Trying to get my 350 to run better
 

My 79 Silverado is a good strong running truck, but there are some issues that are annoying me that I'd like to fix if possible. I'm not the most experienced gear head so I don't know all the little tricks and secrets to getting your engine to run as optimally as possible all the time.

A little about the truck: 79, 2wd, SWB, 350 sbc, th400, 3.55 posi. The truck has 12,000 original miles. It was a show truck most of its life. Now its my daily driver in the warmer months. The engine has a brand new Edelbrock 1405 carburetor sitting on a Performer EPS intake, and it has hei ignition and headers, other than that everything on the engine is stock. Initial timing is currently set at 8 degrees, thinking about bumping it up to 12 degrees. I just replaced the spark plugs for a new set of AC Delco r45ts gapped to .045.

The issues: It never fires right up and goes in the morning. Usually it takes several tries and pedal pumps before she will idle on her own. Then it needs to warm up for a minute before I can go without the risk of stalling it out. A manual choke would probably help this particular issue. Any other suggestions?
Also, when I go to get on it from a dead stop or at low speeds it stumbles. I understand that a stock truck 350 isn't going to plant me in the back of my seat, but it should squeal the tires a bit in my opinion. So what's the issue? Too much or not enough fuel? Or something else?
Lastly, it idles rough. I just changed the spark plugs hoping this would fix the issue but so far it hasn't. The old plugs looked like the engine had been running rich, but I also just changed carburetors, and the previous carburetor was not running right at all.

So... what's causing these problems and how do I go about fixing them? None of them are bad, just annoying. And most importantly, I want my truck to perform as it should. It bugs me that something's not right. Are there any simple fixes, like Seafoam, adjust the accelerator pump (currently in the middle position), more timing, etc that I can do? Things I should check? Any and all help would be appreciated. Thanks.

Re: Trying to get my 350 to run better
 

Bump your initial timing up. Try it at 14 initial. Your idle will speed up of course. Turn the idle back down and adjust your mix screws for the best idle.
14 initial is just a starting point. Your motor might like more. Experiment by adding 2 degrees at a time until it's hard to start when hot.

Re: Trying to get my 350 to run better
 

Have you adjusted your floats, idle mixture, choke, fast idle and idle? I did all this to the 1406 Edelbrock carb on my truck and it fires right up, choke works and idles high and idles good when warm. No stumbles or hesitation.

Re: Trying to get my 350 to run better
 

I made some adjustments out of the box. Idle is right around 750. Mixture screws I think are 1-3/4 to 2 turns out. It doesn't have a choke on it currently, probly gonna put a manual on soon. Once I do that I can use the fast idle cam as well. Haven't touched the floats. If I take the air horn off I will also be changing jets, and I won't be doing that until I can hook up an A/F meter to the exhaust so I can tune it to exactly where it needs to be.

Re: Trying to get my 350 to run better
 

Have you done a complete tune -up. Could be as simple as cap and rotor and wires. Fiddled with a carb for days before I figured out the cap was bad... Stumbled like a beotch.

Re: Trying to get my 350 to run better
 

The cap rotor and wires are new so it shouldn't be that. I double checked all the connections when I put new plugs in it the other day.

Re: Trying to get my 350 to run better
 

I'd try bumping the idle up a hair see if that helps it start and run better.

Re: Trying to get my 350 to run better
 

First, as previously mentioned check timing and adjust it to 12 or so. Check mixture. By all means, add a choke if one of your largest complaints is cold start issues! Most of your drive ability complaints should be addressed

Re: Trying to get my 350 to run better
 

Timing will get bumped up to 12-14 this weekend and I will bolt on a manual choke as well as set the fast idle. I'll let you guys know if that fixes all my issues or not. Thanks for the feedback.

Re: Trying to get my 350 to run better
 

Regarding your stumbling issues, it could be several things that are the cause, but the primary root cause is "usually" not enough fuel. The contributors to that could be: float level not correct, jets not big enough, etc. I am not familiar with the Edelbrock you mentioned, but all the Holley's I have had in the past have a squirter at the top of the plenums that I would change to increase the squirt of fuel into the carb/intake when I got on it.

Hope this gives you something to think about, anyway.

Steve

Re: Trying to get my 350 to run better
 

Everything you mentioned is related to your choke or lack there of. The butterfly should be closed on initial start up. Then when it reaches normal operating temp it should be straight up. Then tackle the other things like timing and you could also open up the spark plug gap for that HEI. Good luck

Re: Trying to get my 350 to run better
 

Ok, so I bumped the timing up to 12 degrees, made a world of difference. The engine is so much more alive and responsive. I also installed a manual choke. The couple days it was cold it fired right up. I also bumped idle up from 750 to 850 and it idles smoother now. Still not perfect but overall she is running like a champ. I think 14 degrees initial timing is doable. Gonna wait til it gets warmer to try it though. Thanks again for the help.

Re: Trying to get my 350 to run better
 

I'm running 17* BTDC. No problems.