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Double hump heads

Discussion in 'The Garage' started by orangeGMC, Nov 6, 2005.

  1. orangeGMC

    orangeGMC 1/2 ton status

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    What is the going opinion on GM double hump heads? I am thinking about running these on my 400. The specs I could find on them are as follows:

    165cc intake runners
    67cc combustion chambers
    2.02 intake/1.60 exhaust
    1.25 valve springs (good to .520 lift)
    3/8 screw in studs

    they even already have the steam holes drilled in them.
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Is this a set of heads you found that are rebuilt by someone or is that some spec you got as general info on camel hump heads?

    All the camel hump heads i've seen or worked on are either 62cc or 64cc combustion chambers and almost every one is 1.94"/1.50" valves and none came factory with screw-in studs. There are a few RARE hard to find 2.02"/1.60" camel humps still out there but people don't let loose with them very often. You can make a 1.94"/1.50" head into a 2.02"/1.60" easy enough but i can tell the difference if it is a made up set of 2.02"/1.60" heads.
     
  3. orangeGMC

    orangeGMC 1/2 ton status

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    These are from Summit racing, part #sum-152123
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Those are not camel hump heads. Those are aftermarket late style heads that accept either kind of valve covers. Those do have 67cc chambers though and the larger valves.
     
  5. orangeGMC

    orangeGMC 1/2 ton status

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    Well I apologize for the incorrect naming. But what do you think about those heads for a mild 400?
     
  6. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    They will work ok as long as you choose a piston that will give you the correct compression ratio for the cam and induction you're running.
     
  7. orangeGMC

    orangeGMC 1/2 ton status

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    I am running a stock style dish piston and the motor is bored to a 406. I have stock 76cc heads and am running an edelbrock performer air-gap intake. It also has a comp cams xtreme 4x4 cam. I have been running it like this for about 6 months and want to add a little more power. The shops around me are uneasy about drilling heads for steam holes, so I was trying to find some with the holes already drilled and assembled.
     
  8. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I just finished the math and going from a 76cc head to a 67cc head will increase your compression ratio 1.16:1. Do you know what piston is in this engine and also what the deck is set at? I can tell you what your final compression ratio will be if i have those specs.
     
  9. orangeGMC

    orangeGMC 1/2 ton status

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    I am sorry that I do not know exactly what piston or deck is. All I know is that it is a rebuilt recon engine, I swapped in the cam and intake. I can run on cheapo 87 octane with no pinging, I figured swap the heads and have to run premium 91 or 93 octane.
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    At $649/pr, depending on what you want to do, you might want to do a bit more looking around.

    If you can afford maybe $200 more total, you start getting into some good heads, although even stock vortecs are about $500/pair and an infinitely better head.

    Just my opinion, but that old head design is best left in the past.
     
  11. orangeGMC

    orangeGMC 1/2 ton status

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    I don't want to do vortecs because I will then have to get a new manifold. And I haven't been able to find any other iron head that has the steam holes already drilled in them.
     
  12. beater_k20

    beater_k20 Banned

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    camel hump heads make great doorstops.
     
  13. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Those door stops work pretty good when you work them over just a bit. You can gladly send me any of them you get because not only do they work very nicely they also bring big dollars here once rebuilt. Considering i do that kind of work for a living i make a killing on them when i build and sell them.
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    As long as you are making lots of money on them, more power to you! :)

    Stock Vortecs $500, (or so) new edelbrock dual plane vortec intake $150 last I saw, or new double humps for $649. Don't see any savings the double hump route unless your intake is better than an edelbrock dual plane.

    Like I said, look around though, the Vortecs aren't the best out there, just the cheapest with the most benefit. The ones orangeGMC mentioned are a bit better in some regards (valve size, springs, and studs) but if you don't *need* those parts for what you intend to do, they are pointless to pay for.
     
  15. beater_k20

    beater_k20 Banned

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    i'd use a set of swirl port heads from a TBI engine before i even considered using a set of double humps. technology has come too far in the last 30 years to use something that's older than i am.
     
