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- - Norwood (https://www.lateral-g.net/forums/showthread.php?t=36443)

Quote:

Originally Posted by protour73 (Post 466775)

Scott, you are going through exactly the same things that I'm going through on my car, so I love this thread!!

I'm not an experienced carb tuner guy and after purchasing a Holley 4150 DP from Patrick at Pro Systems I'm into all sorts of tuning territory I've never been to before.

I installed a wideband O2 sensor which really helped get a hand on some things like the power valve choice. When you are driving the car, you can actually see when the power valve opens by watching the gauge!! The carb shipped with a 5.5 PV incorrectly, which I've bumped up to a 7.5, and I changed out the idle air bleeds a couple times as well to get rid of a pig rich idle -- so I feel your pain :bang:

Keep on working at it!! :thankyou:

Thank you. :thumbsup:

Your car is awesome! Appears our builds have somewhat similar objectives and I'm a big fan of 2nd Gen's and Yellow.

My carb came with 6.5 power valves and 70 air bleeds.......seat of the pants tuning and experimenting along with baselines from the previous Demon carb have lead me to 5.0 power valve and richening the idle circuit. Somewhat opposite of your situation..........how many inches of vacuum does your motor have at idle? What A/F monitor are you running?

The carb circuit that I don't have a good feel for yet is the idle bypass valve........as is the idle circuit wants that valve completely shut (no additional air) which leads me to believe the idle air bleeds were too big. On the scale of available jets 70's are close to the largest. So I'm assuming smaller idle air bleeds will make the idle bypass valve functional. I don't like having any circuit set at the extreme range of adjustment high or low. If altitude, temp, and air desity change I want to insure there's room to adjust the circuit........balance is good. :)

Here's the tuning guide for the Ultra HP.
http://www.holley.com/data/Products/...R10565rev1.pdf

Getting a carb right in the garages is one thing, on the street is another, and under hard braking yet another.........there are times it could be considered a masochistic process. :D

Sieg... I bought an AEM wideband AFR system. Here is a link to their website http://www.aemelectronics.com/

This setup worked out well, the gauge is easy to read. It's a great tool to get real time feedback on the AFR for tuning like protour73 said.

:thumbsup:

Quote:

Originally Posted by Sieg (Post 466798)

Thanks for the kind words on the car!

Even with the GM H.O.T. cam (fairly mild, but better than the stock ZZ4 cam), I'm at 16-17" inches of vacuum at idle. I've gone to bigger idle air bleeds to try to lean out that rich idle which has improved it, but still needs work. I still have a slight stumble at take off.

The wideband O2 sensor I went with was the Innovate Motorsports MTX-L http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

http://www.innovatemotorsports.com/p...XL_All_Web.jpg

Thanks for the info gentlemen. :thumbsup:

The Innovative unit and Amazon Prime :unibrow:

Were did you boys mount your O2 sensor and guage?
The ideal world would be both engine compartment and cockpit. :grin:

Scott - That stumble may be a simple as lengthening your primary accel pump link by turning 1 or 2 flats (or more) of the adjuster nut. The timing of that squirt of fuel is pretty sensitive and critical in the final stages of clutch engagement IMO. Once that stumble is gone you can then tune for power with squirter volume and cam profiles which effect the fuel delivery curve.

The off-idle power and roll-on performance of my old Demon improved dramtically with a little larger squirter (.028 drilled to .033) and the dark green pump cam in the #1 position.

Roads are actually dry for a change - time to test!

The O2 sensor goes (If running headers) in the header collector (welded bung) just after where the 4 tubes dump into the collector and put the gauage anywhere you can see it

I put the bung for the sensor on the inside of the header on the drivers side a few inches back from where the pipes merge.

Here is a shot of the gauge location I used.

http://i1048.photobucket.com/albums/...psd63f0721.jpg

Thanks again guys :thumbsup:

Is it a major foul to mount it in the pipe behind the flange like Scott did?

I already beat the crap out of the #5 head pipe yesterday, torturing it again vs. installing the bung when the new pipes are installed would be easier. :sieg:

Mounting the bung behind the header flange is fine. On the new LS engine I put the O2 sensor for the ECM on the header side of the flange and the O2 sensor for the wideband on the exhaust side of the flange. Works fine.

:thumbsup:

Quote:

Originally Posted by Sieg (Post 466913)

Sieg, it was way easier when I picked up these new Hooker reducers with the welded flange which seal way better than the slip flange type. I brought the driver side into a locally owned muffler shop and they welded the bung on for $20!!

http://shop.advanceautoparts.com/wcs...r_pri_larg.jpg