Emissions Systems
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Nearly all of this can be tested with one of those hand vacuum pumps, or if you're not concerned about precision, just a piece of vacuum hose and the will to suck. You can also just tap manifold vacuum if you don't desire to suck.
Vacuum advance: Remove the vacuum advance hose from the distributor. Put your vacuum hose on it. Start the engine. Draw about 10"hg or or more and listen to the sound of the idle speed up. If you have a timing light, the timing will show the advance.
EGR: Pull the vacuum hose off the EGR. Apply your own vacuum. If the idle faulters (it may even kill the engine) you know the EGR is functional.
AIR pump can be tested with a vacuum/pressure gauge. It should show about 2psi at 2k rpm. But if it weren't working, it would be making some horrible noises since it's a vane pump.
Evap canister is easy. If you smell gas when you park the car, it ain't workin'. It has only one moving part and that's a checkvalve where the large hose goes in. The only other part is a filter on the bottom that needs to be periodicially replaced.
Vacuum advance: Remove the vacuum advance hose from the distributor. Put your vacuum hose on it. Start the engine. Draw about 10"hg or or more and listen to the sound of the idle speed up. If you have a timing light, the timing will show the advance.
EGR: Pull the vacuum hose off the EGR. Apply your own vacuum. If the idle faulters (it may even kill the engine) you know the EGR is functional.
AIR pump can be tested with a vacuum/pressure gauge. It should show about 2psi at 2k rpm. But if it weren't working, it would be making some horrible noises since it's a vane pump.
Evap canister is easy. If you smell gas when you park the car, it ain't workin'. It has only one moving part and that's a checkvalve where the large hose goes in. The only other part is a filter on the bottom that needs to be periodicially replaced.
Intermediate
Joined: Oct 2016
Posts: 30
Likes: 0
From: Sea Girt NJ
emission lines
I did see that diagram on a 75' and unfortunately its different. (no vacuum and time delay solenoid)
Thanks!
-Ray
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Intermediate
Joined: Oct 2016
Posts: 30
Likes: 0
From: Sea Girt NJ
73 manuals
that carb appears to be wrong for a holley
I have both the service manual and there is nothing on vacuum routing
I have the assembly manual that has a really poor illustration (I can't believe someone could have followed it in the factory)
Intermediate
Joined: Oct 2016
Posts: 30
Likes: 0
From: Sea Girt NJ
Up until a few hours ago I bragged that I had a "numbers matching" 73 Vette. I forgot that I should have a Rochester carb. geez that's why the vacuum lines look different!
the car runs great I was just documenting all the cars' details just in case I develop an issue.
Thanks,
-Ray
the car runs great I was just documenting all the cars' details just in case I develop an issue.
Thanks,
-Ray
