correct fuel pressure

[ramajon]

Hey gang I've been having trouble sorting out my backfire...the issue occurs in the fast exceleration range...3000 rpm...when I put a fuel pump w/ more pressure the situation still occurs, but it is now easier to drive beyond the 3000rpms...one question I would like to know is what would be the desired fuel pressure range for a big healey 100/6 w/ dual 1 3/4 SU carbs...also any advice for concurring the 3000 rpm wall I'm encountering would be way helpful...btw I've done all the obvious stuff incl getting a rebuilt distributer from jeff at advanced distributors...he also put the pertronix points in, new plugs, wires, rebuilt carbs, etc...help please.. thanks to all you

 

[RonMacPherson]

A suggestion, focus more on flow(volume) rather than pressure.

As horsepower requirements go up, amount of fuel, highlight on amount, not pressure required goes up. Too often people will modify their cars and not verify that their fuel lines are not kinked, pinched, corroded, restricted or too darn small.

 

[TimK]

When I was racing an MGB I used a regulator to limit pressure to about 4 lbs psi. Most pumps have plenty of pressure.

 

[bob hughes]

Have you got HS6 carbs?

I had the same problem, turned out to be a blocked line between float chamber and jet. The blockage occured at the float chamber where there is a rubber seal that acts as a stuffing gland when the hollow ' bolt' is tightened up. The rubber seal ended up closing the end of the acrylic fuel line to the jet, had great miles per gallon but no speed above 2400 - 3000 revs. maximum 65 - 70 MPH.

May be worth checking it out.

Bob

 

[ramajon]

Problem solved...and you wont believe it...first lesson...don't trust the experts...my rebuilt distributer was the issue...not the distributer per se but the pertronix points...heres how it all went down...I'm out driving to the garage to replumb some fuel line and the car dies and there is no spark...fortunately I coasted into a parking lot and later got a tow the 1/2 mile to my garage...taking out the pertronix I found the whole problem...rebuilder had not drilled a big enough hole in the distributer for the pertronix wires and everytime the vacuam advance stepped in...around 2500-3000 rpm the wire would get pinched and eventually cut by the distributor...fortunatley I had a set of points and a condencer and the problem was solved...whoohoo...now on to other problems...ah the love of british cars