On top of my dump valve there's an adjusment bolt. Anyone know what changes it makes when you adjust it, and which way you turn it for any relevant change?

Thanks.

ttt.

just had one fitted on mine and would like to know this, also whats the difference between the trumpet or filter bolt-on bit?

You can set the pressure (ventil is underpressure driven) when ventil will be open. More screw in means ventil opens at higher engine pressure

Hi Bryn!

I've spoke to Race Logic about this a few times, and they say every time please do not touch it, as they are set out of the factory and you can end up damaging it.

I hope this helps.

Jamie

www.j-w-racing.com

i think its used to adjust the pre-load on the Dump Valve, the garage who fitted mine said it as ok to play with it and that it wouldnt harm anything???

If you do a search on the american board www.i-club.com/forums there should be at least a couple of recent threads covering this. They seem the be happy to play with the settings over there.

Moray
bbs.22b.com

anyone else got one whos had a play?

The bolt and nut at the top of the Blitz dump valve is the pre load. Sometimes, depending on your engine setup, when you fit the dump valve, the car will stall on overun, and this is normally due to the preload on the dump valve needing adjusting.

Basically, altering the pre load will alter how quickly the dump valve will start opening.

The lower the pre load the sooner the dump valve will start wiiiishing.

The only harm it may cause is if the pre load needs adjustment, from factory settings.

Tools required for adjustment - Flat head screwdriver (small) and pair of plyers.

Insturctions, undo the nut, keeping a note of which way the screw is facing. Then when you can turn the screw, start by going anti clockwise, until your cars idleing is spot on, or clockwise otherwise.