Ok I can work on ANYTHING Rx7 there is. Rebuilt numerous engines, rear ends, trans, etc. I can wire ANYTHING. Completely understand computers and EFI (EGI) but for the life of me can't understand this POS carb. It run incredibly rich, I swear raw gas out the pipe! Before I list jet sizes. It's a stock 12a, straight header to muffler. No cats. Etc runs great with Nikki. It's got a 40 on what I think is the chokes. Isn't that suppose to be a 36?

 

A 40mm choke tube will work, not ideal tho for a stock port. What you running for fuel pressure and idle jet?

 

float level? idle jet? float level? emulsion tube?

the easiest way with the weber, is to tune one thing at a time to get a feel for what each part does

 

2.5 - 3 psi. Under the wing nut thing. 180F11 65F9 I think. I got it all written down at home. When you work the throttle and look inside it doesn't spray a mist like the Nikki it almost looks like drips. I took it apart put it back together. It's actually extremely clean inside. Sorry to sound stupid just don't know about these.

 

Your chokes are a bit too big for a stock port. You want a 36 as mentioned, otherwise the
venturi affect of the choke won't be enough at tip in of the throttle and you won't get smooth
progression. It may idle funny too with the bigger choke, not enough velocity again.

 

so what is the actual problem? if you look in the carb, and it is dripping from the boosters, the float level is too high

 

Ok the problem with it is, its stumbles when accelerated hard. Lightly it will rev. Misses at lot when held constant, say at 3k. Runs EXTRTEEEEMMMMLLLLYYY RICH. Stinks real bad! Smoke on hard throttle.

When operating the throttle the fuel coming out in there isn't a nice uniform mist like on a Nikki. Its almost drip drop looking... I'll take it apart and check the float level. Whats it suppose to be 8mm?

Under the wing nut thing...

180 F11 in there, assumption this is main jet
65 F9 in there, idle jet?

Only thing else I remember seeing a number on under the top part of the carb was 150 85F9

Only thing else was the 40 on the round choke thingy... I can see why 40mm would be too large on a stock part. Not enough velocity to pull fuel through

Sorry to be an idiot here... Too bad I wasn't wiring something rather than this! I was 'told' this came off a perfectly running stock 12A with headers. Which is what I have... Oh well not the first time I got fibbed too. It did get the car running at least tho.

 

The only problem with these webers is ........ you have to understand them.


The good thing is they are really preatty simple.

Until you learn what each circuit does and how the work with each other they can be very frustrating. If you go changing things ***** nilly chances are you will only create new problems.

I reccomend buying a weber manual, they are cheap on ebay. A couple of reading sessions will do wonders.

Now that confounded EFI stuff is rocket science to me.

 

hmmm so are you saying that you have a 65F9 and an 85F9 idle jet in there?



ill quote a post i made a while back that should help w/ the jetting anatomy of the weber, lets find out exactly what you have under the jet cover

 

on a rotary float level is as high as it can go without dripping at idle.

actually i've got a nice weber tuning paper i can email you, its written by a physicist. very simple procedure, once you're familiar with the carb it makes tuning the whole thing about an hour job.

the basic theory of the paper, is that you need to go through each piece of the carb, starting at idle, and working your way up. so like float level, idle jet... etc etc

 

sure take all the help I can get : mikep28@insightbb.com

I checked it out again today. 175 F11 180 in that order , and a 65F9 under the cover

The outside screws that have a jet say 90 in it.

Under the top cover theres another stamping on top of a little brass screw says 150 on it.

 

I have always found a 65F9 idle jet to be way too rich. I've been using a 55F8 with good results.

Your pump jet is also way too big! Should be a 45 or 50.

 

Might explain why it doesn't spray right when it 'attempts' to rev. Choke size is 40. I forgot to mention that. What ever this came of off. It wasn't a 12a stock port with headers.

 

Or it was and it didn't run right so he sold it......

