New rotary owner with a holley carb'd 13b... Oh boy, here we go.
 

So the P-PO (previous-previous owner) installed the 13b and put a racing beat manifold on it, with a Holley 4160. Yes, I know, the devil. Anyway, the seller sent me a video of it running:
https://www.youtube.com/watch?v=FcDBH5r_JmE

I've been trying to get it running for two days now, and the best I can manage is repeated throttle input to keep it going. If I let off the throttle, it leans out and dies. It's like the idle circuit simply isn't there!

If I choke 3/4 barrels I can sorta get it to idle, but of course as soon as I lift the rag, it dies.

I'm fairly familiar with carbs in general, but I've never worked on a Holley (SUs, Solex, Carters, even a little rochester) and it's kicking my ass.

I've rebuilt it, checked fuel pressure and flow, and basically I can keep the engine running indefinitely by using the accel pump to keep it richened, but no adjustments seem to do anything. It's got #64 jets in the primary, and the secondary still has the non-adjustable metering block.

Eventually I'll probably swap to EFI, just because I'm more familiar with tuning those, but for now I just want to get the damn thing running so I can figure out what else needs work!

SO- Ideas? I'll check on the idle cutout below the throttle blades.

sounds like a carb problem, either fuel pressure or maybe something plugged up in the carb from ethanol gas. my boat has that carb and has had a similar issue.

Drew

welcome to the community!

Thanks for the welcome! I checked fuel pressure to the carb, it's fine. I also rebuilt the carb and blasted every passage clean. It's definitely still a possibility, the odd thing is that the seller said he had it running the night before I bought it. I'm thinking of taking it apart again and soaking it in carb cleaner rather than just blasting it.

You make no mention of time frame car has not run. Old gas likely a player here. How old is gas in car currently? Was old gas drained or fresh added to old gas... Was carburetor disassembled and washed in a tank with carb cleaning solvent? Residual ethanol fuel turns into a brown mess that resembles fudge. Clogging of passageways is possible

Sorry,on a phone... pay special attention to primary metering block which contains passages for idle circuit. Carb cleaner & compressed air to all passages,jets and idle mixture screws removed. Float level also important,fuel should be right at lower edge of opening with bowl plug removed. Initial setting for mixture screws is 1 turn out from lightly seated. While carb is disassembled,do the same with throttle plate and carb Venturi body as was done with metering block. Be certain all passages are clear before assembling carb.

I generally take with a grain of salt what a seller says when buying a car til I can prove otherwise.

I've done all of this already, save the soaking the parts in cleaner. Right now, I've got everything but the main body and throttle plate soaking they didn't fit in the can, I'll re-assemble tomorrow.

I don't know how old the gas is, but it doesn't smell much like varnish, the carb is clean, I've blasted all the circuits I could.

It's possible I have the wrong gasket somewhere. I think this MAY be a Racing Beat modified carb, there's definitely some cuts in the air bleeds.

If you don't know how old the gas is,drain tank,purge pump filter and lines. Ethanol gas we have today if unstabilized will begin to degrade in as little as three weeks,adds more to drivability problems than a lot of people realize. You may have a wrong gasket installed in metering block or throttle plate. Holley master kits come with more gaskets than applicable to any individual carb. Plugged up passages in metering block a real possibility. Have had some that needed to be put in carb washer with caustic solvent several times along with using thin wire(jet cleaning tool) carb spray and compressed air. Had to replace one in particular that couldn't be cleared. A lot of people knock these carbs,the biggest problem they suffer from is being turned 90 degrees from their intended orientation to accommodate the rotary engine. Stalling, running lean stumble in hard cornering in one direction and blubbering rich condition on opposite turns. Hard to match straight line acceleration. Having used these carbs on muscle cars,accumulating lots of extra carbs and pieces over the years,I experimented on a couple rotary cars I had. Center hung float bowls,vent tube mods cleared up a lot of drivability problems. New float bowls and associated hardware are not cheap on top of cost of the carb/intake and part of why Holleys get a bad rap in the rotary world.

I got it running today. There was some what looked like aluminum oxide after the metering block soaked all night. The stupid foam air cleaner changed the idle when I installed it, lol.

So now I'm stuck into the task of cleaning up the wiring, which... Well, turns out this was a FI car, so there's a lot of wires I don't need. It's a mess, helped by someone in the past hacking, I mean modifying, the wiring for some MSD boxes.

I'll get it, it's not my first wiring mess (though I think it's the worst). In the immediate future I want to figure out the MSD setup so I can isolate that, since it taps into the factory harness in odd spots. Then I want to see if I need to keep any of the factory FI harness. The clutch master and slave are supposed to arrive Friday, so with some luck and hard work I'd like to have it driveable by then.

if u don't already know or been shown about these, they might come in handy.
Foxed.ca - Mazda RX-7 Manuals

That's awesome you got it up again

I was actually downloading those when you responded. I wish they were laid out like the 944's current flow diagrams, but at least the arrows help. The location with each connector called out is awesome though!

On the wiring situation. I've identified about 90% of the random dangling wires and connectors, at least inside the car. I've made a list of needs/wants for the electrical (things like headlight motors, fuel level, oil pressure, etc), and I decided against trying to remove what I don't need (A/C, remains of cruise). Experience has taught me that doing a half-assed wiring job is only going to make more problems, so until such time as I can label & pull the entire harness to pare it down, I'll leave it be.

That said, I do intend to remove as much of the FI harness as possible, since most of that isn't doing anything. I'll be poring through the diagrams, but offhand does anyone know what the little bit of wiring in the FI harness that connects to the front harness and engine harness does?

