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Author
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Topic: Carb help?
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67 Fastback
Gearhead Posts: 665
From: Beaverton, Oregon
Registered: Aug 99
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posted 11-16-2001 08:29 PM
   
Just developed an issue with the Fastback. Engine is new (700 miles). In the last few days it wants to stumble badly when leaving a stop sign or light, to the point she started stalling. She also tends to idle with stumble increasingly. Once accelerating she flies nicely and same when on the road at regular speeds.Carb is a 5 year old Carter 600. (Yeah I know Alex 'get a REAL carb...'  ) My guess is that I need to fix the accelator pump or to 'enrichen' the pump (it is now set on a leaner setting). Could the fact that the engine is now broken in (and developing more power/demand as a result) contribute to this stumble? My plans are to look at the spray in the carb as I slowly increase throttle. If it is constant, shall enrichen it, if it spits/spurts do a rebuid. Does this make sense or am I way off here? Thanks ------------------
Jerry
www.67Fastback.com
"The danger in communication is the illusion that it has been accomplished."
G.B. Shaw [This message has been edited by 67 Fastback (edited 11-16-2001).]
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Fastymz
Gearhead Posts: 5145
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 11-16-2001 08:49 PM
Jerry my carter did that too,it was the choke was staying closed.Hope thats some help.------------------
65 Coupe with a 351w, RPM intake,carter625,shorty 1-5/8 headers,2.5 exhaust,Flowmasters,Black Magic electric fan,stock C4,peg leg 8" 2:80,Big Boss 429 hood scoop,Cragers SS,Black Suede finish. https://mustangsandmore.com/ubb/Fastymz.html
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SuperDave
Gearhead Posts: 118
From: Tacoma, WA USA
Registered: Jun 2000
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posted 11-16-2001 09:29 PM
And the carb gets the blame again. How is your dwell? What about your timing? I don't know why so many people assume carb problems as the first cause of such complaints. The carb MAY be the problem but other things shoud be verified first.
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Fastymz
Gearhead Posts: 5145
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 11-16-2001 09:35 PM
Jerry my carter did that too,it was the choke was staying closed.Hope thats some help.------------------
65 Coupe with a 351w, RPM intake,carter625,shorty 1-5/8 headers,2.5 exhaust,Flowmasters,Black Magic electric fan,stock C4,peg leg 8" 2:80,Big Boss 429 hood scoop,Cragers SS,Black Suede finish. https://mustangsandmore.com/ubb/Fastymz.html
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Fastymz
Gearhead Posts: 5145
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 11-16-2001 09:37 PM
Opps got on there twice.------------------
65 Coupe with a 351w, RPM intake,carter625,shorty 1-5/8 headers,2.5 exhaust,Flowmasters,Black Magic electric fan,stock C4,peg leg 8" 2:80,Big Boss 429 hood scoop,Cragers SS,Black Suede finish. https://mustangsandmore.com/ubb/Fastymz.html
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67 Fastback
Gearhead Posts: 665
From: Beaverton, Oregon
Registered: Aug 99
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posted 11-16-2001 10:00 PM
Thanks for the replies. Fastymz, I thought about the choke.. not had a chance to look but shall, ty.SuperDave, I discounted the dwell due to using a Pertronix, am going to assess timing as well. Ty. ------------------
Jerry
www.67Fastback.com
"The danger in communication is the illusion that it has been accomplished."
G.B. Shaw
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SuperDave
Gearhead Posts: 118
From: Tacoma, WA USA
Registered: Jun 2000
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posted 11-16-2001 11:12 PM
Ah yes, but remember that dwell can be influenced by wobble of the distributor shaft.
