Twin carb upgrade

[skattrd]

I thought I'd ask for some input from the more mechanically minded around here. I've recently won an auction for twin carbs for my Spyder. Everyone on the Lancia forums fits an electric pump and fuel pressure regulator with these. However my mechanic reckons they would be ok with the stock mechanical fuel pump. The fuel pump is only about a year old, so I'm toying with it .... thoughts/comments appreciated.

[Junkman]

If it works with your standard mechanical pump, you don't need an electric one.

If it doesn't work with your standard mechanical pump, you need an electric one.

[skattrd]

Yes, but can't under-fuelling cause damage?

I know on turbo motors running a mixture too lean is very bad.

[Sigmund Fraud]

The no-risk way would be to spend £££ for a good quality pump and regulator, then fully rebuild the carbs, then take the beast to a rolling road for tuning. That way the mixture is going to be spot on (well... as spot on as carbs can be !).

 

The Autoshite way would be to just bolt the carbs on and see what happens !

[Station]

It should be OK I think, if there isn't a lot of difference between the jets, you may have to to give the mixture screw a few turns.

[Mr_Bo11ox]

I would probably fit a second fuel pump to be sure of flowing a sufficiently large quantity of fuel to keep those thirsty bastards from drying up

[willswitchengage]

Yes, but can't under-fuelling cause damage?

I know on turbo motors running a mixture too lean is very bad.

 

Lean burn is hotter so that could be an issue.

 

Get a Facet pump and wire it across the ignition. I used to have a BX with one installed as it was more reliable. Perhaps add a no-return valve for extra security.

 

http://www.facet-purolator.com/ - can be bought readily online

[barefoot]

Everyone on the Lancia forums fits an electric pump and fuel pressure regulator with these.

 

For a reason?

Why query advice from a specialist forum with 'the more mechanically minded' on a general one?

[Mr_Bo11ox]

In case someone can explain why the elec pump and regulator is necessary surely.

[Junkman]

Get a Facet pump and wire it across the ignition.

 

Oh no no no no no.

 

It'll keep happily pumping after the crash, when the fuel pipes are burst, the car is on fire, and nuns and kittens are trapped inside unconsciously.

Either wire it via a resettable inertia switch, or the oil pressure switch.

Reversing relay advisable for the latter.

[Station]

On the subject of fuel pumps - when you turn the key, and the fuel pump primes, what stops the pump from spinning? Does the fuel pressure regulator control this?

 

Either wire it via a resettable inertia switch, or some control light that's on, when the ignition is on, but the engine off.

 

 

Not spoilt for choice with warning lights on an 80's Lancia?

[Junkman]

On the subject of fuel pumps - when you turn the key, and the fuel pump primes, what stops the pump from spinning? Does the fuel pressure regulator control this?

No, the fuel pressure regulator regulates only the pressure. However, you can buy low pressure pumps designed for carburetters and no regulator would be necessary.

 

Not spoilt for choice with warning lights on an 80's Lancia?

I corrected it to oil pressure switch.

Inertia switch is the sound solution from an engineering point of view, though.

[derskine]

A simple T piece will also work in place of the pressure regulator.

That is, join the feed and return pipes (if it has a return pipe) together, and take the 3rd point to the carbs.

When the needle valve is open, it delivers low pressure fuel to the float bowls, but when its closed it just runs back to the tank.

[Station]

Inertia switch is the sound solution from an engineering point of view, though.

 

K-series have a resettable one right next to the engine if needed.

[forddeliveryboy]

Everyone on the Lancia forums fits an electric pump and fuel pressure regulator with these.

 

For a reason?

Why query advice from a specialist forum with 'the more mechanically minded' on a general one?

 

Well. people can be sheeple even when on hallowed forums...