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Author Topic: Holley 390 cfm 4bbl problem?  (Read 1862 times)

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Offline 72Wagon

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Holley 390 cfm 4bbl problem?
« on: June 26, 2012, 04:54:25 PM »
 I am running a Holley 390 cfm carb, and the problem I am having is that the engine intake vacum is pulling fuel from the accelerator pump squirters at higher RPM's. and causing an erratic miss.  The engine has a a stout camshaft which is not helping. If any one can help me cure this problem I would be a very happy Pinto owner.
1972 Wagon
2.0 (not stock), 4 Speed with Hurst shifter and roll control, Holley 390 4bbl, Spearco intake, MSD Ignition. 8 inch rearend 3.55 gears, custom dash and interior.

Offline 71hotrodpinto

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Re: Holley 390 cfm 4bbl problem?
« Reply #1 on: June 27, 2012, 02:10:43 PM »
At one time i had the same problem on my exact setup. However its been so long i forgot if i ever solved this issue.
 The 2000cc and the 390 carb end up having a very high inlet velocity which cause this problem.
 
Look and see if there is a Ball or a pointed rod underneath the Acc pump nozzle.
You want the pointed rod. Apparently its heavier and less prone to letting fuel by.
 
This is also an idea.
an " Anti Pullover Nozzle ".
 
 
http://www.ebay.com/itm/Holley-121-231-Anti-Pullover-Nozzle-/200722057521
Good luck!
 
 
 


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Offline 72Wagon

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Re: Holley 390 cfm 4bbl problem?
« Reply #2 on: June 27, 2012, 05:05:35 PM »
Yes I did look and it has the ball with a brass weight on top of the ball, still getting pullover siphoning at higher rpms.  I site on the net said that the anti-siphoning nozzle helps but did not stop the siphoning on his 4cyl holley 2bbl set up.
 I am going to try adding a tiny spring since it will be an easy attempt, and if that does not work I had suggested a steel weight in place of the brass.
1972 Wagon
2.0 (not stock), 4 Speed with Hurst shifter and roll control, Holley 390 4bbl, Spearco intake, MSD Ignition. 8 inch rearend 3.55 gears, custom dash and interior.