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67 Fastback
Gearhead Posts: 665
From: Beaverton, Oregon
Registered: Aug 99
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posted 11-17-2001 08:25 PM
After numerous tests and checks and persistant test drives it seems I need to clarify the problem. While it is true that the car does want to stall at takeoff from a red light or stop sign, it is an issue only when the idle too begins to stumble. When the idle stumbles it does so when it is warmed up. It is constant, meaning it occurs eventually on each drive. It usually takes a mile or two of in town driving, with alot of stops and opportunities to idle. When the idle stumbles I need to feather the gas to accelerate. If I sit in a spot and wait while in drive, the car eventually will die (at times). If it is in neutral I can feel the stumble and hear it as well. Once on the road, no issues. The choke is not an issue, it opens fully at the appropriate time. The dwell is a constant 24 degrees (book says should be 27, after many adjustments with the Pertronix it stayed a constant 24). Timing is 10 degrees (no change in the symptoms when I changed and tested up nor down). I looked down throat of carb, with engine off and slowly moved linkage, a steady stream until some spurts, but there was no fuel pressure so am thinking is ok? When running the venturies displace the spray and I cannot see it (no issues in this test as to stumble, hope that makes sense). Is the accelerator pump active while idling? I did replace a nasty Dist cap and rotor (you'd think in the rebuild they would done this). I also fixed an issue I had with a fluctuating charging system, one shop suggested a new harness but after looking around the wires seems the rebuilders forgot to secure a ground lead. I thoroughly set and reset the carb, as per Carter instructions (always worked before). I also tried enrichening the accelerator pump. No change. All the plugs look perfect. So I am flummoxed. Any ideas out there? Thinking about taking it in and give a small shop I know some $ (not the rebuilders) but it should be a rather easy fix  . ------------------
Jerry
www.67Fastback.com
"The danger in communication is the illusion that it has been accomplished."
G.B. Shaw
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franklin
Gearhead Posts: 128
From: VA
Registered: Nov 2000
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posted 11-17-2001 09:17 PM
I would get one of those clear fuel filters. Put it in line and when it starts messing up, get out and see if the filter is full of fuel. While it is stumbling, if the filter is not very full, with big bubbles coming through, you could assume it's a fuel problem. I know the weather is cool now, but are you running headers and a custom exhaust that may be too close to the fuel line? After writing this, I believe this may be a rabbit trail I am leading you down, but I still think the clear fuel filter would help diagnose if it's a fuel problem of some sort or not. The getting warm before it does it is a big clue to something.
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67 Fastback
Gearhead Posts: 665
From: Beaverton, Oregon
Registered: Aug 99
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posted 11-17-2001 09:33 PM
Franklin, I do have a clear fuel filter (for just that reason ) It is 90% full constantly when running independent of the issue. Thanks for the suggestion though. Keep them coming.  ------------------
Jerry
www.67Fastback.com
"The danger in communication is the illusion that it has been accomplished."
G.B. Shaw
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Fastymz
Gearhead Posts: 5145
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 11-17-2001 09:34 PM
My choke was openning but the butterfly would not always stay open.When I'd rev' the car up it would pull the choke closed again. I redid the wire to the choke and fixed it right up.I dont think it was getting enough juice.Just my .02
Ron------------------
65 Coupe with a 351w, RPM intake,carter625,shorty 1-5/8 headers,2.5 exhaust,Flowmasters,Black Magic electric fan,stock C4,peg leg 8" 2:80,Big Boss 429 hood scoop,Cragers SS,Black Suede finish. https://mustangsandmore.com/ubb/Fastymz.html
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67 Fastback
Gearhead Posts: 665
From: Beaverton, Oregon
Registered: Aug 99
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posted 11-17-2001 09:51 PM
Ron, thanks for the reply. That does not seem to be the case here, We had 4 eyes watching and listening as engine stumbled. The butterfly worked well in all conditions, and still the stumble .------------------
Jerry
www.67Fastback.com
"The danger in communication is the illusion that it has been accomplished."
