Weber jets??All who live for their triples please read this

[Zmanco]

I have not seen a float bowl drain system before. But if I had your issue, I would be focused on removing the source of the contamination rather than creating a more convenient way to drain it. You may have water in your gas tank, and once that begins to rust you're going to have a mess that no amount of carb draining is going to solve.

[duragg]

No question about the tank. I drained it once, but will drain again and refill with 100LL Avgas and run the electric pump for a while while letting it drain out up front. Worst case I have a spare fuel tank, but not up for that job again.

 

I figured more for guys racing or running Triples daily in a more humid environment, might come in handy.

 

Aircraft carbs and fuel systems have multiple drains and water catches.

Just a thought.

[Dtsnlvrs]

Well I just rejetted my Webers for the altitude here and this is what I am running.

40DCOE18

33mm chokes

4.5 Aux Vent

50 pump bleed

45 accel pump jet

55f8 idle

135 mains

155 air corr

 

The engine pulls like a raped ape past 2.5k, but is a little sluggish below that and will flat fall on its face if I nail the throttle. Part of it is the cam, and part is I need a smaller pump bleed. I could also try a 60f8 idle (tried a 55f9 and it is way to rich at cruise) and adjust with the idle screws. I am also going to ensure my throttle plates are set properly. I think once I get the differential ratio right for the tranny and engine combo...the carbs will come in nicely. Oh and I am running about 4psi by using a holly red pump fed thru the stock SU fuel rail, keeping the return line intact (no vapor lock here)

 

I have sourced a 4.3 diff from the 720 truck, that should cure the low rpm problems, and I am going to reduce the idle jet to a 50f9

[Zmanco]

Dtsnlvrs, you have a setup very similar to mine. I live a little higher at 6000+. My carbs are set up as follows:

 

Main jets: 115

Air corrector: 190

Idle jets: 45F6

Pump jet: 45

Emulsion tube: F11

Starter Jet Fuel: 60F5

Pump Spill/Drain: 50

Aux venturi: 4.5

Chokes: 32 mm

 

I have an L28 with flat tops pistons, N42 head, 284/284 .480" cam, headers, etc. I'm running a 4.11 diff with the later (82) 5 speed, and the combination is great. I think you'll enjoy your new diff.

 

BTW, I'm still playing around with the mains and air correctors. I may be able to go up a size or 2 on the air correctors but it seems to change depending on the day. Do you have an O2 sensor? If not, you should consider adding one. My butt-o-meter is not able to feel the subtle differences when going lean at WOT.

[Dtsnlvrs]

Dtsnlvrs, you have a setup very similar to mine. I live a little higher at 6000+. My carbs are set up as follows:

 

Main jets: 115

Air corrector: 190

Idle jets: 45F6

Pump jet: 45

Emulsion tube: F11

Starter Jet Fuel: 60F5

Pump Spill/Drain: 50

Aux venturi: 4.5

Chokes: 32 mm

 

I have an L28 with flat tops pistons, N42 head, 284/284 .480" cam, headers, etc. I'm running a 4.11 diff with the later (82) 5 speed, and the combination is great. I think you'll enjoy your new diff.

 

BTW, I'm still playing around with the mains and air correctors. I may be able to go up a size or 2 on the air correctors but it seems to change depending on the day. Do you have an O2 sensor? If not, you should consider adding one. My butt-o-meter is not able to feel the subtle differences when going lean at WOT.

 

Oh I learned my lesson with that many many years ago...like 20...I was driving my fathers 240 from Shelby, NC to Charlotte. I was exiting US 74 onto I-85N at abot 90ish MPH in 3rd gear. All of a sudden...."WHOOSH"...and I was like "WTF over". Turns out the car had backfired (REAL BACKFIRE) into the front carb (3 x 40DCOE) and it caught fire. Ever since then I have been real careful with the jetting on the carbs....Its funny though..I still "feel" like I get a better reading from smell / sound / feel than the oxy sensor gives me, but I do pay attention to it. I know I am rich right now esp at cruise, but I am going to chassis dyno tune the car once I get the new diff installed. BTW the fire destroyed the original engine in his 240....which gave us an excuse to install a 2.8 bored 1mm over and top it with a nice Janspeed (England) head. Damn that car would fly. On a side note...the only carb part that survived the fire were the chokes...33mm to be exact....and they are still in use today on my engine.

[duragg]

When I jet-up to 50F9s or 55F9s and tune to eliminate the idle pop, I get a wicked head snapping stumble on throttle tip in...

 

So I got back to my 45F9s and I can mostly eliminate the stumble but I get occasional idle pops out the carbs (lean pop). This can't be right is it?

