Grose Jet -- the REST of the story...(webers)

[Guest Al 260Z]

Posted a while back about major hassle with needle valves failing to seat.

 

Been running stock L26 with Weber DGVs for over 150k miles w/ virtually no carb headaches except for ping in certain throttle range. Around June I replaced mech fuel pump with new OEM unit cause the old one was leaking oil at WOT and making a mess. Then noticed my idle was getting rough, excess rich. Did all the normal tune-up checks from valve settings up. Finally started focusing on carb inlet needle valves. Set floats to spec - still no change. Got some Grose Jet valves from Pegasus, and these were much worse than original stock in terms of controlling fuel inflow at idle - gas was just bubbling out of main jets and flooding the DGV gooseneck adapters (thankfully not running straight into engine). Checked fuel pressure w/ good low range gauge and found it dead on 260Z FSM spec: 3.5 psi at idle and not over 4.0 psi above 1500 rpm. Ordered Weber needle valves from Pegasus. These sealed better than the Grose Jets but still would not seal adequately at idle. However, they came with a slip from Redline Weber saying recommended fuel pressure to be between 2.5 and 3.0 psi and float level setting 2 mm lower than what the funky book I've got shows. F me, said I to myself as I ordered up a fuel pressure regulator, 600 miles from home with dang Z car that'll run great except not idle (or charge the battery - but that's another story...) Not being home, didn't have pressure gauge handy so after installing FPR, I just cranked 'er out so that the carbs stopped bubbling over at idle. Since getting back home checked pressure and found at 2.4 psi.

 

I did some side-by-side testing of stock Weber DGV needles versus Grose Jets using the 'ol blow in a hose and listen for tight shut-off technique. I can't blow much more than 2.0 psi and test pressure is more like 1.5, but I found that new stock needles would not consistently seal tight until I had the float pushed all the way past the spring-loaded needle plunger and hard up against the needle body. Grose Jets have no spring - they give wide-open to tight-shutoff in a very narrow range of float motion.

 

So, on that note, I opted for the Grose Jets over the stock units. Occassionally car will stall at idle due to flooding but not too often. Sometime, I mean to swap back in the original (300k mile) mech fuel pump and check pressure. It seems to me possible, but not likely that original installer of DGV carbs tweeked the fuel pump regulator spring to lower the pressure. Maybe she was running a satisfactory low pressure jus cuz she was ol' an tired.

 

Anyway that's my latest tail of woe and aggravation. I'm thinking it's time to ditch these dang DGVs even if they did serve well for so many years and miles. They're not real tuner friendly like the DCOE's. All the jets are buried under the top cover that's a bit of a pain to get on and off. Much easier to play with needles in the air piston of an SU or Flat-top Hitachi.

 

Well.... Bein' as I'm feelin a bit ol' n tired meself....

 

Later,

Al