I've found a small hairline crack on my Oselli inlet manifold which is leaking air so I think it's time I stopped mucking around and treat myself to a new one. I'm running a 40 DCOE Weber and was wondering if anyone had any recommendations, from what I can see Maniflow seem to be the ones but what length and will a standard one fit under the bonnet? Any advice would be warmly received
Just to make this even more painful on the wallet, I'm also thinking maybe a change of carb to the 45 would be better than the 40 in the long run as this seems to be the view of most reviews I've read?????????
(My engine is a 1330 with a Piper ST2 High Torque Cam and has the metro cylinder head if this helps)
I have a 6" Maniflow intake with a 1/4" to 3/8" rise. Fits fine with the top mounted Sytech linkage. Plenty of bonnet clearance. Carb's K&N will sit over the frame rail, no problems with running clearance.
I also have used a 5" intake with a 3/8" rise as well. No problems with fit or clearance.
Hi Si. I'm running a 1380 with similar cam and head to you. 6" Maniflow on a 45 with KN Flat air cleaner. It all fits. Can't remember the bore of the manifold tubes, you need to check your inlet tract diameters to get it right then align it all. Using an undermount linkage from Fast Road Cars. Everybody says the 'old' and now quite rare Italian 45 is best as it has different number of progression holes best speakto an expert. Had a problem with the Maniflow from new, the head faces were not a flush fit, even with the competition thick manifold gasket. Caused all sorts of grief with running too rich and resultant bore wash. Sent it back and they sorted it out. Jeted it all as Vizard but not enough knowledge to get it right took it to Gerald Dale in Hastings. He sorted it all in an hour, no rolling road just his experience. Best of luck. Ian
6" Maniflow. Standard Midget item WRT the rise. K&N filter, with the internal trumpets. Underslung carb linkage. It all fits. Just.......
As for the carbs; choked-down 45s. Can't recommend Neil Slark at Slark Race Engineering, Boscombe Down, highly enough when it comes to setting up Webers.
I have used both a 40DCOE and a 45DCOE on my engine with no change other than the carb itself .
The manifold tract diameter suits the 45 whereas the 40 was undersize to the tract . I am unsure
as to the make of the manifold as it was retrieved from a skip , along with the 40DCOE , at the
local tip .
I ran the car with the 40 for 2 1/2 years and it performed well . The 45 was fitted 1 1/2 years ago
and the car has more grunt albeit there are some occasions when going from a trailing throttle to
power back on it will stutter slightly , it clears its throat almost immediately and we are away again .
Top end is definitely improved , I have no idea what has happened to the fuel consumption though .
The engine is at plus 40 thou , 1315 cc ? , nicely ported and chambered with standard sized valves ,
the cam is a standard midget but with 1.5 : 1 forged rockers , so in all nothing excessive .
The 45DCOE is set up as follows :-
Chokes 38mm
Mains 165
Idle 50f8
Pump 45
Emulson F16
Air 180
Aux Vent 4.5
Idle screws 1 1/4 turns out
I do have some 55f8 idles which I am going to try to see if they cure the stutter
Visualy the 45DCOE looks a treat and I have the inlet trumpets that are slightly angled upwards , better still ! !
Check your anti vibration gasket(s) for a bad or improperly installed O ring, or tighten up the carb and gasket set if you have one of the bonded O ring gaskets. Check for broken spring washers if that is what you are using. I have found that the rubber bushing washers work better.
Loosenes of the carb will cause a lean condition on tip in, which may be causing your cracked throttle problem.
Otherwise, richen up the idle jets and the mains. You can balance the top end WOT with larger air corrector jets.
I have twin DCOE 40's on the FWB and finally addresses some nagging problems this Spring. I was having an issue and could not put my finger on the problem. I eventually found one of the vibration seals between the intake manifold and the carb had slipped an O'ring. Whether it was a bad installation or a backfire that moved it I'll never know. I had never taken the carbs off the manifolds but I am glad I did.
The other issues were an intermittent puffing sound from the carbs, transient was marginal and sometimes idle would race. I found I was running too lean. Haynes Weber Carburetor Manual says to start tuning at 3/4 turns open on the idling mixture screw which I had always used as my starting point. However, I found another resource this Spring saying to start at 2 1/2 turns open from the seat on DCOE's. I would have never have opened a screw up that much let alone four had I not read that this is the starting point, but in my book it is. Everything got better.
I can see why Webers have a reputation for being difficult, but when it is right life is good.
I have found that Webers are no more difficult than any other carburetor.
They do have a lot of parts, and are usually in multiples, which always conplicates things.
Add to the challenge is having to start from scratch with the tuning on any modified engine. This is just as difficult when trying to dial in a big old Holley on a V8, or even a single SU, when you have perhaps 20 different needles that can work (sort of) with your combination.
Webers have a lot of adjustments, from ventury size and configuration to a multitude of emulsion tubes, and jets with the idnetical sizes, but different configurations. It's a lot to reconcile.
I took the easy route, and started with an engine configuration that was researched and proven on the dyno, so that there was plenty of Weber information available to start with.
APT had done the work, and David Anton got me within a jet change or two of a useful tune with the parts that he had sent with my new Weber (Nothing like having a new carburetor that has not been previously molested by several mis informed owners. I have never really had much success with old, used carburetors.
The main problem that most people have with Webers is that once they get them working, they are just wonderful. However, often, there is a change (often for no reason), and they start fooling with the carburetor's internals again, when the problem is, well, Ignition or a bad manifold gasket or coupler.
Carburetors don't re jet themselves. if your previously perfect Weber setup is not working properly, don't take the carb apart, other than to see if something has come loose inside (the venturi retention screws can be a problem, and they are UNDER the carb so that they are often missed when tuning problems arrise), or that there is a problem with the anti vibration O Rings, vacuum line or ignition, fuel delivery, choke linkage/pull wire or the throttle cable. That loose venturi? Common, even with the tab locks. Not so much of a problem if you safety wire the retention screws. Anyway, a loose ventury will cause all sorts of problems that might be hard to diagnose, so check beneath the carburetor for loose or missing screws or tab locks.
The previous owner of my car complained bitterly about the Weber and how it never worked... I found that it had inhaled an O ring... and it had been in that condition for more than a decade (maybe two). No wonder it had only traveled about 2500 miles with two owners over nearly 30 years...
Further to my previous comments about the 45 DCOE on my car , I decided to spend some time resetting the idle screws and also
the throttle stop before changing jets . This gave good results for minimum effort with the only difference being the idle screws are
now 1 turn out against the previous 1 1/4 out and the throttle stop is backed off slightly . Now have an even idle at 900 - 950
rpm and the engine picks up cleanly without the stutter .
Further to the inlet manifold cracking , I had an entry under topic 45 DCOE in " Induction noise " where I stated the manifold I was
using had provision for a support bracket which I had made use of to reduce the cantilever loads on the manifold / head flange .
Considering the weight of a DCOE , the distance from the cylinder head flange face and that two of the four mounting holes are
only " Half Holes " it might well be prudent to fit additional brackets anyway , particularly considering how little is involved .
Thanks for all the information chaps, I now have a bit of a plan and once I get my registration number I can do some proper testing on the road and find out what works best.
