Tuning a 45 DCOE weber?
 

So i gave up on my nikki, and ordered a 45 (that was three months ago,....but we wont go there) now I cant, for the life of me get it to run right.

when i started i (again, jut=st like the nikki) got the mixture and ilde srew mixed up (miss-comunication between me and the "supplier") so those where jacked by the time i got it to Ide anything under 3.5k, but i did, so i proceed to do what the "supplier" said to do to tune the carb which i couldnt do so i got on here and SEARCHED and found a good right up, that was almost the same procedure as ,y "supplier" gave me https://www.rx7club.com/showthread.p...t=weber+tuning
so i did this and the damn thing just doesnt even out; I will start it, get it Idling then turn the mixture screws in untill the engine trys to die then turn them out 1.5 times. sometimes i can and sometimes i can go all the way in with them and it wont effect the way the engine is running. so ide unscrew them to 3.5 turns out and adjust the idle and start over somehow adjusting the idle will make it different and turning them in again will make it do what its supposed to , when i gen it set, You know the 1.5 turns out from the cutout point itidles really lopey and sometimes its smooth but when i give it gas it always smokes??? and some times it will spit gass out the right tube( if ur on the right side of the car) it also sometimes just pours fuel out that tube on start up
Im lost and sorry for the long post im trying to convey my troubles, carb's just arent my strongest point

thanks

Dustin

What size is ur idle jet? The larger idle jet, the less turn you would need. For example, since im using a 75 idle jet in the IDA, it idles good with only .75 turn.

Gas spitting out of the tube? Lower the fuel pressure but MAY need to adjust your float.

Gas spitting out? Maybe the banjo bolt needs to be tightened.

Do you have a single inlet banjo or the double? (Are you running a return line?)

Re: Tuning a 45 DCOE weber?
 

These settings are for a 12A Street Port. So I don't know if your engine is 12A or 13B street port or stock.

So here is an example of some settings. These works great on mine...

12A Street Port

WEBER 45DCOE JETTING

40mm Chokes
4.5 Auxiliary Venturies
Accelerator Pump Jet 50
Emulsion Tubes F11
Idle Jets 60F9
Main Jets 200
Air Corrector 180
Fuel Pressure 3.0psi


All carbs are different. So you might have to close both idle mixture screws and then turn one out until the car just bearly runs. Take note of how many turns it took. Then close it back and do the same to the other idle mixture screw. Then close it back. Now open both of them to what ever turns they let the engine run. Then start opening them 1/4 turn at a time on each mixture screw. Take notes so you know how many turns out you are. This will also could be used to get it back to a runing condition should you have to close them again.

The carb may have one mixture screw that needs to open more than the other in order to run the engine. I know, because mine was like that.

According to the book I have. Some carbs depending on what model it is. might need 1 1/2 turns out or some will need 2 turns out. That's why you should close them both and them open one idle screw out 1/2 turn at a time until you car stay runing. it will run but not quite good, you just want it to run even iif is erratic.. then do the same to the other screw. Once you got it running ruff, you can start the proces of adjusting them by turning them 1/4 to 1/2 turns out each at a time, allowing the car to settle for at leat a minute before adjusting again.

By the way the stock fuel pump will not be to good for a 45DCOE. I have a carter high volume pump set a 3.psi

anything more than that will cause the carb to flood...

So it seems that everyone agrees that the stock fuel pump sucks for the Weber upgrade. Alot of people I talk to say the Carter is a good pump, but I'm wondering about just putting a GSL-SE pump on there. Would that do the trick, and would a pressure regulator be necessary too?

In the future, I will not USE a carter again...I have bad experience. Yes, ok to use the stock GSL-SE pump but have to use a regulator with a return as the pressure is too strong for a carb set up.

i am using the stock fuel pump with no return, but i was told this would work by Rob at rotary shack, and have no clue what jets are in it, I told him my setup and he went though the carb to set it up for me.

Really? I didn't think the stock pump moved enough fuel to really do the trick. I know that since I've put the Weber on there that there has been little, if any, increase in power. I dunno though, I'm kinda noob at this.

