First, you aren't dumb. I know that because you are asking questions and seeking information/help. That's what smart people do when faced with uncertainty.

Moving along now. What do you know about the "mid 80's sbc?"

What size engine and what did it come out of?

Has this been rebuilt before and if so how recently?

Do you know any of the casting numbers on the block or cylinder heads?

If this isn't a factory original engine is any information on any replaced parts or machine work done available?

Is the engine making any noises? (pings, taps, knocks, rattles)

Establishing true TDC is a common thing to do with parts interchanges. Did it run with the original TDC mark and how far away is the new TDC mark? (an estimate will do....1/4", 2", opposite side of the balancer/damper?)

Is the gap on the spark plug closed with soot and there is still a gap when clean? Or is the electrode bent closed? What part number spark plug are you using?

What carburetor is this?

This is just a start. Answer what you can and we can go from there.

 

So I believe the motor was originally ba warranty replacement motor when I was researching the casting number a while ago I don't have it now but regardless the motor was rebuilt around early 2000s or so then my dad let it sit until about a year ago I got a hold of the motor to freshen up and put into my truck. The motor started two cranks with fresh gas in the carb from sitting. It's a healthy motor to play knowledge probably bless than 15k maybe 20 on it right now. The motor sounds like it's running healthy no unusual noises. I replaced the balancer and the timing mark was about 4 inches off from tdc when I made my own mark. The gap on the plug was completely bent closed. And the card is an Edelbrock 1406 4barrel from bout the same time motor was built.

 

You have the wrong balancer and if your new mark is 4" off, then I believe it's too much. How did you determine TDC?

Two different balancers below showing the 12 and 2 positions. Third pic shows my new mark.

Note that the key way on both point close to the 2 o'clock position.

 

There is one mark on the balancer and when I ordered it it said it was for this motor, I'm not sure. I turned the motor over until it was at tdc on compression stroke by feeling the piston and seeing if the valves were close. Then I took a paint marker and drew a line at 0 degrees and then timed it to 12 degrees.

 

You mentioned a gauge to measure air/fuel ratio to help to remove some of the guessing. That is a great tool to have and very useful. You can't go wrong by owning one of those.

A piston stop is also great tool to have. It's not expensive and I think (as do some of the others here) that will be the most useful tool in eliminating the largest part of the guessing in this case. It's where true TDC actually is and what your actual ignition timing is right now.

I apologize if this seems like the proverbial "beating a dead horse." I also want you to understand that it's not an attempt at an insult either. I just want to provide a big picture view of the description we were given with regard to locating true TDC in this case.

Let's have a look at where the valves are going to be closed in relation to true TDC. Here are 2 generalized numbers associated with valve timing events to help picture what's going on. The intake valve closes somewhere around 60 degrees ABDC (after bottom dead center) when the piston is moving up in the compression stroke. The exhaust valve opens somewhere around 60 degrees BBDC (before bottom dead center) when the piston is moving down in the power stroke. When you put your finger over the spark plug hole and turn the crank, you feel pressure when the intake valve closes and both valves are closed. 120 degrees of crank rotation to TDC. Then 120 more degrees of rotation until the exhaust valve opens. Both valves were closed for 240 degrees or 2/3 of a full rotation of the crank. During that time....the cylinder before the one you were checking, the one you were checking AND the cylinder after the one you were checking all fired in order. I know you didn't miss by that much, but all of those things happened while the valves you were watching were closed.

Let's say you felt pressure in the cylinder on the compression stroke and slowly rotated the piston up to TDC. You may have inserted something in the spark plug hole to verify the piston was at the top. What if the piston was .032" (less than a spark plug gap) away from the top? Or a tad over 1/8" away (.134")? Slightly less than 1/3" away (.295")? or about 1/2" (.514"). The amount of crankshaft rotation might surprise you:

For a SBC 3.48" stroke, 5.700" rod

10 degrees = .032"

20 degrees = .134"

30 degrees = .295"

40 degrees = .514"

50 degrees = .765"

I know it's long winded example. I hope it illustrates that it's very easy to miss true TDC by observing the valves closed and going by feel. It's very easy to miss VERY BIG. Consider re-evaluating true TDC in the hope of avoiding some frustration.

