1978 New Yorker Brougham 440; misfire above idle

[rsbolin]

All,

After having spent almost $1,500 between a carb rebuild, new plugs, new ignition coil, new wires, new ballast, new voltage regulator, new gas tank, it was running wonderfully. Then this week, anything above idle and she misses like you cannot believe. I have checked plugs, plug wires, ignition coil, voltage regulator, ballast, vacuum hoses. Have changed nothing since I replaced the ballast and the voltage regulator. She has been running nice, except for the carb bog that I still experiencing.

Need some guidance here I what I should be checking. I know there can be similar symptoms between fuel and electrical, but I not sure where to start. Idles nicely.

Ron

 

[Mr C]

I presume it is no longer lean burn and that it has been converted...please confirm.

 

[Davea Lux]

Bog and misfire at higher RPMS are classic symptoms of a stuck EGR valve. Try disconnecting and plugging the hose to it to see if the miss goes away. EGR valves are famous for getting carboned up especially running the moonshine blend fuels available today. Usually better to install a blocking plate to disable the EGR.

Dave

 

[rsbolin]

I presume it is no longer lean burn and that it has been converted...please confirm.

Unfortunately, the Lean Burn lives on this one. That is one of the changes that I want to make.

 

[rsbolin]

Bog and misfire at higher RPMS are classic symptoms of a stuck EGR valve. Try disconnecting and plugging the hose to it to see if the miss goes away. EGR valves are famous for getting carboned up especially running the moonshine blend fuels available today. Usually better to install a blocking plate to disable the EGR.

Dave

I checked the EGR valve on Friday. It rattles easily.

How do I do the blocking plate to disable the EGR?

Ron

 

[CBODY67]

The plate was on 400s and 440s which went into pickup trucks with over 6001lbs GVW rating from the factory. Might be in Edelbrock or Holley catalogs? Needs a gasket which will resist exhaust heat, too.

An alternative would be to remove the valve and clean the part where the valve pintle seats into the intake manifold. Then just don't put vac to the valve via something in the vac supply line to it, incognito. Of course, these things would be for testing purposes, with the "test" being for an undermined period of time, fwiw. Once the valve is removed, if it is reinstalled, a new gasket will be needed.

CBODY67

 

[Davea Lux]

I checked the EGR valve on Friday. It rattles easily.

How do I do the blocking plate to disable the EGR?

Ron

You will need to find one off of a HD pickup motor or you can make one. We used to take a #303 soup can lid and use the EGR gasket for a template to cut it down. The EGR valve has two ports, on some the ports were flush with the manifold, those you just use two gaskets to make a sandwich out of the cut down can lid. Some had a port that stuck out about 1/4". Drill a hole in the can lid to accommodate that port and and install.

Dave

 

[Maindrian Pace]

Kinda sounds distributor related, or Lean Burn as it's all tied in to it. I'd put a timing light on it to see what it's doing at the higher RPMs, and to see total advance with a dial-back timing light.

 

[commando1]

TS-101, Lesson 1.
You use both the terms bog and misfire.
Two totally different issues, each with an infinite causes.
To reduce the troubleshooting to half of infinity, try and describe it better so we know what we're dealing with after you changed the ballast resistor

 

[rsbolin]

TS-101, Lesson 1.
You use both the terms bog and misfire.
Two totally different issues, each with an infinite causes.
To reduce the troubleshooting to half of infinity, try and describe it better so we know what we're dealing with after you changed the ballast resistor

Alright, I have another post asking about a bog upon acceleration. This post I want to primarily focus on what could cause a "misfire", almost a bap, bap, bap sound for anything above idle.

 

[commando1]

Alright, I have another post asking about a bog upon acceleration. This post I want to primarily focus on what could cause a "misfire", almost a bap, bap, bap sound for anything above idle.

Is it an even bap, bap, bap, or does the bap, bap, bap, change according to the engine speed?

 

[rsbolin]

Is it an even bap, bap, bap, or does the bap, bap, bap, change according to the engine speed?

I will see if I can get a video post.

At idle she sounds wonderful. As throttle is applied she bap's evenly.

I checked the EGR valve again this afternoon and noted no suction. So I tapped it several times and I could hear the suction. I will check again in the morning.

 

[Just Carbs]

Timing light on the windshield and drive.

 

[Triple Pickle]

I will see if I can get a video post.

At idle she sounds wonderful. As throttle is applied she bap's evenly.

I checked the EGR valve again this afternoon and noted no suction. So I tapped it several times and I could hear the suction. I will check again in the morning.

I get the feeling you are confusing the PCV valve for the EGR valve. Are you sure we are all on the same page?

 

[rsbolin]

Is it an even bap, bap, bap, or does the bap, bap, bap, change according to the engine speed?

Triple Pickle, that is a big oops, and you are correct. I tapped on the PCV, not the EGR. I will check the EGR valve some time today.

Ron

 

[Triple Pickle]

Triple Pickle, that is a big oops, and you are correct. I tapped on the PCV, not the EGR. I will check the EGR valve some time today.

Ron

That’s what I was thinking! No shame in that. Hopefully you’ll find the problem in the EGR valve. As suggested, I’d plan on blocking it off for sure. They are troublesome and not necessary at best unless you are required to have them where you live.
They only work well when all the other emission system are in place and functioning correctly.

 

[rsbolin]

That’s what I was thinking! No shame in that. Hopefully you’ll find the problem in the EGR valve. As suggested, I’d plan on blocking it off for sure. They are troublesome and not necessary at best unless you are required to have them where you live.
They only work well when all the other emission system are in place and functioning correctly.

Thanks again, Triple Pickle. I just did a search on Rock Auto and found nothing. Gaskets, etc., but no EGR valve. I will contact Murray Park some time today to see if he may have one on hand.

South Carolina does not require emissions testing.

Ron

 

[Just Carbs]

I've not had any negative running effects caused by a properly working EGR valve.
My experience has been that they reduce pre-ignition, and my catalytic converters like them.

 

[Fred A]

Thanks again, Triple Pickle. I just did a search on Rock Auto and found nothing. Gaskets, etc., but no EGR valve. I will contact Murray Park some time today to see if he may have one on hand.

South Carolina does not require emissions testing.

Ron

Hello, did you fix problem? How

 

[rsbolin]

I presume it is no longer lean burn and that it has been converted...please confirm.

MR. C>,

It is still lean burn.

The carb has been removed and sent to Charlie Constanzo in Texas to be rebuilt. He has found so many things that were wrong with it. It is in good hands with Charlie and I expect that when I get back, and installed, this ole girl will purr like a kitten.

Ron