 

Do most people with Triples just live with occasional idle lean pops or a stumble on throttle tip in? Is it that freakin sensitive?

 

I suspect a lot of the stumble has to do with the throttle plates position in reference to the progression ports (NAPABill come back!). But when I adjust the throttle plates per the book or NAPABills suggestion I get a 2000rpm idle.

 

Gak.

TJ

[Dtsnlvrs]

When I jet-up to 50F9s or 55F9s and tune to eliminate the idle pop, I get a wicked head snapping stumble on throttle tip in...

 

So I got back to my 45F9s and I can mostly eliminate the stumble but I get occasional idle pops out the carbs (lean pop). This can't be right is it?

 

Do most people with Triples just live with occasional idle lean pops or a stumble on throttle tip in? Is it that freakin sensitive?

 

I suspect a lot of the stumble has to do with the throttle plates position in reference to the progression ports (NAPABill come back!). But when I adjust the throttle plates per the book or NAPABills suggestion I get a 2000rpm idle.

 

Gak.

TJ

 

 

If I remember right, you have a L24, and are using 30mm chokes, your idle timing is about 30 (WHEW thats high). right?

 

Step one, bring that idle timing down to say 20...if you are still using a stock l24 dizyy I would set the timing @ 3000 rpm no greater than 38deg.

 

The 45F9 should be just fine for your motor....try the timing first..of course you will have to re-tune the rest all of it after that...timing is critical in these carbs. NO VACUUM advance. Set your idle speed at about 900-1100 rpm. Ensure your throttle plates are covering the progression holes..IE NO MORE than 1/2 screw in on the throttle stop screws. Balance Balance Balance...If it sounds like a daunting task....take the drive to Vegas one weekend, and I will help / teach you how to set them up.

[duragg]

THanks,...

I have the timing at about 35 TOTAL at 3000 and whatever at idle.

I have the carbs perfectly balanced with the fancy balancer.

All are rebuilt, valves adjusted, Crane, L24 Dizzy rebuilt, new wires and plugs.

 

Its the hesitation that bugs me.

I know progression ports are critical and will refocus on that today.

 

Thanks,

 

TJ

[Dtsnlvrs]

I think everyone here needs to remember that in our application...the tripples are being used as a performance upgrade. When these carbs were used in OEM applications (Alfas, Fiats, etc) in Italy, they were choked down quite a bit. Like a 2litre Alfa eunning 2X 40DCOM with 28mm chokes. That is a 28mm choke on a 500cc cylinder!! There was almost no hesitation on these motors due to the high velocity of the air in the carb. In our case, to optimize HP in our motors....we run 30 or 32mm chokes on a 2.4litre or 32-34mm chokes on a 2.8litre. That is a 30mm choke on a 400cc cylinder. It WILL hesitate at lower RPM, and there is nothing you can do about it...short of creating a way too rich progression mixture or way too rich accell circuit stream. It is simple physics. I have the same issue and I am using a 33mm choke, that is 33mm choking down 466cc. The car screams like a banshee after 2500rpm, but try to nail it below that and it falls flat on its face. There was and old saying in racing many years ago.."Squeeze on throttle, Squeeze on brakes" If you drive a triple carbed Z that is tuned for performance, you have to drive it this way...IE like a race car...be gentle with the throttle until you get the RPM up into the working range for your exact carb / cam selection and setup, then you can nail it.

[JMortensen]

I think everyone here needs to remember that in our application...the tripples are being used as a performance upgrade. When these carbs were used in OEM applications (Alfas, Fiats, etc) in Italy, they were choked down quite a bit. Like a 2litre Alfa eunning 2X 40DCOM with 28mm chokes. That is a 28mm choke on a 500cc cylinder!! There was almost no hesitation on these motors due to the high velocity of the air in the carb. In our case, to optimize HP in our motors....we run 30 or 32mm chokes on a 2.4litre or 32-34mm chokes on a 2.8litre. That is a 30mm choke on a 400cc cylinder. It WILL hesitate at lower RPM, and there is nothing you can do about it...short of creating a way to rich progression mixture or way to rich accell circuit stream. It is simple physics. I have the same issue and I am using a 33mm choke, that is 33mm choking down 466cc. The car screams like a banshee after 2500rpm, but try to nail it below that and it falls flat on its face. There was and old saying in racing many years ago.."Squeeze on throttle, Squeeze on brakes" If you drive a triple carbed Z that is tuned for performance, you have to drive it this way...IE like a race car...be gentle with the throttle until you get the RPM up into the working range for your exact carb / cam selection and setup, then you can nail it.

