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Author
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Topic: Edlebrock 600 Jet/Metering Rod Tuning
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swiss
Gearhead Posts: 148
From: Duluth, Ga
Registered: Feb 2004
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posted 12-04-2004 12:17 AM
  
I have been changing all combinations of jets and rods in my 1610 to try and get the optimal performance. I am down to a lean condition only under WOT at high RPM's (above 3000). It seems to go lean after going through the gears hard and getting into fourth or running fourth on the highway and stepping on the gas. Almost like I may not be feeding enough fuel. This is a T5 tranny. It will go lean also in 5th going WOT at 2000 rpm and 80 miles per hour. I have taked the secondaries up to the maximum JET size moving up 12% for this carb and have the primaries running at the moment richer than I would like but they are helping compensate for the secondaries. It is okay but I still have a lean condition under WOT. current setup has:
Primaries 101
Secondaries 103 (Maximum Jet Size)
I have moved meter rods around to maximize the primaries Rich but not off the board. I checked the float level and even decreased the clearance to raise the gas level. In addition I moved my pressure regulator to maximum pressure to ensure I was not running out of fuel. This helped somewhat but did not solve the problem. I have not opened the carb after these changes to see the fuel level. I will do in the morning. I have a number of jets and was thinking of just drilling out a smaller jet for the secondary jets to 106. Any other ideas? This is a 302, 351 heads and somewhat restrictive exhaust, (K code Manifolds) Steve
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V8 Thumper
Gearhead Posts: 4359
From: Arizona
Registered: Dec 2001
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posted 12-05-2004 09:17 AM
Certainly sounds pressure/volume related to me. How much fuel pressure do you have, engine hot?Have you replaced the fuel filter?
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1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9"
All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html [This message has been edited by V8 Thumper (edited 12-05-2004).]
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swiss
Gearhead Posts: 148
From: Duluth, Ga
Registered: Feb 2004
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posted 12-05-2004 09:47 PM
Thumper, I pulled the top of the carb and have a good fuel level up to the top of the brass separator plates in the bowls. I double checked the fuel pressure and set it to 5psi. Fuel filter is large canister type and clean. I did not run the car around to check fuel pressure during operation. I drilled the jet out to around 108 and still have a lean condition on WOT. I am stumped. Steve
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V8 Thumper
Gearhead Posts: 4359
From: Arizona
Registered: Dec 2001
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posted 12-06-2004 06:38 AM
In order of likelyhood:1. Insufficient fuel pressure/volume
2. Ignition system fault
3. Debris in carb
4. Weak/broken valvespring(s) I should've asked earlier... what exactally is the motor doing when going 'lean'? Have you verified with a plug read? ------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html
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indyphil
Gearhead Posts: 2072
From: Senoia, G.A. USA
Registered: Jul 2002
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posted 12-06-2004 09:14 AM
The in tank fuel filter (on the sender unit) could be plugged up. Is it bogging down on you? I like Todds suggestions------------------
'68 coupe, '66 289 C code
engine, edel 600cfm carb, performer intake, dual exhaust http://www.geocities.com/ottouk_77/68mustang.htm
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lawless
Gearhead Posts: 390
From: Richmond, VA
Registered: Aug 2000
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posted 12-06-2004 12:32 PM
Use the lightest springs w/ the metering rod. It's been a while since I have messed with an ebrock carb, so I can't remember the color code on them.Also, there is another hole on the secondary linkage to allow the secondaries to open faster.
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swiss
Gearhead Posts: 148
From: Duluth, Ga
Registered: Feb 2004
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posted 12-06-2004 01:14 PM
Morning Gentlemen,I am thinking fuel pressure and volume also. I am verifying lean condition with 02 and air/fuel sensors along which coincides with the "feel". The sensors have been accurate with earlier rich and lean plug visuals. I am going to run the car with my pressure gauge hooked up to see the fuel psi under running conditions. I had 5 psi at idle and reving the motor but did not have enough extra fuel line to test on the road. (Back to the store) Vacuum is a steady 20 at idle and light load, moves towards zero at WOT.
Q: if a valve spring was light or broken this should be reflected in vacuum both at idle and light load? I yanked the in tank filter a while ago as I have a large fuel filter in line and did not want to have additional failure points. Thanks for everyone's input. After driving a while it is pretty consistant with a lean condition only in higher fuel requirement situations which lends itself with the fuel pump not feeding enough volume at high demand. I was going to revisit my fuel lines and such.. Keep everyone posted. Steve
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