Jakter
Active Member
A vacuum reading of around 18 and a steady needle on the gauge will tell you the condition of the cylinders without removing a thing.
Compression numbers PSI on 301
- Thread starter Rusty Muffler
- Start date
Rusty Muffler
Active Member
HAPPY THANKSGIVING EVERYONE!
The clean plugs are #5 and #8. So the third one back on the driver's side and all the way back on the passenger side. Those 2 intake passages connect to the back of the carb. I'm going to check my static timing to see if it's moved and run it one more time before pulling this carb. Remember I just dealt with the intake and probably used too much gasket sealer when replaced. I didn't want to have to pull it off again. I also looked for cracks at that time. Weird that if those 2 cylinders are too lean, why are the other ones too rich? I'm guessing carb again.
The clean plugs are #5 and #8. So the third one back on the driver's side and all the way back on the passenger side. Those 2 intake passages connect to the back of the carb. I'm going to check my static timing to see if it's moved and run it one more time before pulling this carb. Remember I just dealt with the intake and probably used too much gasket sealer when replaced. I didn't want to have to pull it off again. I also looked for cracks at that time. Weird that if those 2 cylinders are too lean, why are the other ones too rich? I'm guessing carb again.
If you're having to keep the choke partially closed to get it to run, the carb is probably ok if the other two are "clean", then those two are lean anyway, and might be the reason the choke has to be partially closed for it to run good.
Look for the air bleeds in the primary venturi area. There should be two near each other. The smaller one is for the idle system (should be directly over where the brass idle feed tubes are on the bottom of the venturi cluster) with the larger ones (for the main system) similarly over the top of the main system feed tubes (the larger tubes with the holes in the side of them, sometimes termed "emulsion tubes"). Both holes should be clean and not corroded. In both cases, the smaller they are from original, the richer they will be.
In the bottom of the idle feed tubes is an orifice termed "Low Speed Jet". It might flow carb cleaner through it, but the size of the "jet" can restrict idle fuel to keep the particular idle circuit from working correctly (i.e., too lean). The jet is located above the bottom of the idle feed tube's bottom, so it is not visible, but it still there. Use a hand-held twist drill to open it up until you "get brass", then flush out any hard deposits and re-install the venturi cluster. That's what I finally discovered was the reason my 1980 Chrysler Newport was trade-in as it would not idle, even after a carb rebuild or two. Once cleaned out, it worked perfect.
Happy Holidays,
CBODY67
Look for the air bleeds in the primary venturi area. There should be two near each other. The smaller one is for the idle system (should be directly over where the brass idle feed tubes are on the bottom of the venturi cluster) with the larger ones (for the main system) similarly over the top of the main system feed tubes (the larger tubes with the holes in the side of them, sometimes termed "emulsion tubes"). Both holes should be clean and not corroded. In both cases, the smaller they are from original, the richer they will be.
In the bottom of the idle feed tubes is an orifice termed "Low Speed Jet". It might flow carb cleaner through it, but the size of the "jet" can restrict idle fuel to keep the particular idle circuit from working correctly (i.e., too lean). The jet is located above the bottom of the idle feed tube's bottom, so it is not visible, but it still there. Use a hand-held twist drill to open it up until you "get brass", then flush out any hard deposits and re-install the venturi cluster. That's what I finally discovered was the reason my 1980 Chrysler Newport was trade-in as it would not idle, even after a carb rebuild or two. Once cleaned out, it worked perfect.
Happy Holidays,
CBODY67
Rusty Muffler
Active Member
A couple things I learned today. My static timing was off by 10 degrees and I had to be careful and adjust it several times because as i cinched the distributor clamp the timing would move. So now I'm at 8 degrees BTDC. I cleaned all the plugs and took another compression test which fared well between 95-110psi. I also found the secondary butterflies with the exterior counter weight was a tight. I sprayed some carb cleaner on it's shafts and it immediately came loose. I know this has a lock out that keeps it from working unless in WOT. I'm not used to these "odd" Carters. I 'm used to working on the common 1406 Edelbrocks. Done for the day and will try to fire it up tomorrow and go from there, Thanks! Happy Thanksgiving to all!
