Adjusted timing- now issues starting and turning off

[Black70c10]

I've done some research on this but I thought I'd see what you guys thought. Long story short, bought a truck a few months back and it was running sluggish. So i checked the timing, and it had a base timing of 33 degrees.....seemed ridiculous so I confirmed TDC, then reduced the timing down to about 12 degrees BTDC. It seems to have a little more acceleration and less pinging. However, it now seems to struggle when I cold start and even more when it's hot.. you guys have any recommendations? I don't have any cam or compression ratio specs and I'm running mid grade gas. When it was at the original timing of 33, it fired right up when cold but always struggled when hot which is common when too at advanced I hear.

Also, when I shut the truck off, it sputters and acts like it wants to keep running for another second or two...what the heck is this about?

Anyways, thanks for the advice.

[swamp rat]

Try re adjusting the air fuel mix, then check timing again and fine tune that, then check the air fuel one last time. And be sure you have the vacuum hose off the distributor when setting the timing, back on for setting air fuel ratio.

[Black70c10]

Will try that, thanks. There is no vac advance, it's a mech advance msd distributor.

[cleszkie]

Run-on is typical problem with too much advance. But you don't want to go too much below 12 degrees. Try 10 degrees. You may also need to use a higher octane fuel, as knocking and run-on are symptoms of low octane fuel.

[GASoline71]

Is this engine stock? If not... what carb, intake, and ignition does it have?

Gary

[Lee H]

Run on is almost always caused by to high of an idle setting. Just my humble opinion, without a properly function mechanical & vacuum advance you will never get good drivability out of a heavy vehicle with a stock to mildly built motor.

[gvw5400]

x2

[swamp rat]

Just another thought, I had a real problem getting my idle down where it should be, then i discovered the grommet at the power booster was bad and i had a vacuum leak, check the entire system for vacuum leaks too..

[Black70c10]

Thanks for the input guys. I really would be surprised at too high of an idle. My tach is broken at the momenyt but it can't be idling more than about 7-800 rpm if I were to guess.

It's mildly built, unknown cam size but definitely mild. Weiand intake manifold, 600 cfnm edelbrock, headers, and MSD pro billet distributor. Unknown compression ratio but I'm running mid grade gas so that may be an issue. What I'm having a hard time understanding is when it was way off on timing, 33 deg BTDC, it started right up but now that I've backed it down to 12 degrees, it really struggles with starting.

[geezer#99]

How did you determine #1 TDC?
What method did you use?

[Black70c10]

The balancer was already marked pretty well, I just confirmed TDC by using my finger on #1 to confirm compression stroke and just wrenched the crank until the air stopped blowing out and it fell right on 0.

[quick60]

I used to use a vaccum gauge to tune my Nova at idle. That method worked very well. Adjust mixture to get max vaccum if I remember correctly.

[geezer#99]

Originally Posted by Black70c10

The balancer was already marked pretty well, I just confirmed TDC by using my finger on #1 to confirm compression stroke and just wrenched the crank until the air stopped blowing out and it fell right on 0.

Not accurate enough! You could easily be 20 degrees off.
Buy or make a piston stop and check the accuracy.
Otherwise you'll never know where your timing is at!
Here's a homebuilt piston stop. Easy to make.
http://www.jerrybramlett.net/tips.html