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Best heads for a 327

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  • Bob Simard

    Best heads for a 327

    I am rebuilding my wrong motor 60 FI engine. The block is done (327 bored 0.060 over and a 320 FI unit), has flat top pistons and an LT-1 cam and lifters. What are the best aftermarket heads for this application? This will be a driver and not see drag strip use. Low end torque is important as is overall power. Thanks for any advice.
  • Patrick H.
    Beyond Control Poster
    • December 1, 1989
    • 11608

    #2
    Re: Best heads for a 327

    If it were mine, I'd consider the Edelbrock Performer RPM heads (#60899). They're aluminum, don't have a heat riser crossover (don't need one with FI) and you can therefore get the smaller combustion chambers (64cc) without having to worry about detonation. Not only that, but easy to order from Summit and have them shipped to your house.

    In fact, we have a similar motor but we installed a retrofit roller cam, and the Edelbrock heads match the ports of the FI intake manifold so well it's scary. The car should be on the road in the next couple of months, and I look forward to driving it to see if the results match my expectations.

    Also, on ours we installed an aluminum water pump and the Corvette script aluminum valve covers. It looks great now, too.

    Patrick
    Vice-Chairman (West), Michigan Chapter NCRS
    71 "deer modified" coupe
    72 5-Star Bowtie / Duntov coupe. https://www.flickr.com/photos/124695...57649252735124
    2008 coupe
    Available stickers: Engine suffix code, exhaust tips & mufflers, shocks, AIR diverter valve broadcast code.

    Comment

    • Joe L.
      Beyond Control Poster
      • February 1, 1988
      • 43193

      #3
      Re: Best heads for a 327

      Bob-----

      The Edelbrock heads that Patrick suggested would be excellent. Edelbrock makes a first-class product with excellent engineering and production quality control. In fact, they manufacture some of the GMPP cylinder heads for GM. In this regard, they are the "successor" to Winters Foundry, although I don't think that they manufacture any PRODUCTION pieces for GM as Winters once did.

      In my opinion, the AFR (Air Flow Research) cylinder heads are the absolute best for a small block. However, they are very expensive, too. The Edelbrock heads are probably the best value, overall.

      One thing to keep in mind: "low end torque" and "top end power" are, basically, "mutually exclusive" terms. Depending which one of these is the most important to you has some effect on cylinder head selection. If low end torque is most important, then I'd go with the smallest intake runner volume heads available from Edelbrock or AFR. If top end power is most important, then go with a larger intake runner volume but ABSOLUTELY NOT the largest available from Edelbrock (i.e Victor series) or the large runner volume AFR heads. You won't be happy with those for a street engine. Period.
      In Appreciation of John Hinckley

      Comment

      • Duke W.
        Beyond Control Poster
        • January 1, 1993
        • 15610

        #4
        Re: Best heads for a 327

        How many aftermarket SB heads are there - two dozen? Three dozen? That's the number of opinions you will probably get.

        IMO a set of 461X with 1.94"/1.50" valves and judicial pocket porting/port matching are tough to beat in terms of both performance and reliability on a relatively small displacement SB, and if you are looking to maintain OE appearance they are that much better.

        As an overall guideline, keep port volume down to about 180 cc max on a 327. Too big a port can reduce flow velocity, which can reduce mixture quality due to inadequte fuel vaporizaton, which can hurt low end torque - not as critical on a FI as a carbureted engine, but it's still important.

        The ideal setup is a relatively small port with a high flow coefficient. This is what pocket porting/port matching does. You're not increasing average port cross section much, but you are improving the flow efficiency.

        You could also consider a head with 2.02"/1.50" valves, especially if you pocket port them. The LT-1 cam has a very early opening exhaust valve. The exhaust valve timing is set up for a restrictive exhaust port, and even with a 1.5" valve final I/E flow ratio (regardless of inlet valve size) will be well above 75 percent after pocket porting, which is more than adequate for the LT-1 cam.

        Pocket porting improves the I/E flow ratio because the exhaust port ends up with a greater improvement in flow than the inlet port due to its short length and simple geometry. Production machined 461 heads have a I/E flow ratio of about 65 percent, but after pocket porting you end up with 80-85 percent. With a ratio of 75 percent, equal duration is indicated. If less, the exhaust valve should open early (longer exhaust than inlet duration). If higher it can opened later (shorter exhaust than inlet duration); however it turns out that opening the valve too early doesn't do much harm, but opening it too late does, so error on the early side, which is what the LT-1 cam does.

        The more material between the valves, the more resistant the heads are to cracking, so a pocket ported 2.02/1.5" valve setup is well matched to the LT-1 cam's early exhaust valve opening.

        Duke

        Comment

        • Bob Simard

          #5
          Best heads for a 327

          Thank you for the info.

          Comment

          • Robert Pelland

            #6
            Re: Best heads for a 327

            Bob,

            If you are looking to obtain the higest performance you can expect with a set of aftermarket heads, Joe as usual is 100% correct in his recommendations. Recently in independent tests conducted by CHP Magasine ( Chevy High Performance ), the AFR heads were shown to be the highest flowing heads on the market, regardless of the size of the engine, or the engine manufacturer.

            As far as pricing, well there is an old saying that goes like this " there are no tools more expensive then cheap tools " and I guess the same could be said for engine parts.

            Regards
            Robert

            Comment

            • Patrick H.
              Beyond Control Poster
              • December 1, 1989
              • 11608

              #7
              Re: Best heads for a 327

              I'd agree.

              But, for a mild street engine, we decided that there was as much "bang for the buck" with the Edelbrock heads as we could expect to efficiently use. The performance-per-dollar margin between those and the AFRs did not seem worth the money.

              If I had a 383, though, I'd consider them.

              Patrick
              Vice-Chairman (West), Michigan Chapter NCRS
              71 "deer modified" coupe
              72 5-Star Bowtie / Duntov coupe. https://www.flickr.com/photos/124695...57649252735124
              2008 coupe
              Available stickers: Engine suffix code, exhaust tips & mufflers, shocks, AIR diverter valve broadcast code.

              Comment

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