Still no power and bogging down
Instructor
Joined: Mar 2010
Posts: 102
Likes: 0
From: Livingston TN
Like i mentioned before, once u backfire through a Holley the power valve blows out and fuel dumps into the carb - yes even with check ball/valve protection. Minimum u need to remove the fuel bowls and test/replace the power vlvs. Reading liquid black soot on the driveway tells me more than a little rich.
That behavoir is similar to retarded timing but i see u are using plenty of advance. Here again it would be nice to have a "toolbox carb".
Good luck dg and it was nice to read u found the major vacuum leak,
cardo0
That behavoir is similar to retarded timing but i see u are using plenty of advance. Here again it would be nice to have a "toolbox carb".
Good luck dg and it was nice to read u found the major vacuum leak,
cardo0
Race Director
Joined: May 2006
Posts: 18,729
Likes: 2,579
You state something about the jets that makes no sense, "but I followed Lars advise in moving one set to the other position and then bumping up the previous set". If you have a list# 80770 the carburetor came with primary jets of 72 and secondary of 75. The primaries are fine, the secondaries can be 76 or at most 78.
If you changed the primaries to a higher number you are too rich and if you put the 72's on the secondary side you are too lean.
Your air cleaner looks way too short. If you have a 14" diameter filter you should not run anything less than 3" in height or you will starve the engine of air at higher engine speeds.
If you changed the primaries to a higher number you are too rich and if you put the 72's on the secondary side you are too lean.
Your air cleaner looks way too short. If you have a 14" diameter filter you should not run anything less than 3" in height or you will starve the engine of air at higher engine speeds.
Pro
Joined: Apr 2009
Posts: 650
Likes: 1
In referencing Lars and his spot on advice he also touched on the bent accelerator pump arms on the Holley Avenger carbs and new out of the box you had to bend them back in place so they struck the diaphram correctly under the float bowl. If the acc pump arm is not contacting the diaphram fully then you have no helper fuel between the idle circuit and the main circuit. Good luck.
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
You state something about the jets that makes no sense, "but I followed Lars advise in moving one set to the other position and then bumping up the previous set". If you have a list# 80770 the carburetor came with primary jets of 72 and secondary of 75. The primaries are fine, the secondaries can be 76 or at most 78.
If you changed the primaries to a higher number you are too rich and if you put the 72's on the secondary side you are too lean.
Your air cleaner looks way too short. If you have a 14" diameter filter you should not run anything less than 3" in height or you will starve the engine of air at higher engine speeds.
If you changed the primaries to a higher number you are too rich and if you put the 72's on the secondary side you are too lean.
Your air cleaner looks way too short. If you have a 14" diameter filter you should not run anything less than 3" in height or you will starve the engine of air at higher engine speeds.
The big thing with the street avenger carbs was the accelerator pump arm being out of adjustment and lean jetting. I already bent the accelerator arm so that it was position correctly, and I upped the jetting to 75/83.
I will try to run the car without the air cleaner and see if it makes a difference. I will also check the hood clearance with some play-doh.
Thanks for all the suggestions.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
It has nothing to do with what you are experiencing
Also if your jetting is way lean you get lean popping back through the carb. Out on the road it will buck and snort. I would look up what the carb came with for jetting and go back to the base line because it will be close and if anything on the rich side from the factory.
I would verify that your timing mark really is close to "Zero" and then set it for 38 degrees with all vacuum blocked off at 3500 rpm.
Race Director
Joined: May 2006
Posts: 18,729
Likes: 2,579
75/83 is way too rich, for comparison purposes I run a 3310, 780 cfm, which is a much older version of the carburetor you are running. I use 72/78 and Chevy used on the 70 LT-1 70/76. Change the jets and use a taller air filter!
Last edited by MelWff; Jun 2, 2011 at 03:34 PM.
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
I am pretty sure that I still have the original jets for the primary. I will put the original jets back in.
As for the timing mark, I don't have a piston stop. Is there another way that I can check to make sure that the "0" on my timing tab matches up exactly with #1 at TDC? What about putting having someone hold a long screwdriver in there to see at what point the piston starts to travel back down?
