Author Topic: Got a problem. Probably fuel supply issue.  (Read 10702 times)

Offline BK

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Re: Got a problem. Probably fuel supply issue.
« Reply #15 on: April 11, 2017, 05:06:58 AM »
Try opening the throttle blades a little. That will lean the idle and get some of your adjustment back.
 In one of your earlier posts you stated the barrel valve adjustment giving some low RPM improvement. The only thing the barrel valve leakdown does is idle mixture. All tuning comes from fuel pressure through the springs and jets.

Offline wideopen231

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Re: Got a problem. Probably fuel supply issue.
« Reply #16 on: April 11, 2017, 09:04:37 AM »
If you have any holes in hat plugged just pull one or two.About 200 rpm per and it leans motor w/o effecting BV.Idle check pressure is basically just to build pressure in system before letting it bypass any fue don't  I don't see it helping with your foot braking deal.
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Offline Spud Miller

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Re: Got a problem. Probably fuel supply issue.
« Reply #17 on: April 11, 2017, 10:18:12 AM »

 Generally, you don't want to regulate idle RPM by adjusting the idle mixture hex link. You mentioned that you ran out of adjustment to get it lean enough to idle down.
 
 You really want to adjust RPM with the butterflies and then correct the idle AFR with the hex link.

 "Short" on the hex link is lean and I believe that's because your idle check valve is set so high. 9 PSI is too much in my opinion for a naturally aspirated setup. 1-2 PSI on that should have your adjustment in a more friendly place.

 I've found with that check valve at 1-2 PSI, you can leak the barrel valve at 7% of the engine size and be almost right on the money every time. Just a flat or two one way or the other and things are running well. So, engine size X .07 and there's your percentage (or very close).

 Spud

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Offline Curly1

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Re: Got a problem. Probably fuel supply issue.
« Reply #18 on: April 11, 2017, 07:55:38 PM »
I understand the throttle blade opening is what determines the RPM and the barrel valve is what determines the fuel mixture at idle and understand if pressure is more at idle you will have to lean it down more to make it lean enough to idle. Just like the rest of the system if you have more pressure it will flow more fuel.

I did try about 1.5 on the idle bypass and I still had to lean it way down on barrel valve to get it lean enough to even idle. I will try lowering it again soon as I had limited time to test and try things. No matter what it is a huge improvement over what it was and gives me a good starting point to tune from here.

Offline BK

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Re: Got a problem. Probably fuel supply issue.
« Reply #19 on: April 12, 2017, 04:33:08 AM »
Make sure you didn't put idle check in backwards. I'm pretty sure I'm not the only one to ever do it at least once.

Offline wideopen231

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Re: Got a problem. Probably fuel supply issue.
« Reply #20 on: April 12, 2017, 05:35:02 AM »
Best way to make sure valve in correct is o-ring end towards jet or incoming flow in most all setups.Specail built blocks like some I have made are exception.I'm good a screwing up my own rules of simple.LMAO
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline hotrod316

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Re: Got a problem. Probably fuel supply issue.
« Reply #21 on: April 12, 2017, 12:18:18 PM »
spool leaking inside ?

Offline Curly1

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Re: Got a problem. Probably fuel supply issue.
« Reply #22 on: April 14, 2017, 07:31:41 AM »
I know how to put the bypasses in from right direction. I do think have it very close now but will take a few weeks to get tune up perfect. I will be trying to lower the idle pressure again. Thanks!

Offline Curly1

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Re: Got a problem. Probably fuel supply issue.
« Reply #23 on: June 01, 2017, 07:38:23 PM »
Okay for a little more information. The car is now able to footbrake at any RPM and will leave hard. Strange thing with same nozzles and main it is now running stupid fat and I have been leaning it down slowly. Right now my O2 are not working so I am going in small steps and looking for improvements getting closer and have it running almost as good as it was before but able to leave at low RPM. My idle or main was set at 18 and the secondary was around 2. The idle is now around 3? and the secondary is around 19. Basically all I did was swap them to where they were supposed to be and it made it really fat and 60 foot still seems a little soft. Not sure why I had to lean it down so much just because I swapped the main / idle and secondary to where they belong?