  16. blazin_blazer

    blazin_blazer 1/2 ton status

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    ahhh technology

    gotta love it! i just forked over the cash for the aluminum vortecs or fast burn whatever you want to call them...i like the fact they can use either the old style or the vortec intake and the same goes for the valve covers centerbolt or perimeter bolt covers....they are going on a 427 world product 427 sbc short block i spent right at $6000 on! the motor is going to replace my iron headed vortec 350...i just cant make up my mind whether to take the gmpp high rise vortec intake off of the 350 or go with the air gap edelbrock...i have a 68 c-10 the vortec iron head roller motor is going into with the nos plate system and all so the intake will probally stay but i talked with lunati and they recomended a cam that should put me aroud 500 hp and 500 ft lbs of torque and not be very detrimental...its a special grind for the big small block and the fast burn heads...they recomended several intakes hi-rise dual plane as the motor tops out at 6000rpm. i could wind it alot tighter and get mo hp but it is about torqued out and it sounded good to me 500 hp and torque the same, altho they fall at different rpms. the torqe peaks just over 3800 rpm and hp should peak at about 5800 rpm...i've ordered msd ignition with rev limiter be cause this is the most expensive motor i have ever had.. i have a highly reputable machine shop in tennessee checking balance and handeling assembly they are actually going to dyno it afterwards...i think that is cool a sheet to carry in glovebox to verify whats under my hood...i cant wait...after it all said and done, i will have close to $10,000 in it with the billit pulleys chrome alternator and billit brackets and a predator carb(still in debate)and its bound for my 69 k-5...i can run the front fender badges that say 8 cylinder and 427...no1 will under stand, but i will have a sheet in glove box to make them scratch their heads over....427 sbc...huh? i can't wait...well, i guess i can. i have to....they talking i can pick it up in late feb to mid march. im just curious when they dyno an engine ..if it happened to fly apart, are they liable...something i need to ask them i guess..any1 know, does that hard run hurt your engine ? or shorten its life? this truck will see very limited offroading...i can't see swamping a motor of this caliber thats what my 80 model is for and i recently got a big block to go in it...the 69 will be the lake truck cruising the swimming holes looking at bikini's truck...man i wish elves would get all this stuff done like the shoemaker...an recomendations on what you think would be the best intake carb setup for the 427 sbc i need around 950-1000 cfm they said, ...i've considered the 1050 dominator, but at the same time i've always liked the predator carb like a box with eagles on it. i may let the machine shop figure it out with the dyno...they already reccomended the adaptor to mount bbc headers on it....i absolutley cant wait!!! i'm wound up like an 8 day clock! :D
     
  17. beater_k20

    beater_k20 Banned

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    very tasteful, a mix of billet and chrome. very similar to a mix of Boggers and All Terrains
    i always choose my carbs by the way they look rather than how the perform too! :doah:
    BBC headers on a small block? have you looked at the port spacing recently on a small block vs a big block? this is not physically possible, while keeping inside the frame.
     
  18. blazin_blazer

    blazin_blazer 1/2 ton status

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    as usual your opionion sux and is wrong!

    mixing billit and chrome is no big deal...oohhh maybe i shouldn't do it, beater says no...like i care what you think... so where you recon i could find some billet inner fenders when i get to that point? i recon i shouldn't use my new aluminum radiator either because its a subtle different shade of SHINY!!!

    the carbs from everything ive read an studied puts those 2 carbs around 1000 cfm, actually they said the predator will not over carb a motor because of the way its built but will put out all is needed , and in my opinion, the 1 that counts!!! i think they both look equaly wicked, and like i said i would probally let the dyno choose for me or was you to busy looking for holes to poke your stick thru and missed that part?

    and the machine shop makes a piece similar to this but has the bigger port and bolt pattern

    http://www.jegs.com/webapp/wcs/stor...eId=10001&categoryId=19849&searchItemId=59817

    that uses something like these

    http://www.jegs.com/webapp/wcs/stor...eId=10001&categoryId=19853&searchItemId=59827

    to put bbc header on a sbc...i know 2 people who have used these kits to put the big tube bbc headers on sbc's in their jet boats....and seen it several times on the dirt tracks! did i say they were going to stay inside of frame actually thinking possibly some lake pipes or just a big mouth(not talking about you ,..so don't start flaming) exiting right behind the doors

    it is better to keep quite and be thought a fool , than to open your mouth and remove all doubt! just because YOU haven't seen it doesn't mean it doesn't exist!!!
     
  19. beater_k20

    beater_k20 Banned

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    i suppose you're right... there are two kinds of people who like lots of shiny things. rednecks and im gonna be nice to you and not tell you the other choice.
    a predator is a very good choice for a carb, there's no disputing that. your method of choosing the "right" carb is a little hoky though.
    a little common sense will tell you that the port spacing is drastically different. of course, you're going to believe whatever your magic machine shop man tells you. or perhaps you didnt hear him correctly, and he mentioned "big tube" headers, and you heard "big block" headers. i stand firm on the fact that you cannot put a set of big block headers on a small block without either A) compromising the fit of the headers, or B) creating a huge flow restriction with your magic adapter plates.

    BTW, the adapters you linked are to put big tube SBC headers on a SBC, it makes no mention of big block headers anywhere. :rolleyes:
     
  20. Brocky

    Brocky 1/2 ton status

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    I agree totally. They dont line up. You ever see guys porting a set of heads to match headers? There is no way to port them that much. You might as well go with no headers or just burn your rig now.
     

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