moparlee
Well-Known Member
Hang in there Ben. You are learning a lot, just keep plugging along. Lots of knowledge and guys here to help you along.
We need more young folks like you in this hobby to keep these old Mopars on the road.
Engine issues carb leaking into engine
- Thread starter Benjamin Nelson
- Start date
We need more young folks like you in this hobby to keep these old Mopars on the road.
sir_veza
Well-Known Member
Hey Ben, Get well soon. Really impressed that you're involved in the Mopar hobby.
Also National Moparts is up here in Canada National Moparts
Summit ships to Canada.
Also National Moparts is up here in Canada National Moparts
Summit ships to Canada.
etbetz
New Member
Fuel dripping into the carb throat is likely an out-of-adjustment or stuck fuel bowl float.
The fuel is gettin too high in the fuel bowl so it runs over into the throat. When adjusted to the correct height, the float will shut off the fuel inlet before the bowl gets too fuel. When the engines running it just gulps a little extra fuel at idle so you don't notice a problem. East to adjust, but the carb has to be opened up.
The fuel is gettin too high in the fuel bowl so it runs over into the throat. When adjusted to the correct height, the float will shut off the fuel inlet before the bowl gets too fuel. When the engines running it just gulps a little extra fuel at idle so you don't notice a problem. East to adjust, but the carb has to be opened up.
etbetz
New Member
Fuel dripping into the carb throat is likely an out-of-adjustment or stuck fuel bowl float.
The fuel is gettin too high in the fuel bowl so it runs over into the throat. When adjusted to the correct height, the float will shut off the fuel inlet before the bowl gets too fuel. When the engines running it just gulps a little extra fuel at idle so you don't notice a problem. East to adjust, but the carb has to be opened up.
craigbred
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Hi Ben,
Seems odd to me that there is so much gas flooding on one side, and nothing on the other?
I bought a couple Holley books, and my favorite is David Vizard's Holley Carb book. Well worth the $30.
While on a carb problem thread, I too have a problem maybe you guys can help me with.
I spent a lot of time last year tuning my 870 Holley on my new 505 and I still have a persistent issue, the 20 - 120 min restart. Stopping and restarting in 5 or 10 min is fine, setting for 3 or more hrs is fine. But 20 to 120min. is a real pain. It cranks and acts like it's flooded, and when it starts it blows a buff of black smoke, AND THEN stops after about 1 - 2 sec. Then it usually takes 3 or so try's to get it to restart acting like it has no gas. I have an electric fuel pump I make run with the engine off (to refill the carb). Pumping the gas peddle seems like the best way to get it to restart. Then when it does restart, it barely wants to run for the first 5 sec. or so, acting like the fuel is on again/off again (no black smoke on this restart).
My guess right now is that the carb gets that hot when setting that the gas boils and slowly pushes through the pilot or main circuits and into the intake and heads. That would explain why it's flooded. Now the carb is still that hot that the new incoming gas boils in the bowls and metering circuits that the carb can't meter fuel to the engine at first.
I have read that this new alcohol/gas boils at a lower temp, making this problem worse. Do you guys see this problem?
My next things to look at are:
1. Pull the lower bowl screw after it sets 1 hr. to see how much gas is in the carb bowl.
2. Measure the temp of the bowl at that time.
3. Run the pump to refill the bowl and watch if it boils. Check if the acc. pump works with the hot gas.
Oh the fun of old school Holleys...
Seems odd to me that there is so much gas flooding on one side, and nothing on the other?
I bought a couple Holley books, and my favorite is David Vizard's Holley Carb book. Well worth the $30.
While on a carb problem thread, I too have a problem maybe you guys can help me with.
I spent a lot of time last year tuning my 870 Holley on my new 505 and I still have a persistent issue, the 20 - 120 min restart. Stopping and restarting in 5 or 10 min is fine, setting for 3 or more hrs is fine. But 20 to 120min. is a real pain. It cranks and acts like it's flooded, and when it starts it blows a buff of black smoke, AND THEN stops after about 1 - 2 sec. Then it usually takes 3 or so try's to get it to restart acting like it has no gas. I have an electric fuel pump I make run with the engine off (to refill the carb). Pumping the gas peddle seems like the best way to get it to restart. Then when it does restart, it barely wants to run for the first 5 sec. or so, acting like the fuel is on again/off again (no black smoke on this restart).
My guess right now is that the carb gets that hot when setting that the gas boils and slowly pushes through the pilot or main circuits and into the intake and heads. That would explain why it's flooded. Now the carb is still that hot that the new incoming gas boils in the bowls and metering circuits that the carb can't meter fuel to the engine at first.
I have read that this new alcohol/gas boils at a lower temp, making this problem worse. Do you guys see this problem?
My next things to look at are:
1. Pull the lower bowl screw after it sets 1 hr. to see how much gas is in the carb bowl.
2. Measure the temp of the bowl at that time.
3. Run the pump to refill the bowl and watch if it boils. Check if the acc. pump works with the hot gas.
Oh the fun of old school Holleys...
