My 1974 REPU Project

[chickenwafer]

Sooooo what's up everybody??! Long time no see!

It's been a while since I checked on here. Some of you may not know me, so a quick recap; my name is Dave. I like long walks on the beach and snackpack pudding. Oh, and rotary engines. Probably an unhealthy amount.

Anyways, I once upon a time had a 2005 RX-8. I did a custom GT3071R turbo kit along with some other mods and made something like 330rwhp and 330ft-lbs of torque back in 2009 (as far as I know still a record for Renesis torque). Picture to remember:



Well, I got bored with the RX-8, parted it out and bought a 93 FD3s RX7. I kept it simple for about 3 weeks then tore it apart with the help of some great friends, rebuilt with a ducted V-Mount, T66 single turbo, blah blah blah. Never did dyno that. Then my wife and were expecting our first kid, wanting to purchase our first home, I decided to be an adult (it sucks) and sell the car. I listed it on CL basically as feeler never expecting it to sell but I got a full cash offer within 24 hours of listing it. Oops. It was gone. Pics for memories:





So after selling the FD is a little heartbroken I guess, and kind of just swore off cars and stuff in general for a little while. Well, that didn't last too long. I was currently dailying my 2006 MKV Jetta GLI and had to tinker, so I started messing with it. Didn't take too long for that to not cut it anymore, so after plenty of searching, thinking, waiting, etc, I finally found my next project; 1974 Mazda REPU.

For those who don't know, the Mazda Rotary Engine PickUp truck (or REPU as it's called) is a Ford Courier-based mini truck Mazda produced exclusively for the North American market from 1974-77. All years of REPU came from the factory with a 13B 1.3L, 2-rotor Wankel Rotary fed by either a Carter (74) or Hitachi (75-77) 4-barrel carburetor paired to either a 4 speed manual (74-76) or 5-speed manual (77) or 3-speed Jatco automatic (all years).

Alongside the REPU and the Ford Courier, Mazda also produced the B1600 and B1800 which were piston powered mini trucks on the same platform. The REPU was actually the premium mini truck of Mazda's lineup, with a better trimmed interior, fender flares, rotary-themed enhancements and badges, and of course, the unique rotary engine. In the day, the 13B's 110bhp/110ft-lbs of torque was far superior to that of the B1600's 1.6L 4-banger with just 70bhp/88 ft-lbs of torque, with similar fuel economy. The Mazda REPU remains the first and only rotary-engine powered pickup truck ever mass produced.

[chickenwafer]

With that awkward history lesson out of the way, here's my 1974 REPU:



And home:



I bought the REPU off a nice older gentlemen in Byers, CO. I'd like to say I'm an expert negotiator because I got the truck, with a clean CO title, for a great deal. The guy was an awesome old-school rotary nut; his daily driver was a 12A swapped Datsun 510. He also had 3 other REPU's, 1 running, 1 not, and 1 converted into a dunebuggy. He took me an Matt into a barn that was lined from wall to wall with rotary engine parts, housings, transmissions, etc. He probably had 5-8 complete 12A's. It was crazy.

This particular REPU was stored outside since 1991 on his properity and hadn't ran since. It's a 3 speed Auto (I know) but these Jatco 3 speeds are actually pretty desirable in drag racing since they bolt right up to any 13B and are essentially indestructible. That being said, I might 5-speed swap it.

The owner also had some aftermarket wheels for the REPU I hashed out in the deal. These will get refinished in gloss black:



Anyway, the truck wasn't running, so Matt and I towed it home. Everything was pretty complete so we were pretty confident we could get it running easily. With a fresh battery in, it wouldn't crank and we quickly caught an electrical short as the main wiring harness started smoking. Whoops! Disconnected it and the short disappeared and allowed the starter to spin. Success! Well, even with copious amounts of starter fluid, it wouldn't light off. Matt suspected an ignition timing issue, and behold the distrubitor was installed out of time. Matt reset it but it was getting late so we called it a night.

Later, I disassembled the Carter carb and cleaned it out. It was filthy and all the jets were completed plugged. Well there's yer problem!

Cleaning the carb:



Some more overall shots:



After this, Matt added some raw gas in the carb and it fired up! The fuel hoses were cracked and the pump wasn't on, so it oly ran for about 30 seconds but sounded great! So pumped.

The interior is pretty rough. I removed the beat up white vinyl door cards and I'm going to run a bare/race inspired interior look. Plus, it's cheaper haha.

