help with tripples PLEASE SEND ME TO SCHOOL

[Guest LAYTON]

im just now starting to get the ground up 240 done it has a warmed up l-28 and a cam and a set of tripple 45mm webbers ,ive rebuilt a few q-jets in my days and a couple 2 brl motorcrafts (webbers built for ford/mercurcy german capri's )

but this is my first stab at dcoe/sidedrafts

completely tore down all 3 and had them cleaned in a carb acleaner/agitater

reassembled by a haynes webber manual /they are on car seem to have them close to in synce but the lil bast**** puke and and backfire under a rev-load and barf/seep gas out the barrels of corse this if a complete nightmare i have a new motor /and all the other new motor gremlins have come out in droves

sorted out the timming triple checked now crank/cam and dist.

that said they still leak gas and puke a lot thry most be getting a lil closer it will free-rev down low i lil nicer but i need to get them to not leak gas they just kinda puddle and uuse out even after shut down

float level ?

to much pressure from cater pump rated at 5-6 psi ?

and once i get them not to leak do you have a jetting suggestion i live in salem or and its a L-28 with 10.5 to compression and a 275-475 cam /headers 2.5 in exhuast

ive been driving efi cars for to long and could use some help and schooling thanks ,john

[Guest LAYTON]

ps im trying to get it to run ok for starters so the panter can have it im late getting it to him already can power tune later if more patience is needed

[Guest LAYTON]

hello ,any webber warriors burning the midnight oil out there ??????

[DavyZ]

*bump*

[Ruben]

John,

 

It's late so I only have a couple things. Fuel pressure should not exceed 3.5 psi or the carburetors will flood. Ideally fuel pressure should be between 3 - 3.5 psi, if it exceeds 3.5 psi then you will have to install a regulator. The pooling of fuel is most likely caused by incorrect float level. I don’t know which 45 DOCE model you have otherwise I could give you the float level adjustment setting.

 

If the Carbs are “sneezing†under light to moderate throttle then you are too lean. Try opening the mixture screws, if that does not work then your idle jets are too small. Also try advancing the timing and see if that helps. Weber’s like a lot of advanced timing, 15 – 20 degrees initial advance.

 

Hope this helps.

 

Ruben

’72 240Z

[Lockjaw]

For main jets, take your " choke" diameter times 4 to get an apporximate main jet. Add 60 to the main for the proper air corrector. That is your starting point.

[Guest LAYTON]

hey ruben

they are 152's dose your webber book suggest a jetting for 45's on a l-28 the one i have only lists 40's and 240-260 application in the jetting index in back

[Guest LAYTON]

found the jet rocomendation in the how to hot rod your datsun book ,and i have to say i cheatted i wasnt quite sure what you meant lockjaw but now i do it just happened to make a example of a 280 motor with tripple 45's and the gas bs was the float level

now im off to find the right jets any suggestions were to get 'em ?

thanks for all the help

[Guest LAYTON]

i got some on the way ,ive talked to that guy at top end for a couple thing know he is a real di**head attitude and knows all his way is deffinately the only way asked him about a fuel rail he said no such thing ever made funny its in the nissan motorsports book they were out so i coppied my friends its a mikunipart but not hard to make used 5/16 brake line and then had cad plated a couple hours and it looks sweet and anyway im just not reel impressed with that guy so i gave someone else the $$

if you gotta give someone money it might as well be someone who isnnt a a**hole about trying to help you out you know there are so many different opinions out there sometimes its hard to figure things out

damn those jets arnt cheap are they hope these ones work out

[Lockjaw]

TWM induction, Topend Performance, and or Advanced Engine Management.

 

Good luck with it. When you get them right, it is a sweet thing.

[Guest bastaad525]

I have to agree with Layton... I've called that guy at Top End on a couple occasions and he's got a real attitude plus he is kinda close-minded. I was asking him what I would need to do to make SU's work on a bored out L28 and he was basically like "it can't be done, the SU's won't provide enough fuel, it won't work you either need aftermarket EFI or tripple carbs on there or it won't run right.". Funny I found these boards and I see all kinds of guys running SU's on beefed up L28's with no problems. Makes me wonder... I had some other things I asked him about too and he just always seems like he can't be bothered and when he can he only has ONE solution to a given problem, no alternatives allowed. Anyways sorry for the rant it just kinda got to me when I read that someone else had the same experience with that guy.

[Lockjaw]

Sounds like you guys may be talking about Steve, at least I think that is his name.

 

Seems like I run into people like that all the time that say you can't do something. I don't blame you for not wanting to deal with them.

 

I have had the same issue with Jim Wolf at JWT. He may really know his stuff, but I do not like talking with him, and only talk with Clark. I told Clark one day I did not like talking to Jim.

