Do injectors need freedom of movement?

sebch · Post by **sebch** » Mon Feb 04, 2008 5:01 am

Hi,
I have to adapt my K-jet manifold to accept EFI injectors. The easiest way to bolt them onto the manifold would imply that the body of the injectors would be in contact with the aluminium of the manifold, as opposed to inserted into the big rubber ring that is then itself secured in place, avoiding friction between injector and manifold.

Will this non-flexible setup be a problem? Thanks for your answers! Seb

oughtsix · Post by **oughtsix** » Mon Feb 04, 2008 10:51 am

In my K-Jetronic conversion I put the injectors directly in contact with the manifold. It has been working very well. When I tried to use some K-Jetronic rubber washers the whole assembly was to tall to get a good seal.

Here is a pict: http://www.hitechengineering.net/DNN/Me ... fault.aspx

What is your project?

sebch · Post by **sebch** » Wed Feb 06, 2008 2:31 am

Hi oughtsix, thanks for your input. I'll do as you say, so who has the same setup as mine also runs w/o rubber between manifold and injector.

My project is a Classic '84 Saab 900 (non turbo) which uses a bit too much gas for my tastes (as it's my daily driver) due to the crappy K-Jet system.

Cheers, Seb

oughtsix · Post by **oughtsix** » Wed Feb 06, 2008 12:26 pm

Hi sebch,

I have exchanged e-mails with other MegaSquirted K-Jetronic Mercedes owners and they have all gone with putting the fuel injector directly in the manifold without any buffering device. This has worked out very well. We had some worries about heat soak from the manifold causing problems with the injectors but this has not been an issue at all. Your intake design will dictate whether this is even possible or not and if you can build a solid fuel rail or have to go with fuel hoses. Does your saab have individual retaining clips for each K-Jetronic injector?

The hardest part was fabricating a fuel rail with the exact right fuel injector spacing so the fuel injectors sit squarely in the manifold. This took me a couple of tries. If the spacing on the fuel rail is a little off then you will get a vacuum leak between the injector and manifold. My engine ran with my first set of fuel rails but boy did she HISSSSSS...

I am no expert but I have been though this conversion once. I'll be happy to answer any questions I can. Is your saab still on the road? If it is I would suggest getting an O2 sensor bung welded into the exhaust before you start to rip out the existing K-Jetronic if you don't have one already.

One of the selling points for MegaSquirt for me was fuel savings also. I should see a return on my investment in a couple of hundred thousand miles

What has made my MegaSquirt install worth the effort is the huge increase in engine response and smoothness! (Bragging rights are also an underrated bonus!). It is definitely worth doing the conversion but the only one I could convince on the fuel savings concept was my wife (But that was enough!).

sebch · Post by **sebch** » Tue Feb 12, 2008 1:52 am

Hi again,

Thanks for looking around on this topic. I'll definitely won't use rubber between the two, but I'll be putting an o-ring on the tip of the injector to ensure a tight install and not fiddle around with several fuel rails. These don't come cheap here in europe!!

My Saab is on the road, yes, and I will of course weld a bung for the O2 sensor on the manifold. I think I will mod the extra exhaust manifold I have as I have done for the intake one prior to taking anything apart on the car.

The idea is to make the most money-saving install for the return on investment starting as soon as possible, as I have done before on my volvo. 500 USD made the trick in that case and I have already saved dozens of liters of fuel!! The car went down from 10-15l/100km (dual carbs) to 8-10 (MS) and as it was my daily driver a that time, it made a huge difference!!

Cheers, Seb