New Best on Friday Night!

-

Walker434

Well-Known Member
Joined
Aug 29, 2012
Messages
1,018
Reaction score
815
Location
Nashville, TN
Took the dart to the track Friday night. I didn't know it was import night until I got there :violent1: I thought, Oh well I'll make a couple passes anyway. First pass off the trailer was a new best of 7.83 in the 1/8th at 85.70 MPH. I went back to my trailer and changed my stock 750 DP jets from 71/80 to 73/82 thinking I would jet up until it slowed down.

Problem is by the time I got back in line all these high school kids in there manual transmission imports were smoking their street tires off the line. So the second pass with the new jets I blew the tires off. No traction. Played with the tire pressure and made a 3rd pass..... again no traction.

Question: I'm trying to figure out if my jet change did any good. The MPH was exactly the same on my second pass when spinning. How does spinning through first affect MPH? I think I spun because of all the street tire rubber balls at the start line. Any help is appreciated. All and all it was a good night because I didn't break anything and got home safe.
 

Attachments

  • Dart Track.jpg
    52 KB · Views: 385
  • Dart Track 2.jpg
    63.7 KB · Views: 366
1.66 is really a good 60 ft time for 7.83 1/8. That would be about low 12's, I think. Details on the motor, gears, converter?
 
Yeah according to the 60ft I should be running a quicker ET. It seams I'm losing time down the track. I need to get a fuel pressure gauge for my cowl so I can see my fuel pressure as I'm running down the track. I'm just frustrated I didn't get a clean pass after the jet change so I could know if that helped.

The combo is listed below:

It's a junkyard 2001 5.9 magnum. Just freshened it up with rings and bearings so I'm still running stock Pistons, rods, crank and heads. Had comp custom grind the cam on an LA core so I could run a mechanical fuel pump. Cam is 230/236 duration at .050, .506/.513 lift with the stock 1.6 magnum rocker ratio. Edelbrock air gap, Holley 750 DP and cheap summit headers. Running an x pipe and 2.5 inch flow masters.

It's got 90/10 shocks up front and ss springs in the back. 8 3/4 with 3.91 sure grip. This has been a poor mans budget build over the last few years so I'm pretty proud of it. I've gotten tons of good advice from some wise folks on this forum. Also learned a lot from lxguy and magnum swap.com

That 60 ft time is also largely due to the ultimate 3,800 stall converter.
 
Your spin off the line did not affect your trap speed; that is calculated by a pair of beams , one 60ft (I think) before the finish line, and one at the finish line.

Your jet change, as you kinda guessed, did not do any good. Next time, take jet out, OR put timing in, do only one thing at a time.

Congrats on new best!!
 
How are your plugs looking. Jet change may or may not be improving ET but can be improving consistency once you get hooked up.
 
I'm one of the younger guys on the site so not yet good at reading plugs. I've been reading up on what to look for so I'll take a look tonight and take some pictures.
 
I'm one of the younger guys on the site so not yet good at reading plugs. I've been reading up on what to look for so I'll take a look tonight and take some pictures.

Too late now if you drove home. You need to shut your engine down ASAP after your last run and immediately pull the plugs to get an accurate read.
 
Your spin off the line did not affect your trap speed; that is calculated by a pair of beams , one 60ft (I think) before the finish line, and one at the finish line.

Your jet change, as you kinda guessed, did not do any good. Next time, take jet out, OR put timing in, do only one thing at a time.

Congrats on new best!!

I do not agree with this statement, in my case anyway. EVERY TIME I have wheel spin at the starting line I loose MPH.
 
Your 60' is good..my duster 60's in the low 1.60's with a best of 1.62 11.78..your right about no traction those cars running street tires tend to ruin the traction on the starting line..
 
My setup is almost the same except 67 dart/3360 lbs with driver/home ported OEM heads/pro products airgap/demon 750DP/3200 tight convertor

You should be running around 89-90 mph
Best so far for me is 11.86 with a 650 Demon DP
75* at sea level
60' 1.631
330' 4.828
1/8 7.525
1/8 MPH 90.98
1/4 11.86
1/4 MPH 113.43

I just changed to a Demon 750 DP and ran the car the other night. Had to up the front pump shot from 31 to 33. Also did jetting and got it close with 75 front/83 rear.
My metering blocks have 3 emulsion bleeds all have .030 bleeds. MAB is 39 and the fuel curve stays around 12.7 at WOT. I'm going Wed night and upping the front jets to 76.
I realize you have a Holley but they all work the same.
Definitely check fuel pressure. My car has 3/8" fuel line and a $20 stock pump.
My guess is you need to jet up a little and see if your mph changes. I always make 2 runs after a change to verify good or bad.
Hope this helps and have fun.
 
