1 way check valve question

[Turbo6Smackdown]

Ok, first question is, does gm part no. 25525315 (one way check valve) hold up to 25 psi of boost, or were they just barely adequate for 15 psi back in the day.

Question two. If my cruise and all the other stuff that's operated by vacuum relies on vacuum, then what does it do when the check valve's closed due to a positive manifold environment? Does boost getting into my cruise control system due to a leaky check valve screw with the way my cruise works?

 

[earlbrown]

How often do you cruise at 25PSI?

 

[Turbo6Smackdown]

Well I don't cruise there but was wondering what boost would do to the cruise control system. Anything?

 

[Raeban]

I did some testing on how much vacuum it takes to effectively operate the cruise control servo. It looked to me like the bare minimum was 5" of vacuum for the servo to actuate, so if you have less vacuum than that you cruise won't work.

 

[Raeban]

Oh and if I was going to change any more check valves this is the way I am going.

http://www.usplastic.com/catalog/item.aspx?sku=64175

I got this information from another board member who reported they work great for a pcv check valve, but the site has smaller ones and I see no reason why they won't do the trick in the other location.

 

[Pronto]

If you want to spend more money: http://www.boombaracing.com/check-valves/

 

[Turbo6Smackdown]

Oh and if I was going to change any more check valves this is the way I am going.

http://www.usplastic.com/catalog/item.aspx?sku=64175

I got this information from another board member who reported they work great for a pcv check valve, but the site has smaller ones and I see no reason why they won't do the trick in the other location.

Do you trust those? Will they hold up? And do our stock valves in new condition hold up to 25 psi?

 

[bison]

In 20 years of running the factory check valve I never had a problem. Even at 35-40psi

 

[Turbo6Smackdown]

Oh sweet, thank you Bison.

 

[earlbrown]

I did some testing on how much vacuum it takes to effectively operate the cruise control servo. It looked to me like the bare minimum was 5" of vacuum for the servo to actuate, so if you have less vacuum than that you cruise won't work.

It's not the average cruise vacuum that sets your minimum available vac. Keep in mind that every throttle chop drives the vac reading through the roof. That charges the crap out of your vacuum reservoir ball. Even when cruising at a constant speed, topping a hill and backing off the throttle a little bit will cause a vac spike.

 

[Raeban]

It's not the average cruise vacuum that sets your minimum available vac. Keep in mind that every throttle chop drives the vac reading through the roof. That charges the crap out of your vacuum reservoir ball. Even when cruising at a constant speed, topping a hill and backing off the throttle a little bit will cause a vac spike.

Most definitely agree. My test was done using a mighty vac on the vacuum system checking the amount of vacuum and manually activating the cruise servo. Engine was off so it had no effect.