James Bostick to the SCJB Phone

Got a few questions for the motor heads I'm looking at upgrading my heads on my 496 I think it's about the only thing stock on my set up guesstimating my HP I would say somewhere around 550 based on RPM and MPH currently I have rectangular port iron heads nothing to fancy bigger valves if anything and a decent cam set up .im looking at either AFR or DART aluminum heads I would like to continue to run 91 Octane   My basic set up is 496ci. Solid flatt tappet cam. Hp 950 Holley carb I will probably Change the cam when I swap out the heads and go full roller but this is about the heads what do you guys prefer


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Thank thing runs really well bud.

Thank thing runs really well bud.

thank you it does run good and for the most part pretty reliable just looked to go a little faster naturally aspirated


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Has anybody had a problem with corrosion with the aluminum heads is there anything  you can do about it if so


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Stay out of firebird lol.

My boat has only been in Elsinore or the river so sounds like shouldn't be a problem


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They sure don't give those heads away around 3000 for the darts and 2800 for the AFR good thing the motor goes from boat to boat


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$3k?

You should be buying them bare and should only be about $900 a head.

What are you looking at?

GT

Complete assembled set of heads off summit racing but  I also need to get with my engine builder on what cc heads to get.


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Just my pinion,  I would buy them bare. Have your machinist build them with the best valves,  retainers, springs and rotators.

Remember to use larger than stock guide to valve clearance.

JMHO

GT

If you have the option, go for a "cast smaller" combustion chamber.  Otherwise you will need to deck the heads to bring the compression ratio back up.

First, you are switching to aluminum heads.  Aluminum is a greater conductor of heat which will pull heat out of the combustion chamber.  To maintain equal performance between identical heads, with the only difference being iron vs. aluminum, the general rule of thumb is increase the aluminum head compression by one ratio point.  The act of compressing air generates heat.  The additional point of compression puts that lost heat back into the combustion chamber.

Second, going to a more aggressive roller cam will most likely result in increased timing events.  That means that your dynamic compression ratio will be down compared to what it is now.

Working with your engine builder and starting out with bare castings will help you arrive at what is best for your combination.  It would also allow you to hard anodized the heads if you are overly concerned about corrosion.

Good luck,

Joe

To be honest, pump gas deal 496... Gm iron rectangle heads with a little fluff and buff... and right cam combo... 650-670 is not too hard to get... In a jet usable range (6200-6400). I mean spend money if you want some aluminum heads, but bang for buck... You got a good deal of potential left with what you got already.

I mean my po-dunker single carb 461 with iron 990 heads made 658 @ 6300 on Valero 91... But everything is just right and the cam/head combo works very well. So don't think of them as door stops just yet.


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by all means my iron heads do get the job done but loosing 60-70 pounds and going full roller should wake it up that much more and talking to my motor guy going with 650-700 lift cam opens up a few more possibilities that those iron heads won't allow the heads and cam combo that I will be taking off will be put on the shelf ready for another motor project


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Iron rectangles not allow performane @.650-.700 lift range? On a pump gas deal? News to me.

Well... Then nevermind... You got it figured out.


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didn't say iron heads don't get the job done I want the most I can get out of my motor rectangular port 990 we'll never flow as good as a set of AFR OR  DARTS  heads and if I'm going to go dump a grand into stock heads why not spend a little more s go bigger and better so whether I got it figured out or not 👍🏻you like the 990s that much I'll sell you mine  give you a hell of a deal that way you dump more money into them and it not hurt so bad 🤔


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Nah... I'm good... You asked an opinion... I offered one that involved spending a considerable amount less money, using much of what you already  have, and making a decent power gain... My opinion was wrong... No big deal.


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I've seen some real bad ass engines running iron rectangle ports. If I hadn't been lucky in getting a good deal buying aluminum heads id gladly run 990's over procrap or something of the like that was in my price range. I'd vote for giving them some love and finding the proper solid roller for the combo, Bostick knows his stuff!


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