REW Swap; Front Cover and CAS questions
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Mazzei Formula
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From: Birmingham, Al
REW Swap; Front Cover and CAS questions
In the process of swapping my old FD motor into an FB. Searched around and read a few of the write-ups but can't seem to find the answer to my question.
The current motor in the FB is a 13b; I was told it was swapped from an early cosmo. It uses a distributor system and retains the mechanical fan driven cooling system / old school front cover with motor mounts in the front.
I have the following:
Full rew-long block incuding ecu, trans, clutch and ported turbos and a walbro 255lph.
My question:
If I swap this cosmo 13b front cover over to the REW, and swap over the oil pan/motor mounts, and find a clutch disk that mates with the current cosmo or fb trans (whatever is in it) I should be able to bolt it all in. However, how am I suppose to run my Crank Angle Sensors with a distributor front cover?
The current motor in the FB is a 13b; I was told it was swapped from an early cosmo. It uses a distributor system and retains the mechanical fan driven cooling system / old school front cover with motor mounts in the front.
I have the following:
Full rew-long block incuding ecu, trans, clutch and ported turbos and a walbro 255lph.
My question:
If I swap this cosmo 13b front cover over to the REW, and swap over the oil pan/motor mounts, and find a clutch disk that mates with the current cosmo or fb trans (whatever is in it) I should be able to bolt it all in. However, how am I suppose to run my Crank Angle Sensors with a distributor front cover?
Joined: Mar 2001
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From: https://www2.mazda.com/en/100th/
the signal is the same (12+1), but the resistance is different between the two CAS's, so the FD cas won't work with the FC ecu, although this isn't a problem, because apparently i'm the first and only person to try that.
Joined: Aug 2011
Posts: 3,078
Likes: 42
From: Cambridge, Minnesota
I thought in my readings that an REW was harder to swap due to the necessity to fabricate a motor mount. That it needs to keep the same front cover and that won't mount to the FB engine mounts or the FC mounts if you swap in an FC subframe.
Correct me if I'm wrong, that's just what I remember..
EDIT:
From his build thread:
81 custom widebody
Correct me if I'm wrong, that's just what I remember..
EDIT:
Originally Posted by Frankenmazda
I have an REW motor with all accessories, S4 TII transmission, 12a front cover, 12a oil pick up, TII starter, and to attempt to make wiring as easy as possible, also have a PFC.
81 custom widebody
Last edited by DreamInRotary; Oct 26, 2013 at 02:18 PM. Reason: Found what I was looking for
Joined: Mar 2001
Posts: 31,837
Likes: 3,234
From: https://www2.mazda.com/en/100th/
i don't see why you couldn't put a 12A/GSL-SE front cover on an REW, although i could be wrong.
i have also seen an REW front cover with a couple of aluminum blocks wended to it, so it could just use the REW cover AND mount like a 12A
i have also seen an REW front cover with a couple of aluminum blocks wended to it, so it could just use the REW cover AND mount like a 12A
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if you want to go for simple mounting solution, then it's easiest if you just use the Gen II CAS.
what do you plan to do for management?
I'll be using a 12a front cover on my REW swap and have confirmed it fits without issues...and am using the rx8 metal gasket with it. I'll also be using the FC CAS but am not using the stock ECU but a PFC.
my fb has the REW swap done....used a 12A front cover, modded the OMP linkage to work with the RotaryWerks TB (i still premix just to be on the safe side). 12a front bolted right up to the REW iron. I also used a TII water pump with no issues. npo need to use a front cover gasket, i just ran a small bead of silicone and sealed it all up. never worry about o ring issues!!
Joined: Aug 2011
Posts: 3,078
Likes: 42
From: Cambridge, Minnesota
Anybody have experience mounting an REW into a 1st Gen with the FC front subframe swap?? Just curious - would like to do my next build that way.
Joined: Mar 2001
Posts: 31,837
Likes: 3,234
From: https://www2.mazda.com/en/100th/
dont do it! i have an REW in an FC, and its a PITA, nothing fits. i would suggest using a T2 engine and putting an FD upper intake on it, or keeping the stock FB subframe
Yep, stock FB subframe, RB front mount bar, NEW GSL-SE oil pan (due to lack of some holes in the back, and I'd recommend old school load spreaders back there or make your own). And yeah the front cover doesn't matter whether 12A or GSL-SE.
my fb has the REW swap done....used a 12A front cover, modded the OMP linkage to work with the RotaryWerks TB (i still premix just to be on the safe side). 12a front bolted right up to the REW iron. I also used a TII water pump with no issues. npo need to use a front cover gasket, i just ran a small bead of silicone and sealed it all up. never worry about o ring issues!!
Joined: Aug 2011
Posts: 3,078
Likes: 42
From: Cambridge, Minnesota
I think the OP now knows more than he intended, that's why I love this forum
Here you go.
It's an fd block, RE intake ported to match the fd block (lots of put it on, check, take it off, port here, port there etc!), rotary works throttle body, custom IC built, with a garrett gt4094r on a Gato. Performance manifold...all this works thanks to a haltech PS1000.

I used the 12A front cover and gslse oil pan. I had to drill/tap 2 holes on rear iron so oil pan would bolt in using all bolts. Not all line up exactly, there's always that one or two that dont cooperate!!
It's an fd block, RE intake ported to match the fd block (lots of put it on, check, take it off, port here, port there etc!), rotary works throttle body, custom IC built, with a garrett gt4094r on a Gato. Performance manifold...all this works thanks to a haltech PS1000.

I used the 12A front cover and gslse oil pan. I had to drill/tap 2 holes on rear iron so oil pan would bolt in using all bolts. Not all line up exactly, there's always that one or two that dont cooperate!!
Thread Starter
Mazzei Formula
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Joined: Jun 2006
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From: Birmingham, Al
Motor is in the car.
Used fd cover and made our own mounts up front, ill show pics later. Used fb trans and flywheel.
Everything mechanical is hooked up, just need to weld up ic and rad brackets piping etc.
However, I'm stumped w the ecu and wiring.
I'm using stock fd ecu, two slots left open where it connects to body harness. Iv discovered that the ignitor connects to ecu through the body harness.
Bought an fd ignitor to utilize.
Question is how to wire up the ecu to the ignitor, clutch switch nuetral switch etc. Is there a write up on here?
Do you guys just buy connectors and create your own wires to splice into body and ignitor from ecu?
Used fd cover and made our own mounts up front, ill show pics later. Used fb trans and flywheel.
Everything mechanical is hooked up, just need to weld up ic and rad brackets piping etc.
However, I'm stumped w the ecu and wiring.
I'm using stock fd ecu, two slots left open where it connects to body harness. Iv discovered that the ignitor connects to ecu through the body harness.
Bought an fd ignitor to utilize.
Question is how to wire up the ecu to the ignitor, clutch switch nuetral switch etc. Is there a write up on here?
Do you guys just buy connectors and create your own wires to splice into body and ignitor from ecu?
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