Rough Idle

Karoshi · Post by **Karoshi** » Mon Feb 21, 2005 6:54 pm

I'm experiencing rough idle and hunting. This is particularly bad from a cols start. I've checked all the obvious...... points, plugs timing etc and wonder if this is an air leak, vacuum or maybe carb problem. Is there a known fault?

Karoshi

armydriver · Post by **armydriver** » Mon Feb 28, 2005 11:42 am

I was experiencing the same problem and this weekend solved the problem. I replaced all of the spark plugs with Champion J8 Copper Plus plugs and replaced the spark plug wires with NAPA pt. no. 700173 metallic wires with brass ends. I was stunned. She fired on all 6 cylinders and idled like a new engine.
My carburator has been totally re-built and I replaced all of the fuel lines with new 3/8 " copper tubing and also installed a new fuel pump.
Good luck.

Karoshi · Post by **Karoshi** » Mon Feb 28, 2005 2:29 pm

Thats great to hear, but in my days of racing, (oh! so long ago) we would change Champion plugs for ANYTHING else available to cure misfire problems!

Don't hold them in high regard. To each his own.

Did you do your own carb rebuild?

Karoshi

bobc · Post by **bobc** » Mon Feb 28, 2005 9:41 pm

I had some friend come to me with a problem,it was on a fork lift,the engine was freshly rebuilt ,new plugs, wires,points ,condenser,rotor,cap and the carb was rebuilt,It would only run with the choke mostly closed,then it didn't have much power,the thing ran great for two days after the major overhaul,then started missing,First I check for spark and gas all good,timing was right on,good even compression,I spent two days messing with it,finally I went to my truck and got a set of autolite plugs,took out the new champs and it ran fine,great power no missing,they replaced the champions with a new set and they only lasted two days,for some reason the thing will not run with the champion plugs. We even tried changing the heat range,maybe they raised the compression,but it still didn't help.

Bill_Wolf · Post by **Bill_Wolf** » Tue Mar 01, 2005 12:22 am

I believe that GMC specified the correct spark plug for the 270 motor to be the AC-44.

This plug is very difficult if not impossible to find.

It also happens that this is a lawn mower plug (no laughing please...never seen a lawnmower with a gun ring and Ma-deuce?

).

I have posted in the tech section the cross over for the AC-44. Champion is the J8...now J8C...

http://www.cckw.org/ac-44_cross_ref.htm

If I go to the parts store they try to sell me ACR-45's which is a heat range hotter and a resistor plug as that is all AC now makes.

Thus I am forced to use the Champs even though they are not immune to fouling. The other thing is at $1.50 each it is acceptible.

Thinking about trying some NGK B6S plugs...anyone have any experience with these?

Bill

Karoshi · Post by **Karoshi** » Tue Mar 01, 2005 3:00 am

I've just fitted NGK's as part of the basic service/overhaul. Not done any miles yet, pending valve clearance checks. In 20 years of racing and 35 years of motoring I've never had an NGK fail me!

I'll let you know.

Karoshi

Minnie · Post by **Minnie** » Tue Mar 01, 2005 1:39 pm

Hello

Seems like Champion sparks is a "sparka non grata".... hehe
I have had no bad experience with champion. After a total engine rebuildt fall of 02 the engine is running smooth as h.. cold or hot.
I was so lucky that i obtained a "New" unuseed carb (Late type).
The old carb was worn in the throtle axel housing caus'n erratic idle.
black smoke and unpleasent gas milage...

Remember that result of a rebuildt carb is limited if the throtle axle hole in carb housing shows exessive wear.

Regards

Sturla holtan

armydriver · Post by **armydriver** » Mon Mar 07, 2005 11:39 am

I had not planned on racing my CCKW

, and drive it less than 200 miles a year. My carb was rebuilt at a commerical re-building place in San Antonio and was bench tested before I picked it up. They work on a lot of old carburators here, as there is a big classic car interest in this area.

Karoshi · Post by **Karoshi** » Mon Mar 07, 2005 2:19 pm

Well it just goes to show. New dizy cap had a misplaced tit ( off centre ! ) that the rotor picks up on. Replaced the cap for another and....... bingo, sweet as a nut.

The NGK's are holding up just fine.

Karoshi

Bill_Wolf · Post by **Bill_Wolf** » Mon Mar 07, 2005 2:36 pm

armydriver wrote:I had not planned on racing my CCKW

What Driver!?......Everybody is starting to do it...see here:

http://www.cckw.org/phpbb2/viewtopic.php?p=192#192

armydriver · Post by **armydriver** » Tue Mar 08, 2005 10:43 am

Oh my gosh. What a beauty. I am afraid my truck can only race with old ladys with four wheel walkers on a sunday afternoon stroll around the nursing home.

My truck is almost as old as I am. We find our strength in low gear and slow motion.

I do love the model though.

bobc · Post by **bobc** » Tue Mar 08, 2005 8:53 pm

That is way cool,has anbody been able to read the story? Is it stock,how did it do? Looks like alot of fun.

Degsy · Post by **Degsy** » Thu May 26, 2005 5:50 pm

We have been using a set of NGK`s for over 12 months and have done about 3,000 miles including Normandy 60th with no problems at all. I have had problems with Champions in a variety of vehicles over the last 40 years but have never had a problem with NGKs.

The GMC CCKW

Rough Idle

Rough Idle

idel problem

NGK's

Rough Idle

Re:

racing CCKW

Spark plugs