Hey guys, just picked up a Weber 42DCOE off ebay, and i can't get my car started. I was wondering what size jets i should run with this setup as well.

Right now im runing this
115 Main jets
180 air correctors
F11 emulsion tubes
55F8 (no clue what it is)

 

Well for starters weber didnt make a 42 dcoe, they make 40,45,48,50, and i belive you can get a 55 custom.

Secondly, your main jet is way too small and your a/c is way too big. You should have a smaller a/c than main jet.

Your car should still start with your setup but wont run worth a ****. So ill walk you through starting procedures.

1. turn key on and let fuel bowls fill in the carb (30 seconds).
2. pump throttle about 10 times.
3. start the car. (if it wont start engage the choke by wiring it open on carb)
4.If it still wont start you either arent getting fuel or its flodded or you have no spark.

A good starting spot for a 45dcoe on a 12 a is 180 a/c and 180 main, a 65f8/f9 or a 70-75f8 f9 idle jet. If you dont have a fuel pressure guage your wasting your time and if you running the stock fuel pump your wasting even more time. Do a search as there is tons and tons of info on your very topic. good luck hope this helps.

 

To add to the above post, Webers don't have choke butterfly's but they do have a starter circuit, which has the same function. As long as the choke worked on the Nikki, it will perform the same with the Weber. As far as jetting, I can't offer any additional advice.

 

I live in california at sea level, so your jets may differ being that your atmospheric pressure is different.

But, I'm on 200 mains, f11 emulsions, 55f8 IDLE JETS, I forget my air corrections.. I'll take a look.

Another thing to look for when you tune it is the fuel bleeding jet on the bottom of the float bowl. If you take out the float, its easy to get too. When you remove it, check to see if there are any numbers or holes on the side of it (thats the amount of cc the float bowl discharges) You should order a 0 bypass valve.

When tampering with these jets, be super careful, they are made of soft brass metal. Easy to strip, use correct sized flat heads..

What kind of manifold are you using? Do you have a plastic adapter kit to the manifold, or a metal one? Definitely upgrade to metal if you do. Could Help with vacuum leaks. Make sure your Idle screws start out at 2 turns TO SEATED position. Might be easier to start like that. Was it a used carb? Might want to check the floats to make sure its not fucked with. Should look pretty 45 degree'ish to the naked eyes. DO NOT MESS With it if it is not..... YET...

There are people who are way better at tuning these things than I am, for damn sure. I'm just getting you started.

 

look it up. weber did make a weber 42dcoe at one time, that is what is stamped on the carb. and its a racingbeat 2 peice manifold, got them both used off ebay for 300 shipped.

and i removed the choke on the nikki

ill be out of town for 2 days, but my dad sad he was going to mess with it to try and get it running

 

dont waste your time, that carb is too small to run a single one on a rotary. a 45 is the limit on the 12a motors and even those are on the small side for a stockport 12a. that is a rare carb size tho.. they stopped making those a long time ago..

 

ok well i figured out my weber 42 was complete crap, and i picked up a dhla 40, if i hold the choke it will start and run on one rotor only, but only for about 10 seconds and then dies. I plan on picking up some carb cleaner tomarrow, and cleaning out what i can on that carb. and give it another shot.

whats the best way to get a car started with a carb that hasnt been tuned to the application yet?

 

read above post

 

read again. a del 40 is even smaller than what you had... it's smaller and will flow less than a stock nikki.

 

The only DHLAs I've seen are a 48, I suppose they did make smaller ones. By the off chance it's a 48 with a 40 mm venturi, measure the ID of the throat. It it's over 50 mm, you might be able to swap in a 48 mm venturi. Don't get your hopes up though. If it's a true 40 mm, put it back on eBay, along with the Weber.

 

well i have a book on webers and dellorto's and i have read it. from my understanding, rb uses 37mm chokes on there 48 for a street port setup, and i figure if i get a 37 mm choke for the dellorto and use there reccomendations for the 48 as a starting point, i should be good.

I'll let you guys know how this goes even though everybody says it wont work

 

There was a guy running a 40IDF (not sure of the IDF/IDA whatever, but it was a 40 iirc) on here about a year back.

 

was it n/a or was it boosted? boosted it will be ok, but n/a, no good too small

 

so if i buy the turbo rebuild kit for the dellorto, would that be all i need to prep the carb? f so i'll just go that way, would be much simpler

 

NA. I can't remember who it was! Gonna go search now..

 

Boo yeah.

Weber 40 IDF on NA 12a.
https://www.rx7club.com/1st-generation-specific-1979-1985-18/my-project-near-completion-56k-dont-even-690172/

 

a 37mm choke (venturi) on a carb with 40 mm throttle plates is not much of a choke; I don't think it will function as a venturi very well. The venturi is very important, with out it, fuel would not get sucked out of the float bowl; the carb will not work. The venturi must be quite a bit smaller than the throttle plates in order to make the air flow speed up and drop pressure.
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I am suprised everyone waited until now to start talking about venturies. Without knowing what size venturi he had in his 42DCOE, the jet recommendations are worthless. A certain number jet size is only good with a certain size of venturi; otherwise you are trying to compare apples to oranges.