anyone modify a holley ?

[Belgian1979vette]

Seems like I need to change airbleeds and/or IFR's on my carb in order to get the engine the get the right mixture. Currently too lean.

Anyone done that ? Is there a good how to ?

 

[Twin_Turbo]

before drilling out the idle feed restrictors, are you 100% sure you have the throttle plate/ transition slot setting correct front and rear? exposed slots must look like a small square with rest blocked off. Front and rear!

What does the AFR gauge do with a very very slight throttle? Opening the transition slot a little more, does it climb way up even leaner?

 

[Belgian1979vette]

before drilling out the idle feed restrictors, are you 100% sure you have the throttle plate/ transition slot setting correct front and rear? exposed slots must look like a small square with rest blocked off. Front and rear!

What does the AFR gauge do with a very very slight throttle? Opening the transition slot a little more, does it climb way up even leaner?

I'm a little above the proper transfer slot opening (1/2 turn).

I seems to go to stoichiometric at slight throttle although still AFR spikes (lean)

 

[Twin_Turbo]

set the transfer slot opening to a perfect square, nothign else will do. then go from there. Would be a shame if you drilled out the carb and it's an adjustment issue.

Misfires can cause spikes and good amounts of raw unburnt fuel is picked up as lean on these sensors also

 

[mrvette]

set the transfer slot opening to a perfect square, nothign else will do. then go from there. Would be a shame if you drilled out the carb and it's an adjustment issue.

Misfires can cause spikes and good amounts of raw unburnt fuel is picked up as lean on these sensors also

:clobbered: Seems odd, but I have never heard of a LEAN running Holley carb....fuel leaks and rich running is all I have ever heard about....

 

[Belgian1979vette]

set the transfer slot opening to a perfect square, nothign else will do. then go from there. Would be a shame if you drilled out the carb and it's an adjustment issue.

Misfires can cause spikes and good amounts of raw unburnt fuel is picked up as lean on these sensors also

:clobbered: Seems odd, but I have never heard of a LEAN running Holley carb....fuel leaks and rich running is all I have ever heard about....

Large cams give reversion and intake dillution. This requires you to put lots of fuel into the engine in order to get the mixture to burn without excessive misfires. It sometimes runs out of the normal tuned range of the carb.

Which is why you have applications with 4-corner idle, removeable ifr's/airbleeds.

 

[TimAT]

Years ago, we drilled air bleed holes in the primary throttle plates to get back into the transition slot correctly. Had a major off idle stumble without it.
I'm running a Demon carb now, it has the idle bleed built into the baseplate.

 

[pancake]

I second TimAT's post.. I got tired of messing with the Holley and bought a Demon that had the adjustable air bleeds.

 

[Belgian1979vette]

Well, one of the cullprits was the pcv. As the engine has a low vacuum setting it was open all the way, causing a big vacuum leak, that somehow got tuned out...with a lot of fuel. I removed it from the system, but then it started to idle low because of too little air getting in. Had to tweak the secondaries some, but then it started dieseling...had to turn the secondaries in and drill some holes in the plugged rubber line that goes to the 3/8 fitting. What a mess...I hate carbs

 

[Belgian1979vette]

I'm going with these guys for the PCV.

http://mewagner.com/

In case someone ever needs something like this.