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Racing Fuel Systems • View topic - 750 Mighty Demon hard to start

750 Mighty Demon hard to start

Re: 750 Mighty Demon hard to start

Postby rgalajda » Sat Sep 11, 2021 10:02 am

I was looking back at your posts to see if you mentioned IFR size . was it .033" ? and .076" IAB
I would think that is to lean . Even if it idles ok after warmed up ( heat soaked ) it's probably to lean for start up.
Some 750 holleys came originally with IFR .038" and .070" IAB . The bigger the venturi , the bigger the IFR. Grumpy cams ( low vacuum ) require more idle fuel. Less signal to pull the fuel.
I would go to at least IFR .036" - >038" and .070" IAB. That would be close to what the 750 Mighty Demon had originally.
As someone else mentioned , check the passage is drilled ( clean ) while your at it.

As for chokes. Even at 90 degrees ambient temp a properly set electric choke will still close on a cold engine ( just not as tightly ) and open very quickly on start up greatly assisting the start up of a grumpy cam.
rgalajda
 
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Re: 750 Mighty Demon hard to start

Postby 2x4b4fun » Sun Sep 12, 2021 2:56 pm

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