As for the timing mark, I don't have a piston stop. Is there another way that I can check to make sure that the "0" on my timing tab matches up exactly with #1 at TDC? What about putting having someone hold a long screwdriver in there to see at what point the piston starts to travel back down?
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
I am pretty sure that I still have the original jets for the primary. I will put the original jets back in.
As for the timing mark, I don't have a piston stop. Is there another way that I can check to make sure that the "0" on my timing tab matches up exactly with #1 at TDC? What about putting having someone hold a long screwdriver in there to see at what point the piston starts to travel back down?
As for the timing mark, I don't have a piston stop. Is there another way that I can check to make sure that the "0" on my timing tab matches up exactly with #1 at TDC? What about putting having someone hold a long screwdriver in there to see at what point the piston starts to travel back down?
OMG! Don't stick a screwdriver in the spark plug hole, what are you nuts?
Stick a wooden pencil or something in there.
Scott
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Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
Tonight I put the original jets back in. They are now 72 primary and 75 secondary. They were 75/81. I also looked at the power valve, although I did not remove it from the assembly. It appeared to open and close.
I also verified (with a long pencil) that the #1 cylinder started to go back down after the timing mark on the balancer was at "0" on the timing tab. I advanced it a little to 38* all in.
It seems to idle pretty smooth but it was still putting out black soot on the floor. I did not have time to test drive it. Also, when I pulled the #1 plug, it was pretty fouled with black liquid that smelled like gas. I wonder if it would help to replace all the plugs now. I am running NGK (UR5 I believe).
I also verified (with a long pencil) that the #1 cylinder started to go back down after the timing mark on the balancer was at "0" on the timing tab. I advanced it a little to 38* all in.
It seems to idle pretty smooth but it was still putting out black soot on the floor. I did not have time to test drive it. Also, when I pulled the #1 plug, it was pretty fouled with black liquid that smelled like gas. I wonder if it would help to replace all the plugs now. I am running NGK (UR5 I believe).
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Tonight I put the original jets back in. They are now 72 primary and 75 secondary. They were 75/81. I also looked at the power valve, although I did not remove it from the assembly. It appeared to open and close.
I also verified (with a long pencil) that the #1 cylinder started to go back down after the timing mark on the balancer was at "0" on the timing tab. I advanced it a little to 38* all in.
It seems to idle pretty smooth but it was still putting out black soot on the floor. I did not have time to test drive it. Also, when I pulled the #1 plug, it was pretty fouled with black liquid that smelled like gas. I wonder if it would help to replace all the plugs now. I am running NGK (UR5 I believe).
I also verified (with a long pencil) that the #1 cylinder started to go back down after the timing mark on the balancer was at "0" on the timing tab. I advanced it a little to 38* all in.
It seems to idle pretty smooth but it was still putting out black soot on the floor. I did not have time to test drive it. Also, when I pulled the #1 plug, it was pretty fouled with black liquid that smelled like gas. I wonder if it would help to replace all the plugs now. I am running NGK (UR5 I believe).
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
U have to select the correct power vlv for your engine.
BTW pwr vlvs are only 9 bucks each at Jeg's or Summit and at most u will need 2 - though i suspect your carb only uses 1 pwr vlv.
As for a TDC stop i make mine out of an old spark plug. Just bust out the porcelin and tap the hole for a nice 4" or 5" stove bolt - u can use a nut to lock it in too. I read u will soon have plenty of old spark plugs so better than throw them out u can make TDC tools for nearly cheaper than the postage to send u mine.
Good luck,
cardo0
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
I picked up new spark plugs today. The parts store also stocks the 65 Holley power valve so I will pick that up tomorrow and change it out just to give it a shot. The carb came with the 65 p/v and my vacuum is around 18-19 hg in park so the 65 should be good.
I know that the accelerator pump is working because when I had the fuel bowl off yesterday, I pushed the pump arm and it shot gas on me. Good thing my wife didn't see it or she would never let me live it down.
