Ignition problems

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swinger 74

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I am having possible ignition problems. I was wondering if anyone has had problems with reman stock distributors? My distributor, cap, rotor, plugs, and wires are all new. I am having problems with trying to get to run smooth at idle. Im thinking that something in the ignition system is causing this and can figure out what and why. Anyone have any ideas? Im thinking of swapping out to a better distributor and coil. Can the wrong coil also cause rough idle problems?
 
NO, I wouldn't be looking at the ignition just yet.

Time for a compression test.Or prepare to chase your tail.

Here is a partial list;
compression/cam-lobes/lifters/burned valves,
plug-gaps,late timing/too-early timing,
mixture screws/bleeds/AFRs,fuel and fuel-level,T-port sync, and
of course engine vacuum loss; booster/PCV/gaskets,vacuum pots,etc.
 
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Took the distributor out to have a look at it and found that it was just a big POS lol. The remanufacturing job done on it was crap so i decided to return it along with the cap and rotor and used the money from the refund and bought a brand new distributor with a cap and rotor along with a new coil to make sure i had the right coil. Anyways i put on the new distributor and fired it up. It actually ran a little better but not much so i decided to check for vacuum leaks and played with the carb mixture screws. I pluged off all the vacuum ports and found out that when i had all the vacuum ports plugged off i had one left. The PCV valve. I unhooked it and plugged it off an bam the engine ran ******* great after a couple adjustments to the carb and timing. Now im guessing the cheap chrome autozone pcv is to weak because it pulls to much vacuum at idle causing a lean rough idle vacuum leak basically. Im wondering what part# pcv valve i need to get to fix the idle problem when its hooked up
 
So no compression test yet?

Well how about an idle vacuum test then.

PCVs work the other way. In your case the calibration spring may be stronger than your vacuum is able to overcome. This suggests that your idle vacuum is low, not high. But if it rattles when you shake it then that suggests that the calibration spring is not too strong, again suggesting that the idle vacuum is weak. Cranking up the Idle timing and having the engine run better also suggests the idle vacuum is weak.
If the vacuum is indeed low, this will require cranking in the curb idle screw, in an effort to get the rpm up.This,of course, will upset the T-port sync and will require compensation from the idle circuit.
Cranking in some timing, might allow the closing of the butterflies,thus restoring the sync.
Now, it is entirely possible to find no vacuum leak.But if just one intake valve is not closing properly, the carb will read the compression dump into the intake,exactly as if the butterflies were open much further than they really are;ie a vacuum leak. The PCV needs a factory vacuum signal to work at idle.
Now it may be that yours is faulty,I cannot say. But I suspect not.
This is called chasing your tail.
 
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AJ/FormS said:
So no compression test yet?

Well how about an idle vacuum test then.
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AJ/FormS said:
So no compression test yet?

Well how about an idle vacuum test then.

PCVs work the other way. In your case the calibration spring may be stronger than your vacuum is able to overcome. This suggests that your idle vacuum is low, not high. But if it rattles when you shake it then that suggests that the calibration spring is not too strong, again suggesting that the idle vacuum is weak. Cranking up the Idle timing and having the engine run better also suggests the idle vacuum is weak.
This is called chasing your tail.
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Vacuum at idle is
AJ/FormS said:
So no compression test yet?

Well how about an idle vacuum test then.

PCVs work the other way. In your case the calibration spring may be stronger than your vacuum is able to overcome. This suggests that your idle vacuum is low, not high. But if it rattles when you shake it then that suggests that the calibration spring is not too strong, again suggesting that the idle vacuum is weak. Cranking up the Idle timing and having the engine run better also suggests the idle vacuum is weak.
This is called chasing your tail.
Click to expand...
Engine idles at about 20 HG and timing set at 8 degrees BTDC. Runs real good with out pcv hooked up. With pcv hooked up at idle it runs like **** and you can hear the pcv rattling like crazy and engine runs like it has a major vacuum leak until rpms get higher
 
Ok now we are getting somewhere. A nice steady 20, in a stock teener say, is very good.
So then pop the pcv out of the cover,leaving it hooked up to the intake. Find a small screwdriver and push the little valve in there all the way in. This is the where that guy should be running at idle;minimum flow. If the idle smooths out and becomes normal than yes I would suspect that valve. But I tell you what; the rattling puzzles me. But for $5 bucks or so,you can try another.
If no change, then I would skip the compression test and go straight to a LeakDown test to prove the valves are closing.See fresh rebuild can mean different things to different people. To me it just introduces all kinds of variables.And valves not closing is one of them.
And we still don't know what engine we are working on.
 
