Flat Six Carb, problems again
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Junior User
Joined: Aug 2004
Posts: 79
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From: Port Lavaca, Texas
Flat Six Carb, problems again
I bought a kit and rebuilt my Holly897, I'm still not sure what the diffference is between the 897 and the 847 that is called for. The upper gasket was definately different but the part number for the two kits was the same.
The kit was not a full kit so I did not replace the main jet or the power valve, I did replace the float valve and seat and both the pumps.
The engine idles and starts great and the idle circuit is working perfectly. When I give it a little throttle it chokes the engine down. When looking down the throat I see the accelerator pump work as it should but it sure seems I get an excessive amount of fuel coming from around the air bleed in the bar assembly. To get the engine to run half descent I have to choke the engine to about 3/4 choke. Anything less than that and it seems to flood out pretty bad. Any idea on what I missed? I thought I had it all in order. I did kill the engine under idle by closing off the idle adjusting needle which should tell me that the power valve is holding and not leeking buy but I am a little suspect beacuase the new kit did not come with a new power valve.
As always, thanks!
The kit was not a full kit so I did not replace the main jet or the power valve, I did replace the float valve and seat and both the pumps.
The engine idles and starts great and the idle circuit is working perfectly. When I give it a little throttle it chokes the engine down. When looking down the throat I see the accelerator pump work as it should but it sure seems I get an excessive amount of fuel coming from around the air bleed in the bar assembly. To get the engine to run half descent I have to choke the engine to about 3/4 choke. Anything less than that and it seems to flood out pretty bad. Any idea on what I missed? I thought I had it all in order. I did kill the engine under idle by closing off the idle adjusting needle which should tell me that the power valve is holding and not leeking buy but I am a little suspect beacuase the new kit did not come with a new power valve.
As always, thanks!
Fleet Mechanic
Joined: Jun 2004
Posts: 1,784
Likes: 45
From: Minnesota
- I am not 100% sure but I think you are backwards, you may be running lean. When you use the choke it richens up the mixture.
- Does the engine smooth out after you get to a set RPM? For example does it load down under acceleration then even out when a higher stable rpm is reached?
Thread Starter
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Junior User
Joined: Aug 2004
Posts: 79
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From: Port Lavaca, Texas
I think you are right, I should have explained better.
To get the engine to run at any speed down the road I have to leave the choke at about 3/4 choke . When accelerating quickly from idle it seems to choke down and that is when I'm seeing all of the raw fuel I was describing. I think I have several problems, I plan on taking it back off and going through it again.
To get the engine to run at any speed down the road I have to leave the choke at about 3/4 choke . When accelerating quickly from idle it seems to choke down and that is when I'm seeing all of the raw fuel I was describing. I think I have several problems, I plan on taking it back off and going through it again.
Fleet Mechanic
Joined: Jun 2004
Posts: 1,784
Likes: 45
From: Minnesota
It sounds like you are fuel starved. Have you ever used this setup and had it work properly? The fact that it idles fine would suggest you do not have any vaccuum leaks. Usually a vaccuum leak shows up worse at idle. I would check the float height and main jet passage again. Maybe get the carburetor boiled out at a professional shop. I soaked mine for close to a week before blowing out the passages with compressed air they both ran fine after that.
Posting Guru
Joined: Apr 2004
Posts: 1,908
Likes: 2
From: Seattle WA.
I was having the same dead spot off idle on my 51 226 it would go away when the choke was on, or after the engine was run hard for a few miles and got hot. I suspected it was the valve in the exhaust manifold not properly heating up the fuel mixture. Last week when the weather dropped to the mid 40 here at night and it started dying when started. Seemed like the fast idle cam was not working properly, it idled fine at fast idle before the colder weather set in. After I got home from work I took the fast idle cam rod off and increased the bend so it would be on the high part of the cam for sure when the choke was on. Strange thing happened, the dead spot went away after that, and I haven't noticed it sense. I think the change in the arm adjustment took up the slack in the accelerator linkage by putting the butterfly rod on a higher part of the cam and has increased the accelerator pump stroke.The idle should have changed but it didn't and I haven't had to adjust it yet.
Rod
Rod
Last edited by 51ford fan; Oct 9, 2005 at 11:09 PM.
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