boggero Posted May 19, 2012 Share Posted May 19, 2012 Hi guys, i have been trying to get a good et ticket but sometimes my engine runs good and the next day it doesnt but i don't know whats going on. There are days that the engine revs up to 6300 with no effort and it pulls really hard until there, the next run it only revs to 5000 rpm and its like it hits a wall and wont pull anymore. Also the days it revs to 6300 i can tune the carb with the idle screws and works perfectly, the days it doesnt rev its really rich and the idle screws doesnt work. I always have the engine around 650 rpm at idle, i have been trying to find a vacuun leak the days the idle screws doesnt work, but cant find anything Here are the specs Sbc with stock vortec heads , comp cams xe274 Edelbrock 600 cfm carb antipump up lifters And a b&m torque converter of 1800 rpm Any ideas of whats wrong? I just can't find whats wrong with it. Quote Link to comment Share on other sites More sharing options...
Miles Posted May 19, 2012 Share Posted May 19, 2012 I used an Edelbrock 650 cfm carb on my SBC 240Z project initially. It acted acted as you described plus the engine just never seemed to run at peak performance. Performance always seemed sluggish. After much wasted time, effort and money tweeking the Edelbrock carb I replaced it with a Holley 575 cfm Street Avenger. Excellent drivability. Summit p/n Holley 0-80770 The difference was night and day. Haven't had a problem in the three years since the engine was dyno'd. Quote Link to comment Share on other sites More sharing options...
dexter72 Posted May 19, 2012 Share Posted May 19, 2012 I would definately look into trying another carb, do you have another?. Or maybe a friend will let you swap his, with yours to see for sure. Is this a vacuum secondary carb?. Check for vacuum leaks all over the intake, engine, and brake booster hose. What ignition and distributor are you using?. Quote Link to comment Share on other sites More sharing options...
boggero Posted May 20, 2012 Author Share Posted May 20, 2012 (edited) I would definately look into trying another carb, do you have another?. Or maybe a friend will let you swap his, with yours to see for sure. Is this a vacuum secondary carb?. Check for vacuum leaks all over the intake, engine, and brake booster hose. What ignition and distributor are you using?. its a regular chinese Hei, im going to change it on monday, a friend of mine has several carbs at work, I'm going to try some of them and i think there are new HEIs, gonna try another one. Already changed the hoses and sprayed carb cleaner everywhere lol, also i just sprayied the holes of the air screws and its work great. Let see. How is going to work in few hours lol Hope it works, im about to boost the **** out of it lol so i can get the ticket i want hehe my dad just bought that turbo for a Ram charger, but if he doesnt start to build the pipes soon, ill have to borrow it fo lr a while haha Edited May 20, 2012 by boggero Quote Link to comment Share on other sites More sharing options...
ttsbc280z Posted May 22, 2012 Share Posted May 22, 2012 That carb hat is very small! When i used my K&N low profile carb hat the car ran really really weird under full throttle. Changed to a procharger carb hat and all is well now. (but that is with a turbo lol) Also i cant believe you are running an edelbrock, i bolted my brand new holley street avenger on my old 350 and without touching a dial the car ran better then ever and with some more tinkering it ran top notch! those are kick ass carbs! Quote Link to comment Share on other sites More sharing options...
ttsbc280z Posted May 22, 2012 Share Posted May 22, 2012 also what is your base timing set at and what is your total timing? Quote Link to comment Share on other sites More sharing options...
boggero Posted May 22, 2012 Author Share Posted May 22, 2012 (edited) also what is your base timing set at and what is your total timing? yesterday i bought a timing light and fixed it a little bit lol i had the initial at 25 degrees and total of 35 degrees, so i put it at 18 initial and also changed the springs of the HEI and its giving 38 total, and its running alot better, also remove the damn spectre air filter and it ran so much better, now i need to do an spacer for that hat, just for few months while i get all the parts to turbo de car The issue with the carb was that, there was debris inside of the little holes where you screw the idle screws. also i live in guadalajara that is 4900 feet so i tried bigger carbs but i lose a lot of torque, and for a daily driver the edelbrock is really economical hahah Edited May 22, 2012 by boggero Quote Link to comment Share on other sites More sharing options...
ttsbc280z Posted May 22, 2012 Share Posted May 22, 2012 do you have the vacuum advance hooked up? it could help alot with economy... Quote Link to comment Share on other sites More sharing options...
boggero Posted May 22, 2012 Author Share Posted May 22, 2012 do you have the vacuum advance hooked up? it could help alot with economy... nop, what would it be better to the intake? or the carb? Quote Link to comment Share on other sites More sharing options...
