Missfire @2500 rpm

Old 08-07-2008, 09:47 AM
  #1  
doorjammer
Junior Member
APPRENTICE
Thread Starter
 
Join Date: Nov 2003
Posts: 19
Default Missfire @2500 rpm

hi guys
At 2500 t0 3000 cruse rpm i have a missfire but when i stand on
it no miss car pulls hard . all msd new wires and cap :idea:
doorjammer is offline  
Old 08-07-2008, 11:49 AM
  #2  
gimmemud
Senior Member
MASTER BUILDER
 
Join Date: Apr 2006
Location: Ms.
Posts: 191
Default

Vacuum leak maybe???
gimmemud is offline  
Old 08-07-2008, 01:47 PM
  #3  
itsabird
Senior Member
RACING JUNKIE
 
Join Date: Dec 2007
Location: ohio
Posts: 812
Default

sound,s like vac leak, to me also.
itsabird is offline  
Old 08-07-2008, 04:35 PM
  #4  
johnracer
Senior Member
DYNO OPERATOR
 
Join Date: Aug 2005
Location: Rifle Colorado
Posts: 585
Default

More info on the car/engine would help. Street, race, ign type, vacuum advance, valvetrain, etc....if it has vacuum advance, try unhooking it. It may be messed up and advancing it too far at part throttle/high vacuum.
johnracer is offline  
Old 08-07-2008, 06:19 PM
  #5  
doorjammer
Junior Member
APPRENTICE
Thread Starter
 
Join Date: Nov 2003
Posts: 19
Default Missfire @2500 rpm

hi
It is a street MSD DIS........with no vacuum davance
zz4 350 /355 power plus intake open plain crane hyd roller cam
234/[email protected]/558 lift...adv dur 398.304 crane 1.5 roller rockers
demon 750 carb.......after 2500rpm......car runs strong
doorjammer is offline  
Old 08-07-2008, 09:04 PM
  #6  
cepx111
Senior Member
RACING JUNKIE
 
Join Date: May 2006
Posts: 2,044
Default

You changed the cam correct?
More lift and duration than the crate motor cam had?
I think its fuel related.
Sounds like the power valve is trying to open up part throttle and dumping unatomized fuel down into the intake or drippling out of the boosters. With the car in park have someone rev it up to around 2500 and CAREFULLY lean over the carb and see if fuel is drippling out of the boosters.
If my memory serves me well, you need a power valve with a lower number with a higher lift cam or just take it out put a plug in it then go up about 4 jet sizes and be done.
Goodluck, Charles
cepx111 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