to upgrade carb or not?

[rodney3010]

I've currently got my 2000 spider running but she's not as smooth as she could be. For want of a better description she 'chokes' up on a lot of revs and I'm now assuming its a carb problem. Before I go any further I have to be realistic and admit these are old carbs and I really ought to sort this properly. I've been reading past posts and get the impression that the standard carbs may not have been the best. Is this correct? If so, what do I upgrade to? 45's sound the first choice but 40's are cheaper. Anyone got any idea what 'cheaper' means? Just how much would I need to throw at this? Plus how easy is this? I suppose I could get the originals refurb'ed. But need to look at the cost of all options before deciding.

[MattNoVAT]

I thought along these lines, but first I took the car to a old school tuner and put it on his rolling road.

Second thing I've done more recently is to change the two gaskets between the inlet manifold and the plastic spacer underneath the carb. This worked wonders for me and she now like a different car.

Next buy a carb repair kit £11 off eBay and replace all those bits.  If you don't want to buy the repair kit just try tightening the 6 or 8 screw bolts that secure the top half of carb to bottom.

As they get old the gaskets fail and let air in where it shouldn't  and the the engine runs rough.

I'd say try this before going down a more expensive road.

The carbs are ok IMO, just the auto chokes sometimes fill up with crud and the gaskets age and get affected by the petrol over the years.

[HFStuart]

If you do decide to 'upgrade' the carb there is a single 40/45 DCOE manifold available that you could probably make work - it wouldn't give quite the power of a twin set up but I suspect it would be a lot better than standard and one carb is cheaper than two!

[rodney3010]

Thanks for the info gents. I've used one of the repair kits and replaced all those bits - no difference before or after.
Any sugestions for who's the best supplier for the single 40/45 DCOe manifold? Unless anybody has anything out gathering dust they may want to get rid of just before Xmas?
Next question (and technically not carb related) but just for ease of mind I may replace the HT leads. Does anybody have any preference for manufacturer and is it really worthwhile spending a few more pennies?

[MattNoVAT]

8mm leads only, depends on budget and if it's race spec your after.

You gets what you pay for!!

[HFStuart]

Not sure about the best supplier as I think there's only the Mangoletsi design

http://www.dellorto.com/merchandise/products_details.asp?PartNo=MFIATSINGLE45&CategoryID=8&PartsectionID=46

Note that to use this you'll need to get an angled spacer made up so the carb sits horizontal. You might also have to relocate the rad fan to in front of the radiator.

I'd go with Matt's suggestion first though and try a rolling road you might find it's not carb related at all. A friend of mine had a symptom the same as yours and it turned out to be the second stage ignition advance wasn't happening. A new distributor transformed the car.

I've got Magnecor leads on mine  - pretty much just because I like the colour! They do seem well made however and no issues so far.

[rodney3010]

Thanks chaps
I think logic (and Mrs Rodney) will dictate that I try the rolling road first. I've quickly priced up the manifold and carb at the best end of £500.
However, I can't help thinking how much improvement it might give! Has anybody out there done this and able to give feedback? If i do have a rash moment and give the credit card a good bashing I'll post the results.
Alternatively, has anyone got a second set-up surplus to requirements?
Rodders

[WestonE]

Rodders

Just in case you do not know Guy Croft has had another run made of twin 45 manifolds done that bolt right on. Fast road cars on ebay probably best price on twin 45 DCOEs new and if you ask nicely you can get the right jets included (GC will tell you the spec). Magnecor make great quality leads and I have been very happy with the KV85 items. Beware SH DCOEs as they can have twisted spindles or damaged idle jet bases from over tightened idle screws which no gasket kit will fix plus the pair must be the same type for the progression holes to match. You can try bike carbs but jetting can be a real challenge. If you have never done it expect to pay for rolling road setup including balance and idle setup. Do not skimp on the airfilter and trumpets as good full radius items (ITG Pipercross) make a big difference to torque. Lastly make sure you fit a fully matched linkage including the carb balance links. My personal favourite is the weber one having built 4 Beta engines and 1 Montecarlo engine on twin side drafts I have had some practice!
Lastly get and fit an IE radiator with a curved hot air deflector (pattern in card made in aluminium) under your airfilter to ensure you feed your carbs nice cold air and have good itake clearance from the trumpets.
This makes the domed filters easiest to fit in the space.

Fit the longest trumpets you can, but have at least the outer diameter of the trumpet mouth as clearance to the inside face of the airfilter typically 60mm. 1 single filter and back plate is better than 2 and you can have a blank cut to suit by Pipercross/ ITG. Just use paper then cardboard to make a template. 

If your dizzy has vacuum advance keep it but fit a 0.8mm MIG welder hozzle in line as a restrictor to stop the base plate shuffling at idle.

This will give you 155BHP 140 ftlbs and great throttle response and a big grin. However you will not have a cheap fuel bill if you keep using the addictive acceleration.
The standard carb can be re-built to a high standard with a K&N filter and re-jet to a high standard IF you can find a good condition low mileage base carb. BUT it will always be 2 stage and 130BHP is the best you will ever see even with a great cylinder head.



Enjoy
Eric
     

[WestonE]

Rodders

You will need a facet silver top competition pump and a filter king with the means to fit a guage that reads in Ftlbs to set 3 ftlbs. No return is needed so blank that at the tank. The standard pump will NOT provide enough fuel so buy or fit a blanking plate.

Eric

[rodney3010]

Brilliant, thanks Eric. Sounds very tempting. I will post an update and grin factor when finished.
Rodders

[Zagato]

Eric

Do you have any pictures you can post of the air filter/intake and radiator set up

Thanks
Richard

[WestonE]

Zagato

Hang in there whilst I search for and scan old school photos.

Eric

[ck037]

Good Afternoon to everyone.

I had a serious problem with fast cornering.
I found the below Weber 36. It is from a rear wheel drive car...do not know the car model.
It works perfectly and I managed to gain almost 7 Hp and 2 Lbs torque...
The air filter and its box remain the same



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