Testing check valves

When your testing an idle check or high speed check; when should you read the gauge when it's just opening and you can just hear the air coming out or when it is further open?

 

between the two...more on the open side..Dave
www.myspace.com/daveloweswr

 

When it's opend, and then look at the gage

 

You guys have a lot more experience than I do at this but I always heard you want to be pretty accurate; that seems to leave a lot to interpretation.

Can anyone else tell me how they check them?

Thanks,

 

A bowl of water, and when you get more than the initial bubbles, is the opening point.

 

we do ours like gregM784 as soon as you see bubbles not 1 or 2 but several that is were you want to be....Dave
www.myspace.com/daveloweswr

 

This is also known as crack pressure. It's very hard to tell when the poppet has opened all the way, let alone half way. So you check them when they crack open. Just as you hear air escaping the check valve.

 

I like to set checks with fuel in line when possible. Another thing is to protect your dial gauges when turning air supply on and off. Gently pressurize gauge/line on supply side using regulator so as not to damage small gears that drive dial.


Jeff

 

After the initial crack dose the pressure drop or increase ?

 

Tony; you must be a lot younger than me! After 47 yrs. on the startline, no way would I try to listen! Thank the lord, with my contacts/readers, I can still see
Taster's Choice bottle is my fav., half full of water. If you see bubbles creeping then increasing, it simply means your seat is poor in the valve. When it really opens, all hell breaks loose in the bottle!
To repair your valve at the track (if necessary) someone will have a valve lapping stick they never use anymore. Pop off the rubber and you may have to do a little "whittling" on the wood to tap it into your popit piston as a mandrel. Then useing a cap on the other end, you can stand the body up on the back of the vise and "TAP" the wood mandrel w/ piston into the seat to help reseat those surfaces. Sometimes if that doesn't do it, you can use a little lapping compound for a good seal.
It takes "finese" and patience, but then you lose the bubbles, which means it now opens the way it is intended.
Above taken from Uncle Bob's "know what dumb is"- been there- have NO money, racing program (s)
Remember: poor preparation on your part does NOT mean the guy kickin' your ass is cheating!!!

 

My point in asking about dose it increase or drop in pressure ,it has to maintain that pressure to keep it opened, example. if it is set at 60 lbs it has to hold 60 lb to keep it opened, and once it's opened it's opened "KISS" if theres more pressure it don't open any more than it already is. you do remember what the definition of is is.

 

I've been on the startingline about 20 years. I can't see worth a shit, but I can still hear, somewhat. The Tasters Choice bottle is not too far off in the future.

 

Strange as it may seem, toothpowder is excellent for lapping tapered seat check valves.