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#13 Re: 'A' series head question.
ddgonzal Posted on: 2013/6/6 19:07
That is an A12 head as it has the original manifold bolt pattern

A14 round port head has the newer pattern

It will be good for max power at 4600 rpm on an A15


#12 Re: 'A' series head question.
D Posted on: 2013/6/6 5:16
a12 heart chambers with gx springs nice for A14 bottom end should go well with revvs and still have good torque due to round ports. Small ports are best used with high rod stroke ratios while oval ports with short rod stroke ratios. This becomes clear when when looking at bike vs car engines or even the SR16ve vs sr20de heads.
A14 has almost ideal road RSR so usually slightly ported round port is good
but the Oval port head will have more hp ability up high yet less midrange.
Round port heads are underrated for mainly mild streeter engines.

a14 (133mm rod / 77mm stroke) RSR 1.727
a15 (133mm rod / 82mm stroke) RSR 1.621
a12 (121.5mm rod / 70mm stroke) RSR 1.735
A14 with A12 crank (133mm rod / 70mm) RSR 1.9
last hybrid is perfect for that round port head
providing you have high rpm cam & required gear to suit
eg. comp, 38mm bike carbs, headers, ignition & fly/clutch.


#11 Re: 'A' series head question.
Rallytwit Posted on: 2013/6/6 3:05
That head you have appears to be an early style that is listed in the competition catalog as SCCA H=Production. It has a smaller combustion chamber (27cc I think) which would give it a higher compression ratio. Since you have the head why not run it and see how it works.


Tom


#10 Re: 'A' series head question.
shane0o7 Posted on: 2013/6/4 5:56
Is there any benefit running an a12 head on an a14


#9 Re: 'A' series head question.
shane0o7 Posted on: 2013/6/4 5:56
Yeah this will need one. I have noticed on the block where the oil journal is it is plugged


#8 Re: 'A' series head question.
Dundee1000 Posted on: 2013/6/4 4:50
looks like an A12 unit,
double springs is a bonus,
all the heads are interchangeable, only some need an oil gallery modification...




#6 Re: 'A' series head question.
shane0o7 Posted on: 2013/6/4 4:01
The ports are all round.


#5 Re: 'A' series head question.
shane0o7 Posted on: 2013/6/4 4:00
Yeah that's what I thought also. Could an a12 head go on an a15 or a14


#4 Re: 'A' series head question.
Stock1200Ute1 Posted on: 2013/6/4 3:54
i believe there was also an a15 round port head?

DD will be able to tell you...



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