71 454 vacuum check valve

[Mike S.]

I had rough idle .block off vacuum port to vacuum resivoir.rough idle gone.lights and wipers work fine when hooked back up.could not find any vacuum leaks. so i replaced vacuum check valve . idle fine .but lights wont pop up. any thoughts.

[Mike S.]

Re: 71 454 vacuum check valve

I reinstalled old vacuum ck valve lights pop up .but rough idle.

[Joe L.]

Re: 71 454 vacuum check valve

Mike-----

I'd guess that the new vacuum check valve is defective. It's preventing any vacuum leak (that's why the idle smoothed out), but it's not allowing any vacuum to build in the tank or the vacuum system (that's why the lights won't come up).

[Mike S.]

Re: 71 454 vacuum check valve

its an after market check valve.is there oem still offered?is there any in the check valve to keep the vacuum from afecting the engine?thanks

[Joe L.]

Re: 71 454 vacuum check valve

Mike----

The GM check valve is discontinued. The check valve simply prevents the leak back of vacuum from the resevoir tank after engine shut-down. If it leaks, though, it can cause a vacuum leak during engine operation and, thus, a rough idle.

[Mike S.]

Re: THANKS Joe *NM*

[Mike S.]

Re:joe ZL1

Joe hows your ZL1 coming.Mike

[Joe L.]

Re:joe ZL1

Mike-----

I'm hoping to finish the engine "tomorrow". "Tomorrow" is the absolute best time to finish any project.

[Mike S.]

Re:joe ZL1

should be nice ride. hope everything turns out well for you.thanks for all the info.mike

[Patrick H.]

Re: 71 454 vacuum check valve

Mike,

I believe there is more than one company is reproducing the check valve. At one point one of them was allegedly advertised as "more correct" in internal construction. I can't verify that is was or was not.

Patrick

[Mark #28455]

check valve backwards?

Is it possible you installed the valve backwards? Try to suck air through the original and the repro. If it's backwards, it won't leak but the headlights won't work either. Did you visually check the vacuum reservoir? Over time, they commonly crack in the reinforcing grooves on both sides. If you want a cheaper fix than replacing, you can braze the cracks and it'll probably last another 20 years.

Good luck,
Mark

[Mike S.]

Re: checkvalve

any one know of a good mfg for check valves.

[Jack H.]

Re: checkvalve

Chicago Corvette tends to specialize in carb parts that that aren't available elsewhere (Holley, Carter, & QJet). You might check there before concluding this/that can't be found....

[Dick W.]

Re: checkvalve

Most of the vendors carry them. They were originally made by Trico for GM but never available thru the Trico distribution system to retail customers.

[Mike S.]

Re: thanks guys *NM*