SBC 18 degree head compared to 23 degree head powerwise? - Hot Rod Forum : Hotrodders Bulletin Board
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Old 03-29-2004, 10:20 AM
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SBC 18 degree head compared to 23 degree head powerwise?

Hello,

I was wondering if 18 degree heads are worth it. If you use the same brand and everything the same, how much more power can you exspect out of a 18 degree head, compared to a 23 degree head. I am just intrested on how much more power you can exspect out of them?

Thanks

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Old 03-29-2004, 12:43 PM
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I think they should make fairly good power. That is what they are designed to do. The intake runners and valves are large and can flow a hefty amount of air/fuel. I think they generally have smaller combustion chambers and will increase your compression ratio.
You will need special components to go with the heads. The pistons have the valve relief’s at a different angle, the intake manifold is cut at the 18* angle, and you will also need shaft-mounted rocker arms that are offset at the roller tips. You can find these from Jesel, T&D, Comp, or others, but they are very expensive...as are the rest of the parts.
Oh.. and you will also need lifters with an offset to match up with one or both rocker arms.
With heads like these, would you plan to be on the street much? You would probably need a very large cam for these heads and might loose the bottom end. I think they are mostly used for strictly racing applications such as sprint cars.
I say for the street, stay with 23*... if this is a race motor and you have the money, go for it... Let us know how it turns out.

Rick
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Old 03-29-2004, 12:52 PM
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He is right about all of the special parts you have to buy for 18 degree heads. They will make more hp, but you will pay for it. I dont know why this is, but I have also heard that an 18 degree motor is less dependable than a 23 degree motor. I would look AFRs website, and check out their raised runner heads. They flow pretty much the same as an 18 degree head, but I am pretty sure that they dont demand all the special parts.

Good luck
Adam
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Old 03-29-2004, 01:18 PM
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An 18 degree head will make about 100HP over a 23 degree head when compared on the same CID engine combination. 18 degree stuff is just as reliable as 23. Ford has the adv. over chevy here, their head was 20 degree from the factory on the wedge stuff.

chris
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Old 03-29-2004, 01:29 PM
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I have the aluminum raised runner heads on my 69 355 camaro. they used the same roller rockers, guide plates, I'm using a longer push rod, but could have used the stock ones. I had to get a special intake gasket to use my DZ intake, partly because it had been cut to run severally decked heads. They are angle plug heads, so I had to get a special header. I could tell a big difference in the performance.

Troy

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Old 03-29-2004, 02:08 PM
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A lot of guys don't know this but the Holley 300-552-1 SystemMAX aluminum heads are 20^ valve angle heads and some of their small-block Ford heads are 17^.
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Old 03-09-2010, 01:46 PM
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Will 18 degree headss fit a TBI manifold?? Help

I hate to jump into this thred, but I have one question. I have a set of 18 degree heasd and wanted to know if they will fit on my truck with a Edelbrock TBI intake manifold???? I will be using the truck to pull with. I hope a cam will tame these heads a little bit..

Thanks you for any help, and sorry again for jumping into this thred

Shawn
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Old 03-09-2010, 02:01 PM
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If you're looking to jump into 18º territory I suggest you just start with an LS engine. For the street it seems like the smarter choice.
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