38/38 weber?

[Rasp933]

Backfire was due to too lean of mixture

[Rasp933]

Car runs fine now seem like to me .but iam not a professional mechanic.and I dont have machines to do tuning.and every time I change sumthing like splug gap or fuel air screw I take from a spin before I check my plugs for analysis. Lol.

[Rasp933]

But I got it to where there is no backfire in the exhaust.

[KlassicMotion]

Uhhhhh..... Wow.

 

This is the last thing I'm going to say, basically repeating myself.

 

Put everything on the carb, back to factory specs.

 

Put a fuel pressure regulator in line before the carb (see pic below.  It's not pretty, but it works for now).  set it to 2.5 for starters.

 

Set your plug gap to .40

 

Set your timing to 12 degrees btdc

 

Then once the engine is running, set your idle.  Then 1/4 turn adjust your mixture needles as per the instructions I posted earlier.

 

You still haven't said whether or not the carb was new, and if the carb was marketed for the L16, L18, L20.

 

Assuming it was both. Then the carb should work.  If you don't do this, I believe you will continue to fight it.

 

[Rasp933]

I bought it from ebay .part# wk663-38 .said it will work wit l series. Toyotas etc.etc.

[Rasp933]

Now I get what ur say .wit the help of fuel regulator I can control the amount of fuel entering the carb.is that what ur trying to explain to me?

[Rasp933]

Btw.that engine looks clean.

[Rasp933]

R u still using stock fuel pump or electrical?

[banzai510(hainz)]

Personally I dont think a fuel reg is going to be needed.

I have not run one using a stock pump or a aftermarket stock TYPE pump.EVER and all my motors have been fine.

Even stock L motors with SU carbs use a stock pump.So why would one be needed here.

 

electric fuel pumps yes run a reg as most are 7 pound pumps unless you know what the pump flow is.

 

most stock pumps if you hand pump it up to the carb the arm will go limp once the carb is full.

 

 

i say adjust the timming . ck the valave lash and adjust the mixture close as good as you can and run it

[littlejason]

Do you have a return line?

[banzai510(hainz)]

No I dont have a return line. MY 521 ran fine with out one. with 32/36 or 38/38 or sidedrafts

all stock fuel pumps.

[Stoffregen Motorsports]

I agree with Hainz. A regulator shouldn't be needed. I only use a regulator when I install an electric pump, and then I don't use the style shown as they are actually restricting fuel flow. Those type of regulators were designed to be used on the fuel return line.

 

For the OP; I know what you're saying about not being a mechanic, but if you spend the money once, to have someone dial you in, you will no regret it. It will save you a lot of time and aggravation.

[tr8er]

No fuel regulator in line. But my 32/36 was rebuilt like 11/2 yrs ago.so dey might have changed.it.also as of rite now iam only using secondary bore which I have at 11/2 turn out n it had eliminated the backfire which the engine was expriencing.primary bore is closed all the way.ie the one close to valve cover.

http://www.redlineweber.com/html/Tech/38_dgas_tunning.htm

 

I went through hell trying to tune my 38/38.  I never got it right until I switched to electric ignition.  Points were my main problem.  Adjusting Dwell, gap, timing, and carb at once was too much.  Hats off to the mechanics of that era.  Once I got the electric ignition in, adjusting the carb was much easier.  I did end up re-jetting with a jet kit.  I can't recall what jet sizes I ended up using though.  Your getting a bunch of action on this thread.  I'm not going to claim to be any expert on this topic, but I did go through this process.  Having an expert adjust one time is never bad advise.  Show up with a few beers in a cooler around 5:00 and you might even get a chance to look over his/(her if your lucky) shoulder. 

 

Outside of that, one comment caught my attention.  My understanding of this carburetor does not include setting each barrel independently.  You want these two barrels synchronous.  Meaning both sides screws need to be set to the same number of turns out.  The speed screw is set separate though.  1/2 turn or so.  

[Rasp933]

Tr83r

I went and listen to your advice on opening both bore.n so I did .there bout 1/2 turn out on both bores.and its seems like I have to where its tiny bit more towards the leaner mixture den rhe rich side.but I think iam done tweaking on this carb for today.lol

[KlassicMotion]

I bought it from ebay .part# wk663-38 .said it will work wit l series. Toyotas etc.etc.

The part number is the correct number.

 

R u still using stock fuel pump or electrical?

Stock 1980 L20B fuel pump.

 

And yes, to me, it sounds like you are getting too much fuel into the carb.

 

 

Personally I dont think a fuel reg is going to be needed.

I have not run one using a stock pump or a aftermarket stock TYPE pump.EVER and all my motors have been fine.

Even stock L motors with SU carbs use a stock pump.So why would one be needed here.

 

electric fuel pumps yes run a reg as most are 7 pound pumps unless you know what the pump flow is.

 

most stock pumps if you hand pump it up to the carb the arm will go limp once the carb is full.

 

 

i say adjust the timming . ck the valave lash and adjust the mixture close as good as you can and run it

 

Since I don't know what pressure the stock pump is pumping at, and since there is a "Warning" in the instruction manual that says you must run a fuel pressure regulator with this carb, I choose to follow Weber's advice.... 

 

A good tune up can never hurt.

[Rasp933]

Now r all this adjustments to the carb done with the air filter on or off of the carb?

[KlassicMotion]

I do it with them on, since that is how you will be driving it.

[banzai510(hainz)]

the L20fuel pump might pump more fuel.thus the return line.

But Im guessing if he has a 510 pump in there for the correct input out put lines so it looks right. and hoses come out in the stock places.

 

then again if the 32/36 or stock carb was in there before why did it work

[Stoffregen Motorsports]

If there was too much pressure the needle and seat would stick and it would be flooding over.

[tr8er]

I do it with them on, since that is how you will be driving it.

Also, you should adjust it while driving down the freeway*.  Since that is how you drive it.  Have a helper drive, cause safer that way.  

 

    *don't

[Rasp933]

Kool .I got it to where both bores open about 3/4s of a turn out.speed screw bout turn in.and wen iam on the street driving it.i dont feel any missing at low rpms.faster throttle response. Hear no backfiring while deceleration or acceleration. is it sounds like I did sum thing rite with it?

[tr8er]

ahhhh.  Closure.  

[KlassicMotion]

What jets are you running?  Still the 32/36 jets, or did you put the 38 jets back in?  Did you look to see what they were labeled before swapping out?

[TENDRIL]

There's no progression in the 38/38 I thought. that's why they are great for racing and off roading . Period its going to be hard next to impossiable to get it running right in all stages for a DD

[Rasp933]

Still the 32/36 jets in the carb.so I took a look at plugs .but I still c sum carbon on them.so I closed the bores like 1/4 turn more in . This adjustment better fix that .lol