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which head??
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Aiming for a nice street engine with 90-95hp. I have an a15 with h89 head, a gx head with carbs and exhaust maniflod, and another set of gx carbs. I haven't had a lot to do with the gx stuff, but just wanted opinions on which would be the better option
1. porting a15 head to match gx manifold or
2. using gx head on a15
I know the gx ports are slightly bigger but the valves are smaller?? any help would be appreciated

Posted on: 2010/6/1 4:54

Edited by grant76 on 2010/6/1 5:14:52
Edited by grant76 on 2010/6/1 5:27:02
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Re: which head??
No life (a.k.a. DattoMaster)
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The GX head is the pick of the bunch grant.
Plus there is enough meat in the valve seat inserts to allow them to be opened up to take the larger A14/A14 valves. (You'd be mad not to do this) With a bit of a cam, the GX carbs might run out of puff, but they should be okay. Best would be to have a sidedraft manifold for 40mm carbs ported to match the GX head. Big leap in costs though.

Posted on: 2010/6/1 7:48
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Re: which head??
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cheers Bart, just starting to plan for the latest money pit (you know that dented sedan on trademe??)

Posted on: 2010/6/1 8:48
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Re: which head??
No life (a.k.a. DattoMaster)
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Work the A15 H89 head I reckon Grant, leave the GX put away nicely somewhere. They're pretty sparse at the moment....especially in your neck of the woods. And you might as well run SU's seeing as you have two sets.

You could always sell a set, that'd make a decent start on your saving for a Twin Weber, Dello, Mikuni setup.

Posted on: 2010/6/1 9:47
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Re: which head??
No life (a.k.a. DattoMaster)
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Quote:

clyons8 wrote:
Work the A15 H89 head I reckon Grant, leave the GX put away nicely somewhere. They're pretty sparse at the moment....especially in your neck of the woods. And you might as well run SU's seeing as you have two sets.

You could always sell a set, that'd make a decent start on your saving for a Twin Weber, Dello, Mikuni setup.
I'll go along with that.
You are looking for a realistic power figure & using the A15 head means a saving on the larger valve upgrade on the GX head.

The A15 head should flow quite enough air, particularly with a reasonable induction & a bit of a cam.

Posted on: 2010/6/1 12:46
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Re: which head??
No life (a.k.a. DattoMaster)
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I agree with the above but either port the manifold for english 1 3/4 SUS
or run quad bike carbies like Rallyetwit (Ernie) is doing and some others.

Posted on: 2010/6/1 13:20
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Re: which head??
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whats the advantage of british su's over hitachi's (apart from parts availibility and its easier to find specialists to tune them)?? they're pretty common over here in NZ so getting a set is easy enough

Posted on: 2010/6/1 22:39
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Re: which head??
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No advantage except keeping it "All Nissan". The Hitachis are well-made, as are most SUs. Just make sure you don't get worn out carbs, especially check that the throttle shaft bores have no play.

Posted on: 2010/6/2 2:52
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Re: which head??
No life (a.k.a. DattoMaster)
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When I had the A15 valves put in My GX head, it was no more expensive than having a simple valve reseating done. Which should be part of any sound build anyway.

Posted on: 2010/6/2 5:34
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Re: which head??
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I had SU's on my bakkie and NO complains. I put SU's on my sedan and was disipointed, I dont know how to balance SU,s. A15 head is great aspesialy if you port and skim it, BUT us injection, single sidedraft, or whatever You can sort that give lots of petrol. No matter how grate your setup is, it means nothing if you cannot it. Best of luck...

Posted on: 2010/6/2 7:47
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