 

You need a piston stop, used very gingerly, to find TDC.

 

EIther a piston stop(bolts to the deck) or simply indicate .100 in the normal rotation and mark the damper, then roll it over the other way till you indicate .100 and split the difference.

 

That's essentially what I did. Im certain it's tdc right now maybe +- half a degree or so but that doesn't exactly explain why it's running so terrible which was my main problem.

 

Running terribly.
A couple words explains it.
’Edelbrock 1406 carb.
fuel pressure and heat sensitive.

 

See what I also don't get is this setup has been on this motor and was running great previously before it sat so I don't know what changed. Is the carb just old and needs replacing?

 

Or rebuilt.
open it up, see what kinda chunk you find.

 

I've gotten two rebuilt kits and cleaned out about 7 times at this point

 

On the 7th time you cleaned it out were you still finding debris in the carburetor? The first time or two you could expect that but if you're getting debris each time I would wonder about the fuel tank having a lot of junk in it. Is there an inline filter somewhere? Sometimes debris in the tank won't rear it's ugly head when it's full but when it starts to run low on fuel it makes its way into the lines and into the carburetor.

Where did replacing the balancer/damper happen in the sequence of all of this? Was this done before it sat and was running well? Or was this done recently and coincides with the problems you're having?

Like the others mentioned, going by feel and eyeballing valves closed leaves a pretty wide margin for error in locating true TDC. If I wasn't sure where TDC was I would put down the timing light and use a "give it what it needs" approach. You don't mention hearing detonation (the rest of what you described sounds more like retarded timing too) so get the distributor hold down secure enough that you can turn it by hand but it will stay in place. Start turning the distributor counterclockwise a little at a time and drive it in the yard or close by on the road. Don't worry if you're turning it a bit. It could be pretty far off. You'll hear detonation and it will start pretty hard if you're getting too much timing into it.

Too far in either direction on the timing (retarded or advanced) it can set the stage for really hot conditions. The kind of heat that softens the electrode on the spark plug where it can be bent closed. Advanced too much and you're causing a bad burn in the chamber, retarded too much and your burn is happening on the way out the exhaust valve.

I'm just throwing out ideas here while brainstorming a bit. I'm a shade tree mechanic and in no way a professional.

 

Stalls when engine is hot, cold or both?

Did you have the distributor out and then put it back in, if so please describe how you maintained alignment. Roughly when installed the rotor should point to the number one terminal which should be aimed at the number one cylinder. At the same time the vacuum advance can if so equipped should point at the number 6 cylinder. The distributor being installed off a gear tooth will make the damper timing mark appear if you assume the configuration as described above. The Chevy distributor always rotates as it disengages the cam’s driving gear which also rotates the oil pump drive shaft so the distributor upon installation never engages the gear and pump drive correctly. One of the easiest way around this is to mark alignments on the distributor and intake with the rotor and cap positioned at number one fitting. At reinstall align all of these positions and set the distributor in, it will be sitting slightly proud (above) the intake. Now rotate the crankshaft in the clockwise direction by wrench, when the distributor drops on its intake seat the engine is timed, button it up.

Finding true TDC is not “essentially” doing the process, it is doing the process. A lot of degrees pass with nearly invisible motion to the piston as the crank swings over the top or through the bottom of its travels. The process of positively stopping in one direction and marling that then reversing rotation and marking that stop then marking the half way point is true TDC. Any other process leaves space for error.

Yes GM used different tab and damper combinations, most part sellers are clueless to this. We now have two generations or more of parts clerks that have no knowledge of parts beyond the computer data base if that is incomplete they have no knowledge beyond that. Consider that computer data bases inherently no nothing they are only as good as the initial information put into them by a person usually someone young, inexperienced and paid minimum wage. Combine that with it’s been a generation and some years since a last Gen 1, SBC was bolted into a chassis by GM.

