Vacuum advance on Dellortos

zac · August 15, 2007, 01:41:34 PM

My Murena is now running!

Few little things to do for the MOT and a gearchange kit so we can reverse it out of the garage

The car has twin Dellorto DHLA 40s which I think originally came from a Jensen-Healey. The connection on the carbs where the pipe to the vacuum advance would normally go looks like it was sealed when manufactured, do other people running twin dellortos use the vacuum advance and if so how is it plumbed in?

I should have taken the camera down with me...

Anders Dinsen · August 15, 2007, 02:46:41 PM

Hooray, Zac! Good to hear progress.

Krede is running Dellortos, I think we can expect him to post photos later

Yes, you should always run with the vacuum advance. You can get home without it

, but there's no reason not to implement it on a road car.

- Anders

krede · August 15, 2007, 03:39:43 PM

The vacuum hose is the one in the middle.... don't know what's more to say...
I can take some better pics tomorrow if you'd like ?

macaroni · August 15, 2007, 07:58:28 PM

Zac,
on my DHLA45s, there is a blanking screw on each barrel. On one barrel, the screw has been replaced with a little screw-in pipe (6mm I think). The vacuum pipe is pushed onto this.

Hope this helps.

Antony

zac · August 16, 2007, 07:24:20 AM

I'll have to have another look, the mechanic said that were there would normally be the blanking plate then the barrel was actually solid, hence asking if there was anywhere else we could take vacuum from.

macaroni · August 16, 2007, 10:01:52 AM

On this diagram, it is the only 2 screws not annotated at the bottom of the picture.

krede · August 21, 2007, 01:28:22 PM

Just replaced my vacuum hose today...as you can see the one on the picture is pretty well "cooked"..
I noticed that after a drive it got soft..almost to the point of melting.. so It had to go...
I believe I can feel a difference... but It might just be wishful thinking

Now lets see how long this one lasts... It sure gets hot in the enginebay... I found that out first hand last Sunday when I had to remove the carbs/manifold from the engine RIGHT after a 100km drive... av....AV AV AV!!!

Anders Dinsen · August 21, 2007, 02:32:44 PM

Quote from: krede on August 21, 2007, 01:28:22 PM
Just replaced my vacuum hose today...as you can see the one on the picture is pretty well "cooked"..
I noticed that after a drive it got soft..almost to the point of melting.. so It had to go...
I believe I can feel a difference... but It might just be wishful thinking

It doesn't have to be! Check the fuel consumption. The vacuum advance is an "economy device" which advances the ignition when there's little load on the engine (coasting, idling, part throtltle driving), so if the vacuum hose has been leaking and the advance mechanism not working, you should be able to see a difference.