Not 100% what's wrong here

[77chevyC20]

OK, have a 1977 Chevy c-20 2wd. 350 v8 4 barrel.

Alright, so I replaced my intake manifold with a Pro comp dual plane intake, and a new 600cfm edelbrock Carb. I failed to get it to TDC before doing this,but marked where the rotor pointed. Put it all together and could not get the distributor in the proper spot, so we put it in thinking maybe 1 tooth off.? Got it running but was missing badly, turned the distributor clockwise over 90 degrees to bring the timing mark up using a timing light. Had it running decent at idle, so took it around the block, would sputter and pop from the Carb/intake under load or when I would give anymore pedal that lightly feathering it. It may or may not have backfired out of the tailpipe. Got it back home installed a newer distrubutor a friend had,( since mine was all rusted and corroded under the rotor. Now it will not start, will pop fireballs from the Carb(yes,burned my hair). Also no 1 cylinder spark plug appears dry and does not smell like gas.

So, I am thinking it may have jumped time when I drove it like that?

Someone else says may be a flattened lobe on the cam?

Was told the harmonic balance can slip over time and not be true to the timing groove?

Also heard I may have ruined a valve(s) running it out of time?

Any advice, tip, direction, would be appreciated. Help me save this truck!

[bd]

How did it run before you replaced the intake?

Verify the firing order, correctly stab the distributor and set the timing.  Begin with the firing order: 1-8-4-3-6-5-7-2 clockwise, looking down on the cap.  Next, remove the #1 spark plug and bring the engine up on #1 compression.  Align the timing marks to TDC and stab the distributor, so the business end of the rotor points to the #1 plug wire on the cap.  Disconnect the vacuum advance, plug the vacuum hose, then set your timing using a light.  If that doesn't solve your dilemma, post an update and we'll go from there. 

But, DON'T jump the gun and start chasing random suggestions!  Remain cool and work systematically.  Everything you listed can be easily checked, so begin with the basics.

[77chevyC20]

It ran great, it drove OK, it would sputter from a stop but would sail nice and smooth other than that.I had gas leaking from the Carb and all the gaskets to the Carb were soiled/saturated. This is why I decided to replace parts in the first place.

My next step(weather permitting) is pulling the valve covers when I go for tdc AGAIN, to be even more certain it's at tdc on the proper stroke and keep an eye on the valves.

I have redone the spark plug wires and triple checked them, new wires and plugs.

[bd]

While you have the valve covers off, have an assistant crank the engine over as you watch to make sure all the valves are opening and closing as they should - essentially, equally and very roughly 3/8" for a stock cam.  When a factory cam rounds off a lobe sufficiently to cause the symptoms you're describing, it should be visually apparent.

You can accurately verify a piston is at TDC by using a piston stop (pictured).  The piston stop method will also allow you to verify that the harmonic balancer hasn't spun on its hub and that the timing marks are accurate. 

To use a piston stop, remove all the spark plugs to allow the engine to rotate easily without building compression.  With your thumb or finger pressed over the #1 spark plug hole, have an assistant tap the engine over with the starter until you feel compression beginning to build.  Alternatively, you can watch the #1 intake and exhaust valve motions - both valves will be closed on the compression stroke.  Before the piston is all the way up, thread the piston stop all the way into cylinder #1, finger tight.  Bar the engine over slowly in either direction by hand until the piston just contacts the stop.  Mark the balancer with a welders pencil at 0°.  Rotate the engine in the opposite direction almost one full revolution, until the piston again just contacts the stop.  Mark the balancer again at 0°.  Half way between the two marks that you just added to the balancer is 0° actual.  If the balancer is properly indexed on its hub, and you have the correct balancer for the application, the split between the penciled marks will coincide with the factory mark.  If it doesn't, replace the balancer.  As soon as you establish TDC, remove the piston stop so you don't forget and damage the piston or bend the tool accidentally.

With the foregoing procedure, you will have verified camshaft condition, TDC compression to correctly stab the distributor, and the timing marks.

To check the stretch of the timing chain, lift the distributor cap and bar the engine clockwise, by hand, to TDC.  Now, while watching the distributor rotor, bar the engine slowly counterclockwise, by hand, until the rotor just barely begins to move.  The distance between the timing mark and 0° represents the amount of stretch in the timing chain and gear set - zero separation is no wear.  If you're pushing an inch of separation, it may have, or may shortly, jump a tooth.

[77chevyC20]

So I am a little confused.?

By marking the balance at 0° when the piston is all the way up, on both strokes. Wouldn't the first mark be 0° tdc?

Trying to understand how actual 0° tdc will end up between the marks made when the piston is up.?

I know I'm still learning.

Thanks

[rich weyand]

Because the piston stop is set *near* the top, not *at* the top.  You came around one way until you hit it, then you come around the other way until you hit it, and the absolute top is between the two marks.

[77chevyC20]

Got it. Thanks for clearing that up!