[DeTomaso] Intake Reversion

Sean seanmundy at hotmail.com
Thu May 2 02:14:44 EDT 2013


Thank you Jack.  The holley carb is a vacuum secondary electric choke model. 
Changing out power valve and 
ignition wires sounds 
like something easy to try 
and eliminate some of the factors.  



On May 1, 2013, at 10:50 PM, JDeRyke at aol.com wrote:

> Reversion is normally found with very strong pulsations from IR-mounted carbs like quadruple Webers, not Holley 4bbls. It causes a visible cloud of air & fuel to appear 6" or so above the carb throats at a critical rpm. Exhaust reversion is harder to diagnose but is normally a low rpm quirk. The port-restrictors you speak of can be used in both intake and exhaust, but the effect of intake stuffers is usually to sharpen up the midrange and utterly torpedo the top end. Exhaust stuffers are less noticable and work best at higher rpms. Neither will likely fix the engine problems you mention. Simply going lean might do what you describe. What kind of "750 Holley" is this- a vac-sec or a DP? You may need a tuner-Holley for that beast; an out-of-the-box carb isn't likely to work very well unless you get luckier than I ever did. It's also very hard to separate ignition and fuel problems 'cause they give identical symptoms. 
> As a pure guess, I'll go with JT on this: some sort of carb problem- possibly a blown or wrong range power valve. I'd try another Holley and maybe different plug wires, too. Good luck- J Deryke



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