BAD240Z
BAD240Z New Reader
2/25/24 8:50 a.m.

I have a set of triple SK (now called OER) carbs set on a Datsun 240Z w/ L28-N42 engine, Schneinder cam 

Trying to get the right jetting/ setup with no luck. Motor runs rich at low and mid rpm's but really comes to life at WOT

Carbs have Weber style jets, floats are set, fuel and spark in my opinion are good

Looking to trailer the car somewhere or someone to assist in final tune.

Philly area

See pics in BAD240Z profile

Thanks

ShawnG
ShawnG MegaDork
2/25/24 1:09 p.m.

Bet you're getting reversion in the intake from the lumpy cam.

Moving fuel/air mix hits a closed intake valve, goes back out of the carburetor and then gets sucked back in again, adding more fuel on the way in.

Run it with the air cleaners off and look for a fuel mist over the air horns at idle. 

The Weber tuning manual can help with this. It's been a long time since I played with triple sidedraft Webers but I'd maybe try running a size smaller idle jet and adding a balance tube to the manifold if you don't already have one.

Running more initial advance on the distributor timing can help a bit too. I had a lumpy cam and a 32/36DGV that was a bit fat at idle and had reversion issues, 12 degrees advance helped get rid of the stumble.

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