1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

early 13b

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Old 08-30-13, 10:35 PM
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early 13b

I bought my current rx7 a short while back, 85 GSL with a carbureted 13b in it.
As far as I can tell the motor is a very early (late 70s) version out of a cosmo or rx4.
Are there many differences between these and the more common later EFI motors?
Fairly certain the were 4port not 6port?

Last edited by lwrobins; 08-30-13 at 10:47 PM.
Old 08-30-13, 10:46 PM
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There are some differences. Your engine is a 4 port. Some would say it's a superior to the later 6 port designs, and I'd agree with them.
Old 08-30-13, 11:37 PM
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mine from a 74 rx4

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Old 08-31-13, 12:06 AM
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Mine with 74 ported nitrided R5 irons and J-spec rotor housings with a GSL-SE exhaust port timing.


Right after stacking
Old 08-31-13, 10:12 AM
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Originally Posted by lwrobins
I bought my current rx7 a short while back, 85 GSL with a carbureted 13b in it.
As far as I can tell the motor is a very early (late 70s) version out of a cosmo or rx4.
Are there many differences between these and the more common later EFI motors?
Fairly certain the were 4port not 6port?
its basically a 12A with wider rotors, the later EFI engines have a bunch of differences that make them, well different.
Old 09-02-13, 02:39 AM
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Originally Posted by rxtasy3
mine from a 74 rx4

so clean
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