So I bought an FB after owning an SA so I own two rx7s but the FB has a Weber 45 and I've tuned the air screws multiple times and when I rev it up it stumbles and almost dies in the beginning and I can't figure it out it has a rats nest delete air pump delete and a full racing beat exhaust so please help me

 

the screws are for idle adjustments, they will not do anything over ~1500rpm.

you might want to find a FAQ with the DCOE, or something, and then see what jets you have in it.

https://www.piercemanifolds.com

 

Foxed.ca may also have some weber tuning books in the misc section.

 

ok when it stumbles it then proceedes to make me go deaf and shoot a 3 foot flame so what about it's running rich how would I adjust that

 

Use the link in my last post and read the Weber tuning books, they cover most of t his. Plus the other book, modifiying your RX7 will cover the rest.

 

if it is rich, you would need smaller main jets

 

I'd like to see those flames! lol

 

Do you need to mess with the timing when tuning a weber carb?

 

Yes you may. RB has some advice for various timings, ports, and weber setups.

 

You can look at Ur spark plugs as well to get a pretty good idea of whats going on in there...

at least thats the way I've always done my motorcycles..... I don't see these rotary engines being any different... burning fuel is burning fuel....

anyone please correct me,. if I'm off the mark here...

 

i find its best not to, there is enough to deal with tuning the carb, that you can get lost when you add timing.

i do like to start with a new cap, rotor, good wires (check them with a multimeter), and decent plugs (i like to not start with new ones, just ones that are ok. unless you have big bucks, then new plugs would be good), and set timing to stock

 

I agree, timing is the last thing to tweak. Get it all running good at stock timing first.

 

Is it true that air jets should always be no more than 60 size less than main jet being used? For example if im running 200 main, I should not be running anything lower than 140 air. A friend mentioned to me that he was advised not to run over 60 sizes down from the main jet when tuning. To keep the air jet with with in 60 size down from the main jet.

 

I'm not too sure about that since different carbs use different sets as standards. Some go by 5's while others are incremental by 1's. Foxed.ca - Mazda RX-7 Manuals there is a lot of information on this site. Look up your year can and go from there. I was able to find a couple Weber manuals that show the breakdown to every last nut and bolt. Lots of info.

 

view it as a guideline and not a rule. if you were starting from scratch it would be where you started. if you had a running car, you'd just start with what was in there

when i was messing with mine i found a nice white paper (and the guy who wrote it), and his method was to tune the carb in order. you start with the, venturi/emulsion tube, as these are sort of fixed mechanical things, then float level/fuel pressure, idle jet, idle air (if applicable), main fuel jet, and then the main air jet is last.

it really does help to work through each jet in order like this, it takes away all the guess work and mystery.

i've been meaning to 3d print some blank air correctors, so you could just start with no hole and drill it to the size the engine wants, and then you only need to buy 1 set