single 45 DCOE on a Lynx mani, about to throw in the towel!

[bento]

2 hours ago, TobyB said:

A question- does the Lynx split 1&4, 2&3, or is it common plenum?

I can't tell from search/pix.

 

t

Looks like 1&4/2&3 from the photos on the TEP website.

 

https://www.racetep.com/manufacturer/carbs-and-injection/weber/conversion-kits/bmw-2002-320i-m10-engine-single-sidedraft-dcoe-conversion-kits.html

[Simeon]

It splits (crosses over as they call it)

https://www.lynxauto.com.au/bmw-2002-weber-dcoe-crossover-manifold.html

 

Not like this splits (just because). 

 

 

 

[eurotrash]

does not compute. 

 

['76mintgrün'02]

I stole this from Bento's link:

 

"The patented crossover design does just that- it splits the pulses (in firing order sequence) that are created by the downward movement of the piston so as one throat receives one pulse, and the next pulse (in the firing order sequence) goes to the other side of the carb. This way the pulses that the carb sees are evenly spaced, allowing better cylinder filling than the conventional design, hence more power and torque."

 

 

[TobyB]

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The “Lynx Crossover” manifold is unique in that it connects venturi A to cylinders 2 and 3 and venturi B to cylinders 1 and 4,

 

Oh, yeah, lookit that.  Thanks!

 

From that, I'd tend to agree with a smaller (32-34) venturi for better metering at around- town speeds- especially if it's being hard to tune.

 

Also, if it says

Quote

Quote

Spaid in Maine

 

on the carb, it's time to find a DCOE expert and have them check it.

 

Not all of the Spanish carb- shaped objects are actually carburettors.  

AND even a properly made carb can get clogged up, have a leaky float, etc.

 

Personally, I'd try to get the Lynx working over a 38/38, although both would be OK for this application.

 

As would a 32/36...

 

t

 

[inquisitive]

21 hours ago, eurotrash said:

Some suggestions:

Stick with the side draft set up you have.. 

Get in touch with Jeff Chang.  He bought Todd21's blue car that had a screaming single side draft motor.  you may be able to get the jetting info from Jeff.

Or.. Try Le Tran, he's in Ontario, CA.  He may have experience with that kit. 

Get your wide band in, it tells you volumes..Not having it is like having paper and no pen.  A smoke and no lighter..  

or try this one  (CLICK HERE).. its great when installed into the dash pod.  Very discrete.    

and any motor worth its build $ is worthy of a 123 ignition distributor.  Consider it.  

 

Well the plot thickens. Thanks for the recommendation. 

 

I got ahold of Jeff Chang and he advised against sticking with the 45DCOE. He said it was too much carb for my setup and recommended I go with a 38/38 instead. He told me the 45DCOE is good for setups pushing 150hp+ and it would be very difficult to tune it for all around drivability.  

 

Hmmm, so far I've been told to go with a 38/38, dual 45's, or replace the 45 DCOE 152 with a 45 DCOE 152G (4 progression holes). So confused! 

 

 

[Tommy]

6 minutes ago, inquisitive said:

Hmmm, so far I've been told to go with a 38/38, dual 45's, or replace the 45 DCOE 152 with a 45 DCOE 152G (4 progression holes). So confused!

 

All options are possible

Anyway I see single 45 better and easier to tune than dual 45's that I would rule out first.

I had 292 cam with Lynx and 45 DCOE and I'm 99% sure the chokes were 36mm. It was a racecar but would have been totally streetable. I was looking my files yesterday but failed to find info about jetting - sorry.

[eurotrash]

This set up was all the rage and in high demand a four or five years ago.. I find it hard to believe that there aren't more guys ringing in with advice!  I had a manifold myself once, but never implemented it..  Ordered it from Lynx directly when they were NLA and supposedly not going to be reproduced.  

[TobyB]

Quote

Hmmm, so far I've been told to go with a 38/38, dual 45's, or replace the 45 DCOE 152 with a 45 DCOE 152G (4 progression holes).

