Started up the '84 12a for the first time in the MGB tonight. Getting exhaust (just a header pipe now) and the air cleaner monday. Idles great at ~800 seems to start to crap out at ~4000 just in neutral. I'm not going to be running it any more till it gets towed up to the shop for the exhaust. Doubt it's too good for the apex seals with no back pressure.

Does the carb look all plugged off right to you guys?

Yes all the block off plates are done and they don't leak and it's running pre mix. The red and black wires are not hooked up but I don't think they have to be.

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carb looks dirty inside and out. you may have partially obsrtucted jets, perhaps picking up filth from the float bowles.. i would suggest a full rebuild. the kits are readily available and run about $20.

 

^^^^^

when working on a carb you need to start fresh. Then go from there.

So first thing first rebuild it, then if any more problems exist post about them

 

Is your shutter valve jammed in the open position?

 

Yep. If it ain't broke, then clean it. Rebuilding isn't too bad, and you can get some tips from reading the writeups at Sterling's site (www.sterlingmetalworks.com).

 

pic 1 you need to plug that nipple on the shutter valve. also, why is your oil intake plugged, are you running pre-mix?

and +1 on the cleaning and rebuilding, make it look all purrty and perform well

 

First off. Unblock the top left red cap. That's the float bowl vent. You want to run al vac line from that to under the engine (away from heat). That's where you float bowl vapors come out when the engine is off. It needs to vent or you will boil your gasoline inside the carb. That will be dangerous and it will cause start up problems.

Next. You have the caps on your shutter valve reversed. Cap the big barb and leave the little barb uncapped.

You don't need the middle part capped under the fuel inlet. I have always just kept it open.

When the engine is running, and you blip the secondaries open, can you see fuel spraying out? If yes, your secondary linkage is sticky. If no fuel, it's time for a rebuild.

 

I pit my finger over the big one with it running and didn't feel anything bit it's easy to cap


So first picture, red cap under the vent solenoid?

please elaborate... at idol reach in and pump the secondaries? Or rev it up and watch for fuel down the secondaries? I am still running with (I hope) vac secondaries or have I pulled out too much stuff?

Thanks guys

 

^ What he said and your shutter valve is jammed in the open position, as already mentioned. It should look like this at rest. The way yours is means the shutter valve butterfly is almost closing off the intake to the rear rotor (unless you removed it). Be sure your timing is correct also.

 

If you're modded to mechanical secondaries then you may not be getting enough gas to the carb. I modded my Nikki to mechanical secondaries and it ran awesome until about 4000 rpm. I just installed a better fuel pump and a FPR and now it kicks ***!

 

I think they might be in a similar position. Mine is slightly farther to the left ... rod is farther out of the vac pot. Does the linkage all the way right (pulled in the vac pot) make the flap inside the intake open?

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also how do you plan to vent your oil system?

 

You are correct. The photo angle was deceiving me. Here are some not too pretty pictures.

 

Also, is that hose heading out the bottom of your first pic going to your distributor? That's manifold vaccuum if I'm not mistaken. You need venturi vac for the dizzy.

 

Yes. Everything I've read on this subject (rat's nest removal) says second from the left is where to stick it. Actually I did see once it was said to put it on the far left one. If you have a better proven way post it up.

Also I was going to route the top oil vent in the oil filler into a nipple on the bottom of the air cleaner housing.

FYI I'mRunning a fuel pressure regulator and it's at about 4 psi

 

Have you replaced the fuel filter yet?

 

It has 2 new filters with 15min or run time on them, one large spin on style after the MGB rear pump and the cheap inline after the aftermarket pump and fuel pressure regulator and pressure gauge. It is getting steady pressure to the carb all the time.

I'm more concerned about if the nipples etc are all plugged off right on the carb and if the stock vac secondaries should still work given what I've taken off.

Yes, it's probably got crap in in but if I have things plugged off wrong the rebuild I'll do on it won't help.

Glad I've learned about sticking a hose on that bowl vent that I capped

 

u can still do some more stripping...plus if i were u i wuld take that black plastic sht off...then under that theres some pollution stuff and racing beat sells a little metal plate for it..it helps run better and looks 69697869x bettter...if you dont know what im talking about lemme kno ill post pics of my old set up

 

Secondary vacuum supply comes from inside the carb, The capped vacuum lines should not effect it.

 

Thanks all.

I'm delaying the exhaust and going to order a carb kit monday. hope I can find one through lordco, auto sense or napa (any fellow canadians have any luck getting one?) Pulled the top off it tonight ... not good inside.

Sino.... everything on the intake is already plated off. Not going to get rid of the plastic shield due to heat getting back up to the carb. Also, I did the 20mm frost plugs for the coolant block off when I had the engine out and the intake off.

 

The pictures on my site may be helpful. http://intertron.com/ron/carb.html

I like to soak the parts overnight in Gunk cold parts cleaner. Don't loose the two tiny ball and weight combos. Blow out the passages and jets with compressed air before reassembly. The FSM has good directions, but the 79-85 carb manual, downloadable from these sites has more detail.
http://www.wright-here.net/cars/rx7/manuals.html
http://www.foxed.ca/foxed/index.php?page=rx7manual

 

dam....looks like your on your sht...good job..i love stock carbs tho..u have no idea how many rotors with holleys ive given it to with my old stock carb setup...its amazing..lol

 

Runs good now that I did the carb. Exhaust on friday. It's hard to set the rich lean with only 2' of exhaust pipe and a home made manifold.

 

Don't tease us too much longer... we demand wider-angle pix of the whole project!

 

is there a write up on how to tune a stock carberator..?