Rough idle low throttle surge

[Dinosport]

im sure I'm not the first. I ran a search under surge but didn't find my exact symptoms. So once again I come you guys. My friends lol. Any Saturday I was driving along. I had an hr drive out and back to make. When I reached where I was going I felt the idle got really low and choppier than normal. I notice the idle got really low it never shut off but when stopped I neutraled it and feathered the throttle. Next thing I noticed was say around 30-40 mph if I had it a slight throttle I can feel the engine surging if I layed into it say half throttle or more it cleared up and just revved.
I didn't get a chance to play at all with it because it was my daughters birthday bbq, the house was crowded. I just got home, rolled it in the garage and left it there.
Any ideas where I should start?

 

[MrSony]

Take the carb apart and clean it. Check the float and the needle and seat. If they look sketchy or if the float looks dicked up, buy a rebuild kit. You could luck out and have it just be some dirt or something. Also, what kind of carb...?

 

[Dinosport]

Sorry I should've mentioned a little more about my set up. Its a small block with a edelbrock on it. I dont remember if its a 600 or 650, it came already there, and you know its never really run right and had a little surge at idle before but it wasn't as noticeable as it now. Thanks.

 

[64nailhead]

Vacuum leak would be my guess. I agree that it could be something up with the carb, but start with vacuum check first. Make sure it's steady from no throttle to light throttle. And then my next step to be to check the timing. Make sure it isn't jumping around at varying rpms. If the vacuum and timing is good, then dive into the carb.

Good luck - Jim

 

[pontiacgp]

It could even be you got some bad gas at your last fill up

 

[Dinosport]

Thanks guys. I doubt the bad gas because I was just under half tank from the last fill up. You never know but I would guess it would've started earlier than that if it were from that fill up, vacuum leak? I assume that'll be the place to start. Not very many vacuums so that should be a quick easy thing to rule out or find. I'll spray the intake with some carb clean too and see if anything happens.
Thanks guys

 

[Dinosport]

I'm hoping it's something stupid or cheap because I have a motor to swap in once I have all the parts I need. So I don't really want to spend a lot on the 350. But we'll see I guess. I won't be able to mess with it till Saturday or Sunday at this point.

 

[pontiacgp]

I would try 64nailhead's suggestion to check the timing

 

[Dinosport]

Timing is definitely on my mind as well. I know Ive had a few timing issues and the light seems to jump all over the place. I havent gotten around to turning the engine to see if there timing chain slop, I was told to try to power the light from another source because that can cause it to jump around. Oh brother If it could just run good for the rest of this season I could then start focusing more on dropping the LS in. I hope its not down for the season I really enjoy driving it and was looking forward to driving more in the fall with the family being that it wont be so hot out.

 

[pontiacgp]

I had a chinese performance distributor that had the ring which activates the pick up coil come loose on the knurls. That caused me to reset the timing every few weeks and couldn't find the issue. Found the problem when the race car blew up a distributor so I put mine in and the car was losing a second a lap. I took a good look at it and finally noticed the problem