79280zx Posted July 12, 2009 Share Posted July 12, 2009 Hi all, i have an annoying problem and im not sure where to start diagnosing. i have a 79 zx w/ 88 sbc tbi block and heads(home ported). its got an edelbrock perfomer intake and 1405 carb vacuum sec. 700r4 w/ 2400 stall. after it warms up i get a terrible stumble about 10 feet off the line when i stomp it. it occurs right around 2500-3200,its like hitting a wall... my car pulls hard for a half a second and then missfires badly. i had the stock 1200 stall converter in the car for a while and had it "tuned" and it ran fine, as long as i didnt try to stomp it from a dead stop, as it would sputter/stutter just the same it does, but at a lower rpm. it seems to only do this once its warmed up a while. Could super hot intake air be the cause? or is my fuel boiling in the bowls? im not much of a carb tuner. Maybe the accel pump running out too soon causing lean sputter? the car pulls great once past this point, but i want to roast my tires soooo bad sometimes,(as we all do at times) and its so irritating because i just get vvrroompopperuuewapfjdda... i wish i could record the noise as im sure its some no brainer for someone with more knowledge. any advice? the pump shot is in the middle hole. should i try a diff hole? i dont want to do anything detrimental to my engine. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted July 12, 2009 Share Posted July 12, 2009 (edited) in about 90% of the cases I see with that problem the accellerator pump shot length, or duration and volume is to small/short. occasionally the metering rods need to be changed and the float levels need to be reset or the fuel flow pressure and volume feeding the carb needs to be fixed to supply more fuel, and you'll need to verify the fuel pressure stays at a rock steady 5 psi and the system needs a decent size fuel line, return style fuel pressure regulator, and a low restriction fuel filter, theres also a chance the ignition curve is advancing too rapidly of ideal power, but that's less likely it sure won,t hurt to read thru these http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1820&p=4717&hilit=edelbrock#p4717 Edited July 12, 2009 by grumpyvette Quote Link to comment Share on other sites More sharing options...
79280zx Posted July 12, 2009 Author Share Posted July 12, 2009 thanks grumpy, the info from edelbrock will definately help me understand their carbs more. I think im going to invest in an a/f meter to help me diagnos this problem. Wish me luck. Luke Quote Link to comment Share on other sites More sharing options...
jhm Posted July 12, 2009 Share Posted July 12, 2009 Is the choke opening fully upon warm-up? If not, that could be the cause of your problem. If you've got an electric choke, a loose connection in your hot lead or ground could prevent proper operation of the choke (and thereby cause stumbling on acceleration once the engine is warmed up). Good luck with the trouble-shooting, and be sure to let us know what the problem and solution were once solved! Quote Link to comment Share on other sites More sharing options...
Pyro Posted July 13, 2009 Share Posted July 13, 2009 I hate those edelbrock carbs! get a holley! what is the ignition timing setup? (initial, total mechanical, how much vacuum advance, ported or manifold vacuum advance) stock cam? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.