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You have the wrong gasket, it should not have a hot slot. Also, if you installed the gasket like you show it in the pictures it's upside down, the hot slot goes toward the front of the carburetor.
This is correct. You need the solid gasket without the hot slot.
You have the wrong gasket, it should not have a hot slot. Also, if you installed the gasket like you show it in the pictures it's upside down, the hot slot goes toward the front of the carburetor.
This is correct. You need the solid gasket without the hot slot. It looks like this:
I don't know if the wrong gasket is causing any of your problems. I don't remember what the bottom of your base plate looks like. Still, I'd replace it with the correct one because of the potential of lack of sealing
Good inputs. I am going to try the gasket first as it is the easiest. The carb seems to be leaking out of the bottom slot (and maybe I did put it in backward) but that still doesn't explain the secondary flooding. The floats being messed up DOES explain the flooding of the secondary. The most painful thing is I was most careful with the floats. I will check back in in a few with the results!
Good news: Gasket was the cause of the leak, that is now fixed.
Bad news: Engine still will not start. This is what is happening. I turn it over a couple times, and it cranks. About every 2 or 3 revolutions there is a puff that comes up through the carb. Not fire, not a backfire, but a puff of vapor. Keep in mind the timing is ok and nothing has changed but the carb. I even started it right before I removed the carb. I am going to take apart the top and check the floats as I hear they seem to cause a lot of problems....and both intakes are flooded again.
Any other suggestions I am all ears. Its trouble shooting mode now.
I took the top off and this is what it looks like below. I am a little perplexed. I thought it was the gasket, but the leak has been isolated to the secondary arm. Meaning it leaks out of the arm with the spring on it, that turns the secondary butterflies. Perhaps I put them back in wrong? There wasn't any seal that I saw.
They seem about half full.
Last edited by mferreira2; 07-10-2018 at 02:44 PM.
And the top gasket seems to be different. Maybe a leak on the sealing line, as there is a hole that isn't supposed to be there. I am likely going to switch out this gasket too.
You have the wrong gasket, it should not have a hot slot. Also, if you installed the gasket like you show it in the pictures it's upside down, the hot slot goes toward the front of the carburetor.
Did you use the little gaskets under the needle and seats. The floats can bind up on the sides of the main body and cause flooding.
I missed this one. Yes, the kit says to use 3 of the gaskets...so I used 3.
If it's flooded the engine bad make sure you have a fire extinguisher and a few rags just in case it pops back and a little fire. Try to find a way to pressure check those needle and seats as it seems like they are not holding back the fuel.
What kind of fuel pump is on the engine, if you can't find anything wrong check the pump pressure. One more thing to think about, how old is the fuel and is there any chance the filter is allowing particles to pass and fouling the needle/seat seal. As a last resort maybe crank a cup full of fuel out and take a look but get someone to help you.
My opinion is the top gasket is ok to use, it's probably a generic gasket used for many different Carter model carburetors. Focus on those needle and seats, did you install the gasket on the seat before you screwed it into the carburetor top. If you boil hot water and submerge the floats one at a time a leaky float will show up as tiny bubbles. I will chew on it as well and post if I have any new ideas.
If it's flooded the engine bad make sure you have a fire extinguisher and a few rags just in case it pops back and a little fire. Try to find a way to pressure check those needle and seats as it seems like they are not holding back the fuel.
What kind of fuel pump is on the engine, if you can't find anything wrong check the pump pressure. One more thing to think about, how old is the fuel and is there any chance the filter is allowing particles to pass and fouling the needle/seat seal. As a last resort maybe crank a cup full of fuel out and take a look but get someone to help you.
My opinion is the top gasket is ok to use, it's probably a generic gasket used for many different Carter model carburetors. Focus on those needle and seats, did you install the gasket on the seat before you screwed it into the carburetor top. If you boil hot water and submerge the floats one at a time a leaky float will show up as tiny bubbles. I will chew on it as well and post if I have any new ideas.
Funny you mention fuel pump. That was just replaced as the last rebuild had a leak issue and it turned out the pump was over pressure. I am 100% sure the pump is ok now. It seems like it is all pointing to needle and seat/float issues. I guess that makes sense because where it is leaking (the butterfly) would not flood unless there was too much gas in the bowls. I tested the floats and they are sealed. That was one of the first things I did.
I saved all the old parts so I can put the old needle and seats back in, but that defeats the purpose of the kit which has fancy new ones that are supposed to work "better".
It is worth mentioning that I did set the floats to the factory setting. The kit didn't say anything about adjusting them to accommodate the new needle and seats. Thanks for the help!
