Carb tuning for restrictor plates - need help

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Carb tuning for restrictor plates - need help

Post  512Fairlane on June 22nd 2015, 7:13 pm

I have a 3 circuit Holley 1050 #8896 carb.  I started running an EZ plate restrictor plate system to run the 10.0 index class.  The restrictor plate kit works great I ran 10.019, 10.022, 10.013, and 10.008 at the Hot Rod Reunion this weekend.  The only issue I have is while on the footbrake against the converter the thing is way rich.  The restrictor plates I run are 4 holes each ranging from 1.701" down to around 1.375".  When I bring it up to around 2500 rpm it starts to load up.  It also seems way rich while idling around and is difficult to clear out.  Here is my current set up:  No power valves.  Primary jets 86.  Secondary 88.  Idle air bleeds .053".  Intermediate air bleeds .091".  High speed air bleeds .041".  What would you suggest I change first?  Int. air bleeds?  Idle air bleeds? Or?  Thanks.
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Re: Carb tuning for restrictor plates - need help

Post  bbf-falcon on June 22nd 2015, 9:59 pm

How did it act Before the restrictor plate?

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Re: Carb tuning for restrictor plates - need help

Post  512Fairlane on June 22nd 2015, 10:31 pm

It was fine without the restrictor. I had kept going larger with the intermediate air bleeds until it would leave decent. With the stock air bleeds it was way too rich in the 2500-3000 range. It may have still been on the rich side but didn't seem to "load up" as easy. With the restrictor it seems like it is dumping more fuel than it needs.
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Re: Carb tuning for restrictor plates - need help

Post  maverick on June 22nd 2015, 11:16 pm

If you leaned it with air bleeds just to the point where it would "leave decent", I'd say it's still way fat...and restricting airflow a bit probably isn't helping things.

If it was mine, I'd square the main jets and look for an improvement WITHOUT the plates, then fine tune the carb some more.  The guys I know who use the plates (not me) have deadly consistent bracket cars that don't show any symptom like you describe.  It seems to me that a restrictor plate would MURDER the booster signal, making the AFR less consistent...all the more reason to start with a perfectly tuned carb.  Good bracket racers are really fussy about not not running a fat carb, otherwise our cars tend to go like hell when the sun goes down....not a good thing.

Optimize your tune without the plates....then have fun.
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