 

But I can see why they can get to be that way. I well known shop probably gets a million calls from people who are lulu's. I am sure it is frustrating for them, especially if you are not buying anything from them.

 

I went thru alot of that with my webers and TWM induction, and ended up buying almost everything from AEM since they were nicer to me. I am not an ASE certified master mechanic, but I am not stupid either, and if someone will just explain something, then I am there.

 

Good luck with those webers. I miss mine sometimes.

[Guest LAYTON]

I HERE YA

ya i had a few long conversations with clarke that guy is cool as soon as he can tell your not a retard the info just uuuussssseeees out from the phone my god that guy know alotta stuff the things he can come up with wow i especially like the abillity to write a seperate program into the ecu for nos for pre boost the it shuts down when the boost comes on , can you say

"what is turbo lag never herd of it "

i guess the point is im open for suggestions just tell me why id wanna do it ,dont tell my oh thats bs it cant be done or there is no such thing when its in the mother book of old school cool the nissan motor sports ctalog youd think if a guy that just plays around with datsuns knows about something a specialty datsun shop should come on !

[DAW]

Layton, that was an excellent description of what's going on but it's a bit baffling...sounds like too lean with the stumble and backfire; yet too rich with the fuel spilling over.

I agree with Ruben re knowing your fuel pressure. Get a regulator and go for about 3.5 to 4lbs, timing and condition of ignition system is critical re throttle response. Get your main jet requirements sorted out (WOT) then tune down from there. DAW

[Guest LAYTON]

i got the fuel spillage handled my float levels were a bit to high but , it will pump it out still if i leave the pump on whith out th motor running got a fpr coming ,and more jets my timing is at 15 deg, and have triple checked the markes a tdc ,crank ,cam ,and dist drive gear , so i think i have that part nailed please excuse my lack of knowledge with these but my 45'have f-8 iddle jets ,my friend 40's have f-11 we have tied his 50-f-11 but too lean i have both 55/60 f-8's should i switch to f-11's as well ?

i have tried 180mains and 220 airs 145 main and 180 airs the 180mains was a real flat spot i think cuz the aires ar too far away and the 145/180 set up is just too lean i have 175 mns and 195 airs and 205 airs on the way (they were out of 200 aires ) i hope that that might do it but i have to wounder if i might need f-11 iddles to make them have a better transitiion from iddle to mains

what do you guys think?

[Guest LAYTON]

those a**wipes at gi joes gave me some messed up wrong spark plugs i should have duble checked but i guess i was to excited at the time and had way to much confidence in the part s guy

its getting better i keep you up to speed its not farting through the carbs anymore it dose still have a flat spot though just off iddle

[Guest Anonymous]

Here's the deal.....

 

1) You ABSOLUTELY need to regulate the fuel pressure. Weber carbs need lots of flow, but NOT PRESSURE. Ideal pressure for the Weber's is between 2.5-3.0Psi. 3.5Psi is about the max. If your fuel pump is putting out 6Psi that's double what they want and they will spill the excess and your fuel circuitry (I'm speaking mechanically here) will not operate as it should. Holley makes a decent regulator for carbs and while you're at it, install a gauge and you're set. You can add fuel return lines if you wish, but with Weber's I have found they are not absolutely necessary.

 

2) Before you start swapping all kinds of jets (which can add up quickly since each one is a few bucks and you need 6 at a time) take an inventory of your current settings. Just saying you have 45DCOEs doesn't really tell anyone much other than you have Weber sidedrafts and 45mm butterfly valves. Before I can really steer you in the right direction, you need to provide some details specific to the webers you have installed.

 

Please fill in the blanks:

Choke Size (Main): 36mm? 38mm?

Choke Size (Aux): 4.5mm? 5.0mm?

Main Jet: 145?

Air Jet: 180?

Emulsion Tube: F11? F16?

Pump Jets: 45? 50?

Idle Jet: 45F8? 50F11?

 

Just based on what you have given, I don't think your 145 mains and 180 airs are that far off. I think your main problem is that your idle jet is too lean. Remember, webers are a progressive carburetor and there is some overlap in the circuit. The idle jet doesn't just regulate idle (in fact it doesn't regulate it much at all), but also off idle/low rpm fuel delivery as well. Also, weber idle jets have a built-in air corrector hole which is designated by the Fx following the main fuel orifice size. The larger the hole, the leaner the mixture. However, there is no real pattern to the numbers. For example, an F8 is richer than a F3 but leaner than an F6.

