Q: What size is the hole?
The gascolator hole in the mount is approx 1-7/8".
Q: What is the mounting hole diameter of the ACS GASCOLATOR Installation Bracket?
0.166"
Q: Does the ACS 10371 Gascolator Installation bracket work with the High Pressure ACS Gascolator 10585HP?
No, you would need 05-00907 for the high pressure unit.
Q: Is the bracket used in place of the firewall fitting or with it?
This bracket is for the 10580 gascolator. The 10374 firewall fitting is used with the high pressure gascolator. They are not interchangeable.