At the carb yo need to be sure the choke comes off. It sounds like something is happening as the transition to the secondaries is occurring. Check the secondary air-valve for free movement. Comment to us what it feels like in the transition to where does the engine feel like it’s going to or does backfire or does it rather shudder and fall on its face. Trying to discern if it’s it’s going lean or rich. Lean often sneezes back through the air horn, rich tends to lay down on power then may come back. Either will get better by backing out of the throttle some distance.

All of this engine sounds like it’s old and unused, this does not preserve parts especially carburetors and ignition. If the carb had been run then left to dry out it is dirty and gummy inside. Electrical components are made of dissimilar elements they corrode and rot especially in damp environments.

Yes the AFB Performer and its cousin the AVS Thunder don’t like being heated, thus the need for an insulator between them and the intake, they dont deal with fuel pressures beyond 6 psi at all but unless your using a high pressure racing style mechanical or an electric fuel pump this should see pressures high enough to warrant a regulator.


Bogie

 

I have a one inch spacer between the carb and fuel pressure is regulated to 4.5 psi. The motor tried to stall regardless of temperature. It hass all brand new ignition components and when I replaced the distributor I marked the direction the rotor was facing when it was removed and replicated that and it slid right onto the oil pump drive. I've re checked that twice and had someone else check that just to make sure I didn't screw that up either. When accelerating it stutters with a loss of power randomly throughout the primaries. Once the secondaries start to open up it bucks a little until they fully open then all throughout the secondary range it's fine no issues.

 

What intake.....I suspect the carb doesn't like the spacer.

 

That's the only thing that's different actually. It's a weiand dual plane I don't know exactly what model it is though.

 

Two kits, eh!
Have you set the float level and float drop correctly On each float.
Both are critical settings on an eddy carb.

 

Yes sir I have both times. I was trying to do everything I can to the best I can with what I got and still seemed to not work in my favor.

 

It sounds like timing to me, you need 32 degrees of advance at 3000 RPM without the vacuum advanced plugged in. At idle you should have around 12 degrees advance with vacuum advance port plugged off to start. rev it to 3000 rpm + until the advance is maxed out, it should be maxed at 3000 RPM, if not change springs until it is. You want 32 degrees advance at 3k, that is more important than the idle number. Plug the vacuum advance into the ported vacuum on the carb. After the timing is working correctly, then adjust the carb. A lot of carb issues are really just timing issues.

You can get HEI springs for about $7, One medium or stock spring and one lite spring is a good guess to start off.

 

I run my AVS one jet size up, secondary and primary on a 350 with an LT4HOT cam and about 11:1 compression using aluminum head’s and a GMPP dual plane intake. It’s very smooth through the secondary transition it’s not anything that is felt it just keeps pulling as the revs go up.

Bogie

 

I'll mess with timing some more and see what that does I guess.

 

no debris but soot from running poorly im assuming, but the soot was wet like it was full of gas. The tank is perfect and there's a new filter on it. I replaced the balancer about a month after I put it in the truck. And as far as timing goes thats usually how I did it. It was at tdc +- a degree or so and I do it by ear and driving it around. I'll keep trying to just fine tune it and see where it goes. Im just hoping the carb isnt the issue I dont really feel like putting the money out for a new one.

 

Just took the truck out to go to the store and decided to see how it ran when driven hard. bogged heavy when it got to 5k then fixed itself right after I shifted. Then further down the road it bogged again randomly then drove fine bout a 1/4 mile then completely died and hard a really hard time restarting. This is the fourth time so far this has happened. and I'm not sure what's causing it. Also I decided to see if all cylinders were firing because last time this happened a spark plug closed up and all cylinders are running at exhaust temp of about 550 degrees except cylinder 6 which is 700. I don't know what that indicates maybe its lean? I'm not sure.

 

I may have missed something but I don't recall any one explaining the bent electrode on the spark plugs just asking

 

Im not sure how to quote it but 1979 malibu second to last paragraph mentioned a possible cause in his most recent post.

 

Where was this intake manifold swap done in relation to the onset of this problem?

Did the problem you're having begin after you put a different intake manifold on?

Was this what started the whole process of putting a mark on the balancer?