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350 TBI HEAD GASKET

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by rh88k5, Mar 7, 2003.

  1. rh88k5

    rh88k5 Registered Member

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    Ok, I'm new to tbi, aside from the extras its the same as "carbed" head gasket replacement right? just mark everything and put it back, no hidden dangers right?
     
  2. 4DiggerDan

    4DiggerDan 1/2 ton status

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    No, its pretty straight forward. DO NOT put the steel (AKA early style) head gaskets on any 350 built after 78 or so. Use only the "composition" style. Lots of guys like to run the steel gaskets to make up for some of GM's deficiencies in quench height and get a little more compression out of their motor. If you stay with like a Fel-Pro or something, you'll be okay.

    You might want to take those heads down and have them milled when you've got them off the truck too (if there's a machine shop open in your neighborhood on Saturdays) The factory finish on TBI heads pretty much sucks... Shops charge between 20-50 bucks a head to flat mill. Ask the guy what he uses to surface cast iron heads. If he says "A belt sander..." Run like hell. Lots of guys still use stones to surface cast iron, which works fine. I use CBN (Cubic Boron Nitride) in .500" pucks in a Berco head on a Peterson machine. It turns the spindle like 12,000 RPM and gives a super nice finish. The advantage to CBN over stones is that CBN doesn't require that you douse the head with honing oil (you run it DRY...) I've been expiramenting with ceramic bits too lately. They give a nice finish too, except the bit dulls up about every 5 passes, so you have to shut everything down and rotate the bit 1/16th turn for the last (or finish) pass every head. The advantage is that Ceramic is 8.50 a bit and CBN is 286 a bit (although CBN can be resharpened 5 or 6 times if you don't try and surface a 7.3 Furd diesel heads with the pre-cups still in.) Ceramic, once both sides of the puck are dull, you throw in the garbage...

    Come to think of it, you should have those TBI's Magna-fluxed too. They don't like getting hot... If you haven't overheated them, you should be okay. I'm assuming that you have... Thats usually what gets TBI head gaskets. That or detonation. If they've been detonated on, look at all the intake valve heads and make sure none of them look like they're pulling up into the head (lots of times looking down all the stems and seeing if they're more or less in a straight line will indicate this too.)

    Any more questions feel free to e-mail me or send me a PM.
     
  3. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    I changed my headgaskets on my 88' tbi blazer about 6 months ago. And if I were you I would definitely get the heads machined. Because now mine seem to be leaking again. I'm putting on brand new vortec heads on this summer so it's not the big of a deal. The only real problem we ran into was not setting the engine to TDC before we pulled out the distributor and the rocker arms and pushrods. When we were putting everything back together, I ended up tightening down my rocker arms in the wrong order (I was 180 degrees off) and when I went to start it, fire shot out the throttle body. Not to mention I probably damaged my pushrods as well. And if you are reusing your stock exhasut manifolds I would go to Carquest and by an "exhuast manifold spreader" otherwise you will have a hard time getting your bolts back in. Other than that, it was pretty straightforward. It shouldn't take you much longer than a Saturday or a weekend to finish. Good luck.
     
  4. smack

    smack 1/2 ton status

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    [ QUOTE ]
    And if you are reusing your stock exhasut manifolds I would go to Carquest and by an "exhuast manifold spreader" otherwise you will have a hard time getting your bolts back in.

    [/ QUOTE ]
    I'll second and third that one, this little tool is WELL worth it's weight, believe me, I pryed and pryed and nothing I did work until I went down and got the tool and it worked perfectly. Do it. Do it now..!!
    smack
     
  5. rh88k5

    rh88k5 Registered Member

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    Spreader tool? Carquest? No Carquest around here, can I get more info on the tool?
     
  6. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    I found out about the spreader through CK5, and I was told that Carquest was the only people who sold it. I called the local Autozone and they had no clue what I was talking about. Maybe try O'reilly or Advance Autoparts. Basically it's a hex-head sleeve with 2 threaded bolts coming out both sides each with a groove to fit between one of the 2 spaces in the manifold. But if you have the money, do what everyone and their momma on CK5 told me: "Go buy some headers if you can afford it" which is what I eventually did anyway. If I were you, I would just start taking everything apart and hope that the exhaust manifolds don't spread on you. And if they do, then go searching for a spreader or some headers. The only one I had problems with was the passenger side manifold, the driver side bolted right in to place without any problems. I think if you do the whole thing quickly you'll have less of a chance of them spreading. My manifolds sat in an open carport in Louisiana's 100% humidity for about 2 weeks, so that may have contributed to the problem. Anyway, good luck.

    Matt
     
  7. BigRed89

    BigRed89 1/2 ton status

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    I bought my exhaust manifold spreader from Snap-On. It cost somewhere in the neighborhood of $15-$20. I definitely would not try installing the exhaust manifolds again without the spreader. Fortunately I have headers now so I don't have to worry about it.
     

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