Shadow2

Good day all,

The car (1982 Rx7 GS 12A) had to sit for while after i messed up my carb. I had to replace the intake manifold to engine housing seal, and after i got it all back together the carb leaked gas all over the place, and the secondaries filled up with gas if you left the pump running. So long story short, i lost my job, i meet a girl, found a job, got married, bought a house, and have now rebuild a carb. yeaaaaaaaa!

The car was not perfect before it sat for a good years or two. I have it running again, the exhaust is rusting out. It is not smooth, it shakes at idle, and smooths out as you rev it. Also, some times under constant throttle it bucks, but is smooth under acceleration. Some times it smooth as can be in any gear at any speed. Its getting better as i get the idle set closer to 750. It does back fire from time to time, i know it did that before it sat, and i think the idle was a little high(1000 +/- 200). I think i had all the vacuum leaks fixed. I could spray ether all day and not get a response from the engine. (Which is true now also.)

I think i may have a plugged cat. The car sounds like a train going down the road. chug chug chug (from inside). It only chugs once you hit a constant speed, not as you accelerate. It is also louder inside then out. So the hole may be on the top of what ever is broke.

Mods that may affect your help, i have an electric fan that is run off a switch right now.

The plugs, wires, coils, and internals on the distributer are newish. I have good spark on the all plugs. Other then that the car is all stock. The motor has 68k on it i think, the car has 168k. All the rotors sound good, but that is an ear thing. I don't have the tool for compression. Does not drive like seal is bad or anything.

I don't have a digital tach, or exhaust gas analyzer like the book asks for. I am "tuning" the carb like Stirling sites says.

Ok my questions, what would make a rotary shake?
Also can i try to set idle with an exhaust leak?
Should i set the idle with the fan on or off? (I think on cause that is when it is on most of the time, when I'm setting at a light.)
How much air flow is there at idle out the tail pipe?
How much loader will the car get if i gut the cat? (if i can even get it off.)

mazdaverx713b

iTrader: (91)

-can i try to set idle with an exhaust leak?- you can, shouldn't effect the idle much

-Should i set the idle with the fan on or off? - set the idle with all accessories switched off

-How much air flow is there at idle out the tail pipe?- it should blow you into the next block and burn the dickens out of your hand

-How much loader will the car get if i gut the cat?- it won't be bad at all. the stock muffler does a great job of keeping the exhaust quiet. will seem a tad sharper and a hair more tinny than stock.

Kentetsu

1. Have you replaced the fuel filter yet?

2. Get an automatic fan controller. Using a switch to control it puts you in a situation where you are one minor distraction away from a blown motor. Forget to turn it on once, and that's all it will take. The one I use comes from Autozone, and the cost is under 20 bucks, which is a hell of a lot less than a new motor.

3. Exhaust issues should not interfere with tuning the idle. Glad you found Sterling's website, otherwise I would have sent you there.

4. Gutting the cat shouldn't make the car much louder if you have the stock muffler. Better yet, replace the cat with a straight section of pipe (assuming you don't have emissions testing).

5. Double check all of the work you did on the ignition system. You would be surprised at how easy it is to make a small mistake which leads to very frustrating problems. Make sure everything is routed correctly, and that the leading ignition is actually firing the leading plugs.

6. Since the car sat for so long, grab a can of Seafoam while you are at Autozone getting your fan controller. Don't get fancy with it, just dump it into the gas tank and it will do what it is supposed to.

7. The shaking issue itself could be due to a number of things: something blocked in the carb, a sticky apex seal (either issue may be helped with the Seafoam), or an ignition issue.


Anyway, that should be enough to get you started. And seriously, get that fan controller!

Good luck....










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Shadow2

I did not think to replace the filter since it has sat. It had a new one right after I bought the car. New one won’t hurt. I have never done the sea foam, will give it a try this week end I think. Will also go over the ignition, will not hurt either.

I am going to try to wire the fan into the temp sensor for the car, and the air conditioning solenoid. Then see about getting a controller that will turn the fan on and off at different temps. So far I don't need the fan, unless I’m just sitting idling. Car has not overheated yet with the new radiator. Has been great, and I think I found all my coolant leaks. (A heater hose blow the first drive after getting the carb rebuilt.)

If the sea foam does not stop my shake, should I focus on the ignition system?

Thanks for all the input!

Shadow2

Does any thing electrical play a role in the idle? When i turn my headlights or even my parking lights on the car dies (when at idle). I can keep the car alive by giving it some gas, but makes driving at night hard. My electric fan does not kill not car, but does lower the idle, 100 to 200.

I have done one can of sea foam, still need to go get my fuel filter. All the spark plugs wires are right, i get a spark on all the plugs.

I can not get the idle lower then about 1200, with out it dieing. So something is wrong, i just can't find it. It is still rough at idle and just off idle but smooth all the way 8k.... I have had a few time where when i leave a light it just falls on it face, but then comes right back. Only when i go light on the throttle (does not happen much).

I don't know i still have somethings on list to try anything else to add to list with some new information?

ricerockettuner

my car shook at idle with the stock nikki and all. had hesitation off idle and studdered at a constant speed too.. all of your same things.. theres a butterfly on one of the primary barrels under the carb but above the manifold that is vacuum operated.. someone told me that it had been closing at idle and some at constant speed making it run on one rotor unless i was gaining speed

Shadow2

Ok forgot about that guy.... At idle should it move around (open and close) or just sit in one position? I have no honking or vacuum noise. But I do have a rough idle.

My other question, can I just lock it open if I'm not worried about emissions? (And for testing.) Or does it do something to protect the engine? Also will this make the car idle weird or run bad? I also don't mind it backfiring if I know why....

Kentetsu

Yes, you can lock it open without any bad side effects. I removed mine years ago.

A high idle that you just can't reduce is usually a sign of a vacuum leak.

Read up at Sterling's site on how to tune the idle: www.sterlingmetalworks.com