So I switched over intakes and now I'm getting a bog right after punching it. It can be from idle to off idle acceleration. I messed with the two cams that I have for my Holley 750 with vacuum secondaries and they seemed to affect it. Got it a little better. Messed with the accelerator pump arm and that seemed to help also but no fix it. Went from a 32 squirter to a 37 and I'm not sure if it was better or not. The jets in the primary side are the stock 72's with the stock metering plate on the back which roughly equates to a 75 - 76 jet iirc. I have a set of 78 jets that I haven't tried out yet also. I also have a metering block that I can swap out for the plate with the correct circuits for my carb so I can tune the secondaries better with jets.

Now my question is, would you go with a 50cc accelerator pump at this time, buy a cam kit or a jet kit. My funds are extremely limited right now so I could only really do one of these options. I don't have the funds to get all three options and tune from there so I'm asking what would you guys do?

 

You messed with the accelerator cams, but what did you end up doing? Did you increase or decrease pump travel? How about the duration, faster or slower? Since whatever you did made it a little better, you must be on the right track. What you did should tell you if your initial shot still needs to be richer or leaner.
Also, have you checked the float bowl levels?

 

Yeah, the float bowl levels are set correctly. I can't remember exactly what I did to the cam(s) 100% but I'm pretty sure it was a faster shot that helped and I tightened the pump arm up. All this was before the transmission swap and when I fired it up Sunday I was revving it and it was hitting a flat spot with a delay. Like it would accelerate RPM's fast quick and then hit the flat spot and then go back to climbing RPM's.

 

That's why I like manual secondaries & double pumper carbs.
Sorry I know that's no help.
What are the specs on your motor?
It may be too much carb if there isn't enough other supporting parts.
Perhaps the secondaries are cutting in too early?
pretty common with Q-jet carbs with vacuum secondaries.

 

You can't overcarb with a vacuum secondary as the secondaries open based off of engine load. It also does it when sitting and a vacuum secondary doesn't open while sitting since there's no load on the engine. That tells me that there's something with the air/fuel delivery. Plus the engine is built for it and handled it fine before the intake swap. We even had an 850 on it that woke it up some more but just swallowed gas by the gallon each time we hit it. Even with the 750 I can run like a **** for a 1/4 mile and just watch my needle go down. I went from an Eddy 2101 performer to a Weiand 8501 Stealth Air Strike. It's similar to an Edelbrock Air Gap but with a better powerband more suited for my cam.

I had a QFT adjustable secondary controller on it and it worked fine till the intake swap also. I thought maybe that was causing the problem so swapped it out with the stock vacuum secondary housing. Still did it after that.

I wouldn't mind going to a DP carb but I just don't have the funds for it right now. Ha, I can only afford one of the above options in my original post. I was just asking what you guys would do. I hope to have the car back on the road this weekend and enjoy my six speed swap. I just want to do it without a hesitation and then a big BAM and out of the gates type deal.

Oh yeah, that's something I didn't mention that makes me think it's a lean stumble. I could punch it and I would get the bog and right after the bog the car picks itself up and just screams. Now that I think about it do you think it could a timing issue?

 

When you're getting your mid-range stumble, are the secondaries starting to open at that point? You could have two different issues causing the off-idle and mid throttle stumble.

 

Yeah, they are. I did the paperclip trick to check and they're opening.

 

Any chance the secondaries are opening too soon?

 

I would say maybe but I don't think so. Going through both the QFT vacuum secondary controller and the stock vacuum secondary pod and they both behave the same way I would say that it's a really slim chance with the secondaries being the main culprit. The QFT controller is adjustable and allows you to dial it in with the turn of a screw.



That screw on the side controls how fast the secondaries can open. You can adjust it kind of like how you test out your timing. It's supposed to help with getting rid of bogs and being able to tune for different conditions, altitudes, etc.

 

This is going to be an off the wall test. Tape off part of the intake. The air bog is over-riding the fuel pull. If say, you mask off so much, then see if the bog cleared?

Next is to see if the top stumbles to where there is less air due to the closing gap. Now you remove a few inches or inch of opening at a time, fell the bog clear, fell the top end clear = Off the wall is my guess is too much air flow. Slow it down is way too simple and a quick run around the block will prove out you are throwing jetting at it, not matching air to fuel flow.