SpeedD408
Active Member
I would definitely look into that crack. Even though it's on an air bleed it still needs addressing. Fuel does silly things inside a Holley.
You can adjust your float level easily on that Holley, which I'm assuming is a 4781. The float adjustment is top center on the float bowl; the screw head is a lock and the nut is the adjustment. With the proper factory setting, fuel should just barely dribble out of the sight plug hole with the plug removed. If you have glass sight plugs, the fuel level should just barely show on them.
As far as the carb being too big, I've got an 830 annular-discharge double-pumper (Holley 9381) on a 340. Several carburetor gurus seem to think it's just about right (7,500RPM shift) despite "the math". The suggested baseline tune is 78 primary jets and 88 secondaries (blocked power valve). Did I mention I have 100 less cubes than you? My car is a 4-speed; if your car's an automatic it might not appreciate all that accelerator pump shot, but most of the arguments saying "over-carbureted" can actually be traced to "under-tuned". Without getting into too much, Holley jets/metering plates do very little if any metering during normal driving. What really needs attention are the air and fuel bleeds atop and inside the carburetor. Guys get "way too big" carbs to run great--as Chryco Psycho has--by paying attention to something other than jets and/or power valves. And, as he also pointed out, the factory used 850CFM carburetors as original equipment on 440s. No, they're not mechanical secondaries (double pumpers) but they used the same size carb on '71-'73 340s. Nobody seemed to think those engines were overcarbureted.
You can prove all the Negative Nancies wrong on the carb size. It's just going to take some work to get there. Find out where your jetting is; if it's not box-stock make it so it is. Then start familiarizing yourself with terms like IAB, HSAB, IFR, E-bleeds, PVCR, etc. That's where the drivability (and economy) lives.
You can adjust your float level easily on that Holley, which I'm assuming is a 4781. The float adjustment is top center on the float bowl; the screw head is a lock and the nut is the adjustment. With the proper factory setting, fuel should just barely dribble out of the sight plug hole with the plug removed. If you have glass sight plugs, the fuel level should just barely show on them.
As far as the carb being too big, I've got an 830 annular-discharge double-pumper (Holley 9381) on a 340. Several carburetor gurus seem to think it's just about right (7,500RPM shift) despite "the math". The suggested baseline tune is 78 primary jets and 88 secondaries (blocked power valve). Did I mention I have 100 less cubes than you? My car is a 4-speed; if your car's an automatic it might not appreciate all that accelerator pump shot, but most of the arguments saying "over-carbureted" can actually be traced to "under-tuned". Without getting into too much, Holley jets/metering plates do very little if any metering during normal driving. What really needs attention are the air and fuel bleeds atop and inside the carburetor. Guys get "way too big" carbs to run great--as Chryco Psycho has--by paying attention to something other than jets and/or power valves. And, as he also pointed out, the factory used 850CFM carburetors as original equipment on 440s. No, they're not mechanical secondaries (double pumpers) but they used the same size carb on '71-'73 340s. Nobody seemed to think those engines were overcarbureted.
You can prove all the Negative Nancies wrong on the carb size. It's just going to take some work to get there. Find out where your jetting is; if it's not box-stock make it so it is. Then start familiarizing yourself with terms like IAB, HSAB, IFR, E-bleeds, PVCR, etc. That's where the drivability (and economy) lives.
moparleo
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Or get away from Holley carbs. They are a lot of constant work.
Chryco Psycho
Well-Known Member
I have tuned Holley 6 packs that have stayed tuned for decades , Holley is not the problem !
Not to get picky but the TQ is actually a mechanical secondary carb , it just has an air door to taper the transition instead of a second accelerator pump circuit !
Not to get picky but the TQ is actually a mechanical secondary carb , it just has an air door to taper the transition instead of a second accelerator pump circuit !
Benjamin Nelson
Well-Known Member
Well the carb problem seems to have fixed itself, new issue though, only about 20 psi of compression on number 8 cylinder, no bent pushrods and all the rod bearings look fine. Number one cylinder only has just over 100 psi. That huffing noise from the exhaust was cylinder 8 doing nothing, I took the plug wire off and it made no difference in how it was running. Figured out there is a lot of slop in the timing chain and maybe that could cause the popping out of the exhaust and carb? I know. My motor is a dog
Steve340
Well-Known Member
Just patch it up. New rings and a valve grind/timing chain.
It will probably go OK for quite a while if you don't batter it too much.
It will probably go OK for quite a while if you don't batter it too much.
moparleo
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Wow.. looks like some good diagnostics going on now ? Used parts especially carburetors usually have some type of problem/modifications that will haunt you.
Replace it when you can. You don't need the most expensive carb right off the back. Prioritize your repairs. Always safety is first.
Not everybody is interested in the top Dyno potential on a (street car). The manufacturers put carbs that required the least amount of maintenance which meant less warranty service required at the dealer.. The Holley carbs generally came on the Performance models, not the mainstream cars that were sold.
My point is every car is not a race car but everybody seems to go in that direction. I have toys to play with and then I have what I drive everyday. And the extra 15 hp and the $$ and time to get it are not the priority for most daily drivers. I have had many Holley's over many years and I just don't care for the fuel bowl setups, leaks, metering block problems. etc.. Those carbs make HP but you have to stay on top of them. Nobody "tunes" those and then just shuts the hood..
