More tuning on the Holley. Found and corrected several issues which created the touchy throttle and have it MUCH better now. Super easy to be very smooth on throttle now. Also added some enrichment on MAP rate of change which it didn't have before, helped tremendously with tip in power. Can't wait to race it again Sunday.
Video for attention...
Had a pretty scary hung throttle while testing yesterday. Had a green light with no traffic in front so made a pretty hard hit in first and second gear, then the throttle hung wide open going to third. Pedal was on the floor so I immediately hit the key to switch it off. After I caught my breath while still coasting, I started it again with same result. Once stopped I pulled air cleaner but didn't see the culprit, fiddled with throttle cable and all seemed good so I started it again and it was fine. Once I got it back home, I discovered this...
The screws holding the throttle position sensor had come loose, one completely gone and the other finally loose enough that the shaft jumped the slot in the sensor and the sensor held the throttle open. Yes, the replacement screws got a dose of loc-tite upon reinstall and yes, throttle application is much smoother now.
I was running a datalog during the hung throttle...finally got up the nerve to look at it.
The green line is RPM... At least I know my rev limiter works now...
__________________
Lance
1985 Monte Carlo SS Street Car
Spent the day yesterday throwing Barney around another AZ Region SCCA Solo autocross course testing the recent changes made to correct the touchy throttle issue and I can report it is MUCH better...almost Quadrajet smooth once again. Thanks to all of those that helped diagnose and tweak the oddities that created the issue. The car ran great, rear end stayed under it for the most part and the engine made fantastic power everywhere.
Now if only the driver could do his part... The course was tough, it required patience, something I don't have much of as you'll see in the video. The real strange thing though was I ran a 54.541 on my 3rd run...AND my 4th run...using two completely different strategies... Both runs are in the attached video.
Now off to SEMA for a couple days... See a bunch of you there...
__________________
Lance
1985 Monte Carlo SS Street Car
Still wore out from a fantastic motorsports filled weekend. Spent Friday and Saturday racing Barney at the Good Guys Fall Nationals and then spent Sunday wheeling our new Jeep up Crown King Road from Lake Pleasant to Crown King and back down.
Good Guys went fantastic. The changes made to the car to better prepare it for these kinds of courses worked great. The new rear suspension setup really helped plant the awesome power the new Holley EFI created which resulted in fast times comparable to or better than a lot of shop built, high horsepower, big tired cars on Friday. The newly sealed surface was challenging for sure but we made it work pretty well for us I thought. Then they used a vac truck to clean it up Saturday morning and man did the surface get better quick. Some drivers were running times 2-3 seconds faster Saturday morning than they did on Friday, I picked up about a second on Saturday...typically unheard of at any autocross event. We ended up 2 positions out of the 32 car field shootout after Saturday morning runs were done...then one car in the field could not continue, so Scot Spiewak made the field...leaving me out by just a few thousandths of a second. I'm okay with that as the field was stacked with purpose built cars and championship quality drivers, I was just happy to be in the running and able to head home early.
Here is my fastest run which was also my last run of the day on Saturday.
My friend Paul was in town from Iowa and took this video from the sidelines of the same run.
Had a great time seeing and hanging out with all of my racing friend from across the Country, love this event and the way it brings people to the wonderful fall weather here in Phoenix.
Speaking of wonderful fall weather, we took out Sunday morning in our other new vehicle to tackle some off road trails. The new to us Jeep did much better than even I expected and showed the 4 others with me a new form of recreation. I think they are all now fans of off roading and can't wait to do it again. The trail went from easy, to moderate, to difficult the higher we went and the Rubicon handled each obstacle with ease. Even had to go around a nice Can Am Side by Side so that we could pull him over a large rock he kept getting high centered on. Of course the Go Pro and cell phones were rolling the whole time. The views up the mountain were spectacular and the landscaped changed to 3 completely different ecosystems as we climbed. Hard to believe the views in these pics are from less than 30 miles from our house in a huge City like Phoenix. Love living here!!!
Here is a video I put together showing a bit of the trail and pulling the SXS out.
And a few of the pics from up above...
__________________
Lance
1985 Monte Carlo SS Street Car
The Following User Says Thank You to SSLance For This Useful Post:
Nice view and great pics! I spent an hour in Phoenix traffic today, which may sound bad, but it is impressive how explosively the area is growing. Lots of new stuff and tons of new people probably amount to your property values improving as you age. That's a good result!
More tuning on the Holley. Found and corrected several issues which created the touchy throttle and have it MUCH better now. Super easy to be very smooth on throttle now. Also added some enrichment on MAP rate of change which it didn't have before, helped tremendously with tip in power. Can't wait to race it again Sunday.
Video for attention...
Had a pretty scary hung throttle while testing yesterday. Had a green light with no traffic in front so made a pretty hard hit in first and second gear, then the throttle hung wide open going to third. Pedal was on the floor so I immediately hit the key to switch it off. After I caught my breath while still coasting, I started it again with same result. Once stopped I pulled air cleaner but didn't see the culprit, fiddled with throttle cable and all seemed good so I started it again and it was fine. Once I got it back home, I discovered this...
The screws holding the throttle position sensor had come loose, one completely gone and the other finally loose enough that the shaft jumped the slot in the sensor and the sensor held the throttle open. Yes, the replacement screws got a dose of loc-tite upon reinstall and yes, throttle application is much smoother now.
I was running a datalog during the hung throttle...finally got up the nerve to look at it.
The green line is RPM... At least I know my rev limiter works now...
This may be the answer you are looking for. A long rev limiter hit is tough on your bottom end, especially with cast pistons. When I had my ZL-1 built, my engine builder preferred I raise the rev limiter vs. bounce it off repeatedly.
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
Short clips: Goodguys Pleasanton autocross and pit videos
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