OK here is what happened. ill tell you the whole story. Steve i would really like your input.

OK about a month ago i was just driving my truck to work and it was running fine. i came up to a stop sign and it idled down really low and was barley even running. it sounded like it wasn't getting enough fuel. i had a really bad problem with rust getting in my carb so i thought it was something to do with that so i took apart my carb and cleaned everything and put it back on and it still would not run very good(it would miss every so often and shake my truck) so i replaced my plugs and it made it run a little better but still not at all like it should. so i did a compression test on it here are my readings. #1.) 117 #2.)45 #3.)90 5.)120 6.)115 7.)115 8.)110. so i talked to some people and they asked if i had checked my valve lash adjustments cause they said there was a slim chance that could be the problem and i said no so thats were i am.

oh and i know its E I I E E I I E but i dont think my fireing order is messed up but ill double check it

ben

 

we use to adjust our big block chevs. with the engine running. pull the valve cover back off the rocker arm till it rattles then tighten just till the rattle stops then 1/4 to 3/4 turn more, continue thru the valve train. these were hydralic flat tappet lifters and compensated for the dish wear in the rockers. Would not try it till knew for sure it wouldn't damage your motor, especially if solid or rollers.

 

Ben-

Some comments and questions.

The compression on the 2 center cylinders is pretty low. When adjacent cylinders have low compression like that it CAN mean a bad head gasket, leaking compression between the two. Even so, with the compression real low like that, you should be able to get the engine to run without 'missing".

First- Am I correct in assuming this is a fairly stock 292 with a 2 barrel carb?

Was the carb dirty inside? Did you soak the carb in cleaner and spray carb cleaner through each orifice? You might consider an inline filter between the fuel pump and carb if you don't have one already.

How do the plugs look? Are they all fairly uniform in color from plug to plug or are some of them oily?

What kind of ignition are you using? Stock points and condenser? Have you checked the timing? It should be close to 10 degrees BTDC at idle, vacuum advance disconnected. Are the plug wires in decent shape?

Is the miss intermittent? At idle? How does it run under load eg pulling a grade?

Speaking of vacuum advance, check to make sure the vacuum canister on the distributor is not leaking. If the diaphragm is leaking it would cause a vacuum leak. Also- is the vacuum advance connected to a manifold source of vacuum? If it is and the canister is leaky, then you would have a vacuum leak and later timing which together could easily have caused the original sudden appearance of a low idle.

Steve

 

yes its all stock no the carb wasnt all that dirty it had been rebuil about 2 months befour this happened and the fuel filter, plugs, wires, and points are all new. a couple of the plus had some oil on them. i havent checked the timing yet. it misses intermittent at idle but not when im accelerating. and its vacuum advance is not connected to a manifold sorce but ill check it at the distributer. i relly think im not adjusting them correctly and ill keep adjusting them till i get it but i just wanted to know what else could be causing this.

 

ok dont know if this means any thing but i readjusted them and as soon as i started it ran fine for about 2 seconds and than started ideling bad again.

 

were should the rotor be at 0 btdc

 

Ben-

At Top Dead Center (TDC) for cylinder #1, the rotor should point at the tower on the distributor cap that you are using for #1 plug wire. It should line up pretty closely. If it ran well for a couple of seconds, then the firing order is right and the valves are probably adjusted pretty close.

You may have a carb problem after all....

Steve

 

if it doesnt line up very close that would mean the timings off right. i still havent checked it.

 

wooooo this is my hudreth post

 

You have gone through valve lash adjustment many times. Check timing, and if reasonably good, the problem regarding low compression pressure gets bumped to the top of the list.

 

I had a problem like that, and it turned out to be a loose timming chain, I saw it with a timming light and just let it idle and watching the timming mark and every time it missed I watched the timming jump around. I then removed the fuel pump reached in their with my finger and found the chain very loose, the new chain wasn't that tight eather but no more missing at idle. It can be any number of things that can do this, so make sure before you pull the motor apart.

 

Yeah but I keep coming back to the "it was running fine and then suddenly it wasn't" scenario. What causes that? Well to me it indicates either something not right in the ignition department or the fuel delivery department.

He could check his timing chain by turning the crank one way a little and then while observing the distributor rotor, turn the crank the other direction. More that about 5-10 degrees of movement of the crank before the rotor turns again indicates a worn chain.

But really I think a low compression truck motor like he has is pretty forgiving when it comes to a worn engine. Clearly, it's probably pretty tired, but a good ignition and a clean carb should allow it to "run well enough".

Ben- was the oily plug from the low cylinder? It is so oily that it isn't firing? If the ground strap and center electrode are oily, clean the plugs and see how it runs.... If it cures it, you may want to run a hotter plug to fire through the oil, but that's really only a band-aid.

Steve

 

ok ahhhhhhhhhhhhhhhhhhhhhhhhhhh i hate this. ok now i got a question if my rockers are pitted that would make my gap bigger than what im actually setting them to right. and if there to loose would it make it pop

 

ok i just got done looking at my rockers and there pitted pretty bad. so i titend them up alittle bit and it seemed to run better. it seems like now that its not poping out of every cylinder. does this sound like a possibility.

 

Ben-
Refer to the 6th post of the first page of this thread. In short, for your pitted, standard ratio rocker arms, try closing the adjustment until you get zero lash- all the slack taken out but no more- and then using your wrench handle as a clock minute hand, turn the adjustment screw counterclockwise for 16 minutes of rotation. That should get you in the ball park. Eventually you should have the rocker assemblies re-surfaced, re-bushed etc.

Steve