Reading spark plugs ?

danny waters sr · 04-12-2011, 09:10 AM

I ran my 283 stocker this past weekend at MIR. ( L/SA )
Shut it down at top end after run and checked plugs ,they look like they just came out of the box.
I run the 4-gc carb .
My question is ,do i need to jet it up or maybe leave it alone since the weather is going to change to hot conditions very soon here.
The weather was very good this past weekend except for the humidity.
And if i change jets is it going to pick the car up very much if any ?
It seems to be sort of laying down at top end now (good fuel pressure at top end ) , but not popping or snapping ,just lazy feeling from just past the 1,000 ft mark to the 1/4. It ran a 12.18 @ 108 mph.

Thanks in advance for any info....

Bob Bender · 04-12-2011, 12:00 PM

I do not have anything trick but, I have a rich and lean carb I use. What you said it sounds lean. That 4GC is a pain to jet at the track so get another and faten it up a little.

Glenn1066 · 04-12-2011, 01:07 PM

What jets did you have in for that run? Dean Oliver is the guy to talk to about 4GC's, I have tried a multitude of different jet set ups and have found very little performance gain in the the 4GC. I have 67/69 jets in now and will likely end up with 68's in all. As for laying down at 1000 ft, it's a 283 all my car does on the top end is make noise!

Glenn

Bill Belden · 04-12-2011, 05:22 PM

I ran 64/66 jets when I ran the 283

danny waters sr · 04-12-2011, 05:27 PM

I have 65 and 67's..
It ran 108 mph and 7.64 @ 88 in the 1/8

cad · 04-12-2011, 10:04 PM

FWIW....We learned a lot on our local chassis dyno. We used the shop's O2 sensor in my O2 sensor bung. I do have headers extensions on my super comps. The key is...we took our Computech weather station with us and documented the CF, DA, etc. We jetted for 13.0 AFR. Now, we run the jet program on the Computech and it tells is whether we need to go up or down 1-2 jet sizes. We dyno'd at 2600' DA (dont remember the CF at the moment), and now we have our baseline. We know if we'll slow down or pick up based on the weather if we dont change jets. It took 2 hours and $150 which beats beating our head against the wall trying to repeat testing on the track for old school mph jetting.
IMO, reading the plugs is hit and miss. I only read them for the heat stripe (hot/cold) and base ring for jetting.

Clark

Phillip marvetz · 04-13-2011, 02:56 AM

What was the RPM at the 1000ft and finish line?

danny waters sr · 04-13-2011, 07:46 AM

Quote:

Originally Posted by Phillip marvetz

What was the RPM at the 1000ft and finish line?

6900 and 7100
538 gear and 28x9 hoosier.
I run a 26x9 for the 1/8 and is faster than the 28's in the 1/8
test and tune here Thursday and will try jets

Think i will get me some extra $$$$$ and call Deano

Thanks again

MOTORSPORTS Innovations · 04-13-2011, 11:15 PM

I'll vote for O2. A LM-1 only costs $269. I have done rental/loaner LM-1's with racers that goes like this. You get the LM-1 with two bungs and plugs and I charge your card $269 + shipping. You return it within 3 weeks (without the bungs & plugs cause they are welded on you headers) and you get a refund for $234 if it's not damaged (so it cost you $35). Keep it longer or damage it and I just send it back to you.

Dean Oliver got his O2 & logger from me.

Wade_Owens · 04-19-2011, 08:30 PM

Danny, call me at 573-651-3158 and I'll try to help. As Deano says, the law of physics arent any different under my hood than yours. (Even though I argued with him for better part of a year!)

AND, if you havent had your carb back to Dean in the last 6 months to a year, you're missing quit a bit of 60' and et. Get your carb updated, you wont be sorry......

Wade O

04-12-2011, 09:10 AM	#1
danny waters sr VIP Member Join Date: Apr 2007 Location: lagrange,nc Posts: 2,224 Likes: 1 Liked 0 Times in 0 Posts	Reading spark plugs ? I ran my 283 stocker this past weekend at MIR. ( L/SA ) Shut it down at top end after run and checked plugs ,they look like they just came out of the box. I run the 4-gc carb . My question is ,do i need to jet it up or maybe leave it alone since the weather is going to change to hot conditions very soon here. The weather was very good this past weekend except for the humidity. And if i change jets is it going to pick the car up very much if any ? It seems to be sort of laying down at top end now (good fuel pressure at top end ) , but not popping or snapping ,just lazy feeling from just past the 1,000 ft mark to the 1/4. It ran a 12.18 @ 108 mph. Thanks in advance for any info.... __________________ Danny Waters, Sr / 73 Duster "340"