Some interior shots:







And the biggest rust issue in the lower rear passenger compartment:



Yeah, not pretty. Luckily this isn't the end of the world and will be easily fixable.

So, as it sits, I made a list of To-Do's:



Not terrible, this is just to get it driving (roughly). Then I can get it regiestered as a classic/collector vehicle which means it's emissions excempt and I can get 5 year tags. Schweet.

As of now, here are some rough plans for it:

Engine (If the OE 13B is good)
-Oil Change/Coolant flush
-Delete all emissions equipment
-Fuel Pump upgrade
-Direct Port Nitrous Kit

Interior
-Reupholster factory bench seat
-Gut the interior further
-Repair rust
-New door seals/weatherstripping
-MOMO Steering wheel with aftermarket hub adapter

If the OE engine, despite running, isn't good then I'll probably do an FD 13B-REW engine swap. But that's down the road. That's it for now! This build won't go as quick as my previous, so I will be slower to update it. Thanks!

Dave

[Shadowden]

Very cool. Enjoy the project!

[chickenwafer]

So haven't been as good updating here, been a while since I had a "build" thread haha. Admittedly, progress will be slower than with the FD, money is tighter after having a family and all.

Anyways, determined the factory fuel pump to be faulty, so ordered a Weber Redline pump, replaced the filter, and replaced all soft rubber fuel feed and return hoses as the OE hoses were dry rotted and crumbling. I wasn't feeling great during this process so I didn't really take pictures, but here's some of the parts prior to install:



Well, as soon as firing up the new fuel pump, and with fresh fuel in the tank, it was obvious the fuel tank was in a poor state. I had drained it before, and lots of nasty, varnish like vinegarish fuel came out, rust colored. I thought I had flushed it good but apparently not as it clogged my brand new filter in about 2 minutes. Replaced the filter with a new one and it did the same. Well crap.

Tried to get it to run but wouldn't idle for more than a couple seconds before dying. The choke cable is broken/missing so without a choke that doesn't help things. But this varnish like, gummy fuel wasn't helping and kept clogging up the float bowls in the carb. Well enough of that.

I ordered a 5 gal fuel jug so run a "temp tank" so I can ensure i have clean fuel. This will sit in the bed of the truck in a temp fashion with a fuel hose ran into it and then to the pump/filter. I'm guessing at this point the stock tank will need to be dropped and taken to a radiator shop to be hot tanked/cleaned out. If that doesn't work then it time for a replacement aluminum racing fuel cell as there aren't OE replacement tanks for the REPU. If I go the aftermarket racing fuel cell route, I want to try to get one as close to the dimensions of the stock fuel tank as possible and mount it in the same OE tank location, under the bed, and cut an access hole in the bed for refueling purposes. So we'll see.

I also ordered some new tires for the 16x9 wheels I got with the purchase of the truck. They are a HUGE wheel but will hopefully look pretty badass once done. Hopefully get some pictures up once the wheels are on.

Funny story with the wheels- I had the truck up in the air on stands and was using my 500ft-lbs compressor-driven impact to remove the lugs and they just won't bust loose. I was like holy crap these things are seized! So I drop the truck on the ground and hook up my 3ft breaker bar with a 2.5ft jack handle on top of that and STILL the lugs won't bust! So I'm talking to Matt and he recalls a story when a car had reverse lug nuts and the mechanic snapped 2 lug bolts before figuring it out. So I go into the garage and pull my breaker in the righty-tighty direction and holy crap they came right off! Every lug on the truck is reverse threaded! So weird.

Well hopefully I get some good pictures up soon as I, fingers crossed, get the engine to stay running with a clean fuel source that won't keep gumming up the carb and fresh tires to roll on instead of dry rotted rubber that came with it (all flat too).

[Shadowden]

Thanks for the update. I'm looking forward to hearing you are up and running.

Will you keep the exterior of the truck as is?

[RX-7 Chris]

When I get a chance, I'll post about how I restored my rusty tank.

[chickenwafer]

When I get a chance, I'll post about how I restored my rusty tank.

That would be a HUGE help if you could man! Right now I'm thinking I'll have to drop it and call up some radiator shops as I've heard they can hot tank and reseal fuel tanks.

Thanks for the update. I'm looking forward to hearing you are up and running.

Will you keep the exterior of the truck as is?

