If you get the same results with a 650 dbl pumper then I would say take the intake off and reseal it. because that carb should work perfectly.
It does squirt gas instantly but light off idle throttle movements don't pump enough to matter. The idle and transition circuit is supposed to cover those small movements. If i put a size 40 squirter in there it would possibly cover it up a little but my shot would run out too soon.
I have had the electrical system stumble the engine when I was having trouble with it I tried to index the plugs once and it wreaked havic on the electrical system so I got rid of that. I never figured out the problem so just did not do it. I did it to just see if the thing would do anything in 60 ft or the 1/4.
I can't tell anything from those videos. Your combination is wrong. You may have other issues too. I'll repeat, I have NEVER seen anyone have this much trouble with carburetors. A 650 is a waste of money.
At 600 rpm the afr is at 13ish watch where my tach starts climbing at around 900 the afr is reading 19 to 20. That's the off idle stumble being witnessed in real time. Watch the gauges ignore the background noise.
Lol sorry guys but the afr is right under the tach. Clear as day. The sun is shining on the tach but still easy to see what's going on. Maybe your settings on your phones aren't showing high definition video. The tach numbers and afr numbers show clearly.
There is no reason for that with a double pumper. There is something you are missing. I can see it, it's just irrelevant to me. There is something else going on.
I mentioned a long time ago that intake could have leak but Covering the carb with a rag kills the engine quickly and i have good vacuum. And remember that my 650 eddy has nice off idle response.
The point is that it's a lean stumble that happens long before the pump shot is really being actuated. Them slight throttle movements don't pump alot of fuel. This lean stumble does not happen with my eddy on small throttle movements. I think the Difference is them small primaries.
You touch the throttle on my 1000 DP and fuel shoots out. That leanness shouldn't be. You should be able to tune that out. This whole thread makes no sense to me.
Even with the 4500 dominator yellow pump cam I had a lean stumble off idle with small throttle movements. Brown cam is what I'm using now. And I instantly get fuel squirting at the blip of the throttle. I'm about to Arizona. Phone is going off. Sometime after I get home I'll take the carb back to its stock jetting in all of the circuits and start over. I've spent alot of evenings reading about carb tuning. Ive head problems since day 1 with both carbs. I'm ready to accept that the intake was never a good match despite TA saying it is a great option for a mild 350.
I'm sorry to have to say,.. But I luv the SP3 single plane intake. I have two & have sold all my dual planes. A Grand Slam for TA.....
covering the carb with a wrag will of course stall it you are chocking the engine with fuel I Said you put your thumbs over both bowl vent tubes and the engine should stall if noy carb has internal leak
Short story. Annular booster carb is the problem. Read along if you are interested in how I came to this conclusion. I had the opportunity today to try out a friends vacuum secondary 750 cfm quick fuel with down leg boosters. Interesting things happened. This is a fairly new carb that has never been messed with. The out-of-the-box jetting is very similar to the out-of-the-box jetting of my quick fuel double pumper. What I find very interesting is that it's no where near as rich as mine. Idle was a little better but not great but the cruise was pretty decent. wide open throttle was a little too rich. Keep in mind with my annular booster carb I had to jet it down 7 sizes on the primary to get the cruise to a good AFR. This down leg carb is close right out of the box... I read an article where a carb tuner was trying to get Cruise afr into a decent range and developed a lean stumble after jetting down too many sizes so they jetted it down just far enough to lean the cruise a little and just settled on slightly rich cruise afr. This is why I had the lean stumble. over all I'm not big on the vacuum secondary. I tried to delay the opening rate of the secondaries as much as I possibly could and still had a pretty bad bog off the line. A 50cc pump could possibly cure that. But i dont care to mess with somebody else's carb. I think my ultimate conclusion is the annular boosters have been causing me problems. I had read where other guys were having issues with annular booster carburetors running too rich. And dyno pulls showing that they actuall like a rich mix. Not really a street car setup. I put my quick fuel completely back to stock. Other than the 50cc accelerator pump. Idle AFR was right around 11.5 to 12, light cruise was 11- 12, highway cruise was 11, WOT was 10 BUT there was no lean stumble. From there I jetted down a total of 4 sizes on the primaries to get cruise in the high 12s low 13s but started developing a slight lean stumble again. The downleg carb had way better low speed drivability and jetting was close out of the box. Instead of swapping to the dual plane intake I think I'm going to get a holley with downleg boosters.
Walts 72 & myself both run annular boosters. Great fuel aeration. We both luv them. Might just be that particular QF carb you have.... Oh BTW, the vacuum secondary 750 Holley I tried years ago wasn't quick enough response for me. Sold it to a chebby guy.... Yes, also tried all the light springs on a quick change secondary setup too.
I love the concept behind the annular booster. But I think this is just too much of a high horsepower drag carburetor for a street engine. When I have to jet it down seven sizes to get my AFR in the right range that causes all kinds of problems in the emultion circuits.