AJ/FormS said:
Ok now we are getting somewhere. A nice steady 20, in a stock teener say, is very good.
So then pop the pcv out of the cover,leaving it hooked up to the intake. Find a small screwdriver and push the little valve in there all the way in. This is the where that guy should be running at idle;minimum flow. If the idle smooths out and becomes normal than yes I would suspect that valve. But I tell you what; the rattling puzzles me. But for $5 bucks or so,you can try another.
If no change, then I would skip the compression test and go straight to a LeakDown test to prove the valves are closing.See fresh rebuild can mean different things to different people. To me it just introduces all kinds of variables.And valves not closing is one of them.
And we still don't know what engine we are working on.
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Im working on a Small Block 360. The rattling im talking about it the pcv valve going crazy at idle from vacuum sucking through im guessing. I was just thinking of going a and buying a stock replacement valve from the parts store and ditching the cheap chrome one.
 
At this point that seems as good an idea as any. Cuz at 20 inches there is no way it should be rattling; the little valve inside should be sucked up and jammed into the minimum draw-thru orifice and be dead quiet.
If yout PCV and brake booster are both drawing from the same intake runner,this is a no-no. The Pcv should be drawing off the base of the carb from the factory provided port. The booster should be drawing from an intake runner;and make sure the engine is not sucking atmospheric air right through it.
 
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AJ/FormS said:
At this point that seems as good an idea as any. Cuz at 20 inches there is no way it should be rattling; the little valve inside should be sucked up and jammed into the minimum draw-thru orifice and be dead quiet.
If yout PCV and brake booster are both drawing from the same intake runner,this is a no-no. The Pcv should be drawing off the base of the carb from the factory provided port. The booster should be drawing from an intake runner;and make sure the engine is not sucking atmospheric air right through it.
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The cheap chrome pcv was definitely the problem and defective. I took it off and examined is and found it had a crack half way around it on the bottom side causing it not to work properly and cause a huge vacuum leak. So i replaced it with a factory style one and all is good with that problem. Now i encountered another problem that i had before. Damn remanufactured carburator. POS. This is the second one and is doing the same thing as the last one. Flooding out and dumping fuel after shut off. Damn national carburators
 
swinger 74 said:
The cheap chrome pcv was definitely the problem and defective. I took it off and examined is and found it had a crack half way around it on the bottom side causing it not to work properly and cause a huge vacuum leak. So i replaced it with a factory style one and all is good with that problem. Now i encountered another problem that i had before. Damn remanufactured carburator. POS. This is the second one and is doing the same thing as the last one. Flooding out and dumping fuel after shut off. Damn national carburators
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Put a good needle and seat in it, and make sure your float is doing it's thing and as long as your fuel pressure isn't too high you should be golden.
You should also make sure garbage is coming through the fuel line and sticking the needle or holding it open.

I get it that it's the second one, but this is a simple issue to solve.
 
Hey your making progress! Lots of good advice here. People have spent a lot more $$ on new heads that require work right OOTB (out of the box). So 2 carbs in a row is entirely possible.
Hopefully its a cheap fix as well
 
Warranty will void if i take it apart. The company marks everthing so the know if its been tampered with. Trying to get cash refund. Thinking of aftermatket intake and edelbrock carb.
 
AJ/FormS said:
Gudonya
I learned something too, so thanx. I'm assumung the crack was between the intake and the valve;that is to say on the manifold side?
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Crack was on the bottom side of chrome push on pcv valve causinig it to pull manifold vacuum through it. Thats why it was rattling like crazy.
 
20161101_161022.jpg
 
4spdragtop said:
Is that pcv or strictly a breather?
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That looks suspiciously like an aftermarket combination of both?
Most breathers I have seen have a bigger nipple that goes in the V cover grommet and is flared a bit on the end to keep it from just poping out.

If it's just a breather the engine wouldn't have changed how it ran by removing it either. (cracked or not)
 
Well the rattle kinda points to something being inside there!
But I have never seen a thing like that. The Pcv and the Breather need to be on opposite covers else what's the point? And the breather is best when routed back to the airbox, so that at WOT, the blowby has someplace to go rather than all over your nice clean engine;if nothing else.
 
AJ/FormS said:
Well the rattle kinda points to something being inside there!
But I have never seen a thing like that. The Pcv and the Breather need to be on opposite covers else what's the point? And the breather is best when routed back to the airbox, so that at WOT, the blowby has someplace to go rather than all over your nice clean engine;if nothing else.
Click to expand...

It may have a regular breather on the other cover as far as we know, and that could be a PCV disguised as chrome breather.

Maybe?
 
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