Hi,
just a quick question, I am currently running a 2.0 pinto on twin 40 carbs in a sierra.
i have read that you shouldn't (don't need) use a dizzy with vacuum advance? I have piped mine in but can't get it running right, it idles ok but feels like it's dropping a cyl down the road. Where I have piped vac in is on the back carb.
so do I need to get a dizzy without vac advance on it?
cheers

 

Can you not just block off the vac pipe?

 

thats my first job tomorrow morning, Car is at my work so cant mess with it until then! Would be nice if thats all it is

 

If your dizzy has a vacuum advance, then it would make sense to use it.


Should run smoother and be better on fuel at constant speeds with it connected.


I'm not sure that the vacuum signal from one carb will be smooth enough though.


One trick that MegaSquirt users do is to drill each inlet and join all 4 vacuum signals together - then add a moped fuel filter between the ECU and signal to act as a damper and smooth the signal out.


You might find that your timing is jumping all over the place with it plumbed into one port !

 

Thanks for your reply, if it affecting the timing with plumbing into one port that's where my issue lies I think!
Its got a outlet off one of the carbs which I've used for the vac advance, I haven't gone into the inlet manifold directly onto the carb,
i might still disconnect the vac advance pipe tomorrow and bung it up and see what happens. I do have a non vac dizzy somewhere

 

The car would be nicer to drive, easier to set up and better on fuel with throttle bodies.

 

Could T off the vac pipe for the brake servo.

Or you can buy a mappable dizzy to get your advance perfect.

 

I kind of didn't want to spend much more on the set up I've got, was hoping to get it running somewhere near for this summer, then winter I am thinking of turbo. I'll mess with the vac pipe tomorrow, do people agree that the vac pipe shouldn't just go to one carb then? It connects to cyl 4 carb at the moment

 

Been messing with it further, done a compression test, all very slow to rise and only reach max 75 psi, which is half it should be.
I have a P100 engine but will that be slow?

 

It might be a low comp transit lump.

 

For a low comp pinto engine id be expecting in between 10-12 bar which is 145psi - 174psi