Yes the breather can get to atmosphere, or vented to the aircleaner lid depending if it had the Clean Air Package.
You could throw the breather in the garbage and the engine wouldn't care.
Other than sucking dust in.
Pig rich mixture at idle 2 x 4 Gen 2 hemi
- Thread starter Beekeeper
- Start date
You could throw the breather in the garbage and the engine wouldn't care.
Other than sucking dust in.
Ok i’ll plug the ports until I get the idle issues sorted thanks. So my hose connections are ok I do have a question though as you can see in the pic i posted of a 69’ hemi fresh air cleaner base. the vent hose does not go through the filter element
but can see how it could pull a small amount of vacuum from where it’s located. Also if I
tune the idle with the PCV ports plugged what happens when i introduced the controlled vacuum leak created by hooking up the PCV system?
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Thought PCV were closed under high vacuum conditions like at idle?
That would make sense but it does look as though both front and back ports are below the throttle plates.
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The pcv flow volume is very low at idle. It won't bother anything. The crankcase has to be vented to atmosphere or the system would never flow. The idea of the filter on the valve cooler inlet is to keep contaminants from entering the crankcase. Once blowby exceeds the sprung check valve the pcv flow parh will open.
Doug
Doug
The crankcase is not a closed system. Air is circulated through it to remove the by-products of normal blow by from the rings in the crankcase, and by engine vacuum and PVC valve metering, introduce it back into the intake. If you built a closed crankcase engine you would have all sorts of problems with oil leaks, blown out gaskets, and oil completely fouling in very few miles.
Hemirunner
Well-Known Member
I understand. I’m not saying the crankcase is closed, I’m saying the system is closed when complete. The hose to the air cleaner will have a light vacuum on it at idle so the volume through isn’t so high. Adding the vacuum from a second carb will only complicate tuning. There’s no need for it but if he’s gonna use it, use it with a complete system. Trying to trouble shoot his issues with the PCV system in place is silly. Put some vacuum caps on the carbs, leave the breather open and diagnose all the other issues.
I have plugged the ports on the carbs as I will follow the recommendations you guys have given me. I really do appreciate all the help I have gotten so far I plan to fire it up again tomorrow and see how it does again.
I agree with plugging them remove a variable. The Ol' saying keep it simple......
Ok I fired it up again a few minutes ago.
Here’s what i’ve done:
Plugged PVC port on both carbs
Started with Idle mixture screws 1 turn out
Installed a fuel return with a ball valve
started with the curb idle screws 1 turn in after contact.
put in NGK BP5ES plugs gapped at .032
Installed a new ignition coil
Fired it off and went in half a turn on curb idle screws to get an idle and checked timing it’s at 18 degrees and moves around a little about a degree on each side of 18. adjusted fuel return to get just under 5 psi still smells rich at exhaust so closed all mixture screws and it shuts down. opened mixture screws half a turn and it fired right up. tried adding more timing but seems to run best at 18 degrees it’s very responsive when given throttle.
Went in a 1/4 turn with mixture screws seem to improve the rich smell somewhat.
It idles at 7-8” of vacuum that seems low
to me but not sure and it wants to die after it idles for a couple minutes if i blip the throttle a couple times idle recovers.
I know plugs will be kinda hard to read after
10 minutes of idle and throttle hits but i’ll post pics of the plugs in the next reply.
Here’s what i’ve done:
Plugged PVC port on both carbs
Started with Idle mixture screws 1 turn out
Installed a fuel return with a ball valve
started with the curb idle screws 1 turn in after contact.
put in NGK BP5ES plugs gapped at .032
Installed a new ignition coil
Fired it off and went in half a turn on curb idle screws to get an idle and checked timing it’s at 18 degrees and moves around a little about a degree on each side of 18. adjusted fuel return to get just under 5 psi still smells rich at exhaust so closed all mixture screws and it shuts down. opened mixture screws half a turn and it fired right up. tried adding more timing but seems to run best at 18 degrees it’s very responsive when given throttle.
Went in a 1/4 turn with mixture screws seem to improve the rich smell somewhat.
It idles at 7-8” of vacuum that seems low
to me but not sure and it wants to die after it idles for a couple minutes if i blip the throttle a couple times idle recovers.
I know plugs will be kinda hard to read after
10 minutes of idle and throttle hits but i’ll post pics of the plugs in the next reply.
Plugs look much better the AR53 were black
pics in order of 1-3-5-7 and 2-4-6-8
pics in order of 1-3-5-7 and 2-4-6-8
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Try to lightly choke the carbs with a rag to see if the RPM'S increase. Still sounds like a possible vacuum leak.
What size cam do you have? A bit apples to oranges but for comparison my 66 427 Corvette has an old 256/266 @.050, .579/.600 lift mech flat tappet cam and pulls 8” vacuum max at 950 rpm idle. If you aren’t running something close to that in duration and lift, then you should be seeing a little higher vacuum.
The timing moving around a little might be some excess up/down play in the distributor shaft that could be shimmed out.
The timing moving around a little might be some excess up/down play in the distributor shaft that could be shimmed out.
Rag placed lightly over both carbs kills it
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cam card
Hemirunner
Well-Known Member
I’ve got 10 degrees of cranking advance and 35 degrees at idle pulling 14” manifold vacuum idling at 1000rpm. Does your vacuum advance work? More timing will definitely keep those plugs clean and help lean that mixture out.
Yea the vacuum advance does work I’m guessing connect to ported vacuum?
Hemirunner
Well-Known Member
Manifold vacuum. That way is has a signal at idle and drops out WOT
Yea that makes sense thanks I’ll give that a try
That would be interesting. Then the timing can go up and down with vacuum.
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