Dawes valve and needle valve question

[Limmy]

Hi Guys, got couple of questions

Installed EGR plate , Needle Valve , dawes valve . 2005 GU IV

Regarding the dawes valve . I'm a little confused all the forums i've searched . It appears everyone would open the dawes valve for more boost , and even stretching the spring ( as in opening to show more thread ).
My one does the vice versa . When I close the dawes valve ( show less thread ) . It creates more boost . Is it something i'm doing wrong ? or it doesn't matter ?

My EGT's aren't too bad. Cruising is 300-350 , flat stick up hill around 400ish . Much better boost curve. Around 10psi and 100kmph. It max's out @ 15psi . ( I can only max at 15- 16psi before dawes,egr,needle )

It definately is doing its job at restricting max boost . I've set the dawes with needle valve closed , the max peak spike was bout 17-18 psi . I'm still tweaking the needle valve . It is recommended 5-6psi @ 1500 Rpm and 10psi @ 2000 rpm . When is best time to set this ? in first gear ? car warm ? cold ? etc..

thanks guys appreciate your comments

[BillsGU]

Nope - you have it right. Thats how it should work. It is just a ball valve. The more spring pressure on the ball, the more boost pressure it needs to push the ball and reduce the boost. Opening the valve and stretching the spring puts more pressure on the ball - and screwing the housing closer together compresses the spring and puts more pressure on the ball.

[Limmy]

Thanks heaps for clearing that up. Ive been reading wrongly on forums. When they say open dawes valvle and adjust spring. It literally means OPEN up dawes valvle to do so . :1087:

[threedogs]

more pressure more boost required

[Limmy]

Stretching the spring worked . I even got up to 25 psi . I adjusted to max 19 psi .

needle valve still playing around . how much am I suppose to have at 2000rpm and 3000 rpm . which is best gear ( transmission ) i should go by to set me needle

[mudski]

Stretching the spring worked . I even got up to 25 psi . I adjusted to max 19 psi .

needle valve still playing around . how much am I suppose to have at 2000rpm and 3000 rpm . which is best gear ( transmission ) i should go by to set me needle
19PSI and no limp mode?!:eek:
Go buy speed not rpm. The general rule of thumb is 10psi at 100k's. 5th in manual or D in Auto. Then play from there...

[Limmy]

yeah had limp mode. I wind down the needle straight after . would I be cruising throttle for 100kmph @ 10psi ? what would be max for full throttle

mine spikes at about 17-18psi .



Thank you Mudski ebay needle valve and egr plate ! the needle valve was worth the wait !

[BillsGU]

mine spikes at about 17-18psi .

Thats about right. It should go into limp home mode if you exceed that. It does vary from car to car abit.

[threedogs]

Read Junes thread a few of us have put up results etc there.
Instead of stretching the spring put Stainless washers in , but probably a bit late now.
Pain in the Butt un stretching a spring lol. You may find it works better with 15 psi max,
these motors are never going to be a rocketship. you'll know when you hit the "sweet spot"
10psi at 2000rpm and fine tune more via needle. little steps.

[mudski]

yeah had limp mode. I wind down the needle straight after . would I be cruising throttle for 100kmph @ 10psi ? what would be max for full throttle

mine spikes at about 17-18psi .

Yes cruising throttle for 100k's @10psi is a good start. Max full throttle, will depend on your engine. This is where you play around with it until you find that point just before you get limp mode. Mine used to spike around 17psi, also had 12psi at 100k's, so I opened up the needle valve a little more and the cruising boost dropped to 10psi and I had no more boost spikes, or bounce.


Thank you Mudski ebay needle valve and egr plate ! the needle valve was worth the wait !
Too easy mate.

[Limmy]

i set the dawes at max 16

10psi around 2000rpm . and around 10psi @100kms .

1500rpm is about 4 psi

am I on the right track. are those safe limits . I rather be slightly under then over

[threedogs]

Yeah all motors are different, but your the same as most, even June was very similar , You could try putting more boost into it using small washers
But hey its a 3 ltr , .Rule of thumb by Chaz is 10psi at 2000 rpm with the EGR block. I'd say you're spot on if not getting limp mode

[mudski]

As what TD said. Cool pic of your dog John...

[Limmy]

thanks guys ! it feels much better

[threedogs]

@ Mudski that's Tyson the pretend wombat ATM,
He was eating all Cruisers food when he was crook.


@ Limmy should be good now between Mudski and myself not much left to do to the motor.
Mudski wants to convert to 4.2TD, I want a ute or GU dual cab time will tell