Recommended fuel pump and fuel pressure for Weber 40s?

[M3M3]

Harry,

no need to carried away. the stock mechanical pump is just fine. you may have a clearance issue depending on the intake manifolds selected, but the stock pump puts out plenty of fuel.

note that the stock ti with dual solexes runs the stock pump, and i ran my ti for decades on the webers with the stock pump with no issue.

why bother wiring up a noisy electric pump? why make things more complicaed than they need to be?

just my $0.02 worth...

Jon

+1 I think stock mechanical pumps have gotten a bad reputation over the years (misunderstood perhaps or just inferior quality replacement junk?).

-1

the stock mech pump gets in the way of the carbs and an elec pump and pressure regulater allow for more precise control of fuel pressure.

and not all elec pumps are noisy. even noisy ones can be mounted to minimise the noise.

give me an electric pump every time over a mech one...

[jgerock]

Harry,

no need to carried away. the stock mechanical pump is just fine. you may have a clearance issue depending on the intake manifolds selected, but the stock pump puts out plenty of fuel.

note that the stock ti with dual solexes runs the stock pump, and i ran my ti for decades on the webers with the stock pump with no issue.

why bother wiring up a noisy electric pump? why make things more complicaed than they need to be?

just my $0.02 worth...

Jon

+1 I think stock mechanical pumps have gotten a bad reputation over the years (misunderstood perhaps or just inferior quality replacement junk?).

-1

the stock mech pump gets in the way of the carbs and an elec pump and pressure regulater allow for more precise control of fuel pressure.

and not all elec pumps are noisy. even noisy ones can be mounted to minimise the noise.

give me an electric pump every time over a mech one...

Yikes! Am I a hippocrite for running an electric pump in my VW??

[Kidasters]

Jim -

No.

I hear what Marshall is saying. But, on the flip side of that, I am an electrical moron. Those little electrons scare the stink out of me. So, a little shaft making a little mechanical pump work? Love it.

Either way - there's a way to get fuel to carbys for vroom vroom.

[TobyB]

I have had terrible luck with the cheap aftermarket

regulators. the OLD holleys were great-

but the new version sucks. Period.

Mallory makes a nice one, $80- something, but it's bypass,

so you have to add some plumbing. I put one of those on,

and have not had a problem since.

2.5psi here.

t

[tjones02]

-1

the stock mech pump gets in the way of the carbs and an elec pump and pressure regulater allow for more precise control of fuel pressure.

and not all elec pumps are noisy. even noisy ones can be mounted to minimise the noise.

give me an electric pump every time over a mech one...

There are two versions of the '02 mechanical pump. the early one (same as used in Ti's) will clear the sidedrafts. The big six fuel pumps are of the same layout that will clear the sidedrafts and have a bit more volume. Remember that the 3.0 carbbed big sixes were 170+ horse power....

[73tiijeff]

Webers hate too much pressure! A Mallory regulator or Holley Blue one will work well, whether you run an electric or mechanical fuel pump. Any pump will overpower the needle and seat in Webers. Regulators are necessary at all times to avoid flooding. A fuel pressure gauge is a good idea while setting up the carbs. I like 2 psi to avoid flooding with mechanical pumps and 2.5 is okay with electrical pumps. This is from experience with downdraft Webers used on VW engines and it may differ on sidedrafts...

Best of Luck

73tiijeff[/u]

[jp02ti]

Hey, great little debate here, I love how everybody is being respectful.

Here is another reason why I like the mechanical pump: no need for a pressure regulator! Because the mechanical pump is driven off the cam the pressure supplied is directly related to engine speed. Low speed, low fuel need, lower pressure. Rev it up, more fuel supplied for more fuel consumed.

Oh, and yes, we now run a 3.0 mechanical pump on the ti with the solex 40phh setup and it is really smart. Enough fuel supplied, lots of low end torque and strong pull all through the range, right up to redline.

That being said, I do actually have an electric pump running fuel supply to my dual webers on my '70. However, it was only to diagnose a suspected fuel supply problem, which it wasn't. Soon I will switch it back, as while I know there do exist quiet electric pumps, mine is not one!

Jon

[TobyB]

Any pump will overpower the needle and seat in Webers.

I have found the same thing- the pressure from a mechanical pump's set

by the spring inside it, and SOME mechanical pumps build significant pressure.

I've also had problems with delivery- the mechanical pump, when it's

overwhelmed, really pulses. That pounds hell out of the needle seat,

and I even had it tear a pressure regulator apart. This was on the

'track car' with a 38/38. I replaced the fuel line with 1/4" steel, which

I wouldn't recommend, and ever since, it's had marginal delivery

with the mechanical pump. An electric pusher in the trunk would

probably do the trick...

A mechanical pump with the wrong (too short) pushrod would do the same

thing.

jus' sayin...

t

[M3M3]

Hey, great little debate here, I love how everybody is being respectful.

Here is another reason why I like the mechanical pump: no need for a pressure regulator! Because the mechanical pump is driven off the cam the pressure supplied is directly related to engine speed. Low speed, low fuel need, lower pressure. Rev it up, more fuel supplied for more fuel consumed.

Jon

this actually builds an excellent case for using an electric pump. or at least a fuel pressure regulator with the mech pump. you DO NOT want the pressure to vary. the carb controls the fuel supply to the engine, not the fuel pump. you want a constant pressure level filling the bowl. not too much to over power the needle valve, and not too little to leave the bowl low. the pump used must have sufficient flow capacity (this is not psi) to supply the carbs at the max load.

2.5psi max for sidedraft webers.