Ignorant small block head and intake questions

Discussion in 'Engine Performance + Maintenance' started by RichardWaller87, May 14, 2020.

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  1. RichardWaller87

    RichardWaller87 Newbie

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    I didn't realize there was that much difference in the tbi block and a vortec block. I can always use my original Vortec block. I just want to have some more power than factory and replace wore out parts. The other thing I had given a little thought about was putting in a carbureted small block. That way I could eliminate all of the wiring demons I have had with the hacked up factory harness.
     
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  2. Schurkey

    Schurkey I'm Awesome

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    Some Vortec and TBI blocks have the same casting numbers. They're almost identical. The only differences are the:
    1. Engine driven fuel pump provision (a few Vortec blocks have this, most don't, I don't know of any TBI blocks that have this, but maybe some do)
    2. Missing two bolts for the old-style timing cover. I drilled and tapped them for the engine I built. The bosses are there, they're just not machined.
    3. The old-style coolant bypass isn't used--and usually not drilled--on the Vortec, but it'll be there for the TBI engines.

    If there's other differences between Vortec and TBI blocks, I sure can't think of them.
     
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  3. Erik the Awful

    Erik the Awful I'm Awesome

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    This thread got me thinking, and sure enough, between all the switching between my Suburban and Stepside, I had the TBI water pump and no bypass hole in the heads. I nabbed a water pump at Pull-A-Part and switched it out this weekend. Here are some pics of the differences.

    The water pump on the left is the older-style internal bypass water pump. On the right is the Vortec non-bypass water pump.
    Note the two tubes at the top. The one on the left goes to your heater core. The one on the right goes to the heater hose outlet on your intake manifold.

    There's also some discussion about Vortec water pumps on TBI blocks, and this pic shows why. The old style pump on the left has a coolant port under the bolt hole on the passenger side, while the Vortec on the right does not. The port in the block is between sizes for a standard bolt thread, so I tapped mine metric and found a bolt that would thread in it. I cut the head off the bolt, put a slot in it for a flathead screwdriver, put some RTV on it, and threaded it in until it was flush.
     
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  4. evilunclegrimace

    evilunclegrimace Does not always play well with others

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    All of the early 4 bolt main blocks were drilled for the fuel pump push rod. You could tell by the block off plate that came on them. I do not know what year they stopped.
     
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  5. Schurkey

    Schurkey I'm Awesome

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    I have some Vortec and some TBI core engines. I don't know what vehicles they came from.

    The Vortec water pump and the TBI water pump have different spacing for the pulley; I don't think they interchange. Be careful when swapping water pumps, you might need to swap the entire accessory system to get proper belt alignment, and fan depth in the shroud.

    [​IMG]
     
  6. Erik the Awful

    Erik the Awful I'm Awesome

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