Oh boy, what is causing engine to surge.

[RoadWarrior]

I need to hear from outside my box. New eddy thunder 650 carb and performer intake sitting on my stock 318. Now originally I install a heat insulator gasket since it can get hot here and my last carb always got heat sink.
What happened when I fired it up? Surging. Not bad enough to notice at first. I let it idle high and warm up. As I began to tune the surging wouldn't stop. I am no pro, but I am not a total moron. I've tuned a few carburators in my life. I immediatly knew (or thought) it was a vacuum leak. Idle at 1000 in park warmed up, would drop to 900 and go as high as 1200. I sprayed starter fluid but nothing changed. Couldn't find a leak. I removed the air/fuel ratio screws to clear out any crud that maybe got in there. New fuel filter. Nothing. Took it all out and removed the insulator gasket, installed with the regular adapter plate and gaskets.

It worked, at first. From a cold start it idle'd fine. Once it warmed up and the idle dropped as the choke opened (its electric) it started surging again, but not as bad. It would maintain constant RPM for a few seconds, then surge down 100 and/or up 100. But not constantly like before. Bad heat insulator gasket? Replaced all, new studs and bolts, torqued to 10 lbs. Still sorta does it. Called edelbrock and they verified my install is correct.

My intake bolts lined up and went in. I re-torqued after warm up 3 times. At this moment the only theory I have is my stock mechanical fuel pump is not enough/or too much. Edelbrock says a max of 6.5 psi. From what I can tell the stock 318 fuel pump operates at 7 psi. Could .5 PSI be my problem?

 

[SlinktRR]

lean surge, not enough fuel, clogged filter, idle mixture screws plugged. Fuel pump should be fine. Try to drive it around and see if it improves or gets worse when you start using enough fuel to drain the bowls and get on the main jets.

 

[miller]

Might waste a few minutes, and check the float settings, to be sure their right.

 

[terzmo]

spray around the entire carb base and around the entire intake first...make sure all vacumm lines are installed properly with no leaks or blockage...that's where I would start

 

[RoadWarrior]

I spent 2 days looking for vacuum leaks, replacing carb gaskets twice now just to rule it out. No change when spraying starter fluid.

I decided to just richen the heck out of the carb. Smelled amazing but ran way better. So spot on with the lean surge. I thought of that but man, just didn't open it up enough I guess.

So ya, we got a half chow with crazy fluffy/kinky hair. Guess what I found where the nipple of the fuel rail enters the carb? A long dog hair, wrapped around the nipple haha. We have traveled to the other side of the world and I still wake up with our dogs hair in my beard, on my clothes, etc.

So ya it was my dogs fault. Thanks for the suggestions. I never would have open my idle air screws that much. That told me for sure it was a fuel delivery problem.

Drove it around. Runs great. Still need to dial it in with timing and such but it is already running like a champ. Need to mess with the kick down linkage as well.

 

[oldbee]

I've seen similar a couple times.The best one was a tuneup on a cop car that came back a week later with a miss- ended up being the ceramic insulator broke and fell down blocking the center post when in the head,course if you picked it up by plug wire end like you normally would, everything looked normal.

 

[wagonman]

I've seen similar a couple times.The best one was a tuneup on a cop car that came back a week later with a miss- ended up being the ceramic insulator broke and fell down blocking the center post when in the head,course if you picked it up by plug wire end like you normally would, everything looked normal.

Yup seen a few of them,we called them rattlers. When you shook the plug it rattled.

 

[RoadWarrior]

Yup seen a few of them,we called them rattlers. When you shook the plug it rattled.

This happened to me last month. Pulled the plug to check it out. Looked good, then literally fell apart in my hand. The plug wire was the only thing holding it together.