Yep, planning on keeping the exterior the "rat rod" look. This is very much going to be a budget build and restoring the exterior would be cost prohibitive. It's not that it's terrible but it would be easier to find a clean rust free California/AZ/Desert REPU and ship/drive it over if I was concerned about a rust free body.

[chickenwafer]

Quick update; had a frustrating day with Bumblebee yesterday. I filled up my 5gal jug of fuel and put it in the bed as a "temp" fuel cell and ran a length of fuel hose into it and into the pump. Fresh gas pumping to the carb- check! Still no fire.

Pour fresh fuel/starter fluid down the carb and it would run for 5-10 seconds then die. Pull the top off the carb (which I've done like 6 times now cleaning it out) and only the front bowl as gas, rear bowl is completely dry. WTF. So I'm thinking I reassembled the carb wrong and the rear float was hung up...so I put it back together and crank, nothing. Top of the carb comes off yet again, now the rear bowl is full of fuel and the front is completely dry! Seriously, WTF!

So I carefully, very carefully reassemble the carb, and still won't start. Frustrated, I gave up on attempting to start Bumblebee for today as my battery was getting weak so I needed to put it on the charger.

The choke cable was missing when I got the truck, so I rigged up my super ghetto rebar tie choke cable into the cab. It kinda works LOL



To feel productive, I painted the wheels I picked up with the sale of the truck a gloss black with Duplicolor engine enamel. Used 2 coats of primer and 3 coats of paint and topped with a single coat of clear. So far the finish doesn't seem super durable so I might put some black Plastidip on top for extra wear resistance.

Anyways, pics of said wheel refinishing:

Lined up:



Starting point:



Rinsed the wheels off with Simple Green, water, and wiped down then roughed them up with a wire wheel on my drill:



Layin down some primer:



The finished result:



Tires shipped today so I can finally get some overall shots of Bumblebee once it can roll easily.

[RX-7 Chris]

If you are able to bring that Carb down to me, I can take a look at it. I don't have the time right now to make a trip up there.

Have the radiator shop dip your tank but don't have them seal it. Most of the sealers will start to peel eventually.

Get this: http://www.amazon.com/Caswell-Epoxy-Gas ... ge_o01_s00

I went ahead and followed the directions in the box and re-cleaned the tank after the radiator shop.
http://www.caswellplating.com/epoxy-gas ... ealer.html

What I liked about the Caswell coating is it is a true 2 part epoxy. One thing to note is it is thick and clear so it was a little hard to see where it had coated (just makes the coated area look a little glossy). hake sure you have a flash light on hand to see what has need done and work fast. I actually had a little electric heater blowing on it for about two full days to cure.

[RX-7 Chris]

Take a look at these if you haven't already: http://foxed.ca/index.php?page=rx7manual#repu

All the FSM you would need.

[RX-7 Chris]

Quick update; had a frustrating day with Bumblebee yesterday. I filled up my 5gal jug of fuel and put it in the bed as a "temp" fuel cell and ran a length of fuel hose into it and into the pump. Fresh gas pumping to the carb- check! Still no fire.

Pour fresh fuel/starter fluid down the carb and it would run for 5-10 seconds then die. Pull the top off the carb (which I've done like 6 times now cleaning it out) and only the front bowl as gas, rear bowl is completely dry. WTF. So I'm thinking I reassembled the carb wrong and the rear float was hung up...so I put it back together and crank, nothing. Top of the carb comes off yet again, now the rear bowl is full of fuel and the front is completely dry! Seriously, WTF!

So I carefully, very carefully reassemble the carb, and still won't start. Frustrated, I gave up on attempting to start Bumblebee for today as my battery was getting weak so I needed to put it on the charger.

The choke cable was missing when I got the truck, so I rigged up my super ghetto rebar tie choke cable into the cab. It kinda works LOL

Did you replace the needles and seats with aftermarket? If so do you still have the old ones?
The aftermarket needle and seat is junk. Try taking the originals and giving them a good cleaning with carb cleaner and reinstall. Also it sounds like you may have some dirt in the carb still.

[chickenwafer]

Thanks for the help man! I don't know when I could make it down to the Springs to bring you the carb, but thank you for the offer!

I have not replaced the needles and seats, they are OEM as far as I know. Of course it's a 1974 vehicle so who knows but they looked like no one had removed them. I took them out and soaked them in carb cleaner and pushed piano wire through the jets after soaking them too. I plan on doing it again.


