Quick Fuel SS750AN Tuning

[hysteric]

Call me a quitter but I take the same approach as I do with the stock market. I know when it's time to cut the losses and move on.

That's how you protect your capital. Cut your losses short and let your profits run........

[1980RS]

The first QF carb I ever bought was a 750 Slayer and with all the features it had I thought this was going to be a winner, boy was I wrong. Right off the bat I noticed it idled at 500 RPM out of the box floats were super high so after I fixed all of that the QF still ran pig rich. I took the Slayer off and flipped it over noticed the transfer slots were like .070 open. I closed them down put it back on and still pig rich. Put it back in the box tossed on the new Holley 770 Avenger and set the idle screws, car ran perfect. The other 2 I have were both used and while they both work ok the Demons I have are still quicker and faster.

[1972ho]

https://youtu.be/UVff8o3BPCU How about giving a listen to this guy on carburetors and working with them.

[1980RS]

Just wanted to share this with you all. Was at the local tack today and my good friend was running his BBC testing a few carburetors. The one he has been using lately on races is a 850 Brawler HP dp carb that he has jetted and changed bleeds all over the place and had run in the 1/8 the best of 7 teens. Today he put on his 780 VS carb and it ran the same as the Brawler with the factory jetting. He then switched to a factory 3418-1 and jetted it for the air and that carb went 7.0's and picked up 2 mph in the 1/8 mile. He asked if I wanted to buy a nice shiny carb, lol. Seems those darn factory Holley's seem to get the job done pretty well for old outdated stuff.

[steve cowan]

Just wanted to share this with you all. Was at the local tack today and my good friend was running his BBC testing a few carburetors. The one he has been using lately on races is a 850 Brawler HP dp carb that he has jetted and changed bleeds all over the place and had run in the 1/8 the best of 7 teens. Today he put on his 780 VS carb and it ran the same as the Brawler with the factory jetting. He then switched to a factory 3418-1 and jetted it for the air and that carb went 7.0's and picked up 2 mph in the 1/8 mile. He asked if I wanted to buy a nice shiny carb, lol. Seems those darn factory Holley's seem to get the job done pretty well for old outdated stuff.

I read a few years ago where a couple of carb guys said the older carbs just meter fuel better than OOTB carbs today and QC was probably better as well.i am trying to purchase a Braswell at the moment regardless of cost but hard to get much of anything here in Australia as in performance parts.

[Adger Smith]

I didn't read all the way through, but got enough to see you dyno with headers and added manifolds and a air filter.
In my experience you wasted a dyno session, esp trying to tune the carb.
The headers/exhaust and air filter totally change the acoustics of the system.
You now have reversion that you didn't have on the dyno.
I have also seen Exhaust manifold systems that didn't like split duration cams.
One thing I will say you have going for you is most pump gas engines like to run a little fat. Don't believe the
traditional belief that you have to run at a XX.X -1 A/F ratio. Run it at what the engine is happy with.
My .02 for free

[1980RS]

I didn't read all the way through, but got enough to see you dyno with headers and added manifolds and a air filter.
In my experience you wasted a dyno session, esp trying to tune the carb.
The headers/exhaust and air filter totally change the acoustics of the system.
You now have reversion that you didn't have on the dyno.
I have also seen Exhaust manifold systems that didn't like split duration cams.
One thing I will say you have going for you is most pump gas engines like to run a little fat. Don't believe the
traditional belief that you have to run at a XX.X -1 A/F ratio. Run it at what the engine is happy with.
My .02 for free

That's a good point about running the engine a little fat on pump gas. I always jet the car up until the MPH falls off and drop down a jet or two and it's happy the rest of the day.

[eric8]

I didn't read all the way through, but got enough to see you dyno with headers and added manifolds and a air filter.
In my experience you wasted a dyno session, esp trying to tune the carb.
The headers/exhaust and air filter totally change the acoustics of the system.
You now have reversion that you didn't have on the dyno.
I have also seen Exhaust manifold systems that didn't like split duration cams.
One thing I will say you have going for you is most pump gas engines like to run a little fat. Don't believe the
traditional belief that you have to run at a XX.X -1 A/F ratio. Run it at what the engine is happy with.
My .02 for free

The dyno was required by the builder just to make sure the engine made the power they rated it at (and was also a requirement to get their warranty), so it was far from a tuning session. As a matter of fact, when I pulled the carb apart there wasn't a single thing that had been changed. I think they just set the idle speed and mixture and let it rip.

On another note, the Edelbrock carb is doing the exact same thing the Holley was. Going pig rich at WOT. Even after going 2 stages lean on the secondary jets it has netted no change in the 11:1 WOT afr. So I'm starting to wonder if I have a gauge that is reading wrong at wide open. Possible?

[Tuner]

If you have excessive exhaust back-pressure the WB will read further from 1 lambda than it actually is, both rich and lean.

Here is an edited cherry-pick from this link https://www.theturboforums.com/threads/ ... on.310876/

The NGK/NTK and the Bosch sensors do have different sensitivities. (the original author citing a Bosch report) worked out the error for the Bosch sensor and at ~3psi backpressure, the Bosch sensor was reading about 0.15-0.2 AFR units richer than it should be.

To connect a pressure gauge to your O2 bung you can knock the guts out of an old sensor or an old 18mm spark plug, thread it for a pipe fitting and use a coil of copper tubing to isolate the heat from the hose going to the gauge.

[1972ho]

I have a 9380 annular booster holley that no matter what I changed on it even going as low as 76 jets without a power valve and even changing the size of the emulsion bleeds and it was still rich ,it did start to lean out until I bought a set new metering blocks now it’s lean 13.7 at are so with 78 jets with a power valve with the same emulsion bleeds sizes I had in the holley block with 10.5 are so af