PCV valve? valve lash? i need some help - 460 Ford Forum
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post #1 of 6 (permalink) Old 01-30-2016, 01:16 PM Thread Starter
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PCV valve? valve lash? i need some help

hey guys, i just got my exhaust finished on my car and now the engine is running. i had it out over the winter and did a full rebuild on it but...

when the car is at an idle it makes a popping noise out of the passenger side exhaust. its not all the time, its very random almost sounds like a misfire or something. it doesn't get worse nor better as the car heats up. but it will go away for 30-45 seconds at a time and then come back. the only thing i changed over the winter besides a full rebuild was the carb I'm using a eddy 1407 750cfm carb. the carb is sitting on top of the manifold with no spacer plate. i had removed the PCV valve and stock plate that came on the car cause i was told i didn't need it. every vacuum port on the carb is plugged with those little rubber condom looking things. my vacuum advance on the dizzy gets vacuum from the port on the intake manifold.

all my plugs and wires are new and are firing. my firing order is 100% correct and i set all the valve lash the same when i built the motor on the stand. I've performed a compression test and they are all in the 140-147 range.

mods to the motor
D0VE block and heads
- eddy 750 carb
- eddy performer intake
- summit racing 3500 cam 282/292 486/512
- summit racing lifters
- comp cams push rods
- mild ported heads intake bowl blend and exhaust thermal hump removed
- stock ex manifold 2.25 dual exhaust with flowmaster hush power mufflers, H pipe.
- MSD 6al2 box
- MSD coil
- stock dizzy with pretronix electric conversion.

Can someone help me out? is my carb set up without the PCV valve causing this? wrong valve lash doing something weird?

thanks is advance.
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post #2 of 6 (permalink) Old 01-30-2016, 01:18 PM Thread Starter
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also the motor will rev up and down normally without any hesitations, and actually runs a bit better i find if you rev the piss out of it haha. to me it sounds like carb or ignition problem. but i have no idea at this point.
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post #3 of 6 (permalink) Old 01-30-2016, 01:46 PM Thread Starter
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i think i posted this in the wrong section.... sorry, if someone could move it i would appreciate it.
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post #4 of 6 (permalink) Old 01-31-2016, 07:08 AM
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Quote:
Originally Posted by LoweredLincoln View Post
hey guys, i just got my exhaust finished on my car and now the engine is running. i had it out over the winter and did a full rebuild on it but...

when the car is at an idle it makes a popping noise out of the passenger side exhaust. its not all the time, its very random almost sounds like a misfire or something. it doesn't get worse nor better as the car heats up. but it will go away for 30-45 seconds at a time and then come back. the only thing i changed over the winter besides a full rebuild was the carb I'm using a eddy 1407 750cfm carb. the carb is sitting on top of the manifold with no spacer plate. i had removed the PCV valve and stock plate that came on the car cause i was told i didn't need it. every vacuum port on the carb is plugged with those little rubber condom looking things. my vacuum advance on the dizzy gets vacuum from the port on the intake manifold.

all my plugs and wires are new and are firing. my firing order is 100% correct and i set all the valve lash the same when i built the motor on the stand. I've performed a compression test and they are all in the 140-147 range.

mods to the motor
D0VE block and heads
- eddy 750 carb
- eddy performer intake
- summit racing 3500 cam 282/292 486/512
- summit racing lifters
- comp cams push rods
- mild ported heads intake bowl blend and exhaust thermal hump removed
- stock ex manifold 2.25 dual exhaust with flowmaster hush power mufflers, H pipe.
- MSD 6al2 box
- MSD coil
- stock dizzy with pretronix electric conversion.

Can someone help me out? is my carb set up without the PCV valve causing this? wrong valve lash doing something weird?

thanks is advance.
I don't think the lack of a pcv valve is causing our issue but IMO you should be using one.

First you need to be sure there are no vacuum leaks, the plugs are not fouled and are gaped correctly, and all the other ignition components are in good shape.

You say you have the vacuum advance connected to full manifold vacuum. Do you know what your initial and total timing readings are?

If the distributor was not set up with the intention of using full manifold vacuum you may have too much timing which could cause the issue.

A lean idle setting will also cause misfires.

1973 Mustang Convertible
460 D0VE-C Heads w/CJ size valves, Lunati voodoo 227/233 cam, Edelbrock performer rpm manifold, FPA headers, Holley 950 HP carb, C6 w/2500 stall converter, 3.50 trac lock
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post #5 of 6 (permalink) Old 01-31-2016, 01:51 PM Thread Starter
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ill search for vacuum leaks, clean the plugs and inspect everything again to make sure. i set my initial timing to 10*, where should i connect the vacuum advance line? onto the carb?
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post #6 of 6 (permalink) Old 01-31-2016, 03:59 PM Thread Starter
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Okay so timing is at 12* initial, moved vacuum advance to carb (ported hole), check all wires and installed new plugs, changed coil, put back on PCV.

I used my timing light to check all wires where firing correctly. They all seem to be on the same beat. If I rev it up to 5k and let it come down it will idle fine for 20-30 seconds then go back to the sound. If I throw a rag over my exhaust and choke it that way it will run fine for a little bit. I can't upload the video but will email or text someone the video so they can hear what it's doing.

I'm stumped.
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