Volkswagen valve train

Discussion in 'Volkswagen' started by mcmurphy, Mar 3, 2016.

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  1. Mar 3, 2016 #1

    mcmurphy

    mcmurphy

    mcmurphy

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    I was installing the valve train on my 1915cc today and ran into a situation that I am unsure of. My engine has a stock stroke crankshaft with over size bore for the larger displacement. I have used a .177 shim under the cylinders to get the correct compression ratio. I installed the push rods and rocker shaft assembly and adjusted the valves. At full lift the rocker is not quite level compared with the valve cover surface. When the valves are closed the rocker is on quite an angle and I am nut sure if that is within normal. The rockers have adjustable swivel balls with flat spots that push on the valve stem. According to the builders manual stock push rods (length wise) are usually used with this type of rocker. I guess I am just nervous about the rocker angle and wonder if this is within an acceptable range. The push rods I am using are 5/16 diameter and 11.06 length.
     
  2. Mar 3, 2016 #2

    TFF

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    Ideally the pushrod should be .177 longer. What you can get away with is different.
     
  3. Mar 3, 2016 #3

    StarJar

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    TFF has a good point, and that area on Dubs is not the most trouble free.
    At full open valve your crowfoot will be getting farther from the stem's center. Also more leverage is required when the rocker arm is not level.
    Those are not major issues, but worth considerring IMO.
    My experience is mostly from cars which I used to work in a vw rebuild factory.
     
    Last edited: Mar 3, 2016
  4. Mar 3, 2016 #4

    MikePousson

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    Pops likes this.
  5. Mar 3, 2016 #5

    StarJar

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    The thing is he would need to remove height, and I think shims can only add height.

    Sounds like his push rods are slightly longer than stock, so he's probably not the full .177" short. Probably like .10".

    Edit: I think MikePoussons link will be very helpful. The foot should hit slightly off center. That's probably the main thing anyway.
     
  6. Mar 3, 2016 #6

    Pops

    Pops

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    True-- With the ball type of adjustable rockers you have to use the shims that came with the rockers.
    Another thing---
    The Aero-Vee Manual states the end gap of the oil pump should be .000 to .004. I have measured about 8 oil pumps by putting a straight edge across the face and measuring the gap to the end of the gears, all of them measured .0005 gap. So with the stock oil pump cover gasket of .004 , that gives you to much gap. I made a new cover gasket of .002. So now the gap is .0025 instead of .0045. Raised the oil pressure 10 lbs. So instead of 32 lbs @ 2700 rpm, now I get 42 lbs at 2700. 20 lbs at hot idle.
    When the engine is hot the gears expand the .0005 and closes the gap to .000 so at flying temp the gap is .002 . Don't ask me how I know :)

    Dan
     
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  7. Mar 4, 2016 #7

    MikePousson

    MikePousson

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    double post
     
  8. Mar 4, 2016 #8

    MikePousson

    MikePousson

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    If the valves were cut to fit, you may need to go to a VW shop online (SCAT) and get the tool to set the correct length. All 8 rods should be the same length. The AeroVee manual explains how to get the correct length. Their engine kit comes with the tool. Great Plains probably sells just the tool.

    Here is the page at SCAT. Last item on the bottom.
    Scat VW - PUSH RODS
     

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