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Author Topic:   18 degree heads
Dirt Roller

Total posts: 21
posted November 23, 2005 04:15 PM  
I am runing a 4-bolt main that has been straped and a set of phas-two angle plug heads, I want to put a set of 18-degree heads and intake on, I have heard many differant story's about my block want stand it, Can any one shed some light on this thank's

A. Bighurry
Dirt Full Roller

Total posts: 43
posted November 26, 2005 09:36 PM  
You would need special pistons to use 18* heads.

Dirt Maniac

Total posts: 108
posted November 27, 2005 07:08 AM  

Dirt Freak

Total posts: 241
posted November 27, 2005 09:53 AM  
valve pocket reliefs are different due to altered valve angle.
also combustion chamber on most 18deg heads is different to standard heads.
most 18deg heads require different pistons, exhausts, intake, valve train, lifters, valve covers & possibly camshaft profile.
there is the opportunity for quite a power increase running 18deg over what you currently have so you block life would be reduced. that said, if it is a good casting, you should get a good run from it.

Dirt Freak

Total posts: 263
posted November 27, 2005 10:13 AM  
some pistons will interchange but when put on 23 degree comp will go down a bunch.also on 18 degree you will need a different cam.I run 18 degree heads and have ran 23 heads.If your not going to turn around 7500 and up dont run 18 degree stuff.Plus if you are running a mod on alky use a good set of 23 degree CNC ported heads.That will be all you will need.

Dirt Maniac

Total posts: 108
posted December 15, 2005 07:10 PM  
Who makes good 18 deg heads? Anyone else ever use them? I've got an intake for these type of heads & just wondering if I should (a) source a set of heads to use with this intake - (b) modify the intake or build an adaptor plate to use them with 23 deg heads or - (c) sale the intake but it's an awful sweet intake. Any suggestions, comments, or experience in any of this?


Dirt Forum Champ
Total posts: 846
posted December 16, 2005 08:08 AM  
Dart makes a 16* that are nice, a guy has some for sale on for 2500 bucks. Good deal and use all the normal 18* stuff, pistons etc.

Other than that a 18* Brodix clone head is the best one, or the 18X Brodix.

As well pro topline used to make some 14* stuff that are really nice, but are hard to find anymore.

A stock block and 18* stuff is a recipe for diaster, high RPM's, and serious power. Stock blocks just cant take it.

If your on Alky get a good set of CNCed 23* deals and roll with it.


Dirt Forum Champ
Total posts: 595
posted December 16, 2005 04:14 PM  
you never said what block you are running..400 or 350? a 350 may handle if for a little while. a 400..NO WAY!!


Dirt Freak

Total posts: 263
posted December 16, 2005 07:06 PM  
18x Brodix head is not worth the money-Dart makes a good set-Chapman porting do some nice heads-Dont put 18 degree on a 350 cylinder volume isnt enough.Unless your going to spend $3000-4000 sell the intake a buy a nice set of 23 degree cnc ported heads.

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