I know that the accelerator pump is working because when I had the fuel bowl off yesterday, I pushed the pump arm and it shot gas on me. Good thing my wife didn't see it or she would never let me live it down.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I picked up new spark plugs today. The parts store also stocks the 65 Holley power valve so I will pick that up tomorrow and change it out just to give it a shot. The carb came with the 65 p/v and my vacuum is around 18-19 hg in park so the 65 should be good.
I know that the accelerator pump is working because when I had the fuel bowl off yesterday, I pushed the pump arm and it shot gas on me. Good thing my wife didn't see it or she would never let me live it down.
I know that the accelerator pump is working because when I had the fuel bowl off yesterday, I pushed the pump arm and it shot gas on me. Good thing my wife didn't see it or she would never let me live it down.
Power valves rarely blow out. Nitrous motors cause bangs that blow off hoods - they hurt power valves
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
IMO and also people that all they do for a living is work on carbs. The chance of blowing out a power valve on a carb built within the last 20 some years is very slim. The passage way going to the power valve diaphragm is very small. The backfire belch pressure wave within the manifold and at the base of carb is very minimal in pressure because of a lack of oxygen.
Power valves rarely blow out. Nitrous motors cause bangs that blow off hoods - they hurt power valves
Power valves rarely blow out. Nitrous motors cause bangs that blow off hoods - they hurt power valves
Like I said before, I have never used a Holley before and I am willing to try anything at this point because I am at my wits end.
I read a few posts about gas washing out the piston rings so they would not seat if it was running to rich. What would those symptoms be? I wonder if that is possible?? I have to wipe the liquid off the plugs everytime I pull them.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I'm trying to think this through. You have a normal idle and your were able to adjust the carb to a very high vacuum level 18 inches.
With the air cleaner off and you just slightly move the throttle do the squirter get wet? A fast blip will make the pump squirt, but they should be adjusted to flow even at a slight move ment. Does your motor rev up not under load in the driveway?
With the air cleaner off and you just slightly move the throttle do the squirter get wet? A fast blip will make the pump squirt, but they should be adjusted to flow even at a slight move ment. Does your motor rev up not under load in the driveway?
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I looked up carburater problems. Read this and I would remove the choke completely. No well tuned motor needs or even has one.
We will discuss two types of bog: the first is bog when the vehicle is accelerated from a stop; the second is bog when the vehicle is accelerated from cruise. Bog from a stop is virtually always (and generally erroneously) diagnosed as a faulty accelerator pump (see the section on “accelerator pumps” for testing). Most modern carburetors are designed to function with roughly 0.020 (20 thousanths) clearance between the center of the throttle plate edge, and the throttle body at a point equidistant from the throttle shaft bearing areas. This clearance allows for maximum velocity of idle air past the idle ports. Exceptions to this are GM carburetors with the idle speed air screw, and end carburetors on tripower. Setting the idle for the highest vacuum idle reading will result in too little clearance of the throttle plate; forcing too much of the idle mixture through the lower idle port and too little through the idle transfer slot. This will cause a phenomena called “puddling” where little droplets of gasoline adhere to the intake manifold runners. When the throttle is opened, there is now sufficient velocity of air to sweep all these droplets into the cylinders, creating a mixture which is too rich to burn, hence the bog. As soon as the overrich mixture is pumped out the tailpipe, and a normal mixture is ingested by the cylinders, the bog disappears. A defective advance mechanism can also cause bog; as can a defective accelerator pump. If bog exists only from an idle, not when accelerating from a constant speed, the idle adjustment is probably the culprit.
Bog from a cruise RPM may be caused by a defective advance mechanism, but on 4 barrel carburetors is often caused by the secondary side opening too soon. Most original equipment 4 barrel carburetors have “on-demand” secondaries (I use this term rather than vacuum, as some early 4 barrels used vacuum to accuate the secondary, while most 4 barrels from about 1960 up used either spring tension or weights to control the secondary). The Carter AFB uses weights, and therefore never goes out of adjustment. Other 4 barrel carburetors such as the Carter AVS, Carter TQ, Rochester 4GC, and Rochester Q-Jet have a tensioned secondary spring. As the spring fatigues, the air valve will open too soon, creating an instantaneous lean condition, and a bog. These units, when rebuilt, should virtually always have the tension spring replaced, and adjusted to factory specifications. A defective accelerator pump will rarely cause bog from cruise.