Too late now if you drove home. You need to shut your engine down ASAP after your last run and immediately pull the plugs to get an accurate read.

Post the plugs. You probably are not close enough to do all the work of cut off plug reading.

If you ignition is even decent, you can look at th plugs and see how close you are. Unless you are trying to run down KB racing for the money, you can look at the plugs without th clean cut off on the other end.

Besides, you can get a look at your tune up during part throttle operation.
 
Take a look at my plugs. The car hasn't been started or driven since the last pass. I just idled to the trailer and pulled it on. This is the # 1 plug. Let me know your thoughts, I've been studying plug reading but getting some differing opinions.

I took 3 different pictures of the same plug just trying to get the camera to focus right.
 

Attachments

  • Spark Plug 1.jpg
    43.4 KB · Views: 237
  • Spark Plug 2.jpg
    83.4 KB · Views: 254
  • Spark Plug 3.jpg
    43.8 KB · Views: 249
It looks pretty good. Perhaps a little rich at idle which could have to do with power valve rating or t-slot opening.
 
Look rich to me and either you have too much timing or you need a colder spark plug.

But you really need to shut it off at the finish line, cost out of the way and pull a plug again.

If that was pulled out fresh of a run i would say that it is WAY Rich. but as has been said already, if you have the wrong power valve for your set up and its opening at idle. Well It would be way rich all the way back to you trailer.

I'm no expert on reading spark plugs. have been doing it for years, and now trying the O2 gauge way.
 
Look rich to me and either you have too much timing or you need a colder spark plug.

But you really need to shut it off at the finish line, cost out of the way and pull a plug again.

If that was pulled out fresh of a run i would say that it is WAY Rich. but as has been said already, if you have the wrong power valve for your set up and its opening at idle. Well It would be way rich all the way back to you trailer.

I'm no expert on reading spark plugs. have been doing it for years, and now trying the O2 gauge way.

^^^^^^this^^^^^^^

When you look at the ground wire it looks like you have too much timing. More likely, that long reach plug makes it look like too much timing.

You also need to look down into the bottom of the plug. There should be a .060 wide fuel ring. Or about that.

You are fairly close.
 
These are Autolite 5224 I believe. Do you think that is too hot of plug for my combo? I think I'm going to buy a new set of plugs and back the timing down a couple of degrees. I live on a lonely stretch of road. Maybe with the new plugs I could WOT through first and second on my road and kill it and coast into the driveway.

Thanks FABO for the help so far!
 
These are Autolite 5224 I believe. Do you think that is too hot of plug for my combo? I think I'm going to buy a new set of plugs and back the timing down a couple of degrees. I live on a lonely stretch of road. Maybe with the new plugs I could WOT through first and second on my road and kill it and coast into the driveway.

Thanks FABO for the help so far!


I don't use auto liters much and don't have a catalog for them. I did the cross reference, which is, at very best, somewhat close and it crosses to a Champion RC12YC. It may be the picture, but the tip looks very long, and I'm not a big fan of that, for a couple of reasons.

So, IMHO, you are close on heat range. When the tip is that far into the chamber, you have to account for a couple of things, like the tip being right directly in he path of the incoming fresh air fuel charge. To help keep from fouling, the plug manufacturers will make the same heat range plug ACT hotter. For marketing hype, they say their plugs have a "wider" heat range, which is to simply say they are keeping the tip hotter to stop fouling. Most of that is emissions crap, and CAFE standards and I don't give a tinkers damn about either. So like I said, I'm not a fan of that long nosed plug.

All that said, when you are reading the ground wire for timing, and you are using a long nosed plug like you are, you can run the heat line closer to the plug shell like you have it. I don't think you are that far off. It is difficult so see the minutiae that is all important in plug reading from a picture, but you are close enough for me to say it's time to start picking the fly poop out of the pepper. Get a very good quality plug reading tool, and learn to read plugs. It's simple really. Just know that all you want at WOT is a fuel ring at the bottom of the porcelain where it meets the shell about .060 wide. When you get good at reading plugs, you can make the fuel ring narrow up or widen out with a jet change, or with your air bleeds, or even emulsion. You will know when the ignition is down or going down. I used to be able to tell you when the ignition points were getting weak by looking at the plugs. Yup, I'm that old. Learn to read a plug. Then, once you have that down, you can get an air/fuel meter and work with it. In my world, the only thing that trumps a plug reading is looking at and reading piston tops and combustion chambers. That, and looking at the exhaust ports and headers.