04-12-2011, 12:00 PM	#2
Bob Bender VIP Member Join Date: Jan 2009 Location: Maryland Posts: 1,727 Likes: 1,589 Liked 452 Times in 88 Posts	Re: Reading spark plugs ? I do not have anything trick but, I have a rich and lean carb I use. What you said it sounds lean. That 4GC is a pain to jet at the track so get another and faten it up a little. __________________ Bob Bender 144 O/SA 2010-2012 National Record Holder

04-12-2011, 01:07 PM	#3
Glenn1066 Junior Member Join Date: Dec 2007 Posts: 69 Likes: 39 Liked 1 Time in 1 Post	Re: Reading spark plugs ? What jets did you have in for that run? Dean Oliver is the guy to talk to about 4GC's, I have tried a multitude of different jet set ups and have found very little performance gain in the the 4GC. I have 67/69 jets in now and will likely end up with 68's in all. As for laying down at 1000 ft, it's a 283 all my car does on the top end is make noise! Glenn

04-12-2011, 05:22 PM	#4
Bill Belden Member Join Date: Jun 2002 Location: York, PA Posts: 241 Likes: 0 Liked 1 Time in 1 Post	Re: Reading spark plugs ? I ran 64/66 jets when I ran the 283 __________________ Bill Belden Retired Stock Eliminator [emailSTK1100@comcast.net[/email]

04-12-2011, 05:27 PM	#5
danny waters sr VIP Member Join Date: Apr 2007 Location: lagrange,nc Posts: 2,224 Likes: 1 Liked 0 Times in 0 Posts	Re: Reading spark plugs ? I have 65 and 67's.. It ran 108 mph and 7.64 @ 88 in the 1/8 __________________ Danny Waters, Sr / 73 Duster "340"

04-12-2011, 10:04 PM	#6
cad Senior Member Join Date: Apr 2009 Location: Omaha, NE Posts: 691 Likes: 188 Liked 87 Times in 48 Posts	Re: Reading spark plugs ? FWIW....We learned a lot on our local chassis dyno. We used the shop's O2 sensor in my O2 sensor bung. I do have headers extensions on my super comps. The key is...we took our Computech weather station with us and documented the CF, DA, etc. We jetted for 13.0 AFR. Now, we run the jet program on the Computech and it tells is whether we need to go up or down 1-2 jet sizes. We dyno'd at 2600' DA (dont remember the CF at the moment), and now we have our baseline. We know if we'll slow down or pick up based on the weather if we dont change jets. It took 2 hours and $150 which beats beating our head against the wall trying to repeat testing on the track for old school mph jetting. IMO, reading the plugs is hit and miss. I only read them for the heat stripe (hot/cold) and base ring for jetting. Clark Last edited by cad; 04-12-2011 at 10:41 PM.

04-13-2011, 02:56 AM	#7
Phillip marvetz Senior Member Join Date: Oct 2008 Location: Lynden ,WA Posts: 820 Likes: 0 Liked 3 Times in 3 Posts	Re: Reading spark plugs ? What was the RPM at the 1000ft and finish line? __________________ 2009 V/SA Record Holder

04-13-2011, 11:15 PM	#9
MOTORSPORTS Innovations Member Join Date: Dec 2009 Location: Hainesport, NJ Posts: 123 Likes: 0 Liked 15 Times in 2 Posts	Re: Reading spark plugs ? I'll vote for O2. A LM-1 only costs $269. I have done rental/loaner LM-1's with racers that goes like this. You get the LM-1 with two bungs and plugs and I charge your card $269 + shipping. You return it within 3 weeks (without the bungs & plugs cause they are welded on you headers) and you get a refund for $234 if it's not damaged (so it cost you $35). Keep it longer or damage it and I just send it back to you. Dean Oliver got his O2 & logger from me. __________________ MOTORSPORTS Innovations www.motorsportsinnovations.com

04-19-2011, 08:30 PM	#10
Wade_Owens Senior Member Join Date: Jul 2007 Posts: 578 Likes: 0 Liked 3 Times in 1 Post	Re: Reading spark plugs ? Danny, call me at 573-651-3158 and I'll try to help. As Deano says, the law of physics arent any different under my hood than yours. (Even though I argued with him for better part of a year!) AND, if you havent had your carb back to Dean in the last 6 months to a year, you're missing quit a bit of 60' and et. Get your carb updated, you wont be sorry...... Wade O