Vacuum? Options

[chrispovoas]

Hi fellas, ok next cab off the rank!

Had my injecturs refurbed, so thanks for those who gave some great advice..

Now the fueling is good, its time for the AIR!... Can i get your advice on how you setup the following?

- All hoses attached but when i put my hand over the airbox intake the motor doesnt stall.. (Assuming no air leaks and the only place air is sucked in is through the airbox)

- The air screw valve on the side of the air intake plenum i have set to one full rotation. (closed completey then 180 degree turn open)

- The air seems to be sucking in from around the air plenum/airbox seal (which doesnt seem to be very tight).. Do you guys just put up with it or is there a fix for a better seal?

[emerygt350]

That seal needs to be in the air box, not on the throttle body. It will be a tight fit in the air box, there should be no leaks there when done correctly. You have it upside down I believe.

[chrispovoas]

That seal needs to be in the air box, not on the throttle body. It will be a tight fit in the air box, there should be no leaks there when done correctly. You have it upside down I believe.

ahhh... i see.. This was how the car was when i purchased it 4 months ago. Yes, the airbox just loosely sits on that seal so the air gets sucked in form all around the seal. I'll have a look for some pics on the net, see how it should be.

Thanks for that!

[SirAndy]

Also worth checking, the metal plenum tends to crack around the passages for the mounting through bolts, especially on the underside of the plenum, which creates another possible air leak.
(IMG:style_emoticons/default/idea.gif)

[SirAndy]

Also worth checking, the metal plenum tends to crack around the passages for the mounting through bolts, especially on the underside of the plenum, which creates another possible air leak.
(IMG:style_emoticons/default/idea.gif)

http://www.914world.com/bbs2/index.php?s=&...st&p=589370

17 years ago
(IMG:style_emoticons/default/unsure.gif)

[r_towle]

Here is a methodical way to find the leaks without using a smoke machine.

Remove and inspect your intake plenum, as Andy shows above.
If it’s good, use electrical tape and close off all ports on the plenum except the one for the MPS

Start car with just the MPs attached.
If it’s good and idles properly, you must find which 45 year old part or subsystem needs replacing.

Distributor has a vacuum diaphragm
AAR valve corrode internally and get stuck wide open
All vacuum line s are a look so suspect
Decel valve has a diaphragm

I install one system at a time onto the plenum, start car…see if bad behavior returns.

A few hours of testing and you will KNOW each system on the car that uses vacuum.

[porschetub]

Also worth checking, the metal plenum tends to crack around the passages for the mounting through bolts, especially on the underside of the plenum, which creates another possible air leak.
(IMG:style_emoticons/default/idea.gif)

(IMG:style_emoticons/default/agree.gif) best to do the same test with aircleaner off if it doesn't stall straight off it will be a cracked plenum or bad gasket which would be a better result for you .
Not trying to be critical but your engine bay looks somewhat unloved ,might pay to check all the hoses to and from and have a clean up in there,you will surprised what you find.
Good luck,cheers.

[chrispovoas]

Also worth checking, the metal plenum tends to crack around the passages for the mounting through bolts, especially on the underside of the plenum, which creates another possible air leak.
(IMG:style_emoticons/default/idea.gif)

Cheers, will take a look!

[chrispovoas]

Here is a methodical way to find the leaks without using a smoke machine.

Remove and inspect your intake plenum, as Andy shows above.
If it’s good, use electrical tape and close off all ports on the plenum except the one for the MPS

Start car with just the MPs attached.
If it’s good and idles properly, you must find which 45 year old part or subsystem needs replacing.

Distributor has a vacuum diaphragm
AAR valve corrode internally and get stuck wide open
All vacuum line s are a look so suspect
Decel valve has a diaphragm

I install one system at a time onto the plenum, start car…see if bad behavior returns.

A few hours of testing and you will KNOW each system on the car that uses vacuum.

Cheers!, yeah, ive replaced the AA Valve, and checked the hoses, now looking for the all ellusive leak!

[chrispovoas]

Also worth checking, the metal plenum tends to crack around the passages for the mounting through bolts, especially on the underside of the plenum, which creates another possible air leak.
(IMG:style_emoticons/default/idea.gif)

(IMG:style_emoticons/default/agree.gif) best to do the same test with aircleaner off if it doesn't stall straight off it will be a cracked plenum or bad gasket which would be a better result for you .
Not trying to be critical but your engine bay looks somewhat unloved ,might pay to check all the hoses to and from and have a clean up in there,you will surprised what you find.
Good luck,cheers.

Yes, it was un-loved and stored on a hoist for 9 years... Didnt have the drip tray on it either so suspect it was run without that, contributing to the enginr condition. After i fix the air leak, then a good engine scrub is in order as I've only had it or a few months..