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Vortec head swap

Discussion in 'The Garage' started by dammit32, Feb 1, 2004.

  1. dammit32

    dammit32 1/2 ton status

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    Has anyone done this? Is there anything trick about the swap?
     
  2. TJS

    TJS 1/2 ton status

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    I did it. Note: Do not use the GM headgaskets they are .022". Use the Fel-pro ones that are .040" Ask me how I know. I have to change mine over. The compression is high already, and I made it worse by using the GM H/D. Make sure you get the rail type rockers as well. I got roller ones on e-bay. Also make sure you use a good size bead of RTV on the intake end rails. Ask me how I know again.
    T.J.
    www.tjsperformance.com
     
  3. Confedneck

    Confedneck 3/4 ton status

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    what about drilling the heads?? ive heard this is necessary? someone needs to do a good, complete write up for the rest of us who are scared to just jump into it on our DD's.. /forums/images/graemlins/waytogo.gif
     
  4. Stroked72Blazer

    Stroked72Blazer 1/2 ton status

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    [ QUOTE ]
    Also make sure you use a good size bead of RTV on the intake end rails. Ask me how I know again.


    [/ QUOTE ]

    Did you use the Vortec intake?

    You can get everything you need to do this swap except the center bolt valve covers in a kit from www.sdpc2000.com for around $900. You can also get the valve covers there by themselves. I agree with TJS about the head gasket depending on the setup you start with. Vortec heads are 64cc heads and a stock vortec motor is 9.5:1ish. If you have 72cc heads and are less than 8.75:1 you shouldn't have a problem with the GM gaskets but if you are higher than that and you get the kit from Scoggin Dickey ask if they can send it with the Fel-Pro gaskets instead of the GM. If you have a factory motor and are not sure of the head volume than check your casting # here www.mortec.com.
     
  5. heavy4x4

    heavy4x4 1/2 ton status

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    Drilling the heads would only be necessary if you wanted to keep your current intake (not a good idea). GM changed the design of the head-to-intake bolt pattern on the vortecs; there are 4 bolts per side that go in at a different angle than the tbi/carb intakes. GM makes intakes that work with the vortec heads but they are about $300 for a TBI version and $180 (?) for a carb version. A lot of guys that do the swap with a TBI use a carb intake and an adapter that bolts their 3 bolt TBI to a 4 bolt carb pattern.

    Another thing to note: you need to mess with the exhaust crossover. There's something different about the heads/intake. You have to drill your exhaust manifold and attach a tube that connects up to a hole in the intake.

    So, other than the intake issue and the exhaust crossover, it's pretty much a "bolt-on" swap and will get you around 40hp.
     
  6. Confedneck

    Confedneck 3/4 ton status

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    right now im trying to decide on tbi or quadrajet, and if i can make the qjet work with the vortec heads, i would, but will the headers i have for my regular heads work on a vortec set of heads?
     
  7. Stroked72Blazer

    Stroked72Blazer 1/2 ton status

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    You don't need to drill the heads. Some people try to drill a non vortec intake out to accept the intake bolts that go in streight up and down not angled like the conventional heads. This does not work. Yes you can get everything to seal up, but, your intake runners and head runners will not line up correctly. It is close enough to run but it does not allow you to get the full potential out of your heads. GM and Edelbrock both make square bore and spread bore intakes for the vortec heads.
     
  8. heavy4x4

    heavy4x4 1/2 ton status

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    [ QUOTE ]
    right now im trying to decide on tbi or quadrajet, and if i can make the qjet work with the vortec heads, i would, but will the headers i have for my regular heads work on a vortec set of heads?

    [/ QUOTE ]

    Headers you have now will bolt up. The exhaust bolt-pattern and style didn't change.
     
  9. Stroked72Blazer

    Stroked72Blazer 1/2 ton status

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    [ QUOTE ]
    but will the headers i have for my regular heads work on a vortec set of heads?

    [/ QUOTE ]

    Yes
    The exhaust crosover is not nesscesary unles it is an emisions issue. Arkansas is very lenient on emisions so I used the Scoggin Dickey kit and the headers that were on the old motor. If you use the proper intake it will take care of the crossover. I am also using a Q-jet. The only complaint I have about the setup I have is the ass at PAW told me the pistons I bought would yeild 10:1 compresion but when I got the specks for the pistons they figure to be 10.78:1. I guess he was figuring the CR on a 350 not a 383
     
  10. Confedneck

    Confedneck 3/4 ton status

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    so whats that exhaust crossover you are talking about?? drilling my headers?
     
  11. heavy4x4

    heavy4x4 1/2 ton status

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    In order to get the emissions stuff set up right, you need to connect your header to your intake (as weird as that may sound). You can buy all the parts necessary from www.sdpc2000.com I believe. It involves drilling your header, welding in a bung, threading in the crossover tube and then screwing that into the threaded hole up in the intake next to the distributor.