]
We will discuss two types of bog: the first is bog when the vehicle is accelerated from a stop; the second is bog when the vehicle is accelerated from cruise. Bog from a stop is virtually always (and generally erroneously) diagnosed as a faulty accelerator pump (see the section on “accelerator pumps” for testing). Most modern carburetors are designed to function with roughly 0.020 (20 thousanths) clearance between the center of the throttle plate edge, and the throttle body at a point equidistant from the throttle shaft bearing areas. This clearance allows for maximum velocity of idle air past the idle ports. Exceptions to this are GM carburetors with the idle speed air screw, and end carburetors on tripower. Setting the idle for the highest vacuum idle reading will result in too little clearance of the throttle plate; forcing too much of the idle mixture through the lower idle port and too little through the idle transfer slot. This will cause a phenomena called “puddling” where little droplets of gasoline adhere to the intake manifold runners. When the throttle is opened, there is now sufficient velocity of air to sweep all these droplets into the cylinders, creating a mixture which is too rich to burn, hence the bog. As soon as the overrich mixture is pumped out the tailpipe, and a normal mixture is ingested by the cylinders, the bog disappears. A defective advance mechanism can also cause bog; as can a defective accelerator pump. If bog exists only from an idle, not when accelerating from a constant speed, the idle adjustment is probably the culprit.
Bog from a cruise RPM may be caused by a defective advance mechanism, but on 4 barrel carburetors is often caused by the secondary side opening too soon. Most original equipment 4 barrel carburetors have “on-demand” secondaries (I use this term rather than vacuum, as some early 4 barrels used vacuum to accuate the secondary, while most 4 barrels from about 1960 up used either spring tension or weights to control the secondary). The Carter AFB uses weights, and therefore never goes out of adjustment. Other 4 barrel carburetors such as the Carter AVS, Carter TQ, Rochester 4GC, and Rochester Q-Jet have a tensioned secondary spring. As the spring fatigues, the air valve will open too soon, creating an instantaneous lean condition, and a bog. These units, when rebuilt, should virtually always have the tension spring replaced, and adjusted to factory specifications. A defective accelerator pump will rarely cause bog from cruise.
]
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
Sorry...I wasn't able to touch the car this weekend. I had too much stuff going on.
MelWff: I have checked the floats several times...running and turned off. Each time, the gas is right below the sight holes and when I bump the car, it leaks out the hole.
gkull: I believe that if I move the throttle at all, a little bit of gas comes out...when I "blip" it, the squirters shoot the gas in. It revs up strong sitting in the driveway in park.
I don't think the problem is with the secondaries opening too soon because I put a paperclip on the secondary shaft just under the vacuum mechanism, and the paperclip didn't move after I took it for a drive and tried to open it up.
I already changed the jets. I will change the plugs over and take it for another drive and see if it makes a difference.
MelWff: I have checked the floats several times...running and turned off. Each time, the gas is right below the sight holes and when I bump the car, it leaks out the hole.
gkull: I believe that if I move the throttle at all, a little bit of gas comes out...when I "blip" it, the squirters shoot the gas in. It revs up strong sitting in the driveway in park.
I don't think the problem is with the secondaries opening too soon because I put a paperclip on the secondary shaft just under the vacuum mechanism, and the paperclip didn't move after I took it for a drive and tried to open it up.
I already changed the jets. I will change the plugs over and take it for another drive and see if it makes a difference.
Burning Brakes
Joined: May 2008
Posts: 860
Likes: 0
From: Stratford Ontario
Your squirters on top of carb may be too big I would pull them to see what size they are and try a set 4 sizes smaller to start with. Be very carefull they have tapered washers under screw and a flat one under squirter. Dont let them fall into carb. I can almost guarantee that this is your problem.