 

Check this website for some good general tuning info (keep in mind it is aimed at 4cyl applications). http://members.aol.com/dvandrews/webers.htm

 

3) Weber's like a lot of initial timing advance to give the right snap. Typically ~15-17 degrees at idle. It helps if you have a recurved distributor to accommodate this large initial advance. Also, make sure you have plugged your vacuum advance mechanism and/or disabled it since it is not necessary and wouldn't work correctly anyway with the IR manifold.

 

4) What kind of air filters are you running? ITG makes the best setup (you can find them in Motorsports Auto catalogs now). Personally, I think the three separate filter version is better than the single large version. The reason ITG fiters are better is because the top is an open element unlike other setups like the K&N which use a metal plate on the top which can severely affect flow. Weber's need velocity stacks (air horns) to run correctly and they also require at least an inch, preferably 1.5-2.0" of clearance between the top of the air horn and any plate. This is why the K&N setup doesn't work well unless you have really short air horns.

 

5) Your engine specifications seem like they should run well with the webers once you get them setup properly. Just be patient and don't make any hasty decisions as they will cost you time, money and add to your frustration.

 

Most people give Weber's a bad name because they take more work to setup for a particular application. Very few are setup to run "right out of the box", whereas SUs (due to their constant velocity design) can easily be made to run quite well with little effort thus adding to the bad reputation of webers. However, the very nature that makes webers more difficult to setup is also what makes them great. There are so many small variables that you can adjust, you can fine tune them to your exact application. The key is to educate yourself on their operation and take logical deliberate steps in tuning them. Buy some books if you haven't already, and ask questions whenever you can. If you stick to this routine, you will be pleased with the results, I guarantee.

[Guest LAYTON]

man im telling ya ,i have been a lil frustrated but ,i know that once sorted out and tunned in they ROCK ,ive seen them in action cars with the webbers tuned right hual a** and suond killer

i dont know a hole lot about em but im learnig as i go and mostly from help from you guys and friends ,i do know i have

36mm chokes

f-16 tubes on the mains

and f-8's on the iddles

dont know what acc pump ones

i have 55, 60 iddle jets to use

and 145,175,180 mains

180,195,205,220 airs

dont know on the other chokes

i read the chilton webber book but it did not list a recomendation for my motor just 240/260z with 40's

[Guest LAYTON]

240dave

i looked tonight at painters house it has

35 accel pump jets i think that all i left out of the post above

thanks in advance for any ideas

it getting better but when ya rev it up slow and long it falls off then boggs i tried allotta combos but it still did that on quick snaps was ok but on full pedal mash type action it bogs right away

what to try next ?

[Guest Anonymous]

OK, here goes....remember, these are just my recommendations from my own experience and are in no way an absolute truth.

 

Based on your description, it sounds like you're still running lean. Remember, weber's consist of several fuel circuits so you can easily run too rich in one area while running too lean in another.

 

The good news is that I don't think your carbs are too far off. However, I don't think you have the right types of extra parts lying around. You really don't need the 175,180 main jets or the 195-200+ airs. Try to sell or exchange them if you can. Since you don't have what you need your going to have to buy some new jets, or hopefully trade some of your extras for what you need.

 

So, where does your problem lie? I think it is in two areas, your idle jets and your accelerator pump both of which are too lean. Remember, the idle jets control more than just your idle, AND in a DCOE carb they have a built-in air corrector hole which can drastically affect the characteristics of the jet, even when using different sized fuel holes. The F8s you have are just too lean since an F8 has a fairly large air corrector hole. Everyone running webers on a Z runs F9 jets.

 

That said, here is what I would recommend on your setup. These should get you in the ballpark, but additional tuning would still be required to custom tailor the settings for your application.

Chokes: 36mm (these are about ideal so don't change them)

Main: 145-150

Air: 180-185 (Don't go larger since this will lean your top end and high rpm + lean condition = kaboom)

Emulsion Tubes: F16 (these are fine for now)

Idles: 50-55F9 (F8s are way too lean)

Accel's: 40-45 (35s are way too lean)

 

If you're short on cash, the first thing I would do is buy the idle jets. These have a profound impact on overall driveability. The accel jets are only necessary when you're romping on the pedal.

 

Keep in mind that road testing can only get you so close, if you really want to tune it exactly as it should be you need to measure mixture levels with a oxygen sensor and a meter or at a shop with professional equipment. Also, it's always safer to run slightly rich rather than slightly lean. Running slightly rich hurts power somewhat and returns poor economy, but running lean can cost you the entire engine.

 

Just for reference, here is what I run on my Rebello 3.0L and it's running slightly rich.

Carbs: 45mm DCOE

Chokes: 38mm

Mains: 155

Airs: 185

Tubes: F16

Idle: 55F9

Accel: 45