Much fun stuff for you to learn, even if it is your hobby.
 
After some research it appears the Autolite 3923's (pictured) would be 1 heat range colder and have the shorter porcelain tip. Or, the 3924's would be the same heat range I have now and have the shorter porcelain tip. Any thoughts or suggestions? Maybe just pic one, run it and try to read the plugs again?
 

Attachments

  • Spark Plug.jpg
    8.8 KB · Views: 190
After some research it appears the Autolite 3923's (pictured) would be 1 heat range colder and have the shorter porcelain tip. Or, the 3924's would be the same heat range I have now and have the shorter porcelain tip. Any thoughts or suggestions? Maybe just pic one, run it and try to read the plugs again?

I like that shorter tip. If you have over 11.0:1 use the cooler one, unless you have a bunch of cam and gear.

I would think the 3924 would be the hot poop for you.

Try that and keep us posted.
 
Last night I switched to 3924s. Took the car out for a drive, did WOT through 1st and 2nd then coasted into my driveway. Pulled the #1 plug. There are 3 pictures below. What do you think plug readers?

I took 3 pictures of the same plug to try to get different angles. Any input is appreciated.
 

Attachments

  • Spark Plug 1.jpg
    41.7 KB · Views: 178
  • Spark Plug 2.jpg
    45.6 KB · Views: 176
  • Spark Plug 3.jpg
    43.1 KB · Views: 166
If you have not yet verified your timing marks and timing light, that would be first. Once verified, I would leave the timing mark where it is, meaning leave the timing alone. Then, you need to look at the very bottom of the plug and look at the fuel ring, and verify its there. You MUST use a quality plug reading tool. If you need one, speed talk.com has them for sale, and those are good units.

The next step is learning to read the plugs. You do that with one change at a time. For example, fatten up the system a good bit. I forget your carb, but if it's a Holley, move up 4-6 jet sizes. If you are at the track, watch MPH and then look at that fuel ring, if it goes faster with th fuel ring wider, then that is what it likes. Once you have made 5-6 good, repeatable runs (or tests down your street!!!!) go 3-4 sizes BIGGER on jets again. Watch the MPH and the fuel ring. If the fuel ring is wider, but it is making more HP, that is what YOUR COMBINATION wants. IMHO, I would doubt that a fuel ring wider than .100, as I have never seen it, BUT, you could be the exception.

After you have went to the rich side, you can go back to your starting point, and very VERY CAREFULLY lean it out, from your starting point 2 jet sizes. Again, watch the fuel ring as it should be getting thinner. Watch MPH the same as before. You should be able to watch the fuel ring with 1-2 jet size movements. Once you get to that point, you can work on timing, all though timing and fuel go together.

At that point, when you have all your notes and such (you should be keeping notes) you can get an A/F gauge and when the plugs and the meter agree, you can tune from that. And the A/F meter is easier to use for tuning at a cruise.

When I start getting close, I pull the plugs, put them in the lathe, and machine the the shell off so I can easily measure the fuel ring and look at the texture of the porcelain...things like that.

It's not easy to do, but mastering plug reading and tuning makes the hobby much more fun. You can do it. It just takes time.

You are close on timing, at least to start testing. I can't see the fuel ring to comment on jetting. But I hope I have given you enough to start testing.

BTW and FWIW I almost always start my testing by going RICH first. You can't get hurt doing that. If it's my engine and my starting tune up, and I can see the fuel ring confidently enough, I may start out leaner. Just be dam sure before you go lean.

Keep us posted.
 
Yellow rose, you have been a big help, Thanks! Just ordered a spark plug reader. I'll keep the thread posted on my results in a couple days. Thanks FABO!
 
You still have the better problem than most... a strongish 60' time. Could be 11.90-12.00 at 111ish with that 60'. With your 60', you would like to be in the 7.50's for 1/8 mile at 90ish mph.

Now work on why it's losing time down track and bring that around. mderoy's slip is a pretty good example for you to try and achieve. Makes a good move the last half of track.
 
-
Back
Top