 

If say that's probably more likely... Help!!

 

you have email!

 

I was reading my Weber book today at lunch and it mentioned shaking the floats when you have them out, just to make sure fuel hasn't leaked into them. If you hear sloshing, then you have to get new floats.

Just thought I'd mention that.

I think I'll buy my 45 DCOE new.
But I'll still have to tune it.

 

The floats are empty. And they float I tried it. Adjusted the float level to 10mm. I guess I'll order new pump jets and chokes. That's about all the money I want to spend on it or ill just put a Nikki back on it

 

leave the 40 chokes... put a 160 main fuel jet.. you need a 0 bypass accelerator pump jet(located in the bottom of the float bowl) buy some 55f9 idle jets.. adjust idle mixture screws , done!
if there is still an off idle bog you might need bigger accel pump squirters(because of the larger venturies).. a 45mm weber comes with 45, try 75...

 

actually just to add.

1. don't worry about what jetting you're supposed to have, each combination is a little different (exhaust, fuel pressure, etc etc) and with a jetting chart, we don't know the AFR it was tuned to, or if the car ran well. there are also a couple different ways to handle the transition from the idle to the main circuit, non of which are wrong, but the one they choose might not work for you.

so tune YOUR engine. that all being said, 65F9 idle jet is bigger than i run in the P port, so i'd expect a 55 to be better, although you might end up with an F8.

2. the DCOE idle jets have two holes, and two numbers. the 65 is the size of the fuel jet, which controls how much fuel gets delivered, and thus AFR, and the air hole, F9, controls when the fuel gets delivered. i'm skipping the why, but a smaller hole will deliver fuel until a higher rpm. (this works for the main stack too, its just two separate parts)

3. i've never played with choke size, the P port has 43mm runners, and 43mm venturi's so its pretty easy. i don't we why 40mm venturi's wouldn't work in a stock 12A, i'd leave em

4. somewhere there is an engine size to e tube chart, and a 12A wants an F8, and the 13B an F7, so the F11, is the wrong size. so i'd recommend using an F8, although you can tune around the F11 is you want.

5. i wish you lived closer! i'd gladly give you the stock EFI mess i've got going for the Weber. the Weber is much faster to tune, so its like instant gratification

 

he is complaining his car is running rich, so i would leave in the f11 tubes.. f8 is an even richer emulsion tube, especially in the lower rpm range..

 

true, but i'm not sure the carb is anywhere near being close on anything else. you can tune around an F11, but if you do that, you need to be rich everywhere else.

F8 = mains coming on FAST, the AFR it gets to when it comes on is still the fuel jet

 

I bought a 50 pump jet. It's got a 90 in it. I'll try that with leaning it with the jets you guys recommend.

I do have one other weird question why is the rebuild gasket etc kit I got from mazdatrix holes in the gaskets way smaller than what I have? Im referring to the gaskets where the intake manifold bolt to the carb and also the gasket to the air filter... I didnt use them I reused mine for that. But the ones they sent me for a 45DCOE are way smaller...

I wished Id ripped that T2 UIM/LIM throttle body wire harness, CAS and coils with the ECU.. I'd be done

 

Rebuilt a Nikki I had laying around today. Yelp runs PERFECT. PURRS like a little kitten. I love getting carbs with bad motors. They are almost always good find a motor with no compression or lock up and recently. It'll probably be good cause its been driven.

. New jets will be here in the morning. We'll see what that does. Almost wasted about all the cash I want to on it. Also getting ready to tear down 2 motors. The 85 I did half of today may have a decent rotor and rotor housing. I don't really need anything else off it. Let me know what you might want. The other is suppose to be a 83 LE. It became a 302 swap. It's probably a good motor. It's got power steering and all the stuff on it. I got another 83 with 70,000 miles locked up. Been sitting a LONG time.

 

Yelp no use for this Weber carb stuff... Its for sale...