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Main : Mechanical : Engine A Series Head comparison

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A Series Head comparison
A Series Head comparisonPopular
SubmitterFandatstickMore Photos from Fandatstick   Last Update2009/10/19 11:29    Tell a friendTell a friend
Hits3024  Comments4    0.00 (0 votes)0.00 (0 votes)
Head comparison.

mm A12 GX    H89 (A14/A15) A12 Round Port
Inlet port 39 X 30    35 X 29        27.5 X 26
Exhaust port 28 X 26    28 X 26        27 X 26
Inlet valves 35    37        35
Exhaust valves 29    30        29
Combustion
chamber depth 13    8*        10
Comments *H89 Head has been planed.  
Others are Unmolested.  All Ports appear standard castings

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The comments are owned by the poster. We aren't responsible for their content.

Poster Thread
ddgonzal
Posted: 2009/10/24 18:30  Updated: 2009/10/24 18:30
Moderator
Joined: 2001/5/3
From: 48 North
Posts: 31575
 Re: A Series Head comparison

Next photo

See comments in the next photo. It appears to be an A12T head instead of a GX head.

Poster Thread
Fandatstick
Posted: 2009/10/25 10:31  Updated: 2009/10/25 10:31
Home away from home
Joined: 2003/10/23
From: NZ
Posts: 282
 Re: A Series Head comparison
Meant also to mention a key difference between the H89 and the 'GX' is that GXs appear to have no water gallery above the Inlet ports (giving potential for even greater downporting than what they already have).

Poster Thread
ddgonzal
Posted: 2009/10/26 1:33  Updated: 2009/10/26 1:37
Moderator
Joined: 2001/5/3
From: 48 North
Posts: 31575
 Re: A Series Head comparison
Yes, GX and A12T heads feature a high roof port, the ports are much bigger than the A14/A15 heads including H89. There's no room to port an A14 head this big although it can get close.

Occasionally someone will weld and recut an A14 head like this: