[Vintage-race] Holley fuel regulator adjustment

[Jim Juhas]

Michael:

With more pressure, fuel flows faster. The needle valves don't shut off like a switch.  It's  a gradual closing until off, so a pressure change will change the amount that gets past the valve before it is fully 'off'.  So, more or less fuel in the bowl.  On my car, I use the lower pressure Holley regulator with excellent results set at 2 psi.  The main pump is a Carter that produces 8psi, I think it is.  I made no changes to the float level from where it was with the stock pump.

Jim 
1957 MGA #311

-----Original Message-----

From:  Awgertoo at aol.com
Subj:  [Vintage-race] Holley fuel regulator adjustment
Date:  Wed Mar 26, 2008 5:33 pm
Size:  1K
To:  vintage-race at autox.team.net, VRG_NewsGroup at yahoogroups.com

I recently purchased a Holley Blue fuel pump to  replace the Facet cube I 
have on my Elva which has an MGA 1500 engine w/two HS6  SU's. The pump came with 
the 4.5-9 psi regulator which I have plumbed up to the  carbs using a Y-block 
with a pressure guage installed in a 3rd-outlet. 

I  know that SU's supposedly like 2-4 psi but several folks have told me that 
they  have had good results with this pump/regulator combo and have been able 
to  adjust the regulator's flow down to 4.5 or so psi without any 
overpressure  problems on their SU's, and that the high pressure regulator is better than 
the  1-4 psi Holley regulator. I hope I have made the right selection here. 
I'm using  AN6 lines from the fuel cell to the regulator with a 3/8" nipple to 
the block  and then 5/16" lines from the Y-block to the carbs, 

In any case I am a  bit confused by the Holley instructions which state: 

"Any change made in  fuel pressure will change the fuel bowl float level 
requirements. A readjustment  in fuel bowl levels will be required for proper 
operation of the fuel system."  

Assuming I am able to adjust the pressure down to where it does not  
overwhelm the needle valves in the float bowls I do not understand why I will  need to 
adjust the float bowl level. I thought that on SU's that is pretty much  a 
fixed thing. 

Can someone shed some light here? 

Thanks in  advance--Michael Oritt