'74 240z Carb setup specialist...

Graham Palmer

Graham Palmer

Club Member
Hi all, looking for a spot to 'tune' my 240z...it's a stock L26 carb setup...but would like someone to set them up ..feels like it running a little rich....been a while since anyone took a look at it.

ideally in Oxfordshire/Wiltshire area...but likely happy to travel for best specialists.

cheers Graham
 
Farmer42

Farmer42

Club Member
There aren't many old school tuners left that can tune carbs without asking where they plug in a laptop. I used a place called JPR Tuning in Yate near Bristol. He is ok but I couldn't say he is one of the best. I haven't found anyone else which is why I tune my own but I can't Dyno it after I do so it's a bit trial & error on roads.
 
T

TB24O

Club Member
Can also recommend Northampton motorsport, took my 240 with triple webers for setup after engine build plus mods, excellent job runs a treat now👍
Healey 12 ( David ) also took his 240 down same time as me brillant job, only draw back could be a waiting list to get on rolling road
 
Rob Gaskin

Rob Gaskin

Treasurer
Staff member
Site Administrator
Graham Palmer said:
Hi all, looking for a spot to 'tune' my 240z...it's a stock L26 carb setup...but would like someone to set them up ..feels like it running a little rich....been a while since anyone took a look at it.

ideally in Oxfordshire/Wiltshire area...but likely happy to travel for best specialists.

cheers Graham
Click to expand...
Graham - not the 260 'flat-tops'

These carbs are fairly easy to tune/balance as long as you have mechanical knowledge, a methodical mind and a manual. A rolling road is obviously best but you can get them to run well. Don't forget the basics like compression test, good plugs, tappet adjustment, timing, air filter. Also make sure the linkages and choke cable are operating from fully closed to fully open.
 
I

Ian Patmore

Well-Known Forum User
If it is the HMB46 flat tops, I suggest the Nissan workshop manual for an understanding and setup adjust. Also the USA extra service bulletin for these carbs is also a nice little help addition.

I suspect most tuning places won't have a clue how they work. Did you know they have a separate idle curcuit and a power valve for more fuel at a certain throttle position?

Linkages working well, no slop help. If running rich, there is only 1 mixture screw for both carbs if I remember, so if one carb better than the other its finding a sweet spot for both. It could also be a worn nozzle. Float setting is crucial as is correct fuel pressure.

I know a little about these..... A much maligned carb that is better than its lead to believe.
 
Graham Palmer

Graham Palmer

Club Member
Its the standard round top SU's...I've ordered an airflow-synch tester..and watched a few videos...bought new plugs...got the Haynes manual....:p
 
Farmer42

Farmer42

Club Member
There are plenty of Youtube videos to help with setting up round top SUs. They are pretty simple things really but remember to disconnect the linkage between them before you start. you need to set them independently not together. Before you start messing with idle screws and mixture, take the tops off the float chambers and set the float height. That is very important to getting it running right.
 
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