I wish I had the time to really rip the whole harness down, but especially until the storage situation is finalized I can't make it totally immobile.

Well, I thought I had everything sorted. So I reinstalled the dash. Then the headlights didn't work and something in the cluster burned up... I swapped the passenger motor because the pivot was seized, but forgot a ground, so I suspect it tried to ground through the cluster.

Also it no longer runs. It's definitely a fuel delivery issue. The gauge is showing basically nothing, and the filter is new. Of course the PO ripped out the fuel gauge wiring (WTF) so it may just be low. I'll throw 5 gals in and see if that fixes it. If not, I'll swap the pump.

In the meantime I'll pull the cluster PCB off and see what I melted.

Crap update.
 

Sorry I've been so slow on keeping up with this, the damn day job gets in the way!

Anyway, it was definitely a fuel delivery issue. The holley blue pump's motor had completely failed, the magnets had come unglued and were grinding on the rotor. Amazing it ran at all. So I replaced it with a Carter pump, much nicer. It even ran fairly well for a while- until yesterday. I had just reinstalled the blower, heater core, etc, and was playing around with it to get it working, so I'd unplugged the fuel pump so it wouldn't run the whole time. I got the blower, vent controls, etc., all working, so I started the engine to warm it up (added a thermostat that the PO had left out...) and bleed the coolant.

Totally forgot to plug the fuel pump back in.... And it backfired pretty bad through the carb as it ran out of fuel in the bowl, now it won't start anymore.

I have checked:

• Power Valve (Not torn)
• Vacuum advance diaphragm (also good)
• Oil injector diaphragms (good)
• Vacuum advance diaphragms (good too)
• Spark at all 4 plug (strong)
• Pulled all 4 plugs (wet, but spark)

Tomorrow I will check:

• Ignition timing (I don't know how this could have gotten messed up, but....)
• Compression (could a backfire REALLY damage the engine that bad?)
• Different plugs (I've seen them spark, but... maybe?)

Additional notes:

• It ACTS like it wants to start, but it can't actually catch. Even on starter fluid.
• The rotors housings do get warm, so there's SOMETHING happening.
• The starter sounds... grindy? Hard to describe, but it doesn't sound quite the same as before I reinstalled the heater core, which required moving the battery cables. I wasn't paying attention the only start that worked, so I can't say if it sounded weird then.
• If I play with it enough, it will pop out the exhaust (makes, sense, the combustion's not happening). I guess that means I'm either missing compression or ignition.

So, what are the chances I've really dickered something? I guess maybe it could have cracked an apex seal? The engine wasn't under load when it backfired.

Probably not getting good compression since it ran dry. You can pull plugs and squirt some oil in there and rotate a bit by hand. Don't forget to put the plugs back in. Also you may need to give it some gas with a couple of small pumps on the accelerator as well. The oil should fix the compression and help it start. Will be some smoke from that when it starts but should burn out once it warms up.

I followed your advice, as well as swapping to a different set of (old) plugs, since I'd heard flooded plugs often don't play nice.

Still no start. I tried some starting fluid and got tantalizingly close to starting, but it couldn't quite catch, and then that was it. No further success.

Checked timing, it's good.

At this point, I could try the towing trick to clear it out, I can try a set of brand new plugs, and I can check compression. I could also rebuild the carb, again. It tries harder with the throttle cracked open some, so maybe the carb got damaged and is flooding the engine no matter what now.

I say try starting by towing it.

So the problem was definitely the carb. Spun the engine with no carb or plugs, cleared it out. Cleaned and cooked the plugs. Rebuilt the carb, and I got it to fire by spastically pumping the pedal (so it's running off the accelerator pump). Two reasons for this- I took the metering plate off the secondaries before realizing I didn't have a new gasket. So I made one. Which probably left fibers and crap in the passages. Also, I adjusted the secondary throttle plate stops and... maybe I went too far, leaned it too much.

Anyway, it runs if I constantly slap the pedal, but of course the AFRs are all over the place with the throttle opening/closing. And of course, popping and banging out the exhaust. One in particular sounded like a gunshot.

Soooo of course we got a call from the landlord about neighbors complaining. I figured it was before 9, I was safe. Guess not.

Anyway, it's definitely physically fine now, it's just the damn carb. I don't like carbs on anything other than classics.... I'm putting FI on this. But I need to get it to a friend's house that's a little further from neighbors, so I need to get it running on the carb.

This is a classic but if its a GSL-SE with a carb, then it should be put back to EFI.

Hah, true enough! I meant classic as in "designed to be carbureted", since any carby car is a classic these days. This WAS a GSL-SE until a PO ruined it with this crap carb. But I totally agree.
https://cimg6.ibsrv.net/gimg/www.rx7...5c57f96aba.png

I'm just doing it my own way. :icon_tup:

I can't figure out which IM gasket this thing needs... It's definitely a 4-port motor (based on the racing beat manifold), but are all 4-port 13b gaskets the same? It sure looks like the FC TII has a different gasket. I think the engine in the car may actually be a stock GSL-SE 13b, with 4 ports, except all GSL-SEs were 6-port, right? So does a 12a gasket fit? My understanding was the 12a housings were slightly smaller and therefore the gasket wouldn't line up. So is this a REPU AP engine?

Super lost. I need to figure this out so I can get flanges cut for the intake.

gslse 13b is 6port. if that engine was built using se rotor housings and 12a plates, an intake gasket for the early(pre-80s) 4 port 13b will work.

I think you're right. I pulled the intake off today to see this:
Attachment 750789
Attachment 750790

So I guess it has to be 12A irons with 13B housings.