12a Rebuild: ITS ALIVE!!! But running rough & dies on idle
 

Indeed, it did start.
No leaks found.

Sorry no video. Pics attached.
Some initial white smoke, then a little black smoke.

The heat shields above the exhaust are coated with oil-gunk. This started to smoke after 20 minutes.
Question: Is it OK to let this burn off or is there some danger level to be avoided.

Last October the engine was leaking oil everywhere and the exhaust would have made a great toxic smoke machine. That's all gone now.

Biggest issue:
Before the rebuild and now it runs rough, and will not hold idle and dies.

Noob question:
Could this be caused by something as simple as a clogged fuel filter. I was bleeding the rear brakes and filling the differential today and noticed the inside of the fuel filter appeared dark grey.

I'm thrilled it runs and the big issues have been corrected. But its not road worthy yet.

I'm still waiting on front brake pads and the replacement hanger for the one that melted when the engine barfed oil.

Possible timing issue, possible carb or carb-adjustment issue. If bowl levels look right at idle but it won't hold idle, it's probably not the fuel filter - - filter problems tend to show up as fuel demand increases, instead of the other way around.

Did you work on the carb at all while you had the engine apart?

I personally would clean the heat shields, but can't say definitively if it's a safety issue or not. Probably not.

Did not work on the carb during the process.
I'll check the bowl levels.

Some time back the diaphragm on the AAB 2 was leaking and it died at idle. I'll check that one and other possible vacuum leaking valves.

Yeah, the oil-smoke stinks. Time for it to go.

That was one a hell of a journey. Nothing was overly hard or difficult, just lots and lots of steps. I have been educated.

Clean the oil off with some Purple Power or brake parts cleaner. You never know how long it could be there smoking. I would first start with the timing adjustment. Second, I would pull the carb and rebuild it along with a new fuel filter.

Virgin no more! :egrin:

Thanks.

This is an issue which had grown steadily worse up to the point where the rebuild has required last Oct.

I would make sure you have the timing right also I would rebuild the carb and change the fuel filter

I bought the carb kit from Black Dragon last year as I needed the accelerator pump diaphragm. Still have everything else.

Timing is non-intrusive. A good place to start.

there is a page either in section 1 or the beginning of section 4 in the shop manual, and it tells you the steps to do a tune up, i'd just do that.

it is all simple stuff, like checking the timing, and setting the idle mixture, but its sometimes nice to have a list.

the oil on the heat shields actually can catch fire and burn, but i think you would really have to try to get it to do it, so its a hazard, but not a huge one.

cleaning will suck, but it is nice to have the bottom of the car, not a tarpit

Tune up: Section 1, pages 6-9. Most already done during assembly, but trailing timing is something not obvious.

Thank you.

I'm running out of cut-up bath towels, I'll switch to paper for the initial globs.

When checking the bowl levels, does the engine need to run, or just the key in the on position? (I'm guessing the latter.)

I turned the key on for 10 minutes. The float level in the front bowl did not change from barely visible to barely visible. Bouncing the car I could see gas sloshing inside but not even reaching the glass window.

there you go it looks like your float level is low

Never mind. I found my answer in the On Vehicle Adjustments, page 73 of the Mazda Carburetor Manual 1979-1985.

"With the engine operating, check the fuel level. The fuel level should be in the specified mark in the sight glass."

When you turn on the fuel pump, it should fill the bowls to the line on the sight glass and then stop rising. When the engine is running, fuel level should stay at the mark regardless of RPM.

Whole point of the bowl/float/needle system is to keep fuel at a constant level relative to the height of the various jets, and therefore at a constant pressure. Same reason the bowls have to be vented, to keep air pressure above the fuel constant relative to atmospheric pressure.

Fuel level may or may not be the only issue, but it does make a big difference in mix, specially off idle.

That is what I thought you were implying earlier.
Time to rebuild the carb.

Thank you for the explanation. Really does help.

Im new to RX7's but not to cars, and I just got done rebuilding my Nikki. Its supper easy to rebuild just take cell phone picks for reference and use a god cleaner like simple green or 505 Degreaser. The biggest piece of advice I can give you is be super cautious of the floats. The top of my Nikki fell off the bench and bent my floats. It caused a tiny leak in one float that made float level erratic and threw the other out of adjustment. It took me forever to get them set right. Just replace your needle and seat and don't adjust the floats until after you've tried the carb on your engine. Also NAPA has been having trouble getting me floats seems almost everyone is out of stock.

Its running OK for now. I'm planning on rebuilding the carb over the winter when I don't drive the car.
I'll print your post for reference.

Thank you.

Check all and every nipple coming off of the intake i just rebuilt mine and it popped and sputterd and died on idle only to find i had vacuum leak right at the intake manifold