I hate the Holley 300-36 intake manifold

Discussion in 'High Performance Modifications' started by 1980RS, Jul 23, 2020.

  1. G72Zed

    G72Zed Veteran Member

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    It really makes one think, just like in the "Open Plenum" offerings, the old "outdated" Holley 300-25 is still available NEW, and it still performs to this day, the price is right, the "Shape" is right, and is one of the least expensive intakes. It was still one of the nicest ports right out of the box.

    I have had and tested many, and even though it's old, it works and keeps up with the others OP's, especially in the 450-550HP range, with a 650DP, I have just as much, if not more bottom end than my dual plane setup, more mid range and the top end is just great.

    I had a new in box 300-36 and sold it, and installed it on a customers car, he loved everything about it, it performed as expected. If they ever made it again, I would buy one, and if I had the extra coin, the 69 Z/28 OEM one as well.
     
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  2. 1980RS

    1980RS Veteran Member

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    I have used the 300-25 in the past and it performs up top a lot better then the Eddy 2925. If I ever decide to put my 300-36 on again I will cut the divider down and that will help with the top end charge. Still 118 mph is not bad for a dual plane and if not for the problem hooking up the car I would have left it on the car. Wish I had the time to test the Air Gap and the Brodix dual plane, dang hot weather.
     
  3. G72Zed

    G72Zed Veteran Member

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    The "newer" 2925 are much better, and dividers are cleaned up and thinned down out of the box, but I agree, the SD is a killer on the top.

    Don't cut down the divider, add a 1 inch "notched" spacer (can be tuned) with a matching 1" 4 hole merged spacer and carb up to 950 and hang on LOL.
     
    Last edited: Jul 30, 2020
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  4. 1980RS

    1980RS Veteran Member

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    So here is the lowdown on the 300-36 vs 300-25 test. 1st the Dominator test was not so good (will need to wait for the parts for the 750 conversion) so I switched to the 850 Mighty Demon as that's what worked best with both intakes.
    Best times with the 300-36 were 11.50's@117-118mph
    Best times with the 300-25 were 11.20's@118.5 mph

    Now here is something to think about, my 300-36 is ported into all 8 ports about 3" and the 300-25 has some work done to the port floor. The 300-25 did hook up very well today but to be fair if I was able to hook with the 300-36 I am willing to bet it to would be in the 11.20's, I may in the future cut down the plenum divider and see if it picks up some day. So like I said in the first post, the Holley 300-36 work too good and there is no Air Gap that works as good as the 300-36 IMO. If you have one, better hang on to it.
     
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