Brake efficiency affected by fitting twin delortos

[Oldbones]

I have recently fitted a guy croft inlet manifold and twin 40s to my spyder. Ever since my brake efficiency has been drastically reduced. Could this be coincidence or is it something to do with reduced vacuum  from the inlet manifold. Looking at the standard manifold I have removed seems to have the vac connection open to all 4 ports but the guy croft manifold takes the vac from 2 ports. Has anyone else been affected in this way and have they found a solution, I don't really want to be drilling an additional port in the manifold

Thanks in advance

John

[HFStuart]

I'm sure this question has been asked before and other with webers / delortos said it had made no difference to their cars.

It could be that the non return valve has packed up or just that the servo has chosen this time to fail. I'd check them before I hacked the manifold.

[Oldbones]

There were two non return valves in my vacuum line before the mod. I put one the the new line but made sure it was working and fitted the right way round

John

[lbcoupe76]

Ha, when i saw the title of the post i thought you were proud of how much more power you had got by fitting twin carbs and that now your going too fast to stop

[hf_dave]

Make sure the non return valve is the right way round . If it is wrong you wont get any suction to the servo you can also check to see if it is blocked. I had a similar problem with my Fulvia and I had to release the valve by poking a rod into it to help release it .Thanks, David.

[75coupe]

Maybe the clue is in the 2 non return valves previously fitted. Normally there is only 1 so perhaps at some point someone has fitted another to cure a previous problem?

There will be less vacuum, but still plenty enough from 1 cylinder. Maybe try a vacuum gauge on there to.

I have used GC side draught manifolds on 2 betas with no problems with servo efficiency.

Is there anything else connected to the vacuum line?

[Oldbones]

Hi 75 coupe

You maybe right with it having two fitted originally but on reassembly I did test them with a good suck and they closed off with little effort so just fitted one as it should be. Interesting that you didn't notice any difference when commenting the vac to an inlet with individual ports I will revisit the vac valve and bleed the system to be sure when I can but have my steering rack in bits at the moment so need to get that back in first

Nothing else connected to the vacuum

Thanks for the pointers

John