October 8, 2004Okay I have a 78 350V8 chevy. It has an edlebrock performer 600cfm carb on it. It has a new fuel filter, fuel tank, distributor cap, rotor, roter button, ignition coil, and fuel pump. It wont start. It ran good for a week or so, then just died and wouldn't start. I check and it was not sparking so I replaced all the above and then it had no fuel. Hence the fuel filter and then the pump. Now it still will not start. After repalcing all the above, it started and ran for about 5 minutes and then wouldn't idle. I started it and stood on the gas for am inute, then it idled, just real bad. So I attemtped to move it to my garage. Tried to drive it around the block and everytime I hit the brakes, it died. Started, ran, braked, died. Just like that. Looking inside the carb, it is coated with carbon and is black as night. Pulled the plugs and they are showing a rich condition. I tried to call edelbrock but get no help there. Does anyone here have any suggestions? I would liek to know how to lean out the fuel and the carb a little bit to even out this rich condition but cannot find any info anywhere.
Forums : General Tech Questions : Need carburator help (506 Views)
October 8, 2004Well maybe it isn't the carb. the thing wont even try to start unless I dump gas into the carb. then it tries, but stops as the gas burns off.
October 10, 2004The dying part and not wanting to start almost sounds like vacuum or EGR valve stuck open.
You also said it appeared it was not getting any gas, you replaced the fuel pump in the tank Did you change the sock on it also.
Not being a Chevy person it is hard for me to diagnose, but that would be a good place to start.
October 10, 2004What is the fuel pressure at the carb? Do you have any vacuum leaks at the base of the carb? Is the hose from the brake booster to the intake cracked or broken? Are you getting a hot enough spark/or any spark at the plugs? Did you have any backfire through the carb? Check your base timing and set it to factory specs. Check these things and let us know how you make out.
October 11, 2004Sorry guys, I was workign all weekend. Here is the update....
I feel liek an idiot but since th gauge doesn't work I couldn't tell till I dropped the tank, but it was out of freakin gas. :-) Stupid me.
So I put gas in it and got it started but it wont idol. so I can runit it as long as I hold my foot on the gas. I drove it lie kthis to a friends house who has all the vacum gauges and such that I do not. Heres what he found out.
The timing was advacned about 25 degrees. He brought it back to about 10 degrees I believe he said. Its like 7 off top dead center. I'm not sure what that means. He unhooked the vacum advacne off the distributer to time it. I believe thats right. He also told me based on the Torsonal dampner, that he believe this engine to be a 307 but it has 350 heads on it. What a mess. He then hooked a vacul gauge up to the primary/secodnary vacum ports on the front of this Edelbrock 600cfm carb, and attempted to adjust the air/fuel ratio. The two adjsutment screws aren't changign anything. Its getting about 7 PSI of vacum and thats all it will push. The vacum lines are not cracked or leaking so its probably a bad Carb.
Anyone else got Ideas? I appreciate all the wealth of knowledge on this board. you guys rock.
FYI, Its a 78-84 Checy truck. V8, possibly a 307/327 or a 350. It has a mechanical fuel pump which has been replaced about a week ago, new plugs, coil, dist. cap, rotor and rotor button.
October 11, 2004ROFLMAO!! I wish I had a dollar for every time I have done the "IT WON'T START!!!??!!??" thing, and the reality was it didn't have gas.
I do that on my four wheeler all the time.
I can't help you on this one. Sorry, I just don't know much about Chevy's.
SOMEONE HELP THIS DUDE!!!
October 11, 2004A small block chevy should pull about 20 inches of vacuum, at an idle, at a constant vacuum source at the base of the carb, provided you don't have some kind of wild racing cam in it. If it doesn't, 15 to 17 inches being so-so but OK, then the timing's either way off, or there's a vacuum leak some where. Try starting it up, then take a can of carb cleaner and spray it around where the intake mates with the heads, to check for leaks there, as well as around the base of the carb, to make sure it's not that. You could also spray it around any of the various vacuum hoses and connections. If the engine rpms change, you found the leak .... If no change the carb's the problem .......... Oh, and the difference in the cylinder heads is only the size of the valves and chambers. Most of the small block heads in that year range are interchangeable, with the exception of the 400 small block, the difference will be in the performance of the engine, power wise, but the vacuum at idle will remain the same ..... One more thing .... I believe Chevy stopped making the 307 in 1969 .....
October 12, 2004Cool, I'll do that tonight, the carb cleaner thing that is. Is there a sure fire way to fidn out what engine size this is without pulling it and tearign it apart? The way the vacum seems to be right now, I bet it has some sort of a radical cam in it. No way of knowing seeing as how I boutght it this way. I will post what I find out after the carb cleaner test.
October 12, 2004You could go to this web site http://www.nastyz28.com/sbchevy/sblock.html or any similar site. Get the info they ask and go from there ........ Guess I was wrong about the 307 ..... They say '73 was the last year .....