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Old 07-26-2021, 09:12 AM
65arboc 65arboc is offline
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Join Date: Mar 2021
Location: Warren, PA
Cobra Make, Engine: Factory Five MK 4 289 HI Po with Webers
Posts: 16
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Originally Posted by Earl J View Post
Hello Jim,

I currently run 48 IDA’s on a 65 GT350, I’m up in Northern NY originally from the SF Bay Area CA. Few Questions for you what are you running for:
Size Venturies/Chokes?
Emulsion tubes?
Air Correctors?
main Jets?
Idle Jets?
ByPass Jets? (At the bottom of the bowls)
Discharge nozzles?
Most importantly, are your floats (fuel level adjusted properly)?
Fuel pressure no more than 2.5-3.0 psi
Cam Shaft lobe seperation?

Sorry for the long list, but I need to know in order to help you.
~Earl J
Hi Earl,

Sorry for the delay in getting back to you, as I have been having some medical procedures done in the past few months and have not felt like messing with the car. Now I am feeling somewhat better and feel like trying to get things done that have been neglected for some time.

Let me start by telling you what I know for sure: I purchased my set up from Redline Fuel Management back in March of 2021. It came as a complete set up with the 48IDA carbs mounted and the linkage adjusted according to their factory specs. Even though they said the float levels were set properly, I made a gauge and checked each carb and found set levels to be correct. I also ordered a correct flow meter from them and proceded to adjust the linkages so all the carbs flowed the same at idle and at 1500 rpm.
Then I adjusted the idle mixture screws to get best idle and went back and checked the flow meter on each carb. The engine started fine and idled well but seemed to run very rich and back fired out the exhaust when running above 2000 rpm.. I finally got through to a tech person at RFM and he suggested changing the idle jets from the current .070 to a smaller size so I ordered a set of .060 and a set of .065. The .065 seemed to give me the best idle with less unburned fuel odor. Instead of going further with my frustrated explaination I will tell you what I have ended up with now.

289 block bored .030, stock iron heads and valves
Chokes are 37
Emulsion Tubes are F7
Air correctors are 195- changed from 120
Main Jets-? .135 , I think
Idle Jets are .065
By pass Jets are non vented/ tried .050 vented but made stumble worse
Discharge nozzels are .050
Floats properly set
Fuel pressure is 2.5 to 3 lbs
Cam is a Comp, grind number FS-280H-10 Lobe seperation is 110.0 Duration is 231 for both I & E
Distributer is a Pertronics Flame Thrower 3 non Vacuum Advance type
Coil is a Pertronics FlameThrower 3 -.032 ohm
Timing is set at 16 degrees initial with 36 degrees all in
Plugs now are NGK WR5 with .040 gap.

So there you have it, Earl

Right now engine starts almost instantly and runs like it never has before. acceleration is strong and instantanious except for a slight hesation when the butterfly plates transition across the 2 holes in the venturies.
Redline tech told me I may never get this stumble fixed.

I can drive the car and am happy with the performance except for the stumble.

Where in New York are you located? I am in Warren, Pa.

Thanks Earl for taking an interest in my problem.


Last edited by 65arboc; 07-27-2021 at 03:19 AM..
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