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Minding my own business and felt the back tires rolling over me...

Allen
Well at least it hasn't been thrown into reverse (yet) ;)

John
 

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Discussion Starter · #823 ·
Still having a full lean condition at WOT on long straights. So I eliminated a few more 90 degree fittings and changed from a 180 degree canister filter to a straight through AN filter. Keep chasing this ghost until I find it…

806597
 

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1965 2+2 Vintage Burgundy A-code C4
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Intriguing. Please post your findings. Won’t apply to me but the undeveloped engineer in me is dying to know.
 
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Discussion Starter · #826 ·
Installed 5000lb rear air bags on my truck last weekend to eliminate the “Carolina Squat” when I load the trailer. Noticed the shocks appeared to be OEM so I ordered all new Bilsteins. Installed them this morning. Both rears were 100% collapsed. Right front was borderline. Left front had a little rebound left, but I could compress it with one hand. Hoping for a better ride…at a minimum.
 

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Love the Bilsteins on my Tundra.
 

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Still having a full lean condition at WOT on long straights. So I eliminated a few more 90 degree fittings and changed from a 180 degree canister filter to a straight through AN filter. Keep chasing this ghost until I find it…

View attachment 806597
What is your fuel line size? Some AN-8 is not actually 1/2".
 

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Discussion Starter · #830 ·
Now, it's 1/2" from the cell all the way to the regulator. 3/8" from the regulator to the carb.

Before, it was 1/2" from the cell to the left inner apron and 3/8" from there. The problem (I think/hope), is/was having to many 90 degree fittings in the system.

This is from the tech page from the company that built my carb. SMI Carbs

Q:Check Your Fuel Pressure!!!
A2:Carburetors love fuel volume, but hate pressure. Pressure creates inconsistent aeration of the fuel in the float bowl, which causes inconsistent metering. Picture in your mind a water nozzle spraying into a bucket; the more pressure used, the more froth and air bubbles are created. If you have proper volume, the optimal fuel pressure is 4PSI for modern 2 and 4 BBL carbs. High horsepower drag care may not be able to run this low because G force works against fuel attempting to travel from the fuel cell in rear to carburetors up front.
So now we have established that volume is critical. Let's examine factors that effect low volume, and there are many.
1st the obvious:
Fuel Pump capacity
Fuel Line size
Fuel Pump style
Fuel Pump placement
Capacity: Bigger is better. But… rating methods vary; some are rated with no output pressure or restriction. Others are measured at specified output pressure (A.K.A. 110GPH at 7PSI) (These ratings DO NOT specify the size, length, etc. of inlet of outlet size used.)
Line Size: Because manufacturer ratings fail to specify inlet or outlet size, we must assume the maximum size possible was used. Therefore, any reduction in size, no matter where it occurs, will reduce volume.
Beyond size, angles in fuel lines cause restrictions that reduce volume. Every 90° bend in the system reduces volume by 12%.
Example: Initial = 100GPH
1st 90° = 88GPH
Initial = 88GPH
2nd 90° = 77.44 GPH
Look at the fuel systems on most all vehicles, race, street, off road, etc. Almost without fail you will find at least 1 90° bend, plus 45°, 30° etc. More common you will find 180°, 135°, 90°, 45°, one after the other.
So your 100GPH, by the time it gets to the carburetor, could be as low as 20-30 GPH. This is why fuel pump manufacturers rate GPH vs HP at what seems a completely excessive ratio. They realize that they must consider a worst case scenario: to safeguard against the most unacceptable installation.
To look at this situation from a completely different standpoint, view the following; Cost of engine: $10,000 for 600HP, Cost of Minimum Required Fuel Pump: $200, Cost of Maximum Required Fuel Pump: $600, Differential = $400.
Possible cost of repairing damage to engine to lack of fuel volume is a minimum of $500 and a maximum of $5,000. By using the best possible component when designing your fuel system, you protect a much larger investment, give yourself peace of mind and invest in something that you can trust to grow with you.
 

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That’s a lot of tech. I’m going to ask my old standard OE (operational experience) question, “What are your peers running?” Say for instance, that crusty old [email protected][email protected] from Iowa?
 
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Discussion Starter · #832 ·
Good question. Oddly enough, his car seems to work well with 3/8" (I believe) line everywhere. And again, I may be chasing a ghost and actually have carburetor or fuel pump problems. Yet to be determined.
 

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That’s a lot of tech. I’m going to ask my old standard OE (operational experience) question, “What are your peers running?” Say for instance, that crusty old [email protected][email protected] from Iowa?
My car was thought out and assembled by a non engineer (Me), so of course it works better.


Mark
 

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Discussion Starter · #835 ·
Fingers crossed while knocking on wood…I had no fuel starvation problems this weekend.

On to the next problem. Not happy with the firmness of my brake pedal. Going to change to a larger bore MC.

Will likely change to a road race type seat as well. I had previously stated, when I progress beyond open track I would change to a safer seat.
 

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Did you have the engine on the dyno? It should have had your fuel rate on the dyno sheet like lbs per hour, you can convert that to gal per hour and then measure your flow from the pump and lines.
 

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Discussion Starter · #837 ·
Yes. Engine was ran on dyno. I have the fuel curves.
The new inline filter and larger hose seems to have solved the issue. It had plenty of opportunity to run lean at ECR and never did.
 

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Discussion Starter · #839 ·
-8 line from the cell to the regulator. -6 line from the regulator to the carb. I use a mechanical Holley pump.
 
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