Feb 17th, 17, 1:53 PM
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Mark Whitener
 
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Re: Holley 1050 3-circuit - vapor lock or tuning?

A few problems with the typical 3 circuit carbs, one is the inability to relocate the idle feed restriction below fuel level. The other is with gas you usually don't need an intermediate circuit, it just adds fuel at part throttle where you don't need if you tune and build it correctly to begin with. And then when you start pushing a lot of HP the idle feed tubes in the main wells become a restriction, you can reach a point where increasing jet won't get it rich enough. And you can build the to be decent as a 3 circuit, but most won't need it. I just reworked a Gen 3 1475, 2.350 throttle blade, 2.105 venturi, idle to WOT clean and in between on my SB, fastest 60' ever at 1.046. Carb got runner up on the owners car in Super Rod at Immokalee a few weeks back on a 615 with an inline throttle stop. There is an intermediate circuit available on the carb, but it's plugged off...
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post #15 of 17 (permalink) Old Feb 17th, 17, 2:39 PM
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Re: Holley 1050 3-circuit - vapor lock or tuning?

Been running a 3 circuit on the street for the last 3 years. Works great.

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