Well, today was a day of fail for me. First, my wife calls to let me know her car got a flat tire at work. So we get it towed and $700 bucks later it has new tires. Great.

The tires I ordered for Bumblebee arrived today too, so I got home from work and loaded up the freshly painted wheels and tires and headed over to get them mounted and balanced. No more than 5 minutes in the tech grabs me and says, "You got 16" tires and 15" wheels, dude". FUCK! I measured the wheels incorrectly and ordered 16" diameter tires for 15" wheels.

Sooooo, options. Different tires, wouldn't be super difficult except I ordered the tires on eBay and I'd be out return shipping which is going to be $80-$100 bucks. And then the tire brand/model I bought isn't made in a 15" tire so I'd rather not. OK, well the wheels I have don't fit THAT great, the hub center bore is actually too small soooo I'll just get new 16" wheels.

Couldn't find any 16x9 wheels in the bolt pattern I need that I like so I ordered some 16x8" wheels for my 245/50-16 tires. They will bulge a little but not terrible. I also might need to do some trimming/modifying of the front fenders so everything clears, but we'll see.

Ahh, how I forget the joy of modifying cars LOL.

[RX-7 Chris]

If you want, I can talk you through the carb stuff over the phone.

[speedjunkie]

Man I haven't seen this thread. I'm stoked for you to get this running! Especially since the original engine that has been sitting for years still fires up. I LOVE that.

I still don't understand how you fit in this truck lol. My legs almost hit the dash in Matt's REPU. It cracks me up that as big as you are you keep getting smaller and smaller rotary project vehicles LOL.

That sucks about all your setbacks, but it'll be worth it when you get it going. That's definitely the "joy" of modifying cars though lol.

And if you make it down here you BETTER stop by. I plan on coming up to visit once the car is back on the road.

[chickenwafer]

Man I haven't seen this thread. I'm stoked for you to get this running! Especially since the original engine that has been sitting for years still fires up. I LOVE that.

I still don't understand how you fit in this truck lol. My legs almost hit the dash in Matt's REPU. It cracks me up that as big as you are you keep getting smaller and smaller rotary project vehicles LOL.

That sucks about all your setbacks, but it'll be worth it when you get it going. That's definitely the "joy" of modifying cars though lol.

And if you make it down here you BETTER stop by. I plan on coming up to visit once the car is back on the road.

Haha, the REPU is a tight fit but not terrible. It's different than the FD because the seating position is so different. I plan on replacing the steering wheel with a smaller one which will help. The lack of center console helps because you can slide your feet over. Not something I'd want to spend hours in, but for drives around town it's perfect. Maybe my next rotary project will be a 13B swapped MG Midget LOL

Once it's road worthy I do plan on driving down to the Springs for a visit!

If you want, I can talk you through the carb stuff over the phone.

Thanks for offer man, I might have to take you up on that!


So yesterday got home from work early and got the wheels/tires mounted as the wheels arrived the day before. No issues this time as they were the correct dimensions! Got the wheels home and mounted then up on Bumblebee and they look BADASS!! I can't wait to get some good pictures but with the weather rolling in pictures will have to wait a couple days. I'm also waiting on a few other parts for the exterior.

After throwing the wheels on, I decided to tackle the carb and see if I could figure it out. Took it apart (once again...) and found it was gummed up and dirty as shit! A MASSIVE amount of gunk made it past not one but TWO fuel filters! WTF?!

Inside the bowls:



Cleaned:



I had to pull all the jets and soak them in carb cleaner and push welding wire through them to clean them out again. Confident I got it clean and fixed my problem, I reassembled the carb and fired it up with the fuel pump pulling fresh, clean fuel from the spare 5gal jug. Still wouldn't fire and I'm not sure what's wrong the the carb at this point but I feel like it has to be the problem. It will run if I dump fuel down the throat of the carb but only for a few seconds until that fuel is burned out.

The only other thing I can think of is I replaced the dead OE fuel pump with a "high performance" Weber Redline low pressure fuel pump. Should I put a fuel pressure regulator on this? As it is, the pump goes straight into the carb. This thing moves some fuel but says it's around 6psi which is what I've gathered the carb should be at anyways.

Lastly, I found this cool radio delete trim piece on eBay and snatched it up. Dresses up the interior a little and the OE radio in wasn't working, so win-win: