carburetor spacer

[pyrojim]

Can someone tell me the difference between the four hole and one hole spacer?
Thanks

 

[Ted Carlson]

A four hole will improve power through lower to upper middle RPM range. The open spacer works on the upper mid and high RPM range. A four hole is the way to go for a street strip car. I have 2 open spcers and wish I had one 4 hole spacer.