[Mallia420]

I have a 258 with a Holley 390cfm 4barrel and Clifford intake and headers. I'm chasing a hesitation under hard throttle, my air fuel ratio meter reads lean when this happens. I have a 35 squirter I jut installed and 2nd biggest cam and it still hesitates. Any ideas? Holley says if I go any bigger squirter I need 50cc accelerator pump, is anyone running that 50cc or am I going in wrong direction?

 

[harleydragon]

I only use a 30cc on a 600 sitting on a pretty stout 350

 

[0III0forlife]

I would think you are headed in the wrong direction. a 35cc squirter in a 390 is a lot too much for a little 4.2L. Im not positive but I believe that my 390 has a 26cc in it. And even then it is still a bit much for it.

You have to remember that a 4.2L came stock with a little 2bbl on it. It doesn't require all that gas dumping down its neck to run good.

Although I had the same hesitation that you are experiencing, I fixed mine by installing an HEI distributor, to get a better spark to make the cylinders go boom. The 4.2L is a low end motor, it isn't made to stand on it and open the 4bbl and run like a raped ape. It will perform well with the setup that you have, but you have to have a light foot.

 

[0III0forlife]

One question, how did you get the Clifford header to clear the front driveshaft without issues? Or is it one of those shorty header systems?

 

[harleydragon]

my experience with hotrod motors is pretty much limited to chevys but I know that a really heavy cammed motor usually does not have the greatest response from a very low rpm

 

[roadyrob]

try a stiffer spring in the vacuum secondary so it opens slower. timing can cause this to, also the size of your power valve.