I'm prepping my car for its first outing next month and have some questions. This is the first RX-7 I've really worked on without an RX-7 expert so...

1. I have had a stumbling issue from when I bought it. The tank was dropped and cleaned, new fuel pump, new fuel filter, new lines, etc. It idles smooth, revs smooth until 3500ish it stumbles then clears out and is fine until redline. I made a thread about this when I bought it.

I'm unsure on where to begin but noticed two open plugs on the carb, I wanted to see if these could cause issues and if they should be shut. Both are on the driver side of the carb:

1.


2.



2. I noticed a good oil leak/sludge build up near the OMP. Is it a hard process to block off the OMP and pre-mix? Is it OK to run with this leak (all tech aspects aside) or is it causing damage to properly lubing the apex seals?



3. Today I was just making a checklist on what I need to do and noticed my radiator is fairly dry and quite rusty inside. I'm hoping it's not that bad in the engine yet, on the list now is a radiator flush or replacement and both upper and lower hoses. What could cause the coolant loss? I haven't seen a leak or anything but the car hasn't really been driven. It was last really ran in a race in February but retired due to the stumbling issues, it was sold to me in June, then I drove it home, one quick interstate drive, and I've started it up once a week just to keep some fluids moving, now though that has me worried.

That's about it for now, I'm sure I'll update here as I move along, any input appreciated!

 

OK for the coolant issue I removed the radiator, a LOT of rust chunks in the hoses and radiator, so I'll replace the actual radiator. Most of the rust seems to be around the outlet pipes, is this common? Should I replace the water pump? I guess I'll replace the other outlet as well.

I'm planning to put it back together, run it, then re-flush it, run it, then re-flush it to hopefully get any junk out of the actual engine if it's there.

 

Flushing it would be your best bet, I found a lot of sludge in mine
the first pic you posted is a shutter valve I'd plug it not really what the second one is though

 

Copy that, thanks!

 

Yea on that first one, just look down the carb with the throttle open and make sure the shutter valve is open. I cant recall if its normally open or not. You'll see it down in there. It's like another throttle butterfly in the manifold.

The second pic is just an air vent passage. Leave it or cap it, no difference either way. Now right below that fuel inlet is a hex shaped solenoid (hidden in your pic by the fuel hose). Look at the black wire with the white stripe. It looks disconnected to me. That's bad. It's an air vent solenoid that needs to be functioning or you will have all kinds of problems.

As far as the OMP goes, as long as its outputting the correct volume of oil out the little tubes, your getting adequate lubrication.

 

Cool I'll check that plug, the only running issue I have that I've seen is the stumbling/sputtering thing around 3500 or so and clears out towards redline. That's my main concern, the car never sees street use I've only driven it twice down the road and back and that's all that I could feel engine related.

I may do a basic plugs,cap, rotor, plugs, and maybe coil to see if that helps before I go into unknown territory (carb), they all look fairly new but you know how that goes. lol

 

The air vent solenoid mentioned was indeed unplugged, I plugged it back in, I can't drive it right now as I'm replacing the radiator and some other things, would this have caused any of the stumbling issues? Hopeful thinking but I can't imagine anyone that worked on it before me would have missed it. lol

 

Based on the last picture, I'd also say you have a Oil Metering Pump leak.

 

Yeah I know, I was wondering if the leak however would be an issue properly lubricating as it should or if I need to pre-mix some before I block that off or if pre-mixing with the pump still on is even OK. lol

 

Sounds like you are having issues transitioning from primaries to secondaries (on the carb). Personally, I would convert to mechanical secondaries (takes a paperclip and five minutes if you've done it before). But, I'm partial to mech 2nd's anyway.

Another possiblity would be that the secondary fuel jets are partially clogged. You mentioned that you replaced the fuel filter, but is there any chance that it has since become clogged again? Although, the fact that it clears up near redline kinda rules out a lot of that.

Maybe try taking her for a run again, but try holding the choke **** out when you do it and see if that changes anything. If it improves, then you are probably looking at fuel starvation.

Good luck.



