Compression information

Ghost of Duluth · 02-28-2004, 03:54 PM

Okie dokie, I found a motor but need to test the compression. (for my FD). Here's my question. I do not have access to one of them there fancy-schmancy Rotary testing units to figure out the compression so what I am limited to is a regular compression gauge. It was explained to me that by taking the Schraeder valve out of the tester so it won't hold pressure, you can have someone spin the motor over and see the 3 spikes in compression. My question is this, what are those spikes supposed to read? My same friend, who has done Rotaries ever since I can remember, like the days of the 808, told me that a N/A 13B is around 85lbs or better to be good. So i'm figuring that the turbo one will be lower, but not sure how much lower.

Anyone knowing this info, let me in on the secret so that I may hopefully be ressurected like the Phoenix from Harry Potter. I want to be a wizard too.

Thanks

P1STON2ROTARY · 02-29-2004, 02:44 PM

your going to be looking for something around 90 or 100, to as much as 120 lbs. Very importantly when doing your compression test, make sure to look for three even bounces when you spin the motor. The bounces indicate compression per side of rotor. A bad apex seals would cause you to get uneven readings.

02-28-2004, 03:54 PM	#1
Ghost of Duluth Sixgun Join Date: Nov 2003 Location: Neverland Posts: 2,280	Compression information Okie dokie, I found a motor but need to test the compression. (for my FD). Here's my question. I do not have access to one of them there fancy-schmancy Rotary testing units to figure out the compression so what I am limited to is a regular compression gauge. It was explained to me that by taking the Schraeder valve out of the tester so it won't hold pressure, you can have someone spin the motor over and see the 3 spikes in compression. My question is this, what are those spikes supposed to read? My same friend, who has done Rotaries ever since I can remember, like the days of the 808, told me that a N/A 13B is around 85lbs or better to be good. So i'm figuring that the turbo one will be lower, but not sure how much lower. Anyone knowing this info, let me in on the secret so that I may hopefully be ressurected like the Phoenix from Harry Potter. I want to be a wizard too. Thanks __________________ Team SIXGUN, Don't whine about the food chain, be the top of it. Tokyo Pimps, Godzilla is coming. Lorin, oh Lorin, where have you gone?? If you're in the stands warming the bench, don't whine about the guys in the drivers seats.

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02-29-2004, 02:44 PM	#2
P1STON2ROTARY Moderator Join Date: Jan 2004 Location: LA Area Posts: 155	your going to be looking for something around 90 or 100, to as much as 120 lbs. Very importantly when doing your compression test, make sure to look for three even bounces when you spin the motor. The bounces indicate compression per side of rotor. A bad apex seals would cause you to get uneven readings.