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Vortec Conversion question

Discussion in 'The Garage' started by Dunc03, Aug 25, 2002.

  1. Dunc03

    Dunc03 1/2 ton status

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    I'm swapping my tired 305 for GM's 330 HP 350. I got the old out and went to go back in with the new when I found out so dismaying news. I went to put the exhaust back on and the passenger side manifold wont hook up. The stupid thing is a half inch off or so, which is funny cause the driver side went on fine. Does anyone know where I can get one of these for a reasonable price. I found the driver side at scoggins dickey, but no passenger side. I would go back in with headers, but I don't have the money for the ones I want, and I need to get the thing running. Thanks for all the help.
     
  2. fr8train

    fr8train 1/2 ton status

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    I found that out too. If you get a set of headers it will work just fine. I picked up a set of cheapy dynomaxs for now.
     
  3. Batmanjr

    Batmanjr 1/2 ton status

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    Hey man, don't diss the dynos!!! They work great and are lifetime warrenty!!!! /forums/images/icons/cool.gif
     
  4. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Haha, welcome to cast iron manifolds! /forums/images/icons/laugh.gif Every damn motor I've swamped with those no good POS don't line up. The problem is that they get super hot fast and cool off relatively quickly too. All of this expanision and contraction causes them to warp. GM used to make some that had a bar running in between to insure that this didn't happen. Some design genius decided to do away with that feature (yes, they had stupid designer even then).

    Anyways, you'll need to get some tool-time tim taylor tools to make them work. They have a hydraulic tool called a porta-power that works well. It comes with a spreader stlye attachment that does the trick. Get some bolts in the manifold and use it to spread open the manifold to get the distance you want.

    Or....buy some headers and header bolts and be done with it.
     
  5. Blazer1970

    Blazer1970 1/2 ton status

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    To make sure that this is clear, there is no difference in the heads. Vortecs have the same ports and bolt pattern for the exhaust manifolds as any other small block head. The manifold is warped, and you would have to use a spreader to get it bolted on any head.
     
  6. ftn96

    ftn96 1/2 ton status

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    You may or may not be correct on that issue. But everyone I have ever talked to said that the stock manifolds will not fit on Vortec heads. You must either get headers or purchase some stock vortec manifolds. You can get a set of headers for what you'll pay for one side of the stock vortec manifolds if you were to buy them new from the dealer.
     
  7. Blazer1970

    Blazer1970 1/2 ton status

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    I am 100% absolutely sure of what I posted two posts up.
     
  8. Derf00

    Derf00 1/2 ton status

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    I will second the fact that Vortec heads have the same exhaust port & bolt pattern. I recently installed a 383 w/Vortec heads and the headers bolted up fine. The headers were purchased for a 350 for a '90 Jimmy/Blazer which, as you know was a non-Vortec engine. /forums/images/icons/grin.gif
     
  9. ftn96

    ftn96 1/2 ton status

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    Like I said. YOu have to go to "headers" or a stock "vortec" manifold set to do the swap. RE-read the post if you must. /forums/images/icons/wink.gif
     
  10. ftn96

    ftn96 1/2 ton status

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    Derf...Speaking of 383's and Vortec's. What was it that you did about the compression and those 64 CC heads? Did you use a overlap cam to lower it? Also, what about the TBI? Did you keep it or go carb? I haven't been able to find a definative answer on a good solution for the 350 TBI on top a 383. I know you can go with chips and such from Turbo City but have also read even 4 wheeler mag and Hot Rod mag couldn't find a good setup for this combo or at least one that allowed the combo to perform at or close to its optimal possibilities.
     
  11. Blazer1970

    Blazer1970 1/2 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    YOu have to go to "headers" or a stock "vortec" manifold set to do the swap

    [/ QUOTE ]

    No, you do not. The old manifolds will fit. Any small block exhaust manifold will fit on Vortec heads. The intakes are different. Exhaust is the same. As an example, I have Vortec heads on my '70 Blazer with the original exhaust manifolds. They fit perfect, no issues whatsoever.
     
