k so its not a terminal problem but an annoying one...
the shop i got my car back from with "new" engine(woot 150$) and all.
they say it's running rich, and i can see it's idling high (1100 cold 1000 warm) so (i know where the screws are thats not my question) how exactly to know when my fuel mix is correct, and exactly how to get a low safe idle.

sorry for being incompetent with the search feature

 

Turn the mixture screw in until the engine starts to hunt, then turn it back a half turn. The adjust the idle screw. Repeat until the engine is at 750rpms +/- 50rpms

 

Before you go and adjusting thing that may just be masking another problem.

You need to check and make sure that all vacuum hoses are good, (not leaking) and that you don't have any vacuum leaks anywhere.

In a old thread you stated that a shop said your engine was running lean, now this shop states that it is running rich?

Ask the shop why they believe it is running rich.

 

k i got a new engine, and my carb overhauled so it needs tuning to get the mix right, there not idiots i may have misprinted it if its a recent post so i apologize, but if it was months ago, then the situation has changed.

ps. i dont think i have a vac leak, as the idle though high is strong and it starts easy cold(practically dont need the choke)and warm, but does not having the shutter valve hooked up count as a vacuume leak

 

It would only need tuning if the mixture was touched before you overhauled the carburetor.

Again, also why do they believe it is running rich? Did they hook it up to an gas analyzer?

 

it stinks more than usual and backfires when i lift off the throttle plus it shoots unburnt fuel out the tail pipe when i lift off the throttle sometimes,
but the idle speed needs adjusted at least correct
and i left it with my friends for a while to help with the swap(before i took it the the shop) and they may or may not have f'ed with the carb

 

k i started tuning it and i think its right but i cant get the idle speed down.

k so which way do i turn the mixture(counter or clock) to get the mix leaner, and which way lowers idle, im guessing counter on both but help please if you can.

in exchange i offer pictures of cookies and cakes.

first time with a carb my only real experience is f'ing with my ae86 i had for fun lol so im kind of new even though i had limited experience working with this car.

i really appreciate the help from rx7doctor but my car seems special im turning the screws and not much seems to happen besides the exhaust overheat light coming on when i turned it way to lean lol.

thanks guys

 

If you want to learn how to setup/tune your carb, download the carb manual from the FSM link in my sig. As Doc said, first suspect is usually vacuum leaks. They will cause a high idle that won't come down, but tend to lean out the mixture, not richen it.
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k will do i'll check the vaccume on it, but how exactly do i do this, sorry if im to much of a nub lol.
not really a mechanic, but trying to save some money lol.

 

That's how most mechanics are made...

 

Searching will give you several methods for finding vac leaks. Simply put, with the engine idling, you need to spray something around potential leak areas and listen for any changes in rpms. Carb cleaner, water, brake cleaner an unlit propane torch are a few of the options. Finding vac leaks can be tricky and frustrating, especially with the idle above 1k as the fan can blow whatever you're spraying away from it's intended target.

Hit the usual suspects, vac lines/solenoids, mating joints where there's gaskets on the carb/intake system, pcv system, fuel vapor recovery, etc.. If the carb, vac lines and related components haven't been disturbed, try getting the idle down first.

 

k thanks for all your help i read a bunch of tutorials.

k so i'm going to try tuning it how sterling's tut. says to do it if it cant go down then i'll search for vacuum leaks, but considering i just got the carb rebuilt and the engine installed by professionals i doubt it's a vacuum leak .

but i would like to fix this, it's not essential as it's not my daily so i can work on it over time.

 

Following Sterling's writeups will put you on the right track. DL the manual and familiarize yourself with all of the carbs components before you even start. With the price of gas and parts, getting the idle down to 750 will save coin and pay off in the end.

When you screw in the air/fuel needle, be gentle when it hits bottom. It's very easy to damage the needle/seat by torquing it down too much. Then back it out 3 to 3-1/2 full turns. Next, back off the idle screw. If that doesn't help, first thing to check is the slack in the cable between it's last mount and the carb. Doesn't need much slack, 1/4" is good. It's possible that when they rebuilt the carb, they didn't leave enough slack and the cable is holding the throttle plates open a tad, causing the high idle.

After that, check for vac leaks. If you don't find any, they may have mounted the carb spacer/heat shield incorrectly, used gaskets on that plate, which aren't needed, but still come with all rebuild kits, cracked a dried/rotting vac hose, missed a hidden one, crossed some of them up, etc., the list goes on.

If you do end up digging into it, I would replace all of the vacuum hoses. Be extremely careful when removing them from the plastic solenoids. It's very easy to snap off the barbs. It's best to slit the hose at the barb and and heat/soften the vac hose to remove it. You won't find any pre-bent vac hoses, but you can get around that by using longer new hose and making sure there are no kinks. Buy about 2-1/2 feet. I replace 1 hose at a time so I don't cross them up.

Good luck and post your progress.

 

Also worth checking the throttle opener for the A/C. It can also easily be set incorrectly during a rebuild, holding the throttle open, or it could be worn and sticking. Some rebuilders just take it off & put it back on, never checking it, but if the new base-to-body gasket is thicker than the old one, it'll raise the TO up a smidge.

 

k i think i found my vacuum leak, its anti afterburn valve thing no.2 lol

the hose going into it from somwhere (not sure where need help, not either of the ones going into the filter) isnt in the car, but i found this hose in my car, thats curved and looks like it is for that valve.
so my question is...

the hose goes down to the engine block or to the opposite side of the carb, i found a thing that has a vacuum cap on it down near my exhaust manifold, is that where i connect it?

 

bump need help, where does the anti-afterburn valve#2 connect to on the engine not the intake please help

 

Since I don't have a single 7 with the stock carb setup, my help may be limited. 82 FSM, Sec. 4, p. 7, diagram, 4-25. 85 FSM, Sec 4A, p. 39, diagram at the bottom of that page. Between the 2, you might be able to figure out where the hose connects. Unfortunately, that's the best help I can offer.

I didn't see anything in the carb manual that offered any help, but I do have hard copies of the FSMs. If I understand what I read correctly, the hose for the #2 anti-afterburn connects to the air cleaner. Not sure what cap plug you're referring to, pics would help.

 

thanks, the fsm dosnt really say where it goes but thanks for the help

 

This may help, though it's possible there were differences in the 81 and 82:

Downoad this PDF from Sgt. Fox's archive: 1981 Training Manual:

http://foxed.ca/rx7manual/manuals/19...ing_manual.pdf

Look on page 45: There's a schematic of the emissions system. If you look closely, you can see that it says the #2 AAB is connected " to Rear Secondary Port."

The #2 AAV was new on the 81 build, so it's fairly likely that it didn't change between 81 and 82.

Page 54 on goes into more detail on how it works. Might help ya, too.

 

thanks i found it, now to get the idle down and see if there are more leaks or problems