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I don't think I can do mechanical secondaries in my class, but maybe I could do it just to see if it fixes it then swap it back.

It hasn't really been driven since the fuel filter was swapped to my knowledge, all this work was done before I bought it, then I drove it and the issues were still there it has been driven probably twice since that.

No choke or I'd try that idea. lol

Thanks for the ideas though!

 

As far as the OMP goes, block that sucker off and pre-mix!!!! You don't want that thing failing while you're on track, and the pre-mix is better for the car anyway (imo).

I agree that it sounds like you have some carb issues. Maybe get a fuel pressure regulator and a gauge to confirm it isn't something else.

 

I plan to for sure.

I'll get a fuel pressure regulator and a gauge and check into that. Thanks!

 

Reading up on removing the OMP is it really as simple as just unbolting it, making a plate, and calling it done? Nothing internally has to be messed with?

 

If I rememeber correctly, do not use the old bolts because they will be to long with the block of plate.

 

Well ordered a block off plate as they're cheap, so I'll slap that on and pre-mix.

Also flushed both of my radiators out (the one that was on the car and a spare) and got new hoses.

Quick other question, what is recommended other than antifreeze/coolant? Can I just run straight water + maybe Water Wetter or is that a no no in a rotary? I know running just water will cause rust issues, but I can't run anything that's slippery. Any recommendations?

Edit: Didn't search long enough before asking, here's a good thread for anyone running across this one looking for the same answers:

https://www.rx7club.com/1st-generati...oolent-299071/

 

do 50/50 premix coolant.

 

I can't run coolant.

 

Motul MoCool

Motul - All Products - MoCool

As advertised it's designed to be run specifically on it's own where glycol anti-freeze's cannot be used and is legal in several race series', tech data sheet also provides coverage for aluminum alloy, cast iron, brass etc. which covers just about everything you'll find in a rotary.

Tech Data:
http://www.motul.com/system/product_...pdf?1335380000

I don't have any personal experience with it but its what I've decided to use once I get my 7 back up and running.

Best bet is to ALWAYS double check with tech before but if you can't, go with a safe bet and hope for the best.

 

Nice I'll check that out.

I'm a little more careful now on what's in there as at my last race my co-driver punctured the radiator and what was the one thing I forgot to do? Yeah...coolant everywhere, luckily just in pit lane but now I'm paranoid and would hate to be the cause of someones accident.

 

So I plan on getting this thing back up and running today to drive it around some. I'll need to pre-mix now as I removed the OMP. is 1 ounce per gallon overkill? Remember the car doesn't really see street use so it will be primarily track driven.

I've done a lot of searching on what people like to use but it seems like TCW3 rated oil is the best to get? Anything else to look for?

 

So....first event is done. I didn't want to start a whole new thread, so have some additional questions.

FIRST OFF! Plugging in that air vent solenoid DID fix the sputtering issue. I can't believe it but the car ran smooth after I plugged it in. lol

A few questions:

-What can I check to make sure my carb is setup right? The car feels down on power and I know the carb was messed with by a PO, specifically the float levels. Would that effect performance?

-I am getting some weird drivetrain issues that I just can't pin point. I get a vibration around 100mph, that may be just wheels out of balance, but I also get a whine at any speed/RPM in any gear and a shutter as I move off the clutch. This weekend a few times I noticed a very clear vibration coming through my shift ****. I noticed it driving back to my paddock and thought it COULD be pickup causing it and just tricking me but then I noticed it while idling, it doesn't stay and doesn't happen all the time. On track it all seemed fine, not hard to change gears or anything. Any ideas?

That's really about it for now. The car handled very well, I LOVED it, absolute blast to drive, with a little more power, new brakes, and that vibration smoothed out I think I can drop quite a bit of time.

By the way what does the shift buzzer sound like? I figured it would be removed, but I hear a ringing noise, even at idle now that I didn't hear all weekend, I can't tell if it's a true mechanical noise or something in the car, it doesn't seem to get louder as I rev it or anything. Is there a fuse for it if the buzzer is indeed still hooked up?