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Hello, i resently put an N42 head on my L28, F54 block, with flat top pistons. I have a header and triple Weber 45DCOE's, i am having a little trouble dialing it in and i was wonder if anyone had any tips for what venturies and jets to use...

I think i should go with: 36mm venturis, 1.44 main jets and 1.64 air jets. What do you all think?? :ermm:

Thank you in advance, Chris


Diagnosing carburettor jetting, tuning and setup 'online' is a thankless task! You can't blame people for not wanting to get involved, as there are far too many possible variables that come into play.

Having said that, you should be able to get fairly close to optimal jetting on paper if you know the carbs themselves are in good condition and without twisted butterfly spindles etc.

First of all, what series of 45DCOE do you have ( series type should be stamped on the top covers ) and do you know their origin? Did they come from another known car / engine ( used ) or are they new out of the box? What size are all your other jets, and the emulsion tubes? Do you happen to know what accelerator pump jet actuating rods are installed ( this should be linked to the series type - that's why I ask )?

No disrespect intended, but often these kinds of problems turn out to be due to many things other than the carburettors themselves, or indeed due to inexperienced tinkering.............

Final twiddling is always best carried out by an experienced rolling road operator who knows his way around carbs. Unless you are prepared to go through a lot of trial and error it might be best to stump up the cash and take the car to somebody else.

i didnt mean to sound rude, just tried to spark the thread back up with the hope that someone would reply. Guess it worked!! I am only looking for ball park number, not a lecture.

i guess this thread will die like many other questions that could help others..

Chris,

If you haven't done so, visit HybridZ.com. Look at the L6 forum, listed under Nissan six cylinder forums, and you will find an excellent "sticky" on Weber carburetors. It is several pages long and extremely informative.

The sticky gives lots of info on what others have used regarding emulsion tubes, idle jets, main jets, venturi size, etc. But when all is said and done, count on spending some serious dyno tuning time with someone very familiar with Webers. That's my plan for my 40 DCOE's as soon as I'm up and running, probably in May.

If you don't already own it, I recommend that you purchase Des Hammill's book 'How To Build & Power Tune Weber & Dellorto DCOE, DCO/SP & DHLA Carburettors'. I think you'll find it very helpful. Best wishes, and enjoy your triples.

i didnt mean to sound rude, just tried to spark the thread back up with the hope that someone would reply.

First you apologize for sounding rude, when you really didn't need to. No harm in being careful. :)

i guess this thread will die like many other questions that could help others..

And then it becomes clear that you were actually apologizing in advance because you were planning on following up with a rude comment. :stupid:

Sorry, I'm a little slow, but it's all clear to me now.

.

.

.

For the record. HS30-H is one of the more savvy people you can turn to when it comes to advice.

When I was running the Mikuni's I was chasing my tail for a while and he is right about what he says, for me anyway, it was trial and mostly error.

But that is also how you learn.

Good luck!

  • 4 months later...

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