AND a 32/36, you know.

 

You should do what you want to- ANY of these options will work.  Just pick the one you want, and go for it.  They will all need to be tuned- the 32/36 will probably 

be easiest/most forgiving.

 

Another way is to find an expert you like and trust, and do what THEY recommend, and get them to tune it.  That works, too.

 

t

 

[eurotrash]

I have dual 40s on a tapped out 76 motor with only a 284 cam.. and it shreds.  I have to disagree with Jeff on this one. I am surprised as the motor I referenced earlier was basically the same as yours.  Maybe identical. Did he offer to buy your set up..?

Edited June 14, 2017 by eurotrash

[resra]

I had a 72 that came with a lynx setup and 40 dcoe. Never could get the car to run right. spent money, rebuilding the carb, paying experts to tune it etc. and in the end after spending too much money just replaced with a new electric choke 32/36. Never looked back. Yes a 38/38 would be better but my engine is dead stock and tired from drinking all that extra gas the lynx dumped over the years and miles.

[Harv]

IMHO there is no reason your single 45DCOE setup will not work. Now I've never tuned one of those but from where I sit, your jets are all way too big. Thus rich! What distributer do you have (I may have missed it). 

 

Good lord! 070 idle jets! Do you know how to determine if an idle jet is the right one?  A LOT of driving on a DCOE happens on the idle jet. You want the jet that lets the engine idle with about 1/2 to 1 turn out from closed on the idle mixture screws. If it requires more turns the jet is too small less, too big. If I were starting blind and was at your house I'd start with 055 or 060. Also down on that main jet too. 125 or 130. But as I said, all just guesses from here and without a wide band. 

 

John

[inquisitive]

1 hour ago, Harv said:

IMHO there is no reason your single 45DCOE setup will not work. Now I've never tuned one of those but from where I sit, your jets are all way too big. Thus rich! What distributer do you have (I may have missed it). 

 

Good lord! 070 idle jets! Do you know how to determine if an idle jet is the right one?  A LOT of driving on a DCOE happens on the idle jet. You want the jet that lets the engine idle with about 1/2 to 1 turn out from closed on the idle mixture screws. If it requires more turns the jet is too small less, too big. If I were starting blind and was at your house I'd start with 055 or 060. Also down on that main jet too. 125 or 130. But as I said, all just guesses from here and without a wide band. 

 

John

 

 

This is my first real venture into carburated car ownership. The last 02 I owned was 12 years ago and like the other two I owned, they ran 32/36's that I never messed with. 

 

I just ordered an array of mains, idles down to 50F8, 180 and 185 air correction jets, and  50 pump (I think there are 45's in there now). 

 

FWIW, the engine won't idle under 1 1/4 turns out. I also double checked that the idle lever screw is set to 1/2 a turn past initial contact. 

 

Gonna give it another shot when everything arrives. Found a tuner locally (thanks Ira!) who's willing to dyno tune it for me too, so have that as my fallback. 

[zinz]

Kinda late digging this up, but here's what my old Weber book says for a single 45DCOE13 on a 2000cc engine

 

34 choke size

145 main jet

F2 emulsion tube

185 air corrector

55f4 Idle jet

50 pump jet

2.25 needle valve

 

With your smaller chokes, I would say to decrease the recipe above a bit, but cross referencing for 45DCOEs with 32mm chokes in this Haynes Manual, they still call for a 140 main but a 45f6 idle jet.  As everyone is telling you, most daily street driving is on the idle circuit of a DCOE; you gotta get that one right before the other circuits will cooperate (your current 70f8 is way too big IMO )

 

You are absolutely sure your distributor is fresh and not worn? Easy check... take off the distributor cap and rotor and pull up on the center shaft.  It should be fairly snug up/down. If it is loose, it will give poor running, especially at low rpms.

 

Good luck, I bet you get it figured out pretty quickly.  

 

Ed

[TobyB]

Quote

Did he offer to buy your set up..? 

I was going to...

hee

 

t