EXACTLY! This is why triples and tall gears don't get along together. It's a high rpm induction system, and needs the rpms to work. 4.11's and 4.37's will help you stay in the rpm range where the carbs work. When I put triples on my car I actually went slower at autox than with SU's because I had a hard time keeping the rpms up high enough with my 3.70 gears. But get it on a big track where you can open it up and get the rpms up and OH MY GOD it is faster!!!

[zredbaron]

couldn't agree more, jon. 4.37 works quite well with triples in autox (especially with a quaiffe...)

 

too bad my stroker is too much fun...i ripped a tooth off my 4.37 ring gear jumping too hard on the throttle. whoops. (anyone ever chipped a ring gear tooth before? seemed odd to me)

 

Dtsnlvrs, where did you find your 720 R180? i found mine from random luck, more or less...looking again, but no such luck yet...

[Zmanco]

I found my 4.11 from a 720 pickup in a JY in Coloroado Springs. I used http://www.car-part.com to locate it.

[Dtsnlvrs]

couldn't agree more, jon. 4.37 works quite well with triples in autox (especially with a quaiffe...)

 

too bad my stroker is too much fun...i ripped a tooth off my 4.37 ring gear jumping too hard on the throttle. whoops. (anyone ever chipped a ring gear tooth before? seemed odd to me)

 

Dtsnlvrs, where did you find your 720 R180? i found mine from random luck, more or less...looking again, but no such luck yet...

 

I found the 720 4.37 by blind luck as well, however when I went to pick it up and pay for it, the owner overode the price agreed on by the manager, so I walked away...looking to get a 4.11 from some junkyard....84-88 200sx... http://www.car-part.com.

[bjhines]

I can't get to the bottom of mine without removing the drip pan/heat shield... drain or not... It is just as easy to remove the 4 screws and slap a new gasket on there... get the rubber gasket kit if you do this a lot...

 

A proper air cleaner will greatly reduce amount of debris that gets into the float bowls...

 

 

 

...

[Dtsnlvrs]

 

Nice

[Workinprogress]

BJ, where did you get the airbox? I'm looking for one for my set of tripples

[Sven]

BJHines, I've studied your airbox before, and want to make something similar. It looks very close to the strut tower, have you found any signs of it making contact as the engine torques over? I'd like mine about that size, for plenum volume and stack length.

[Dtsnlvrs]

Found this handy "DOS" based calulator for rough estimates on Weber jetting. I found this on the Alfa Romeo website.

 

It is designed for a 4 banger with double Doubles, so I just input 1600 as the displacement (2/3s of an 2400) to simulate an L24.

 

http://www.airpowerinsurance.com/zcar/jetting.exe

 

This program works very well and as far as I can tell, should be pretty accurate for a base line setup. I suggest everyone play around with this program and see what it reccomends. Remember to ALWAYS take your actual single cylinder displacement and multiply by 4 to get the engine size for this program. Also, be very realistic about your peak HP rpm....in my case, I use 7000...even though I have not dynoed it, but because I will not rev mine past that. L24 guys....input 1600cc, 5500rpm, and F and see what it tells you. Alot of us have been WAY over carbing our engines.

[Dtsnlvrs]

Well my F-16 Emulsion tubes came in today and I re-jetted to suit.

 

33mm chokes

4.5 aux vent

F-16 emulsion

135main

180 airs

50f9 idle

45 accel

50 pump bleed

 

Conclusion...I was better off with the f-11. The f-16 is too fat, however the change in Idle jets was in the right direction....smells better and is a little more crisp at the crack of the throttle, but once the mains start coming in it flat out bogs...ever seen your A/F meter register full lean cause you are so rich!!

 

On a side note..my 4.11 came in today as well...guess I gotta get it in to see what it does.

[Dtsnlvrs]

Well some more changes happening here. Mind you I am still using a 3.54 rear end so this impacts the results. I removed the f-16 emulsion tubes and rejetted to suit. I also advanced the timing to 22deg btdc 34deg all in. This is what we have now.

 

40DCOE18

33mm chokes

4.5 Aux venturi

f-11 emulsion tubes

130 main jets

175 air correctors

50f9 idle jets

45 pump jets

50 pump bleed

 

The car behaves as before the install of the f-16 tubes.

Idle is cleaner and intial throttle response is crisp, maybe slightly lean. Slight pinging when I load the motor up in the wrong gear but this is to be expected. I would like to lean out the idle some more but the next step would be 50f8 and that is too lean for now. I will probably play with thsi some more once we get the 4.11 installed. I have also ordered som F-9 emulsion tubes and will give those a try as well once the diff is installed.