Vortec intake and gasket to Vortec head alignment.

Discussion in 'Engine Topic' started by jeff swisher, Apr 28, 2018.

  1. jeff swisher

    jeff swisher Veteran Member

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    I always check things and I am new to these Vortec heads. I have some 906 heads.

    But i am not new to porting or getting things to line up.

    These aftermarket intakes pose an issue.
    At least the one I got. It is a Jegs dual plane.
    This will be a long read but bear with me I have pictures to explain things and show you how to get it right.
    I have a feeling the misalignment may not only be this intake but others and this could be the issue many have with failed intake gaskets.

    First issue are the holes that bolt the intake to the head they are .473" diameter.
    The bolt is .310" diameter.
    I can move the intake back and forth on the heads .160".
    That throws off the intake port alignment.

    gasket match 906 004.JPG gasket match 906 005.JPG

    Those are pictures of where the gasket will ride with the intake all the way back against the intake bolts and all the way forward against the intake bolts.

    You ask HHHMMM Does the distributor care where the intake is at.
    Not on this intake ..as the hole is larger than the factory GM iron intake hole and the distributors are much smaller where they go into the hole.

    You get that overhang on the beaded gaskets and you will for sure get a leak eventually.

    Now if I split the difference the intake lines up to the ports just fine.

    How do I know what the difference line is when plopping the intake down onto the heads.
    Good question as the intake gaskets can move on the head also and how would you know.

    I trim the gasket so it is flush with the front of the head and this is my reference point so i know the gaskets are lined up with the ports on the head.
    A picture for you.
    Notice the arrow pointing at the trimmed area.. that spot is flush.

    Now if your gasket did not hang over or is short of the end .. you could scribe a line on the head.

    gasket match 906 003.JPG


    Now placing the gasket onto the head and the intake onto that and keeping it all lined up.
    I took a sharpened pencil and drew a mark on the gasket as to where it all rests at when snugged up.
    gasket match 906 006.JPG

    Now I unbolt and flip my intake onto the bench and line up the gasket to the drawn line from the pencil.
    Perfect alignment.
    gasket match 906 007.JPG

    Yep you notice the area I could port larger.
    But that is another story and I will not port here just yet.

    Hope this sheds light on some failed intake gasket issues.
    Or could be this intake is just drilled too large in the mounting bolt area..I have not measured any other Vortec carbed intakes.

    But the larger holes are actually a good thought as you have no idea how much milling a guys block and heads have had. I have taken .060 off the heads and .025" off a block and ran the .015 head gasket and a stock intake was never going to bolt on until I elongated the holes or drill them larger.
    Still up to the installer to line it all up.
     
  2. Chevyforever

    Chevyforever Veteran Member

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    It looks like you are using a Fel Pro gasket. Can you confirm the part number please ? In the picture it looks like 1255.
     
    Last edited: Apr 28, 2018
  3. jeff swisher

    jeff swisher Veteran Member

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    Yes a 1255 gasket is being used. These are quite thick and everything lines up very well with them.
    These heads are Virgin never been surfaced except what GM did to them. The block has been decked about .033" and I am using .039" head gaskets.

    I did notice the bottom of these Vortec runners are higher than old style heads by .030"
    and you know the top is higher.
    The cross section in the runner measuring 1.7" into the runner is actually no larger than my 601 casting 305HO.
    Seems they just opened up at the beginning of the runner.
    1.75 tall give or take a little and .950" wide.

    The jegs intake measures over 1" wide and 2" tall all the way through the runner Plenty of intake runner size if you ask me.

    Just numbers to chew on.
     
  4. Green hornet

    Green hornet Veteran Member

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    if I remember correctly I used a different Fel Pro gasket. It is a hard plastic with a soft seal around the intake runners where the intake and head line up. The gasket has two small pins on it that go into holes in the head to locate the gasket in place and line everything up. Look at FelPro gasket MS 90131.
     
    Last edited: Apr 29, 2018
  5. Damon

    Damon Veteran Member

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    Agreed with above, I would NEVER use a "crush style" (composite) gasket with Vortec heads/intake. Get the kind that's a plastic skeleton with the o-rings around the ports. I use latest-generation GM stuff because it fits and works. They even have the little alignment pins on them so they can't squirm around as you're dropping the intake on.

    A lot of the problems you hear about them is for previous generations of the gasket. More of the problems are due to over-tightening (screwdriver tight is all they need or want). A tiny percentage that's left over is the fault of the gasket itself.
     
    Last edited: Apr 30, 2018
  6. jeff swisher

    jeff swisher Veteran Member

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    I will run these for now and see how they work out.
    To make you really cringe i almost want to drill the heads for early style and run my tunnel-ram with 2 fours.
    I will lay the intake on the heads and see if the runners are tall enough to seal first of course.

    But it is bolted on my 327" in my truck right now.
     
  7. larrylarry

    larrylarry Veteran Member

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    87714819-97E7-4565-8D42-D961E558ED55.jpeg I use that same gasket, 1255 because it’s made to be trimmed up. My 062’s are ported but most of the porting is in the bowl & short side turns & pinch’s. Didn’t do much to the port opening, a little but not much. I have to trim the gaskets or they’ll overhang into the port opening. I do glue (sealer)the gaskets onto the heads then lay the intake on them until it’s dry. Take the intake off an use sealer around the coolant ports. One thing is you’ll have to check the intake bolts often because they’ll loosen up!!! Some of the bolt holes go into the water jacket, use a sealer on the threads. I’ve never had a water leak into the valley.
     
    Last edited: May 1, 2018
    1980RS and jeff swisher like this.
  8. 1980RS

    1980RS Veteran Member

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    Like you little heat plate under the Eddy carb.
     
  9. larrylarry

    larrylarry Veteran Member

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    Thanks. I was bord an made one. The carb still gets warmer than I'd like it to. I'll refine it later.
     
  10. woody80z28

    woody80z28 Veteran Member Lifetime Gold Member

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    Felpro MS98000T metal gaskets with vulcanized rubber ports. Never had a failure since I started using them. I had the paper and plastic ones crap out before them.

    I actually did notice 6 of the 8 bolts had loosened up on my DD truck recently, not even finger tight, but the gaskets didn't leak. I was impressed.
     
    jeff swisher likes this.

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