Parts for hotwire injection rebuild

Mr Bong · Post by **Mr Bong** » Thu Dec 28, 2006 1:16 pm

Currently refurbing a hotwire injection system to fit to my 3.9.

I want to replace all O-rings and gaskets etc, where is the cheapest place to source these parts? Rimmers have the best catalouge but 1.70 per O-ring!

Should there be paper gaskets between the trumpet base and the manifold AND between the plenum and trumpet base? Mine look to have been sealed with welseal in the past. Is this sufficient?

Also is it worth getting the injectors cleaned first? The engine that the system came from was quite high mileage but the manifold wasn't excessively oily inside.

Post by **katanaman** » Thu Dec 28, 2006 2:08 pm

If you mean the injector o-rings you will get them in any place that has anything to do with fuel systems as they are a standard fit. You will probably also get them from anywhere that sells seals and stuff, possibly bearing shops. Whether it will save you money or not I have no idea as your only buying a few and not hundreds. If your get your injectors cleaned (recomended) you will probably get them back with new ones anyway.

There isnt any gasket between the inlet and trumpet base.

Mr Bong · Post by **Mr Bong** » Thu Dec 28, 2006 8:30 pm

Thanks for the relply. Will look for a local firm to clean injectors.

Another question is: should the IAC be open normally? When washing the plenum chamber out in the parrafin bath I noticed that the parrafin passed thro' it. I expected it to be closed normally.

Post by **katanaman** » Thu Dec 28, 2006 9:59 pm

from what I remember I think they park open could be wrong tho.

Mr Bong · Post by **Mr Bong** » Fri Jan 05, 2007 9:59 am

Anybody got any experience of using this firm?

http://www.injectorcleaning.co.uk/

They offer ASNU injector cleaning by post for £11.75 inc VAT per injector. Seems to be a very good price but that doesn't include flow rate testing, would that be neccassary for me considering i'm only refurbishing a standard setup rather than indulging in any performance tuning?

Post by **katanaman** » Fri Jan 05, 2007 4:01 pm

I will clean your injectors for a £5 each if you dont want any flow testing. Without the testing you will have no idea if they are working properly or not as sometimes cleaning alone wont sort them.

Mr Bong · Post by **Mr Bong** » Fri Jan 05, 2007 9:44 pm

Actually it looks like they do flow rate testing, I'd got confused as they offer a premium service for £21 per injector where they map out the injectors performance under various pressure, duty cycle conditions.

How are you cleaning your injectors at home then?

Standard Service
Micro filter, O ring seals and pintle caps are removed if to be renewed.
Check that all the injectors share the same part number.
Check that each injector has the same coil resistance.
Injectors mounted on the flow bench and a leak test performed.
30 seconds at up to 5 bar pressure with the injectors closed.
Flow rate testing at either 2 or 3 bar pressure. 50% duty cycle for 30 seconds.
Check spray patterns in a static (wide open) mode.
Check spray patterns in dynamic (pulsed) mode at a set open duration and speed.
Injectors are placed into the into the ultra-sonic cleaning tank for a minimum of
30 minutes. During this time the injectors are also electrically pulsed.
Leak, Flow test and Spray pattern checks are re performed.
Micro filter, O ring seals and pintle caps that were removed are replaced with new.
Injectors placed in numbered bags and a standard report issued.

Post by **katanaman** » Sat Jan 06, 2007 12:46 am

I wasn't being serious on the cleaning I was trying to make the point that if they don't supply any data they could well be doing nothing and your no better off. Not that I think the company is doing that but it seemed odd that they didn't provide anything to say what was happening with your injectors. The data is important because you need to know your injectors are flowing roughly the same, spray pattern is important too. This goes for any engine whether it is standard road or F1 race spec only the tolerance can be more with standard engines.

Mr Bong · Post by **Mr Bong** » Sat Jan 06, 2007 11:10 am

Good job I didn't embarass myself by asking if I could send them to you to be cleaned!

It seems like a good service to me so i've sent the injectors off to them. £94 for the eight including postage etc. They also do a recon set off the shelf for £105 inclusive. I suppose that gives you some indication of the value of secondhand injectors.

Are there are any other parts worth sorting out before the system is installed. I was wondering whether there is any way of testing the fuel pressure regulator and whether they typlically suffer from problems?

Post by **katanaman** » Sat Jan 06, 2007 1:00 pm

putting a fuel pressure gauge on will soon tell you if the regulator or pump has any problems.