Fastlane
»
Holden Forums
»
Holden General Discussion
»
Closed chamber or shaved open chamber?
Rank: Member
Groups: Registered
Joined: 14/06/2007(UTC)
Posts: 582
|
So im going to do a new head for my motor (red 202), to be put on when i pull these noisey cam gears out. First head was a learning experience, this one's going to be better.
I'm over getting beaten at the last second to Yella Terra heads on the net, and my cam's not really big enough to take advantage of the porting, "bolting" of the ports where the head bolts run, etc.
Question is this: running basically stock compression (9.4.1?), i want to bump it. Already use 98 octane and i'm not too worried with economy. Closed chamber head, larger valves and some work to de-shroud them, which i heard is a problem? Or open chamber, heavily shaved (popular with HQ racing i believe) but risk rocker angle dramas or push rod length?
Any thoughts are appreciated. Ask me if you think more detailed motor specs would help. And i understand that motors are a package, not just one part bolted to another...i'd just like advice on the head.
Cheers! |
"Silly modern cars" |
|
|
|
|
|
Rank: Veteran
Groups: Registered, Veteran
Joined: 2/06/2006(UTC)
Posts: 1,664
|
|
|
|
|
|
|
Rank: Member
Groups: Registered
Joined: 16/06/2005(UTC)
Posts: 424
|
I thought std red donks had closer to 8.8:1 CR?
___________________
Why are you reading this, you should be looking up there^^
- HJ turbotonner looks and goes like a sneezing rhino on heat! - |
___________________
- HJ turbotonner looks and goes like a sneezing rhino on heat! - |
|
|
|
|
|
Rank: Member
Groups: Registered
Joined: 14/06/2007(UTC)
Posts: 582
|
Not going 12. Got a genuine X2 manifold and some twin carbs that im rather fond of...and cost me a lot to get re plated!
For compression, low comp 202 is listed as 7.8/1, but i dindt think many here were low comp? I thought that referred to an export m |
"Silly modern cars" |
|
|
|
|
|
Rank: Member
Groups: Registered
Joined: 13/01/2006(UTC)
Posts: 303
|
I would go the open chamber head...but are YT heads really that hard to get?
|
|
|
|
|
|
Rank: Veteran
Groups: Moderator, Registered, Veteran
Joined: 1/03/2005(UTC)
Posts: 14,897
Thanks: 1 times
Was thanked: 554 time(s) in 529 post(s)
|
Ive had experienced red 6 builders tell me that the closed chamber is better for quench. Have a read of this site, it goes into it pretty well. http://www.bur.st/~oljohnno/holden.html _______________________________________________________ If we al |
_______________________________________________________
If we all had the same (good) taste, who would buy all the Fords? |
|
|
|
|
|
Rank: Veteran
Groups: Moderator, Registered
Joined: 1/03/2005(UTC)
Posts: 6,114
Thanks: 1 times
Was thanked: 219 time(s) in 199 post(s)
|
Yes, I would go the closed chambered head.
If in doubt do what the factory do. XU-1s used the smaller head.
Dr Terry |
If at first you don't succeed, just call it Version 1.0 |
|
|
|
|
|
Rank: Member
Groups: Registered
Joined: 14/06/2007(UTC)
Posts: 582
|
Byron, thats a superb article, thankyou. And Terry, very simple, very true.
Im going a closed head, larger valves and ill decide whether i do the porting again, or stump up the cash to make sure its exactly whats needed.
Cheers. |
"Silly modern cars" |
|
|
|
|
|
Rank: Veteran
Groups: Registered, Veteran
Joined: 2/06/2006(UTC)
Posts: 1,664
|
|
|
|
|
|
|
Rank: Member
Groups: Registered
Joined: 26/02/2009(UTC)
Posts: 20
|
Good luck with the head build. Post up what you finish with and how it goes.
HK1837, that is an awesome site. I reckon I have read most of that information on here at various times but to find it all in one place is unreal.
Cheers
Mike
|
|
|
|
|
|
Fastlane
»
Holden Forums
»
Holden General Discussion
»
Closed chamber or shaved open chamber?
Forum Jump
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.
