One of the most important factors of tuning a carburetor – is having the proper fuel pressure to feed your carb.
Unfortunately, many folks are running fuel pumps (mechanical or electric) that push too much pressure for street use, causing a multitude of headaches, like…
Overfilling the fuel bowl
Poor gas mileage
Damage the needle/seat
The fix is easy – install either a pump with the proper pressure – or plumb in a regulator. As a bonus, adding a return line will improve your pump efficiency, lower fuel temperature, and significantly reduce vaporization.
And the answer to how much pressure you should be running – for a street carburetor… see below. It’s probably less than you expect, and while you (and I) are used to seeing pressures as high as 7PSI, that pressure is not best for street-performance.
Broken carburetor air cleaner studs are common – and are easily repaired with a drill and an easy-out.
You’re going to need to use a power-tool, just do not put too much effort into it, or you can cause more troubles than you already have…
Finesse and plenty of penetrating oil like PB-Blaster goes a long way towards a successful repair. For safe measure, run a bottoming thread repair tap (not a standard tap) to guarantee good thread engagement – and prevent a pull-through. Here’s one I did on a Holley 4412-3 carburetor.
Does the vent tube on your Holley carburetor look like this? This one was damaged in shipping.
It’s an easy fix using an easy-out tool, like the #4 pictured.
With the tool, you can remove and install the tubes. Just be careful not to crack the mounting boss, or you’ll end up with more trouble than you started with.
Also, do this by-hand, do not use a power tool! You need to have a feel for how the progress goes – once you do it, you’ll know what I mean. Unlike engine torque, more is not better here – take it easy.