Super Jet Compression issue

[lazyt747]

Running a 701 bored to a ~705 with an ADA girdled head (35cc, supposed to be around 185 PSI) and a factory mod b-pipe. Just did a compression test and I am reading 150 PSI per cylinder. Using 91 octane with a 40:1 oil mixture.

My carb settings are:
Needle/seat: 1.5
Hi: R 135
Lo: 75

What can be causing the lack of compression?

 

[mgander17]

What brand gauge? Mine reads 150 on a cheap harbor freight gauge, 185 on a snap on

 

[ChrisFiore15]

What altitude?

 

[lazyt747]

What brand gauge? Mine reads 150 on a cheap harbor freight gauge, 185 on a snap on

That is a possibility bit I do not know where the gauge is from. Trying to get another as we speak.

What altitude?

I'm in Northwest Indiana.

 

[lazyt747]

Ran another compression test with an old school tester and I am getting 170-175. Might be the gauges then. Going to buy a reliable gauge first thing tomorrow to make sure. What a pain.

 

[#ZERO]

To get accurate compression numbers, you must have the following:

• Good fully charged battery.
• Good fast cranking starter.
• Good battery cables & tight connections.
• Known good & accurate compression gauge.
• Hold the throttle wide open while testing.
• Compression tester in one hole, spark plug in the other.
• Both coil wire plug leads grounded to prevent shorting.

 

[lazyt747]

Thanks zero.