Carb Questions

[Mike Cardwell]

I have a '71 1.7 914 that has a single carb mounted from the PO. He said it was a Weber but I'm not sure. The only markings I have found are located on the base and they read:
R7760 1990
I would appreciate anyone who can identify this carb because right now the car runs horribly. There is no choke hooked up. The only connections made are the fuel line and the accelerator cable. When I finally get it started, it runs smooth and idles great, but when I step on the gas, it sounds as if I'm choking the car with gas and it wants to die. The accelerator wants to stick also and I believe it is the linkage on the carb because Ireplaced the throttle cable and pedal but it hasn't helped. I plan on replacing with original FI but I just want to get it running right now. Thanks.

[ChrisG]

Carbs are notoriously bad when not set up correctly.
A quick list of things to check before you go any further.
1/ Take a look at all of the joints for the carb set up. Depending upon who installed it and which carb set you are using they could have installed thick card or noeprne (spelling?) seals. The former is okay, but does get choked afer a while and degrades.
The latter gets affected by heat and solidifies, espcially on the single carb type 4 set up. When this happens the seal can be broken by the joint loosening.
From what you describe it sounds like you are pulling air in from somewhere - at low air volocities the car runs fine, however when you increase the pull on the air flow you might be dragging air in from somewhere else.

The second thing is to look into what type of carb you have. I dont have an answer for you on what you have, however in twin barrel weber and Dellotro carbs, they are names are clearly marked.
First of all look at the shape of the carb. how many venturie (Spelling again - how many barrels does it have) and what shape are they?
If it has twin barrels which are circular, with very defined barrels in the main body of the carb, then you most likey have single - twin barrel Weber or Dellotro.

If, on the other hand you have a square single barrel with no defined barrels within the body of the carb you most likey have a single progressive Weber (not good).

Not being that much of an expert in carbs if anyone want to make me look silly, feel free to do so!

To find out if you are running lean or wet, take a spark plug out - if there is chocks of carbon build up - you are running wet (too much fuel)
If the plug is whiteish and possibly corroded you are running lean (not enough fuel)
Another good tip to check if you are running wet is ask yourself how many times it backfires? With too much fuel going in to the engine, the over excess of fuel will tend to leak out into the exhaust system and then ignite when the exhaust valve opens again, causing a nice bang!

The overall diagnosis comes down to this.

If you are running wet, not enough air is getting into the system compared to the amount of fuel going in. This is normally caused by poor Carb set up and the wrong jets in the carb(s).
If you are running dry (check your plugs) this can be down to either poor jetting again, or air being dragged in through somewhere else in the system (ie the Venturie (spelling again) is not being fed the correct information on air flow is is not dumping enough fuel in to compensate.

There is a last factor which affects the set up of the car. The Cam on the 914 is specifically set up to run with FI. Cant remember off the top of my head but I think the valves close earlier that they do with carbed cars - hence while the fuel is still trying to wind its way down from the middle of the engine, the valves can close, letting the fuel seperate (de-emulsify) and when it does enter the cylinder, you dont get a clean burn of the fuel.

Okay - please feel free to rip this answer to bits

LOL!

Chris G

[MJHanna]

Please look to see if you have an aftermaket fuel pump. If the stock unit has not be replaced with a lower pressure unit (3-6 lbs.) you could be pumping way to much gas in to the carb. Most people use a FACET pump with a fuel regulator. Most of the single card set-ups don't work that great. But some of us love our double Weber carb set-ups. Please no flames, I don't knock those that like FI (I like it also), but for my track car the stock FI will NOT pump enough fuel.

Carbs don't do well with the stock distributor, try a 009.

[Mike Cardwell]

I took another look at my carb and I have 2 barrels that are square in shape. There are two openings that have been plugged off with hose and bolts. I thought about what you said and I closed the flap while pushing the accelerator. This made it run better without hesitation so I wired the flap almost closed and drove it down the street. It didn't hesitate but it felt as if it had all the power of a really weak VW bug. Any guesses on where I should go from here?

[ChrisG]

Humm - what you did was shut of the second choke barrel.

What you have is a Single Progressive Weber.
These carbs were fitted to Fords etc.

It works on the principle of having two barrels - One is a largish one which controls low end speed tickover etc etc.
The Second is the Progressive barrel. When you put your foot down, the second barrel will open allowing more fuel and air to pass into the system.
These things were designed to give fuel economy while having that extra "umph!" when you needed it.
This carb is certainly not the best in the world as it is designed for a specific engine.

Actually I have probably an identical carb sat in my garage which I never used. It cost me £15 ($25) from a scrap yard.
It seems that the PO had enough of the FI messing around (I know that feeling) and decided to go for a cheap option.

Knowing this now, you need to check a few things.

Firstly as MJHanna said, check if you have a Bosche 009 fitted. You can tell that by seeing if a vacume chamber is attached. If it is you need to change the dizzy for a 009 - they are relatively inexpensive ($60?) and through using a machanical advance they will solve many problems.

Next up however is the carb itself.
If a 009 has not been installed I can understand better why the car is possibly running rich. In order to get a quicker advance on the car, the jets have been set up to pour fuel in. If this is the case, then a 009 and rejetting of the carb will fix it.
If a 009 has been installed the problem is still most likely down to jettting again.

Venturie size will also affect the fuel mixture.

Needless to say though - if you are going to replace the original FI unit at some point, I would start looking for one now as to be honest, resetting up the engine with the carb will most likely be more hassle that fitting the FI back (and then again, maybe not !)

Anyhow, that me done

Chris G

Good advise above, but I would NOT use the 009. The 050 dist.is by far the better unit and for just another $10 you get rid of the flat spot that the 009 has.

I won't get into the FI vs Carb debate, but pouring gas by hand, into the intake is better than that Pinto/Weber progressive carb. Twin 40 webers can be found on the net for less than $300, complete with air cleaners, manifolds, linkage and fuel pump.

Just my two cents.

[ChrisG]

Ah - that is what they are called - Ford Pinto Webers........

I remember some of my friends with Mark 1 & 2 Escorts (UK only) who had the pinto carbs fitted as standard on the RS models - just forgot what they were called.



Chris

[Conrad W Peden]

This is to Michael. You are sp[ot on with the 050 distributor but where can I find one. They seem to a rare item these days(at least new ones).

[rich]

The weber DGV,DFV,DGAV 32/36 carbs were used on several engines. Ford cortina's,BMW 2002's ,ect. These carbs really do work good if all things are right. To just bolt on an intake an carb without correcting the lift and duration,timing,or advance seldom works. Start at the begining, And remember,long intake runners work best with long duration at hiway speed.(remember the big chryslers with there crossram duel 4 barrels, big cruisers)I assume thats why the duel webers seem to work.Get rid of the progressive single. It's a good carb butI don't think it's best suited for the 914.

Just a thought