Rich AFR off boost.

[GTphil]

Ok so it's widely available knowledge that for more boost you need to increase the second stage bush for more fuel and keep the main jet standard. Also reduce the air corrector jet in size.

However every carb I have done this to fuels great on boost and great at part throttle/cruising but when the accelerator opened fully off boost results in flat 10 afr, probably lower than this as this is as low as the AEM wideband gauge goes.

What do I need to change to try and solve this?

First stage enrichment jet smaller?

[casper]

If it does it as you start to make positive boost then you can either shim the 1st stage to stop it dumping fuel in or make it smaller.I run a 0.6 1st and it works well for me.If its a rich bogging down as you first get on the throttle then that will be acc jet/pump/arm related.If it richens up but stays rich for too long make the rod shorter.I think.:p

[GTphil]

It doesn't bog down or anything just goes uber rich! Scoff always gives me a telling off when it's on the rollers:laugh:

As soon as my foots anywhere past light throttle the afr's are in the 10's until it starts to make boost.

[mk5gtt]

Sounds like the same issuse i had adjusting to acc pump rod should help out with as it does not sqirt fuel till the rod has pushed further leaning it out at part throttle to boost .i can pop round and lend a hand got a spare carb and bits if needed just let me know

[Brigsy]

Decrease the 1st stage enrichment. Mine has been .6 for years. Its leaner on spoolup and feels smoother to drive. I also shimmed the 2nd stage with another curved washer behind the spring.

[GTphil]

Nice one guys, will give everything a whirl and see how it gets on. :agree:

Cheers for the offer mk5gtt at least I know there are a few more carb spares local ;)

Having said that I probably have at least three in bits now myself:laugh:

How are you getting on with the EFI?

[mk5gtt]

Efi all done its runs alot better and and makes more power 193bhp could do with going to a bigger turbo a t28 would be better and more boost have you a had a mess with the acc pump rod yet give me a shout if you are struggling i also have a big ultra sonic cleaner good for cleaning the carbs inside and out

[GTphil]

T28 for sure:agree: a nice 60 trim one also;)

Car isn't road legal yet, needs MOT/Tax should be early doors next week all being well.

Gives me a bit of time to do the first stage mod and to shim the second stage.

Can't wait to drive it properly been almost a year:disagree:

[Alex]

Nice one Phil. I haven't seen your car for years, hopefully you can bring it to the karting event :agree:

[GTphil]

Hope so :agree: Providing it's still in one piece, planning on a session on the rollers at some point to see if it will do the numbers needed for a 12 second quarter.