Modern fuel injection is the ticket. A lot of things have improved in the last several years . I don't like constant tinkering with this stuff anymore.
Just go back and read the posts and then look at what the original problem(s) was and the experience/budget of the owner. Something simple goes to the extremes. really....
Everybody has a story or a buddy...
Replace it when you can. You don't need the most expensive carb right off the back. Prioritize your repairs. Always safety is first.
Not everybody is interested in the top Dyno potential on a (street car). The manufacturers put carbs that required the least amount of maintenance which meant less warranty service required at the dealer.. The Holley carbs generally came on the Performance models, not the mainstream cars that were sold.
My point is every car is not a race car but everybody seems to go in that direction. I have toys to play with and then I have what I drive everyday. And the extra 15 hp and the $$ and time to get it are not the priority for most daily drivers. I have had many Holley's over many years and I just don't care for the fuel bowl setups, leaks, metering block problems. etc.. Those carbs make HP but you have to stay on top of them. Nobody "tunes" those and then just shuts the hood..
Modern fuel injection is the ticket. A lot of things have improved in the last several years . I don't like constant tinkering with this stuff anymore.
Just go back and read the posts and then look at what the original problem(s) was and the experience/budget of the owner. Something simple goes to the extremes. really....
Everybody has a story or a buddy...
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Benjamin Nelson
Well-Known Member
I’ll look into the crack but I’m far more concearned of the lack of compression right now.
Chryco Psycho
Well-Known Member
You can put a bit of oil in the cylinder & see if the compression rises if so the rings are bad & you need to build the whole engine , if it is just an 8:1 engine anyway might as well put in better pistons with the rings & check for bore wear . If the compression doesn't rise not you might get away with pulling the heads for now . The noise from the exhaust was why I asked you to heck the compression .
Tapping on the carb probably loosened some dirt & stopped the flooding .
Funny story a guy with a 69 mustang & a fresh 351 cleveland with roller cam & rockers etc wanted to race me one night in my 69 Dart with a 400 in it , we raced 3 times , we were dead even !! After the race I popped the hood & pulled 1 of the spark plug wires off the engine ran the same , 1 of my cylinders was dead like yours the mustang guy was furious , I was equal with a junk engine !!
No one is right or wrong Leo , I have just proven 20-50 more HP on dynos using Holley style carbs over Carter style.
EFI is best hands down & I far prefer Multiport over Throttle body .
The Factories switched to EFI Around 86 , it is hard to believe it has taken 35 years for EFI to catch on for the aftermarket although I built my first Multiport system from a variety of parts almost 15 years ago now .
Tapping on the carb probably loosened some dirt & stopped the flooding .
Funny story a guy with a 69 mustang & a fresh 351 cleveland with roller cam & rockers etc wanted to race me one night in my 69 Dart with a 400 in it , we raced 3 times , we were dead even !! After the race I popped the hood & pulled 1 of the spark plug wires off the engine ran the same , 1 of my cylinders was dead like yours the mustang guy was furious , I was equal with a junk engine !!
No one is right or wrong Leo , I have just proven 20-50 more HP on dynos using Holley style carbs over Carter style.
EFI is best hands down & I far prefer Multiport over Throttle body .
The Factories switched to EFI Around 86 , it is hard to believe it has taken 35 years for EFI to catch on for the aftermarket although I built my first Multiport system from a variety of parts almost 15 years ago now .
Last edited:
moparleo
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Ben,
You will not get good compression readings with a loose timing chain., A new timing set should be your first repair, Then go back and redo your compression test. Carb should be locked wide open to allow max air into manifold. 3-4 revolutions. If more than 10-15% variance, time to pull heads and inspect further. Follow your service manual.
Be careful when you shop for used parts. We have all bought bad parts before.
You will not get good compression readings with a loose timing chain., A new timing set should be your first repair, Then go back and redo your compression test. Carb should be locked wide open to allow max air into manifold. 3-4 revolutions. If more than 10-15% variance, time to pull heads and inspect further. Follow your service manual.
Be careful when you shop for used parts. We have all bought bad parts before.
Benjamin Nelson
Well-Known Member
It’s making a hissing noise from the valve cover when I turn it over. It last for about 2 seconds after I stop cranking. Valves?
Steve340
Well-Known Member
Make an air adapter fitting out of an old spark plug and stick 80 psi of compressed air in the cylinder.
Make sure the valves are closed.
You can work out were it is going.
Make sure the valves are closed.
You can work out were it is going.
Chryco Psycho
Well-Known Member
The valve cover is part of the crankcase so more likely to be rings letting pressure down into the crankcase
volunteer
Well-Known Member
Mopar rated the two sizes of T.Q.'s at 750 and 800. Carter rated them (marketed as Competition Series) at 850 and 1000. While 340's and most 400's used the 'smaller', most 360's and HP 440's used the larger. Excellent carbs but whole new learning curve to make them run right. My 2-cents.
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