Building a 13B FC motor

Technical info not specifically 1st gen RX7 related.

Re: Building a 13B FC motor

Postby Ghostkls » Fri Oct 10, 2014 10:03 am

Just had a look at the link, Price is not bad, then I saw the shipping price to SA.....

£999.00 Royal Mail International Standard (Small Packets)

Glad I was sitting down. :cry: :cry: :cry: :cry:
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Re: Building a 13B FC motor

Postby TOOL » Fri Oct 10, 2014 10:22 am

Ghostkls wroteColonJust had a look at the link, Price is not bad, then I saw the shipping price to SA.....

£999.00 Royal Mail International Standard (Small Packets)

Glad I was sitting down. :cry: :cry: :cry: :cry:


Nah, insured up to £500 is £60 door to door through the company I use. 5-6 day service tracked.
Now with 3 rotors
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Re: Building a 13B FC motor

Postby TOOL » Fri Oct 10, 2014 1:30 pm

TOOL wroteColonThere's way more tricks.


Like oringing the oil pump. http://www.racingbeat.com/RX7-1975-1985 ... 11806.html

Essentially, you machine a groove into the back of the oil pump body (see link above) and put an oring in. It helps to seal the pump to the front plate to prevent pressure loss.

You can also put some wafer thin gasket paper in there as another option.
Now with 3 rotors
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Re: Building a 13B FC motor

Postby TOOL » Fri Oct 10, 2014 1:32 pm

Hopefully everyone knows about the Racing Beat tech pages:

http://www.racingbeat.com/mazda/perform ... -tips.html
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Re: Building a 13B FC motor

Postby TOOL » Fri Oct 10, 2014 1:41 pm

Flywheels.

Fit a light weight flywheel to dramatically reduce the weight of your rotating assembly. Bang for buck, this is a great mod, and doesn't require you pulling the motor apart.

Use the link here to see what counterweight you need, and what the part number is: http://www.racingbeat.com/RX7-1975-1985 ... 11436.html

Early rotary and RX7 S1/2 are still available for now.
S3 RX7 are very hard to get now. Used is your only option. I've sold mine.
S4 RX7 are available but second hand are hard to find in UK.
S5-8 RX7 are available easily new and used.

Early rotary up to S2 RX7 are 215mm clutch and associated flywheel.
S3 and S4/5 NA motors are 225mm clutch and associated flywheel.
S4-8 turbo flyweeel are 240mm (235mm units might as well be the same thing) clutch and associated flywheel.

You can get aluminium flywheels or steel units. Steel will be a bit more driveable on the street.

Used flywheels don't come up for sale in the UK very often. New units are available but not cheap.
Now with 3 rotors
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Re: Building a 13B FC motor

Postby TOOL » Fri Oct 10, 2014 1:47 pm

Before I forget. You match the flywheel to the gearbox.

215mm and 225mm flywheels are the same diameter. You can interchange the LIGHTWEIGHT flywheels to run 215mm or 225mm flywheel. You CANNOT mix and match the oem Mazda flywheels.

240mm flywheel is larger diameter to suit the turbo box.If you want to put a turbo box behind your 12A, you need a turbo flywheel and either balance the assembly (requires pulling the motor down) or fit a light weight turbo flywheel and appropriate rear counterweight.

S4 NA box will bolt up and use a 215mm or 225mm flywheel no problem. I have a RX4 13B with 215mm clutch and lightweight flywheel with a S4 NA box in my RX2.
Now with 3 rotors
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Re: Building a 13B FC motor

Postby TOOL » Fri Oct 10, 2014 1:53 pm

Clutches. Stock clutches are ok. They'll certainly handle an NA motor unless you start getting some good power.

HD clutches cost more and handle more torque.

Button clutches just get more aggressive in engagement.

You can sprung clutches or button clutches. You can get them in brass button and organic.

Here's a solid organic (asbestos) Mazda 215mm clutch plate:

Image
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Re: Building a 13B FC motor

Postby Ghostkls » Fri Oct 10, 2014 2:26 pm

I am really enjoying this thread! Keep the info flowing! s(c)

I am however now confused as to what clutch my car is running.... I know I have an S5 turbo block and I definitely have the original 12a gearbox so.... What route did the person who did the swap take....
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Re: Building a 13B FC motor

Postby TOOL » Fri Oct 10, 2014 2:47 pm

Dunno. Put up some pics and get the ruler out.
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Re: Building a 13B FC motor

Postby Ghostkls » Fri Oct 10, 2014 2:49 pm

That wont happen until ready to do the motor.... For now all I want to do is drive a bit!
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