I have had okay success with bung welding an O2 and getting an A/F gauge. Gives you a little more to go on than butt dyno and your nose.

That's not a half-bad idea. Has anyone ever used a Colortune? I wasn't terribly impressed with it, but it was fun to see the actual detonation. According the the Colortune, I'm running at ideal. Doesn't feel like it, though.

You may find some useful info on this thread I started almost a year ago. I farted around with a 45dcoe on my stockport12A for a few months. It accelerated great, even down low but I had a pesky hesitation at crusing speeds. Since my car is really for long cruises (not WOT street dragging or racing) I opted to go BACK to a 4bbl Nikki. I'm working now on installing my modded Sterling Nikki (gotta find a vac leak- me thinks)

NOTE- I was tryng to tune an OLD style 45dcoe- so I would imagine your's should be easier. Check out the info:

https://www.rx7club.com/showthread.p...s&pagenumber=2

I'm still learning how to handle it. I know I can't just floor it off the line, because it just dies. Feels like it needs more fuel at that point, but I won't know unless I test.

Hesitation @ cruising speed is the idle fuel jet. Typically too small. My Dellorto's use size 75-82 depending on motor, etc....

aaahhhh....rgh man this is agravating me...... ok I did the; turn both mixture screws in and get on running then do the other thing, it took (from passenger side of car) 8 1/4 turns on the right and 18 on the left, so I put them at that and start it up, it started and idles with a little coaxing but it was missing (thats what it sounded like to me) but Iff i turned the idle down any it would try to die, it was idleing at about 1.7k, any opinions?
anyone know of a carb/weber shop in the springfield MO. area?

i was also wondering what are these screws doing inside the carb, like if i turn them out is it letting more air in or less, r more gas?


thanks

Dustin

I'm having these same issues. I can tell for certain that my floats are not adjusted right. Can anyone please tell me the correct float adjustment specifics. I have all the jetting done for 12a streetport but this thing is flooding badly

http://www.piercemanifolds.com/category_s/317.htm


once float level is set, adjust the fuel pressure regulator to lowest pressure possible, say 2.5, then gradually increase the pressure where fuel is not dripping inside the venturies.

Ah you should only be a turn or less off between the two mixture skrews. Also if you are more than 2-3 turns out your idle jet is too big. But you need to be making adjustments at 800 rpm too.

9 Year old thread resurrection!

Bringing this back
 

So i have read through this thread and the other linked, but am still having a ton of problems. I have a street ported 12a with the "weber" carb from rotaryshack.

Rotary Shack Custom Mazda RX-7 12A Weber Intake Kit | Rotary Shack Store

The guy i bought the car from told me it had jetting problems and to call them. I did and they suggested the jets I currently have in. They are not too far off from alot of the posts, just a little smaller. Ever since I installed the new jets it was a pain to start and it will not run under 3k RPM. With my reading i went through and replaced the regulator with a holly 1-4 psi. I dont know what the fuel pump is. Oh and it leaks fuel from the venturi. I thought that with lowering the fuel pressure that this would go away but now i think that i have to adjust the float level. Any help would be very useful. I really want to get her back on the road again, been sitting in the garage for almost 2 years now.

bump

if it leaks from the venturi at idle, that is step one, its ok in a race car, but a street car you should lower the float a little.

Quick up date, lowered float level and no longer leaks from the venturi. Still wont idle below 3k rpm, i pulled the idle jets and made sure they where not clogged. Perhaps is it my throttle plate adjustment?

the starting point for the throttle plate adjustment is to have the plate just above the 1st idle hole, and you can either take the carb off and measure directly. or just to start you can back off the throttle stop screw until it doesn't touch, screw it back until it does touch and then another 1/2 turn.

if it idles low, there is an air bleed you can adjust on a DCOE. the idle jets also have an air bleed in them too, 65F9 is a 65 fuel, and F9 air. so you can change either or both

what did you do for your vacuum advance ?

I just disconnected it, and set max. advance to about 25°/15° for leading/trailing