G.B. Shaw
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Fastymz
Gearhead Posts: 5145
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 11-17-2001 09:59 PM
Jerry,did you rebuild the carb.Just trying to help.My carter has a stumble around corners,still cant solve that one and many people have looked at it. Ron ------------------
65 Coupe with a 351w, RPM intake,carter625,shorty 1-5/8 headers,2.5 exhaust,Flowmasters,Black Magic electric fan,stock C4,peg leg 8" 2:80,Big Boss 429 hood scoop,Cragers SS,Black Suede finish. https://mustangsandmore.com/ubb/Fastymz.html
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67 Fastback
Gearhead Posts: 665
From: Beaverton, Oregon
Registered: Aug 99
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posted 11-17-2001 10:04 PM
Ron, nope I did not rebuild the carb. I wanted to rule out all other possible causes first (they wanted $95 for the full rebuild kit!). Decided to check it all out first then, if need be, rebuild or get a Road Demon.------------------
Jerry
www.67Fastback.com
"The danger in communication is the illusion that it has been accomplished."
G.B. Shaw
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Fastymz
Gearhead Posts: 5145
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 11-18-2001 01:57 AM
Jerry go for the Demon,it may not be the problem but thats one hell of a carb.The rebuild kit I got from Summit racing for $50.Ron ------------------
65 Coupe with a 351w, RPM intake,carter625,shorty 1-5/8 headers,2.5 exhaust,Flowmasters,Black Magic electric fan,stock C4,peg leg 8" 2:80,Big Boss 429 hood scoop,Cragers SS,Black Suede finish. https://mustangsandmore.com/ubb/Fastymz.html
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Moneymaker
Administrator Posts: 13182
From: Lyons, IL, USA
Registered: May 99
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posted 11-18-2001 01:03 PM
Ah the Jimmy Carter carb curse. Try raising the float level aobut 1/16th of an inch. An accelerator pump is either good or bad so it will never cause an intermittent condition, even in a Jimmy Carter carb. Also an accelerator pump won't effect your idle. If you are certain that there are no contaminants or dirt in the carb that can cause an obstruction, try raising the float level as you may be leaning out when hot. (Jimmy should have stuck to growing peanuts) ------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00 & '01
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link
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67 Fastback
Gearhead Posts: 665
From: Beaverton, Oregon
Registered: Aug 99
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posted 11-21-2001 03:12 PM
Success! I shall chalk this up to making assumptions of "professional rebuilders's" work. After doing all of the above suggestions ('cept for the float bowl, just couldn't help but think was something else, besides I could REALLY screw that up lol). I decided to check for vacuum leaks. Sure enough, the two middle bolts on the drivers side of the intake manifold were loose. I torqued them to spec and Voila! She now idles perfectly and performs extremely well.  Seems the rebuilders did NOT recheck the torques at the 500 mile check up. Sheesh, I don't know when I'll learn that Nobody cares if it is well done as much as I do. Thanks for all the replies and suggestions. And SuperDave, you were right, I immediately assumed was carb and it was not. ------------------
Jerry
www.67Fastback.com
"The danger in communication is the illusion that it has been accomplished."
G.B. Shaw
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Bluegras
Journeyman Posts: 29
From:
Registered: Nov 2001
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posted 11-25-2001 01:10 AM
67FB, sounds like a clasic case of water in the gas. Drygas is cheap. Give it at least a 1/4 tank of gas used to dry it out.Water lays in the bottom of the bowl, right at main jet and idle circuit level to be pulled in. If you open the throttle far enough the power valve opens and is above the water in clean fuel and the engine take off. Sounds like action your discribing.
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mellowyellow
Gearhead Posts: 4608
From: So. Fl.
Registered: Aug 2000
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posted 11-25-2001 08:43 AM
What IS the problem with Carter/Edelcrock carb? I have a 500 cfm Edel on my 65 with a 5.0 etc. and it does fine. I had a 600 Carter and I found the Edel on v-m. THe 500 works better. I think for all around driving the Carter/crock carbs are OK but for performance everyone says that a Buddy Holley is better. Mine always leaked and blew valves. Hoping that EFI will be good.
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