Just an update to let you know how the car is doing (it's doing great), and how I'm doing as a driver (not so great). My new carb finally came in on Friday. It's Quick Fuel 650. I installed it on Saturday. I took the car out yesterday. It was a two day event but we could only make the Sunday race. The impact of that was that I only got two practice runs before the racing started. The car ran 12.436 and 12.530. I was pleased with the first run, but on the second I short-shifted the 1-2 shift. Not on purpose. Sometimes I do stuff and wonder why I did it. It looks like the new carb improved the ET about a tenth. 60ft times remained 1.8-1.9 even thought it felt a bit harder off the line. Speed was 109 both runs. The temp and DA were rising all day long. The first run was at about 78* and the second was at 84*. By eliminations the temp was at 93*. Time to choose my dial-in. Was the difference between the fist and second practice run based on temp, or was it driver induced? I thought it was driver induced and thought I should dial-in at 12.45 (giving it a little bump due to the rising temps). My son thought it was mostly temp and suggested 12.53. After much discussion we compromised at 12.48. So, the first round I cut an .070 light, and ran 12.453. Broke out and lost. I plan on running the club race on Friday night. More opportunity for me to practice!
Can you post your timeslips, or just type your incrementals from your runs? If your 60' is varying a tenth 1.8-1.9 like you posted, that is most likely where your difference is. Any variance in your 60' is going to show up exponentially downtrack. Sounds like you're getting a handle on some things though...
RT/60'/330/ 1/8ET /MPH/ 1000/ 1/4ET/ MPH .458/1.813/5.416/7.949/87.73/10.379/12.436/109.77 .085/1.921/5.250/8.050/87.86/10.472/12.530/109.38 .070/1.848/5.174/7.765/87.87/10.390/12.453/107.87 On the third run I let off right before the finish line because I had half a car, but still broke out. That's the reason for the slower 1/4MPH and ET.
One thing you always have to account for,is that after 5pm it starts cooling off.The air gets better which means the eng. is going to make more power & usually the trk. gets better too.As a spectator for many years & helping other people at the trk,it always gets tricky after dark because everyone is chasing their tails on set ups because of this.I have seen high HP cars easily go 2 tenths quicker late in the day,this is when the fun really starts because it can really be a crap shoot when deciding what number to post on your car.
Dan, that's what happened later in the day when it clouded up. The guys who made it through the first few rounds were scrambling to adjust their dial-in. When I ran it was still getting hotter. I just guessed wrong on my dial-in.
Hang in there Mcknight,it`s just a learning curve,I`ll go through the same thing when I get out there.It`s all in getting to know your car & what it will do,or what you expect it to do,then things will get a lot simpler.
Dan, that's correct. Some day I'm going to make it out of the first round! There are many good comments in this thread that I hope will help others.
here is how I would read those slips. The motor was making more power in the first runs cooler weather but your reaction time was in the crapper. Power wicked away slightly in the second run by the slightly higher temps and the short shift didn't help matters. Combine the higher power of the first run with the reaction time of the third run(and without backing out near the stripe) and you would have broken your records with this combo. Rough and roundabout math equates to.. .070/1.76/5.10/7.60/88.10/10.25/12.30/110.1x Until your consistency improves a bit more I would be dialing in at about 12.42. Once you get more time behind the wheel.. and can confirm the power consistency.. I'd shoot for low 12.3's.. maybe even high 12.2's.
A little playing with jet sizes would probably help you out some, those Quick Fuel carbs with the 4 corner adjustments can be temperamental to get adjusted. I ditched mine for 750 Holley dp I understand them more. I have found that my car runs quicker when it gets hotter but figure it is due to being a little on the rich side, no black smoke and plugs look good but gassy smell maybe a tad over carbed but 650 didnt go as quick More seat time and experimenting with launch rpms and shifting rpms but like others have said 60 foot time are crucial. Bottom line is be consistant and you will win races. Love your track and the racers there a very competitive group as with all tracks, hate the temps and bees and black widows though. Make the team and come on over to Woodburn for the Division 6 finals one of the days or just make the team as it is a really great time racing at the finals
AS far as carbs go,I think I would run an Edelbrock on the street for ease of tuning & reliability but they will not make the power as some of the others at the trk.For ease of tuning & power at the strip I`d go with a Demon which does not use a power valve,causing more headaches.The last 2 years I`ve worked with 3 of them,2 850s & a 750,everyone of them was good right out of the box & I`m seeing more & more of them at the strip.The only thing I don`t like about them is you have to be careful with the fuel fittings going into the bowls because they strip easily,but WOW,they do make the power.
Wait.. Demon's don't use power valves? You must be talking about the newer AVS styled street demons? I've heard that they are more of a street rod type deal than a racer carb because of the more restrictive primaries/triple boosters. Harder to work on in the engine bay too and not good for longer duration cams with bigger single planes either. Then again.. many people, including myself, get biased because they/we get used to what we've worked with for so long and don't want to relearn something new.. haven't ever tuned them myself, so I take what I hear with a grain of salt. Holley's are nice if you figure out how to break all the circuits apart like you're supposed to when tuning them and work from part throttle to full throttle... idle on upwards into the powerband. You can also plug the Holley's power valve/s and add main jet to more accurately dial in the fuel curve.. then once it's dialed in.. pull some jet back out and add it back into the power valve channel restriction(subtract main jet orifice flow area and add it back to the PVCR). Not for the timid inexperienced tuner though and you'll often need to modify the PVCR to accurately dial it all in. You can also learn a LOT about carb tuning with a decent wideband AFR setup too. Wideband tuning pays for itself in power and efficiency gains.
Not rocket science, The car can go 12.436. Dial in at 12.430, (always drop a nickel because you're racing) and cut a lite. These guys can spank the tree. Practice .
Thanks for the comments. My goal for the season is to make the top 58 in points so I can come over for Div 6 finals. But, I've got a lot of points to make up later this season to be able to do it. The QFT 650 is a tenth faster out of the box, so there's promise there. I only have 301 cubic inches, so I think the 750 was too big. I do have a question about the highlighted above: Are you talking some other adjustment other than the four corner idle circuit? The carb came with the following settings/features: see attachment below. My intention is to run it as is until the engine shows me it needs carb adjustment. I ordered the short throw lifters so hopefully I will be able to turn the engine to 6500. I'm also going to have the converter modified so it will stall to 4000. I won't have any of those upgrades done this week. I'll run it as is tomorrow night and put the lifters in next week. I maybe will also get the converter done also.
lol.. only a nickel? Doesn't take a calculator to see that with good air and sharply cut light.. this car will EASILY break out of a 12.43 dial. With all those new parts, some tuning, and a bit more seat time you'll be knocking on 11's before you know it.
Well, actually it was easy. Ran a 12.525 in practice, dialed-in 12.52, cut a .001 light, and made it to the second round! Got a bye run for the second round. Ran a 12.359. Fastest time so far. The car got squirrely at mid track in the third round, so I shut it down. Did not check the tire pressure between rounds, and since the temp had gone down the pressure in the slicks was at 10, rather than 14. More driver mistakes. Had fun, though!
