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2.5L weber 40s start settings


RustyLogic

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Hi,

 

Looking at starting afresh with my webers. How does the following look? (before I waste my money!)

 

Chokes: 34

 

Emulsion Tubes: F16

Main Jet: 135

Air Corrector: 160

 

Aux Venturi: 4.5

Accel Pump Jet: 40

Accel Bleed: 50

 

Idle Jet: 45F2 (not sure about the F2 - picked the one in the 'middle' of the range)

Needle Valve: 175

 

 

 

Current setup:

 

Chokes: 30

 

Emulsion Tubes: F11

Main Jet: 110

Air Corrector: 160

 

Aux Venturi: 4.5

Accel Pump Jet: 40

Accel Bleed: 50

 

Idle Jet: 50F11

Needle Valve: 175

 

All comment welcome  :)

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You'll need 50F9 or 55/F8 idle.

 

45 too lean. F2 unlikely to work.

 

If it works, leave it alone?

 

Thats a massive load of cash those jets, bet thats £400.

 

Unless the engine tuned and cam'ed stick with the 30chokes. Big chokes won't work as you think.

 

It needs what it needs, thats not a book number, it's what it actually wants...So the chances of those jet's being good is reasonable, the chance of them being perfect is remote.

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You don't need to buy all that stuff.

 

If you have 30mm chokes, stick them on a lathe and bore them out 1mm at a time and see if it makes any difference eg......31 ....32mm

 

Then be clever and get yourself a load of number drills at 0.005 or 0.010mm intervals.

so say you use 0.100, 0.110 0.115 0.120 0.125 0.130 until it runs fine.

 

Nobody wants small jets of say 0.090 so you can raid the bins of people who have plenty of s/h ones.

 

Then you just drill 'em out until it runs right.....

 

It's what I always did, that way the money goes into my pocket for tuning cars not into expensive (and usually wasted) parts from retailers... ::)

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I tell you what is bloody annoying, I just found this which puts me fairly spot on already and my purchases would be a total waste of money and completely wrong.

 

40 DCOE jettings and settings for TR250/6

 

D = choke size

E = auxiliary venturi

F = main jet, controls fuel mixture in the emulsion tube as cruise circuit is activated

G = emulsion tube

H = air corrector jet, affects only performance at high RPM

I = idle jet, affects idle and progression circuit

J = accelerator pump jet

K = accelerator pump inlet valve with exhaust orifice (also called a discharge bleed).

L = needle valve, affects fuel flow into the float bowl

 

Reference       D    E    F    G    H     I     J   K   L

-----------------------------------------------------------

Weber (0)       30  4.5  120  F11  160  50/F11  40  50  ?

Haynes (0)      27  4.5  130  F2   160  50/F11  45  0   2.00

Fitzgerald (0)  27  4.5  120  F11  160  49/F9   60  ?   1.75

TriumphTune (0) 28  4.5  115  F16  175  50/F9   35  ?   -

TriumphTune (0) 30  4.5  125  F16  180  50/F9   35  ?   -

Phillips        30  4.5  155  F11  200  45/F9   50  ?   -

C. Kantarjiev   28  4.5  110  F2   160  45/F9   -   ?   -

A. Nugent (1)   28  4.5  120  F16  175  50/F9   35  ?   -

A. Nugent (2)   30  4.5  120  F16  180  50/F9   35  ?   -

A. Nugent (3)   33  4.5  125  F16  185  50/F9   40  ?   -

L. Bickel (4)   28  -    120  F11  160   -/F9   -   ?   -

B. Mains (5)    30  -    120  F11  160  60/F9   50  ?   -

R. Lang (6)     28  4.5  125  F16  160  55/F12  45  ?   -

R. Lang (7)     28  4.5  120  F2   165  55/F12  45  ?   -

S. Ingate (8)   30  -    120  F11  -    50/F11  40  ?   -

40 DCOE-151 (9) 30  4.5  115  F11  200  45/F9   40  100 1.75

S. Ingate (10)                                  45

C. Arnold (11)           140  F11  160  55F9

 

*EDIT* more details and source here: http://triumph.hottr6.com/tr6weber.html   *EDIT*

 

GT - ta, but I have no access to a lathe and my selection of and skill with drill bits is fairly non-existent!

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  GT - ta, but I have no access to a lathe and my selection of and skill with drill bits is fairly non-existent!

 

good grief, just go into a hobby model shop and ask for a 12v model drill!!

 

weber jets are only brass, takes about 30secs to modify one using a finger and thumb.

what could be hard about that?

 

take your chokes into a machine shop. takes about 5 mins to modify!! ::)

 

Oh, and most of the info you cited on that page is twaddle!  :o

 

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I got my drills from http://www.chronos.ltd.uk/.

 

My jetting was OK, except the cruise was really "pulsey". Opened out the hole on the Idles according to Mr Sideways advice and she cruised beautifully now.  Amazing how one small change can have such a dramatic effect!

 

BTW I use 32mm chokes on my 2 litre only because I use 130 mains and I think the "rule of thumb" the relationship of choke to mains is 4:1 i.e 130/4 = 32.5. (I think that's from Des Hammill's book)

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You checked the prices recently, of new stuff :)

 

£150 I wish! That would cover 1 carb at retail.

 

Your current jets are more suited than the suggested ones!

 

If you just hold the drill bits in a vice and twist the jets into the drill, its a finger job as GT says.

 

 

I'm up to £50 so far on jets for just a sigle DCOE 45 that I'm trying to get spot on dialed in... and it's bloody close already. So that's £150 when times by 3 already, and that doesn't include the really expensive bits (i've not bought chokes or emulsion tubes)...

 

On chokes, 34 sounds big... I would have thought 30 to 32 would be right depending on state of engine and where you want your power. General rule I've also read is to stay on the lower side as this will be more drivable offering better midrange sacrificing very little at the top end. As you've got 30's already, thats a good hundred quid or so saved... maybe try tweaking elsewhere first...

 

What exactly are you not happy with at the moment? Maybe people could suggest changes from your current base which may work out a more effective and economical way of tuning? But i'm new here, could have missed that question already...

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Thanks chaps, I'll put them back together and see what the problem is (took them apart and cleaned up due to th accel jets being full of crud). Might take awhile as the front suspension is currently in bits on the garage floor too!

 

Before they came apart there was a fair amount of spitback at idle and she would not rev over 5k. Also noted on stripdown that some main jets were 110 and some 115 which expect was not helping matters!

I have got some 33 chokes, is it worth rebuilding using those?

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I'd leave the 30mm chokes in but get yourself a selection of main jets, if it's that gutless at the top end I think it could be a lack of fuel... I'd start by getting 6 115's, 120's and 125's and go from there...

 

If it were fine lower down the rev's I'd say just drop the air jet which has a more pronounced effect right at the top, but as you say it's poor throughout I'd swap out the main first.

 

Make sure your timing is in a good ball park mind cos if that's miles out it'll all be a fruitless exercise...

 

 

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110/115 for any form of race cam is miles too small.

 

They usually used them in cooking Renaults/Simcas with road cams.

 

I don't think I've ever used anything smaller than 125, but if you have the right bits in the engine, cam head, exhaust, then you can easy take it out to 32mm choke, and you shouldn't fall off a cliff at 33.

Btw you never orginally said if they were 40, 42 or 45 DCOE

 

Timing will be 28-30 or something's wrong with the engine.

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