ttsbc280z Posted May 22, 2012 Share Posted May 22, 2012 either one as long it is a source for engine vacuum. Just make sure you have suction from whatever port you are running the hose to... it should be good for a min of 12* of timing advance with that hooked up which is huge help on fuel efficiency and cooling while at idle and cruise Quote Link to comment Share on other sites More sharing options...
boggero Posted May 22, 2012 Author Share Posted May 22, 2012 either one as long it is a source for engine vacuum. Just make sure you have suction from whatever port you are running the hose to... it should be good for a min of 12* of timing advance with that hooked up which is huge help on fuel efficiency and cooling while at idle and cruise Im going to connect it in the afternoon, I saw your built thread its awsome, also saw the grenades on your youtube, those cars inspire me to boost my car lol Quote Link to comment Share on other sites More sharing options...
ttsbc280z Posted May 22, 2012 Share Posted May 22, 2012 thanks! ya night and day difference with a turbo lol Quote Link to comment Share on other sites More sharing options...
jap tin Posted May 23, 2012 Share Posted May 23, 2012 Take the top of the carb off, remove the boosters and clean air bleeds. Make sure all passages in the boosters are clear. Quote Link to comment Share on other sites More sharing options...
boggero Posted May 23, 2012 Author Share Posted May 23, 2012 Take the top of the carb off, remove the boosters and clean air bleeds. Make sure all passages in the boosters are clear. It does miracles when you do that right? Lol thats the only pain in the a$$ with edelbrock carbs. The ones i never cleaned before were the passages of the idle screws and those were giving me the problems Quote Link to comment Share on other sites More sharing options...
jap tin Posted May 23, 2012 Share Posted May 23, 2012 Plugged up air bleed in a holley will give you grief as well. Air bleeds in carbs are like grounds in electrical, everyone over looks them. Quote Link to comment Share on other sites More sharing options...
ttsbc280z Posted May 23, 2012 Share Posted May 23, 2012 my high speed air bleads are completely blocked of on my car and it runs great.... Quote Link to comment Share on other sites More sharing options...
boggero Posted May 28, 2012 Author Share Posted May 28, 2012 I have another question, i have been searching but can't fine anything. I have a b&m torque converter and they say its a 2000 rpm stall, with my old heads and old cam i was able to rev the car to 1700 rpm and launch from there, but with the vortec heads and new cam , it onlt revs to 700 rpm and starts moving. Oh and i haven't touch the tranny lol Quote Link to comment Share on other sites More sharing options...
Pyro Posted June 1, 2012 Share Posted June 1, 2012 Make sure the ignition advance is working smoothly. If it sticks then it will cause problems like you describe. 20 initial and 36 total would be nice for your setup. Then add another 10 degrees with the vacuum advance (get an adjustable advance). I would also recommend getting a good distributor, like a msd with adjustable mechanical advance and adjustable vacuum advance. A cheap distributor will lead to problems. I like the 750 holley 3310 carb with a regular Edelbrock RPM intake (not air gap). My wife is from guadalajara. Cool town with lots of pretty girls. Quote Link to comment Share on other sites More sharing options...
boggero Posted June 1, 2012 Author Share Posted June 1, 2012 Make sure the ignition advance is working smoothly. If it sticks then it will cause problems like you describe. 20 initial and 36 total would be nice for your setup. Then add another 10 degrees with the vacuum advance (get an adjustable advance). I would also recommend getting a good distributor, like a msd with adjustable mechanical advance and adjustable vacuum advance. A cheap distributor will lead to problems. I like the 750 holley 3310 carb with a regular Edelbrock RPM intake (not air gap). My wife is from guadalajara. Cool town with lots of pretty girls. Its a great town and you are right the girls are pretty cute the only thing is that the dragstrip sucks , they dont use glue, the cars are faster in the street lol Regarding my issue with the HEI i changed the coil and now its revving up to 6300 again and also the engine sounds and revs more smooth If it starts acting like before I'm going to put a coil outside. Quote Link to comment Share on other sites More sharing options...
Scarab73 Posted June 4, 2012 Share Posted June 4, 2012 (edited) Hi, While you're doing all of this cleaning and discovery, have you attached an engine vac gauge for a reading? It will reveal either a wealth of good....or bad news. You want a steady needle with a 18+ reading, depending on your cam events. Happy motoring! Edited June 4, 2012 by Scarab73 Quote Link to comment Share on other sites More sharing options...
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