It sounds like a little love is working out.
weim55
New Member
sounds like you’re getting there without any further input, but I will say your initial compression numbers pre-start are low enough that the engine should not have even started. Anything below 80/90 psi and the cylinder will not even fire. That makes me highly suspect of your compression gauge.
While there could definitely be an entire plethora of issues around the engine, only running with full choke the number one common cause is a massive vacuum leak. Of course checking all of the external of that leak are fairly easy but if this problem persists and you run into a dead end, try digging a little deeper. Twice I have encountered massive vacuum leaks from a carburetor Plenum in the intake manifold that broke through into the exhaust crossover, creating a leak you would never find he easily. Leaks from an improper fitting carburetor to intake. Gasket are also very common, look at that very closely. Bad brake booster is another one.
You mentioned a couple of spark plugs that show a lean condition, look carefully at everything around the Plenum area of those two cylinders around the intake system, very good chance you’re going to find your vacuum leak there.
Good luck with the chase!
Steve weim55 Colorado
While there could definitely be an entire plethora of issues around the engine, only running with full choke the number one common cause is a massive vacuum leak. Of course checking all of the external of that leak are fairly easy but if this problem persists and you run into a dead end, try digging a little deeper. Twice I have encountered massive vacuum leaks from a carburetor Plenum in the intake manifold that broke through into the exhaust crossover, creating a leak you would never find he easily. Leaks from an improper fitting carburetor to intake. Gasket are also very common, look at that very closely. Bad brake booster is another one.
You mentioned a couple of spark plugs that show a lean condition, look carefully at everything around the Plenum area of those two cylinders around the intake system, very good chance you’re going to find your vacuum leak there.
Good luck with the chase!
Steve weim55 Colorado
Rusty Muffler
Active Member
UPDATE: I found the main problem. I took the carb top off and found "silt"? covering the 2 rear jets.(see pics) When I unscrewed those there was still a hard substance blocking one passage amongst other things. This rebuild was used a bit and then shelved for 5 years. Anyway, after cleaning it out it idles with the choke open with only an occasional misfire (points?)
Now that that's done I have 2 more dilemmas. The new 700 CC amps Interstate battery that I've been cranking this with would slow down fast after about 4 revolutions. I figured there was something wrong with it so I exchanged it for a larger 850 CC amps. It does the same thing. Are the starters on these cars weak or draw so much that even a new battery can't handle the draw?
The other is that I've been using a gas can to run the engine to this point so I decided to put 6 gallons into a bone dry tank. The engine has run the first time about 30 seconds and then I've had to use ether to start it. Alas, still wasn't enough draw gas to the engine. I figure something is blocking it in the fuel sender in the tank?(junk yard tank from Big M). I'll check that tomorrow. It was completely clean inside and I used compressed air through the line from the motor to the tank but not inside the tank. 6 gallons is surely enough to picku
p fuel from the bottom of the tank?
Now that that's done I have 2 more dilemmas. The new 700 CC amps Interstate battery that I've been cranking this with would slow down fast after about 4 revolutions. I figured there was something wrong with it so I exchanged it for a larger 850 CC amps. It does the same thing. Are the starters on these cars weak or draw so much that even a new battery can't handle the draw?
The other is that I've been using a gas can to run the engine to this point so I decided to put 6 gallons into a bone dry tank. The engine has run the first time about 30 seconds and then I've had to use ether to start it. Alas, still wasn't enough draw gas to the engine. I figure something is blocking it in the fuel sender in the tank?(junk yard tank from Big M). I'll check that tomorrow. It was completely clean inside and I used compressed air through the line from the motor to the tank but not inside the tank. 6 gallons is surely enough to picku
3175375
Senior Member
I believe that you need to do some deep cleaning to the fuel tank, lines and carburetor. Glad that you are moving forward!
Similar threads
