GMC 305 v6 Holley 500 swap woes

[AngryPirate]

For those on the gmcclub, this is a repeat post...

So, I got a factory refurb Holley 500 2bbl 4412S wallered out the opening a bit to match the opening on the bottom of the new Holley carb adapter plate, torqued everything to spec, hooked up the fuel, throttle linkage, choke and vacuum advance to the dist.

It runs like ****, when I can even get it running. When it does run, the vacuum advance runs the RPMs up super high. I adjust the dist to lower the rpm but it seems to be slightly misfiring. All other vacuum ports are plugged.

I've tried everything... setting the idle mixture screws out 1 1/2 turns from turned in all the way, messed with the ignition timing and I think I smoked my coil (and I'm sure my starter is about to go too).

It ran decently with the Stromburg WW2 carburator.

This is MADDENING.

Any other ideas?

The only other thing I can think of is the timing chain skipped at some point? It there an easy way to determine the initial timing of correct?


Side question: with the new carb, how does anyone access the #3 spark plug to change it or seat the boot easily?

Thanks for any help.

[geezer#99]

Did you set the float level?

[AngryPirate]

Originally Posted by geezer#99

Did you set the float level?

I did not. I guess I foolishly assumed from the factory setting would suffice, but I'm also ignorant in these things.

Let me do some googling how to do that.

Thanks for the suggestion.

[geezer#99]

Be prepared for some fuel leakage when you open the window on the side.
And some leakage when you adjust the level screw and lock nut.
I always set my float so that when you lean on the fender a little fuel leaks out.

Any other questions just ask.