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416 Cyl. Heads, Opinions

This is a discussion on 416 Cyl. Heads, Opinions within the Performance forums, part of the General Discussion category; There is a set of 416 heads for sale locally for $100. Need some TLC, but good heads. I can't ...

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    416 Cyl. Heads, Opinions


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    There is a set of 416 heads for sale locally for $100. Need some TLC, but good heads.

    I can't remember what the casting number of my heads are, but I'm sure someone here has a very good idea. They're stock '93 305 TBI Swirl Port heads.

    Are these a good swap for a real low budget add on. I have a little extra lift and duration in my cam, ultimate TBI mods, afpr, all MSD ignition, long tubes, no cats and 3" exhaust.

    I would have a little porting done and possibly match them up with a Edel. Performer Carb intake.

    I just want something that would breath a little more than the swirl ports up top, but I am not expecting any sort of high rpm power, but the low end torque should be better right?

    Please pipe in with your opinions, I want to hear them all.
    '93 1500 RCLB, 2WD, 5.0L, NV3500, Internal Mods, Lots of Bolt-ons, Lock-Rite w/3.73's

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    GMC RULZZ NEUMANNZZ's Avatar
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    Re: 416 Cyl. Heads, Opinions

    here is more info about them: (assuming the casting # is correct)
    #14014416: 80-86 305 1.84"/1.5" valves, 58cc chambers
    Last edited by NEUMANNZZ; 01-28-2008 at 10:04 AM.
    O2 GMC RCSB 4.8L V8 AUTO 3.73's
    rebuilt/beefed up 4L60E(at 43,000miles)
    Matching Ninja 500r


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    GMC RULZZ NEUMANNZZ's Avatar
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    Re: 416 Cyl. Heads, Opinions

    O2 GMC RCSB 4.8L V8 AUTO 3.73's
    rebuilt/beefed up 4L60E(at 43,000miles)
    Matching Ninja 500r


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    Re: 416 Cyl. Heads, Opinions

    Quote Originally Posted by pringle420
    ....

    I just want something that would breath a little more than the swirl ports up top, but I am not expecting any sort of high rpm power, but the low end torque should be better right?
    Not really.

    There's a thread on www.thirdgen.org that might help you. An owner had a 305 Fcar that still had the stock 305 swirl port (SP) heads. He also had a 214 deg cam, aftermkt exhaust, and he had done a thorough job of retuning it. He made, IIRC, 208 rwhp. I don't recall how fast the car was but it was well into the low 14s.

    He also had a set of 416 heads which he ported, and then installed on the engine. After the swap, and some tuning, he made 226 rwhp. If this seems like a slam dunk, gaining 18 hp, consider that when the two dyno plots were overlaid, the plot for the ported 416s didn't exceed the stock SP head version until over 4000 rpm. At progressively lower rpms, the difference was severe, obviouslt favoring the SP heads. The stock head run also had an AFR which was probaby too rich, so some power had been left on the table (a few hp).

    When you consider the test results, and that the SP heads are faster-burn heads with a central spark plug location and decent squish areas, and that the 416s are older and lack these features then it's not hard to understand the results.

    People that have ported 416s have obtained extremely good flow numbers (on-par with Vortecs) but they are not efficient burners of fuel. And the test that Dewey316 ran more-or-less confirms that: even though the stock unported 305 swirl heads don't flow well, they still managed to out power the same engine using ported 416s at all rpms up to around 4000 rpm.

    The big unanswered question that a few people had (in the thread on thirdgen.org) was what would the results have been if the SP heads had been ported? The idea is to give up some of the swirl by removing only the end of the swirl ramp, in favor of gaining a lot of airflow, in addition to the usual port/bowl cleanup. No one has yet done that test to a set of 305 SP heads, but they have been done to 4.3 v6 heads, as well as to 350 heads with very good results from the flow bench, the dyno, and the track.
    Last edited by kdrolt; 01-29-2008 at 06:40 AM.

 

 

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