what is the difference

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racyroy1

racyroy1

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To all of you experienced racers can you tell me what is, or is there a differnce between running lean and just plain running out/or low of fuel at the big end of the track.

Thanks for any and all responces
Racy
 
if you are racing any. you should have an electric fuel pump. and NO mech pump. if after that it isnt running right learn to tun the carb. remember on carbs a little is a lot .
 
running lean is not having the correct jets in the carb....running out of fuel on the top end is where your fuel system can not supply enough fuel that the engine requires, which will also cause the engine to go lean...only cause it runs out of gas...
 
Well I'm learning for sure. I'm running mechanical but I'm also running really close to stock.
When it runs lean it'll pop on the big end, but when it just runs out of fuel it'll stumble like someone's shutting the fuel off
 
what size fuel line do you have?

what mechanical pump do you have?

what carb do you have...and what jetting is in it?
 
It's running with factory fuel line, I believe it was or is a holley 85 gph mech pump. Jets, I can't remember off the top of my head, I'll get those numbers tomorrow. The carb is a quick fuel 650. It ran great in the cooler weather but I ran the other day in 80 plus temp and it just fell over on the last 3-400 ft.. I have a fuel guage on it set to 6psi. Also I have a new 140gph elec pump and 1/2 fuel line going in this week.
 
Looking at your other thread, this is a mild 340 build. Your stock 5/16 line is more than enough for that. How high are you trying to rev the engine and at what rpm is it starting to fall over.

I'm seriously doubting this is a fuel delivery problem.
 
1968FormulaS340 said:
Looking at your other thread, this is a mild 340 build. Your stock 5/16 line is more than enough for that. How high are you trying to rev the engine and at what rpm is it starting to fall over.

I'm seriously doubting this is a fuel delivery problem.
Click to expand...


I never take it over 6500, it starts to fall at around 5000, 1st and 2nd gear there is no problem. once into 3rd at around 5k it starts to miss and stumble. Could it be the coil? it's happened to me once before.
I've tried jetting up and down from where it started with no change.

and to the question asked about what jets? 71 pri 79 sec.
 
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