Low manifold vacuum 1929 essex

supersixersupersixer Posts: 39Member
in Essex Super 6
I have a 29 Essex when idling manifold vacuum is low 5 in hg  should be 20 in hg will only idle with choke 3/4 closed will stall if throttle is opened even a little, check timing chain and it was not loose riser has been replaced carb is rebuilt, vacuum fuel tank was rebuilt and tested but when vacuum supply to tank disconnected and a vacuum gauge is installed it only showed 5 in hg of vacuum which made me think chain had jumped, but when timing cover was removed chain looked good and was not loose. There are no external vacuum leaks that I can find and after all parts changed and rebuilt the engine still runs the same no improvement at all. So I am wondering if there could be a crack or a hole between the intake and exhaust passages, but since they share the same casting which is part of the engine block. It would be hard to see. Has anyone heard of this happening to this type of engine? I must say before I purchased the car it drove and sounded great but you had to fill the vacuum tank with fuel because the vacuum tank was inoperative, the vehicle went to a local shop ant they tried fitting engine with a electric fuel pump which the couldn’t get to work because of the pressure was too much. When the owner went to pick up the car it would no longer run like it did it would only idle with choke 3/4 closed. I then purchased the car figuring it couldn’t be nothing more than getting the carb and vacuum tank working again. But this has not been the case. Any help with this would be very appreciated. Thanks, Tony Silva 

Comments

  • GlowplugGlowplug Posts: 2,294Expert Adviser
    I have zero first hand knowledge of the Essex cars.  But, you might benefit from a review of the appropriate items applicable to you vehicle that are posted here. http://hudsonterraplane.com/tech/tech_index.htm
  • lostmindlostmind Posts: 1,442Expert Adviser
    Distributor timing retarded will cause  low vacuum. Exhaust in the intake is a possibility.
    Hard to know what the " shop" did , may not be able to get them to admit to any thing.
    Is it possible the ignition wires are crossed? Wrong cap or rotor?
    Exhaust plugged?
    Valves to tight?
    Wellington , Ohio
  • 29sptphaeton29sptphaeton Posts: 396Member
    If it has a Marvel heated intake manifold like 29 Hudson has your Venturi pipe inside the intake is burned out or rusted out. It’s just a sleeve that is pressed in. I had one made out of stainless for my 29 Hudson.
  • supersixersupersixer Posts: 39Member
    The Essex does not use that type of riser and I just replaced mine with a perfect condition replacement, I am really at wits end. after all the testing and checking I have done I’m down to two possibilities one being an air passage on the riser that goes to the carb which is unlikely the problem or one of the exhaust passages cracked or burned through to one of the intake passages. Also I did a compression test cylinders 1 2 3 4 show 110psi cyl 5 90psi cyl 6 60psi not sure what’s going on there either. Hope somebody can help with this problem would like to drive car some day. 
  • GeoffGeoff Posts: 4,424Senior Contributor
    To test for a leak, open the throttle wide, put your hand over the intake and wind the engine over on  the starter.  You should fell a your hand sucked in to the intake.  If not you have a leak somewhere. 
    If you're stuck in a hole, stop digging.
  • supersixersupersixer Posts: 39Member
    Geoff Have you ever heard or seen the exhaust passage burning or cracking through to the intake passages on these motors?
  • HansHans Posts: 215Senior Contributor
    Yes, and another friend had in too.
    Cricket
  • lostmindlostmind Posts: 1,442Expert Adviser
    supersixer said:
    The Essex does not use that type of riser and I just replaced mine with a perfect condition replacement, I am really at wits end. after all the testing and checking I have done I’m down to two possibilities one being an air passage on the riser that goes to the carb which is unlikely the problem or one of the exhaust passages cracked or burned through to one of the intake passages. Also I did a compression test cylinders 1 2 3 4 show 110psi cyl 5 90psi cyl 6 60psi not sure what’s going on there either. Hope somebody can help with this problem would like to drive car some day. 
    Check The valve clearance on number 6?
    Wellington , Ohio
  • supersixersupersixer Posts: 39Member
    Hans were they able to repair the motor or was the block junk?
  • supersixersupersixer Posts: 39Member
    Check the valve clearance on cyl #6 the clearance was good same with cyl #5 I removed carb off the riser installed a plug on riser at vacuum port then placed my hand over intake port on riser reached over and pulled lever on starter and I felt what seemed like a good amount of suction. I did not hear any vacuum leaks while I was doing this. If I connect my vacuum gauge to the vacuum port for vac fuel pump and cover riser, if I get a high vacuum reading would that confirm that I do not have a breach between my intake and exhaust passages? I was going to remove exhaust manifold and look inside the ports to see if there were any cracks or holes, but I am having a problem with un screwing the pipe flange at the manifold. I still might like to get in there and look with a borescope.   
  • HansHans Posts: 215Senior Contributor
    My first thought is the Cam timing is incorrect, proper position of cam to crank position.


  • supersixersupersixer Posts: 39Member
    Hans I still have the timing cover off. I have 20 pins between marks on sprockets and points pointing at #6 just starting to break. I believe that is correct. I went by the shop manual in the library and Geoff confirmed it also, I am about to put cover back on. Chain was to tight to jump a tooth. 
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