Alcohol and gas jetting on 1050 Dominators

Old 08-23-2010, 03:33 PM
  #1  
markdunlap
Senior Member
DYNO OPERATOR
Thread Starter
 
Join Date: Jan 2004
Location: central Illinois
Posts: 459
Default Alcohol and gas jetting on 1050 Dominators

I am thinking my jetting is may be too rich on 2 different combinations and just want an opinion if I should leave well enough alone.

The problem is both cars pick up over .10 ET and .06 60 foot during a race day into the night. This is with 3500' density altitude during the day and 2600' in the evening. This is 1/8 mile bracket racing. Just looking for consistincy.

Some of this may be the track prep not being the best and tightening up when the sun goes down?

The first car is a 3000# back half 496 BBC with a Gary Stinnet throttle stop 1050 gas new style Dominator. It has 94 jets. Timing is 36 degrees. 4000 RPM starting line, 6800 shift rpm. ET varies from 6.46 to 6.36, 60 ' from 1.42 to 1.36.

The second car is a 2700# tube chassis 421 SBC with a George Rupert old style alcohol 1050 Dominator. It has 176 jets. timing is 36 degrees, 4500 starting line RPM, 7400 shift RPM. ET varies from 6.17 to 6.06, 60' varies from 1.32 to 1.26. EGT on #4 cylinder was between 993 and 1009 on 7 passes.

These are times from last Saturday in Central Illinois. Both cars dropped .01-.02 each pass on ET.

I am think about leaning both down 5% to see if they will become more consistant. What do you all think?

Guess you can tell I don't have anything in the garage to work on tonight.
markdunlap is offline  
Old 08-23-2010, 07:05 PM
  #2  
zipper06
Senior Member
RACING JUNKIE
 
Join Date: Jan 2006
Location: La.
Posts: 2,890
Default

Don't know about the B/blk on gas, but down here or around Memphis where the humidity is always relatively high, they seem to run better on alcohol with the EGT around 1050/1100 degrees, which is sometimes hard to do from day to nite because the humidity goes up at nite. Heck sometimes the races don't get over until 1:00/2:00am, at the same track openened at 4:00pm for testing runs. With 2 buybacks and 50 to 70 cars in S/P it can be a long nite.

JMO

Zip.
zipper06 is offline  
Old 08-23-2010, 07:31 PM
  #3  
jmarksdragster
Senior Member
RACING JUNKIE
 
jmarksdragster's Avatar
 
Join Date: Jul 2007
Location: Florida
Posts: 635
Default

As always, the mods made to the carbs will have an impact on jetting, not to mention what your engines want. Alky carbs are way too different from one to the next as well, and will run decent even when too rich. What plugs does the alky engine use, and have you tried a hotter plug?

As far as the gas carb, 94 is borderline rich for just about any engine with a 1050, try going down a couple and watch the plugs, good time to put fresh ones in to read. What do the current ones look like? Got a picture? See how it affects the MPH after going down in jetting.
jmarksdragster is offline  
Old 08-24-2010, 02:12 AM
  #4  
cepx111
Senior Member
RACING JUNKIE
 
Join Date: May 2006
Posts: 2,044
Default

Cant comment on the alky, I like to drink some from time to time but other than that, I'm lost to that deal
But.....
As a comparrison :

I run a 1050 on my 496 BBC bracket turd and I'm running 88 square & no P/V's.
Likewise I run at a track that starts out in the early evening (day light & hot) but elims usually start around 9ish and this track is in the country where there's quite a cool downfrom the start time, most nights anyway.
None the less it cools off nicely and that's usually a recipe for some big ET jumps.

Normally it screaming hot when we do our fist time trial and the first run is always a throw away, not sure why I even make the pass cause the track is always so frigging loose, guess I just love to drive that sum bitch, but anyway.
Normally somewhere around the 1st or 2nd round the track comes around and the ET's level out, that is if your set-up is right. (lean IMO)
With 94's square I can see where it would be struggle getting a handle on them ET's, take the above advise and start by going down a min of 2 sizes sqaure as a starting point. Not saying 88's would work in yours, it very well may but every combo is different :wink:

Goodluck>Cp
cepx111 is offline  
Old 08-24-2010, 07:10 PM
  #5  
markdunlap
Senior Member
DYNO OPERATOR
Thread Starter
 
Join Date: Jan 2004
Location: central Illinois
Posts: 459
Default Alky and gas carb jetting

Thanks for the tips and opinion.

Plugs are NGK 9 on alky and NGK 8 on gas.

Gas plugs look more brown than tan after driving back to pits.
markdunlap is offline  
Old 08-26-2010, 07:32 AM
  #6  
chevyfireball
Senior Member
MASTER BUILDER
 
Join Date: Dec 2005
Location: Napier, New Zealand
Posts: 230
Default

Seems to me at 3600 ft or so, thats too big on the jetting. As the altitude comes down the air is obviously getting better and bigger jetting will work better. I ran a 496 with a 1050 in my Camaro for a time and we'd start out in the heat with 90's and later as the air got better we'd go to 92's or occasionally 94's. If you can burn it - do it!
chevyfireball is offline  
Old 08-26-2010, 04:25 PM
  #7  
jmarksdragster
Senior Member
RACING JUNKIE
 
jmarksdragster's Avatar
 
Join Date: Jul 2007
Location: Florida
Posts: 635
Default

On gas, go down 2 on the jets and up to 7's on the plugs. I run 8's in my 15.5+ to 1 SB2, my brothers 14+ to 1 SB2 runs 7's. Plugs should maintain the white porcelain even after a few runs, just no specs. A little plug info here.

http://www.dragstuff.com/techarticle...ark-plugs.html
jmarksdragster is offline  
Old 08-26-2010, 06:16 PM
  #8  
Tod74
Senior Member
RACING JUNKIE
 
Join Date: Sep 2007
Posts: 4,143
Default

my 1050 is jetted 88 square with no pv 's and I run NGK 8'S.

13 to 1 540 with box stock BRODIX -2X heads and a 454R
Tod74 is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service