I did not have any luck using those Daytona needle valves. Forgot what my problem was but stacking gaskets is never a good idea on any item. I called Daytona for advice and they said use 2 gaskets. Talked to another guy there and he said use 3. I lost confidence in them and went back to the original seat/needle. Again, it's been several years so can not remember if that help but right now the carb runs great with no leaks or hesitation. And hesitation can at times be an issue with the AFB. My car is also a 63, 300HP.
OK, you used the stack of three under the seat assembly and turned the top over to adjust float height, (something like 7/32 I think), correct.
Is there any chance the seat assembly is bottoming out in the lid causing the gasket sandwich not to seal tight. Do you have a miti-vac to pull a vacuum on the fuel inlet line to see if you can locate the leak.
Do you recall what type of fuel pump you installed on the engine and did you ever check the pressure. FWIW, fuel pump pressure is highest at idle Rpm's, that's a condition where the diaphragm compresses the spring the longest because fuel demand is so low and every rotation of the camshaft resets the diaphragm back tight against the spring, that's the condition where you want to check pressure. Six psi is good for a Carter, I think mine checked out at 5 3/4 psi on my vacuum/fuel pump gauge. It was a original 4657 AC pump with a vendor supplied diaphragm kit that I installed.
By the way, try not to get frustrated, you did a very nice job on the overhaul. Most of us here can relate to your problem because we have been there before. Whatever it turns out to be, back in the day you could get genuine Carter parts or top quality tier 1 parts and many of these issues were avoided.
I did not have any luck using those Daytona needle valves. Forgot what my problem was but stacking gaskets is never a good idea on any item. I called Daytona for advice and they said use 2 gaskets. Talked to another guy there and he said use 3. I lost confidence in them and went back to the original seat/needle. Again, it's been several years so can not remember if that help but right now the carb runs great with no leaks or hesitation. And hesitation can at times be an issue with the AFB. My car is also a 63, 300HP.
I use nothing but the Daytona needle valves - never a problem. Prob in 8-10 carbs now.
OK, you used the stack of three under the seat assembly and turned the top over to adjust float height, (something like 7/32 I think), correct.
Is there any chance the seat assembly is bottoming out in the lid causing the gasket sandwich not to seal tight. Do you have a miti-vac to pull a vacuum on the fuel inlet line to see if you can locate the leak.
Do you recall what type of fuel pump you installed on the engine and did you ever check the pressure. FWIW, fuel pump pressure is highest at idle Rpm's, that's a condition where the diaphragm compresses the spring the longest because fuel demand is so low and every rotation of the camshaft resets the diaphragm back tight against the spring, that's the condition where you want to check pressure. Six psi is good for a Carter, I think mine checked out at 5 3/4 psi on my vacuum/fuel pump gauge. It was a original 4657 AC pump with a vendor supplied diaphragm kit that I installed.
By the way, try not to get frustrated, you did a very nice job on the overhaul. Most of us here can relate to your problem because we have been there before. Whatever it turns out to be, back in the day you could get genuine Carter parts or top quality tier 1 parts and many of these issues were avoided.
I don't easily get frustrated..I love a good problem. I am more paranoid. I don't want to damage the engine. I have read stories of people flooding these and the oil getting tainted through the rings etc.
Fuel pump I have no idea. It was done before I got the car. It was done by someone else that I have been told knows corvette carbs in AZ. I don't have a vacuum pump, but that doesn't mean I can't get one.
I just double checked and I can screw the seat all the way in without any gaskets....so I guess why do I need 3? Can I not adjust the float to fix that? I think it was 5/16" or something like that, so the delta it drops is the amount I need to add to adjust the stop for a lower seat.
I just did this last week, sorry I missed your thread until now.
The Daytona parts kit DOES NOT have the correct carb to manifold gasket for a 340 HP application, as you found out. Also, the Felpro parts catalog is incorrect for this application.
I took one look at the float valves in the Daytona kit, and had no faith in that design, so I re-used the pointed-tip valves that came out of the carb.
There are differing specs on the float drop among the spec sheet that Daytona supplies, the spec page in the 1963 shop manual, and the text of the 1963 shop manual. I set my float level at 7/32" with the gasket on the top plate, and it works perfectly since I reinstalled it.
Another problem with the Daytona kit is the check valve for the accelerator pump is garbage. It does not have an internal spring and the ball is excessively heavy, you will not get a good accelerator pump shot with that check valve under any but the most aggressive actuation of the pump. I experimented at length on the bench, and the pump will just push the fuel back into the float cavity.
07-10-2018, 11:14 AM
