I've got a '65 with the L76 engine (327/365hp) with the stock 2818 holly. I just had the carb rebuilt, and am experiencing issues that I figure are due to the carb. This car has 42K original, and is in amazing shape and has always run like a top. I had the carb rebuilt by a very reputable shop that I've used before. It was leaking out of the accelerator pump, this was the reason for the rebuild.

I installed the carb, started it up...which was a pain, and it runs terribly. To start it, I needed to hold the accelerator all the way to the floor....at which point it fired up with misses, which I was eventually able to get to go away. Black smoke out of the side pipes, hi idle of like 2000rpm, even though the idle screw is turned all the way out....and then it will die after about a minute or so. Starting the same process over again.

I've done some searching, but haven't had much luck. I figure it must be the carb settings since it ran perfect before. Any Ideas????

 

Sounds like you should talk to the guy that rebuilt it and see what he thinks. I am assuming you paid to have it rebuilt. Not trying to be a wise guy but I think I would start there first. Greg

 

I agree. You should absolutely contact who ever did the work. If that fails, I would contact Eric Jackson of Vintage Musclecar Parts. He is the best carb guy out there. Extremely knowledgeable and honest.

http://vintagemusclecarparts.com/

-Dave

 

I agree also. Sounds like he screw up big time. He should stand by his work.

 

The black smoke is a sign of way too rich a mixture. The high idle tells me the throttle plate is not closing. Bill.

 

Thanks for the input guys. I definitely will be talking to the rebuild shop, and certainly would have started there had it not been after shop hours when I installed it last night. Figured I'd ask those "in the know" just in case I could get it figured out this weekend. First nice weekend here, so it'd be nice to get the car out. I'll check the throttle plate for any obstructions or defects.

For an extreme rich scenario, float adjustment??? Guessing this wouldn't be the idle mixture screw? Sorry, still learning.

 

Yes, float adjustment, they are to high in the bowl right now. Bill.

 

If you backfired through the carb,you might of blown the power valve,which will also cause the mixture to be very rich. You can test that by turning in the idle mixture screws while the engine is running. If the engine dies,the power valve is good. If you don't know how to adjust the floats,Holley has a step by step procedure on its web site. Its really very easy to do......good luck.

 

Thanks for the reply! It didn't backfire at all, and definitely not through the carb. It acted like it was starving for fuel. Had to hold the pedal all the way to the floor just to get it started. When it did start, it was almost like it was running on 4 cylinders to begin with and was spewing black smoke....then as it ramped up, it sounded normal for the most part....just idling really high. After about a minute or so, it began to idle down at which point it sounded like it was missing again and starving for fuel. Then the black smoke, then a stall.

 

Needs to go back to the re-builder. It should only need minor adjustments after a rebuild to set the idle.

 

I totally agree. I've used this guy several times before with great luck...and virtually bolt and play success. This time is quite a bit different

 

I figured I'd post the progress on my 65.

So, I took the carb back to the rebuilder (who's an awesome guy by the way) and he completely went through the carb again (in his words orifice by orifice). He found no issues with the carb at all. He replaced all the gaskets, the power valve just to be safe (and it was already dis-assembled) and figured that I must have fouled plugs. I pulled them out, and brought them with me to pick up the carb. The plugs are only about 1000 miles old (last summer), but they were quite black due to the ultra rich running (or not running) so I replaced them. Of course replacing the plugs in an A/C car is kind of a pain, not to mention getting the heat shielding right...but no worries. When I put the carb back on, the car fired right up...perfect! I took it for a test drive and for the first minute or so....life was great. Then it started to chug. A little at first...then it got quite a bit worse. If I kept in the throttle, it ran fine...but any kind of cruising or idling and it would try and die out. At this point I had my answer. I figured the choke must be malfunctioning. It was getting choked out. When I was in the throttle, I was into the secondaries which of course has no choke plate. I took off the air cleaner and sure enough, the choke (while warmed up) was completely closed. I manually opened it, and it locked open...I started it up and it ran great...the instant that I would give it any gas on the throttle arm...the choke would click full closed and the engine would die out. I talked with the carb guy again, he seems to think that the spring in the choke (which he tests at 140) is now acting in reverse...as it gets hot, it chokes more and more. He'll fix it for me no problem, but he's like an hour from here. So, I adjusted the choke...rotating it so the choke is held wide open at all times. Little harder to warm up, but no biggie, and now the car runs as it always did. Perfectly!!!!!

Here's the deal....Although I found the path (this time) to the solution, I'm reasonably certain that there was something wrong with the carb on the first go round. None of the choke symptoms were what I was dealing with in the first place. Initially, the car ran at super high idle...had initial misses (4 or 5 seconds worth) and then ran fine on rev but would still idle at about 1800 to 2000. It was completely un-drivable, ran insanely rich....and did so immediately after starting. There was "no runs perfect to start then gets choked out" scenario. Either way, I was able to get the car back to it's norm of perfect stable performance which is what's most important of course. I'll drive the car to the carb shop in the next week or so, and get the choke issue taken care of.

Thanks to everyone for taking the time to reply, and help with the troubleshooting! Greatly appreciated!!!

 

Chokes do not change direction. Either it is set wrong, he replaced the spring, he put the spring in backwards, or the choke stove is not working. Take off the choke cover, and heat the spring with a lighter. It should move counter clockwise when heated. I bet it moves the other way, meaning he took it out of the housing, and put it in backwards. Flip the spring over so it faces the other direction, and reinstall. There should be a scribe line on the cover. Position that so it is one or two notches to the right of the center line on the carb. Then try it again.

BTW, the problem is the carb, and not the plugs.

 

I agree, he must have put it in backwards. I pulled the plugs since he was doing the carb again, and he asked me too. Pretty sure he thought I had other issues, and that it wasn't his work that was faulty. It's a very reputable shop, but no doubt...I think two mistakes were made. 1, after the first rebuild none of these symptoms existed and it ran horribly so something else was wrong with the carb or his rebuild. 2, after the second rebuild, the choke got messed up although the carb is now working perfectly besides that.

Thanks for the walkthrough on the choke. I'll do that for sure, since it will most likely save me a couple hours of driving.