Go crazy?

Don't mind if I do!

Here are my n00b problems. I've been building a 2.0 litre Mk pinto since last year (been away at uni most of that time) The build so far has been great but now i've got to the engine, something I know little about.

The engine is in, ignition all set up, it's timed up (local garage did this last week but at the time the ignition wasn't complete for them to test it) Now the engine turns over and starts but something's not right... It half starts most times and dies out but sometimes it starts really well and revs super high before I cut it.

So the thing I want to know is what is causing this and how to remedy it. Could the webers have the wrong jets (although they were ordered and fit for a 2.0 pinto), adjustment on idle needed? What effect does a performance cam have and would I need to change anything for? I'm using an electric Facet pump which is all set up. It's 7psi, is that right or too high? Are there other options like rolling road or somewhere that can set it up?

Thanks for any help

IMO 7psi is waaaaay too high. 2.5-3 is a good starting point.

Do you know what spec the webers have been delivered to you?
What type of ignition system?
What spec is the engine?

Im using facet red top (cos i had one) and have been told to fit regulator and reduce it right down.

quote:

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Originally posted by DarrenW
Do you know what spec the webers have been delivered to you?
What type of ignition system?
What spec is the engine?

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Sounds to me like the carbs need setting up.

Either take it to a rolling road where they know what they are doing or you could try following Dave Andrews excellent carb tuning guide here

http://hometown.aol.com/dvandrews/webers.htm

Hope this Helps

Cheers

Mark

I presume you have checked for air leaks between the carbs/manifold and between the manifold/head. There's not much that causes an engine to rev off throttle and air leaks are one of them.

Cool thanks for the help.

The biggest air leak of them all.... did you plug the manifold vacuum port for the donor car's brake servo???
cheers
Bob

Yep - 7 is far too high.

Needs to be 2.5-3 for sure.

Pat...

Update: I've now installed a fuel filter/regulator between the pump and the carbs. It's no longer over revving. In fact its not doing much, almost seems to start then dies.

Is it a case of altering the pressure regulator and the idle screws on the carbs?

Oh and one problem I have is at my pump. There seems to be air trapped somewhere and I don't know how to get rid of it. This is probably a basic bit of knowledge so I didn't make a new thread

When the pump is working fine it purrs away but now it gets louder (I turn it off when this happens as I read they wear without fuel in) I've tried disconnecting the fuel lines at either side and filling them up but it still happens. I think the problem is the fuel tank to pump connection, the fuel wants to go back down into the tank before i can reconnect the line. What can I do to get rid of all the air? Clamp the fuel line (flexible) with fuel in then reconnect it?

Thanks for any help

re. the suction line from the tank, don't worry, that's normal, the fuel will run back down into the tank when the pump stops anyway, but they will self prime again no problem anyway! They can draw air for a fair while with no bother.

Hmm how long normally would it take to start pumping properly? Mine never seems to run quietly, it did once but since then I altered the fuel lines between the tank and the pump, if there was a lot of air in there, would it never work properly unless this air was removed?

I've been trying today to get it started again. When I had no pressure regulator the engine started (good) but revved seriously high so I had to cut the power straight away (fuel pump pressure way too high)

Now the engine is starting for a split second then dying. I presume this is due to too little pressure. Can someone tell me something...if the fuel pump is running loudly (which is due to air?) will it not be putting out much fuel pressure?

I feel so close to sorting this out yet the pump keeps on being loud. I've had it sometimes where it's purring like a kitten

Might seem silly but is the tank clean? the suction pipe can get blocked easily by crud foating about and that would make the pump work hard to no effect.

Yeah it's all spanking and shiny

Facet fuel pumps are noisy. You could mount it lower down so it's not lifting fuel all the time and stays primed when you stop. It'll still hammer when you start up though. Your float needles should cope with 7psi for a short time so raise your regulator pressure. How strong is your throttle return spring and have you turned the tickover screw down as you may be running too high for the idle circuit to be operating.

[Edited on 14/7/05 by Peteff]

Throttle return springs are good, so I could screw the tickover screw down?

Are they the ones that say 'Idle mixture adjustment screw' on this diagram?


Shame my carbs came with no instructions really

Your tickover should adjust on the linkage. They are more likely the ones that are marked throttle adjustment screw and will hold the linkage off the stop, undo it to slow it down. Read the page on Dave Andrews site where the diagram came from, he explains it well.



[Edited on 14/7/05 by Peteff]

Thanks for the help, it's starting now Shame it's a bit late or i'd have more time to tinker with it. Tomorrow it shall roar

Update. (Thought I'd drag this out a big further ) I've stopped the high revving by adjusting the screw Peteff suggested

Now the engine starts and actually idles for about 5 seconds Which is awesome. The trouble is it eventually dies out. I'm not sure if this is fuel pressure or it's not getting enough air. Some times it's running on 2 cylinders (front 2) and others times all 4, but mostly 2.

This is the screw I used to stop it revving really high


I was wondering if it's just a case of adjusting these screws:


...or any of these (which I haven't touched yet)



I read that article suggested which helped but I haven't quite grasped it.

Thanks for any help, so close now

The ones in the No7 pic are jets, put the cover back on them and don't touch them unless you have already loosened them in which case nip them down first. There is a balance on the linkage in the picture next to the No6 which doesn't look right. Slacken it off so the tab on there is about halfway between the two stops, it sounds like you're running on one carb more than the other. Get a 12" piece of hosepipe and put one end to your ear and the other in the bellmouth and listen to the hiss then slacken the screw till they sound about same.
Rescued attachment balance.jpg

Thanks Pete, adjusting that screw has helped Seems to be running on all four but still not idling properly, I'll spend tomorrow fannying about with it

After you have adjusted the balance as pete says - by listening to the sound through a tube, you need to adjust the idle mixture screws 1,2,3&4.

With the engine off screw them right in then 2 1/2 turns out then start the engine

Then to quote Dave Andrews:

When you are sure that the carbs are drawing the same volume of air, visit each idle mixture screw, turn the screw counter clockwise (richening) in small increments (quarter of a turn), allowing a good 5 - 10 seconds for the engine to settle after each adjustment. Note whether engine speed increases or decreases, if it increases continue turning in that direction and checking for engine speed, then the moment that engine speed starts to fall, back off a quarter of a turn. If the engine speed goes well over 1000RPM, then trim it down using the idle speed screw, and re-adjust the idle mixture screw. If engine speed decreases then turn the mixture screw clockwise (weakening) in small increments, again if engine speed continues to rise, continue in that direction, then the moment it starts to fall, back off a quarter a turn. The mixture is correct when a quarter of a turn in either direction causes the engine speed to fall. If that barrel is spitting back then the mixture is too weak, so start turning in an anti-clockwise direction to richen. During this procedure, the idle speed may become unacceptably high, so re-adjust it and repeat the procedure for each carb barrel.

Good Luck

Mark

Ahh it's all becoming clear now, thanks a lot. It was starting to get to my head, I actually had a dream last night I was tuning an old radio and to tune it the radio had 4 screws to adjust which I had to get the screwdriver out to turn