    Maybe someone could dig up a pic to show you what I'm talking about.
    Oh, and that setup is the same as you'll find on vortec trucks ('96-later).
     
  12. bowtiepower00

    bowtiepower00 1/2 ton status

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    For the x-over, you can also use a manifold or header out of a vortec truck, to avoid drilling, etc. I'm not sure if the manifolds dump in the same place though...
     
  13. heavy4x4

    heavy4x4 1/2 ton status

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    [ QUOTE ]
    For the x-over, you can also use a manifold or header out of a vortec truck, to avoid drilling, etc

    [/ QUOTE ]

    True. But, he said he's got headers he wants to use...that's why I said he'd have to drill and weld in a bung.
     
  14. beater_k20

    beater_k20 Banned

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    [ QUOTE ]
    I did it. Note: Do not use the GM headgaskets they are .022". Use the Fel-pro ones that are .040"

    [/ QUOTE ]

    that all depends on your engine. if you have a stock engine, that has never been decked the GM head gasket will be almost perfect. it will give you a .047" quench distance (ideally you want .035-.045") Using the Fel Pro .040" gasket with a stock deck height will likely cause the engine to be more prone to detonation, because of the .065" quench distance. if however you have the block decked from the factory 9.025" down to 9.000" and use the .040" gasket, quench distance would be ideal.
     
  15. ntaj*ep

    ntaj*ep 1/2 ton status

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    The small stuff will kill you. V'covers, spark plugs, choke on the carb, and rockers are all diffrent. I used some "higher" performance parts and the swap cost me about 1200 by the time start up came.
    I would also recommend a search on this topic.
     
  16. beater_k20

    beater_k20 Banned

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    [ QUOTE ]
    The small stuff will kill you. V'covers, spark plugs, choke on the carb, and rockers are all diffrent.

    [/ QUOTE ]

    kill you? i highly doubt that. the valve covers are the same as any 87+ small block, the spark plugs are not different than any other small block (stock plugs are platinum, but same size as anything else), rockers can be had for $40 a set through Scoggin Dickey, anbd converting to an electric choke shouldnt cost you anymore than $40.
     
  17. 73K5Kid

    73K5Kid 1/2 ton status

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  18. jms

    jms 1/2 ton status Author

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    [ QUOTE ]
    so whats that exhaust crossover you are talking about?? drilling my headers?

    [/ QUOTE ]

    Vortec heads have no exhaust crossover passage. On my '85, there were two emissions devices related to exhaust x-over:
    1. EFE. When engine is cold, vacuum off on an intake-mounted temp switch closes a valve in the passenger side exhaust collector, forcing the exhaust gases thru the intake passage (EGR valve closed) over to the driver's side exhaust in order to warm up the intake.
    2. EGR. With engine at operating temp, under light load/cruise, exhaust gas from the x-over passage passes the EGR valve to get mixed into the intake charge to alter the combustion mix for emission/mileage purposes.
    The SDPC 2000 kit takes care of EGR but not EFE.
    Just a few info tidbits: Self-aligning rockers are no big $ deal unless you want rollers. I went with shiny aluminum valve covers on my motor, but you can't see them anyway because of all the vacuum/AIR/EGR lines, so I'd go with regular tin.
    Changing to Vortec heads made a huge improvement in driveability/throttle response, etc. Even mileage is better now. Motor runs at higher temp (205-210°F, head temp gauge) than before, requiring an upgrade to my used-up cooling system (old radiator with deposits => new aluminum rad). Carb (Q-jet) linkage bolts back on but angle is better with a 1" spacer.
     
  19. Stroked72Blazer

    Stroked72Blazer 1/2 ton status

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    The $900 I spent on this kit included the high performance springs, skrew in studs and guide plates, and rockers. If you are doing this to an older truck that didn't have the emision cross over from the factory then I doubt even California would require you to use it, but you beter check with the Florida authorities to be sure.
     
  20. TJS

    TJS 1/2 ton status

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    Beaterk20 yes I see your point. That is all on paper and using the volume formula in many of the books. However, with today's fuels I ping under a load cause my compression is too high with the timing set at 8 BTDC using 93 octane I still ping. The block is a undecked standard bore block with stock 4 eyebrow pistons. I do not feel like runnig 93 and still have to feather the gas all the time. So I either need to run a cam with more overlap or lower the compression a little. The cam I have is an RV cam and I cannot remember the specs right now and I do not want to go to a bigger cam so I am going to lower the compression a little by using the fel-pros. I love reading all these books with the formulas and stuff to, but that does not take into account of real world fuels and conditions as well.
    T.J.
    www.tjsperformance.com
     

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