  12. Derf00

    Derf00 1/2 ton status

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    Brandon,

    The issues with the 383 you spoke of almost made me back out of the deal before having the engine built, but very glad I didn't. The cam is one for a LT1, mild by most respects, but is computer friendly. I went with the Edlebrock MPFI which uses the body of the TBI, but not the injectors.

    I used a reputable engine builder, http://www.sunsetracecraft.com/main.htm and trusted what said. All of these guys previously worked for Scoggins&amp; Dickey and know what they are talking about. They told me that the engine would run with the stock chip(which it did) and would run with the TBI(body only) off of the 350. Every chip maker, programmer told me that this combination would not run without a custom chip, and Howell said not only would it not run without a custom chip, it wouldn't run without changing the TBI to one from a 454. As far as I am concerned, they are all wrong.

    It did run on the stock chip; however, after the inital start-up and a short trip around the block, we waited for the chip that Edlebrock supplied us. After installing the Edlebrock chip everything has worked great.

    I know there will be those that say a more "custom," chip and the bigger TBI may produce better results, and I won't argue that point, but at the present time with about 1500 mi on it, the engine is running perfectly, is smog legal, is producing 11-12mpg, and full throttle will roast the 37's.
     
  13. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    I'll give it the third. I put a 355 vortec in my shortbox and was using the crappy old 1983 305 manifolds but changed my mind. I used the stainless tube manifolds that used to come on motor homes and heavy duty trucks in the 80's instead..
     
  14. Dunc03

    Dunc03 1/2 ton status

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    The manifold is not warped in any shape, form, or fashion. IT just doesn't hook up becaus the pattern on the passenger side on mine is different from the one on the driver side. I bought universal gaskets, and they even have a place that would accomidate for the two different styles. Whatever the reason, it doesn't fit much to my dismay. Thanks for all the post and the interesting discussion. I probably have a odd ball year. It is a 86 and that's the rear they went to the rear main seal, so maybethat is why the stupid thing doesn't fit. Oh well looks like cheap headers in my future for now.
     
  15. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    I assure you, they are the same! Just about any generation I SBC manifold from 1955-99 will bolt up to the head. Engine compartment clearance may dictate otherwise though. In 1975 they came out with a 7th exhaust bolt on the head because of a change in the passenger side manifolds on certain vehicles. The 7th bolt is the reason for the additional slot on two of your manifold gaskets. Some heads still didn't have the bolt hole, but the boss was still there and could be drilled for it. That is beside the fact because the vortec heads have the 7 bolts. I have had to install manifolds that were off by a 1/2". Now that took some effort and a half, but I got it. Compare to your old heads if you would like. Good luck, you'll get it to work if you want it bad enough. I would buy some nice headers and not have to worry about the cheapies crapping out.
     
  16. Blazer1970

    Blazer1970 1/2 ton status

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    Yes, your manifold is warped. I have been through this discussion before with someone who swore that the bolt pattern is different. There are no oddball years.
     
  17. ftn96

    ftn96 1/2 ton status

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    Ok, I'll take your word for it. /forums/images/icons/blush.gif But I would like to know then why is ti that Scoggins and Pace parts both tell the exact same thing I was saying? Other than the given of trying to get us to buy more stuff. Of course, I have questioned this before, "Why would stock replacement headers fit but not stock manifolds?" So I have no problems taking your word on this, but now I seem to have created another issue.... /forums/images/icons/tongue.gif /forums/images/icons/grin.gif
     
  18. Blazer1970

    Blazer1970 1/2 ton status

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    I have noticed that Pace's description was not exactly clear when they say that you need a different manifold, they are referring to the intake. Not sure about S-D. The only other possible effect on the exhaust is if you use the Vortec heads on an engine with the EGR valve in the intake manifold. The heads do not have the ports for the exhaust crossover in the intake, so the factory style EGR (like is used on TBI engines, and earlier EGR small blocks) will not work. In that case, in order to retain the EGR function, you would have to use later Vortec style exhaust manifolds that have the provision to plumb the EGR into the manifold, or headers with EGR plumbing provisions. The old exhaust manifolds would bolt on, but the EGR would be non-functional.
     

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