Spark Plugs - T/A Challenger

[whitewatersky]

hey y'all,
been a while since I stopped in.
Just been chasing the ultimate tune on the T/A.

we've tried a few of the "one and only" methods for setting up the Idle - carb/distributor/timing

Just wondering what spark plugs are recommended

I don't have the cam spec, but said to keep it close to original spec when I had the engine rebuilt.

Any other T/A set up tricks would be appreciated

[Roadman]

Can't answer the plug question, but  to the forum.   

[cudabob496]

I use NGK

[Cuda Cody]

Welcome @whitewatersky   

What's the issue with the engine?  Maybe we can help brainstorm some solutions with you. 

[RUNCHARGER]

I have good luck with NGK's as well. You can't get a clean idle?

[whitewatersky]

howdy guys,
I have been over at the Cuda/Challenger forum for years - I thought I had posted here before, but just set up the account a while ago and was obviously only reading...

well..... here's my car:
http://www.cuda-challenger.com/cc/index.php?topic=100322.msg988174#msg988174

so I haven't been driving the Challenger for months now. was running rough and then I got too busy to deal with it.

never been able to get it idling properly, too rich, fouling plugs,  etc etc

have tried a few variants from NGK - not sure which NGK plug to use. their website suggests:

NGK 7149 GR4IX IX Iridium Plug
SKU: #GR4IX
ITEM : # NGK7149
BRAND :  NGK


so, after a lotta checking of this that n the other,

one issue we found was that the shaft was moving upward and pushing the rotor too high in the distributor cap.

That meant the voltage from the rotor was hitting both the contact and the bakelite cap, rather than mid-point on the contact.
figured that's gonna result in a bad spark.

We managed to limit the upward movement of the shaft to only a mm or two, so figure that will deliver better voltage to the spark plugs...

so, now that's done, we've been doing our best to follow this guide to tuning.
third post down the page from "one bad fish"

http://www.cuda-challenger.com/cc/index.php?topic=97471.315

with that in mind we've been
adjusting the idle mixture screws, set the float level, confirmed size of power valve (has a 6.5).

round and round we go.

currently have the outboards set at 1/8 of a turn out

middle about 1/5 out

set the transfer slot according to the attached pic.

still won't idle at all.

Thinking the plugs might be buggered (again) after all the rich running

have the timing advanced about 18 degrees - can't actually see the mark

[Chryco Psycho]

First I do not use NGK , they foul easily & never fire properly again .
I generally use Champ RN12YC , or similar Autolite
, the mixture screws are probably set too lean , center carb should be approx 1 - 1.5 turns out from the bottom , outboards around 1/2 turn out  ,basically you need to get it running even at 2000 rpm & start reducing the speed & making adjustments to keep it running , , I have seen the advance weights in the dist cause a problem , the advance springs were too light & it would idle at 1100 rpm or 350 but nothing between , changed the springs & found the middle zone !!

[cudabob496]

haven't had a problem with NGKs in 25 years

wonder if you have a bad power valve.
float levels ok?
Time to replace all the carb gaskets???

[Jim AAR]

I don't like NGK's either.

I use Champion N9Y at .035" gap.

Timing should be 5 Deg BTC plus or minus 2 1/2 Deg.

If you can't see your Timing Marks, just adjust the Timing with a Vacuum Gauge, needle should be smooth and steady around 20 Hg.

Are you running Points or Electronic Ignition?

Carbs should be adjusted as per Chryco's post.

So glad I went with the Manual Outboard carbs, there is nothing to adjust on them, the only adjustment is on the Center Carb and it has always idled almost perfect as it only uses the Center Carb.

Not original but I prefer usability, driveabliity & performance. If it wasn't a driver, I would put the Vacuum Outboards on but if I ever go that route it would be more than likely a Trailer Queen,  I'll stick with my Manual Outboards until then.

[Cuda Cody]

Can't see the timing mark is a little scary.  I know several people can "tune" by ear, but I can get so much little change out of a few degrees that I always double check my top dead center and make sure my timing is perfect.  Setting both the initial and the full (all in) advance will help an engine a lot.  However, your issue seems to be carb related, right?  Is this the first time you are running the carb or is it a proven good carb?  Was it rebuilt or anything? 

[whitewatersky]

thanks gang 

Yep - Carbs were completely rebuilt. supposedly properly...

i dunno where to start and stop with the description of the symptoms...

one thing I DO know is that those frikken outboard carb mixture screws are so annoyingly positioned when it comes to the rear.... grrrr

getting 22 Hg of vacuum between hits on the throttle. but just gotta keep on giving it a rev to stop it from stalling

fella working with me on it is saying that it's running too rich and that's why it's unable to idle

is it likely that the power valve could be buggered due to so many backfires as we've been messing around with the carbs ?
so it's then letting too much fuel in, regardless of the idle mixture screws and the idle screw and transfer slot ?

[Cuda Cody]

It sounds carb related to me.   

[whitewatersky]

thanks. just dunno where to go with it next.

buggered if i know where to get the power valve, or even check which one we need.

max vacuum is 22 hg

i spose I'll look thru the selection here: https://www.summitracing.com/int/search/product-line/holley-replacement-power-valves

[Chryco Psycho]

Check manifold vacuum at idle [in gear if auto] if it is lower than 8" I would use a lower power valve such as 4.5 ", you need to have at least 2" more vacuum than the power valve rating

[Cuda_mark]

I use NGK

I've also had the best luck with NGK