Spark Plugs??

[mercsrus51]

I have a question regarding which spark plugs are best for a 348, with 3- 2"s, and with a mild cam...seems I put in split fires about a year ago,, and I have real problem when strarting the car when its cold.....once it strarts its fine...pulled out the plugs, and they were all black, wet.. Fuel ...(Not Good) and overloaded...are these not hot enough???? Or is it a carb problem.....???
Had them all rebuilt last year.....when the car runs.does not skip a beat....mallory ignition...so its not the points...???????? :
thankyou...for any info.....

 

[dq409]

It sounds more likely to be a choke problem.

Try backing it off a bit at a time, on each cold start-up, until it starts better. ,,dq

 

[jester]

It sounds more likely to be a choke problem.

Try backing it off a bit at a time, on each cold start-up, until it starts better. ,,dq

Check to see if any of the carbs are draining into the manifold after shut down. I had a holloy single 4 barrel on the car that would dump fuel into the engine after I shut it down. It would foul out the plugs and make it real hard to start . Good luck.

 

[mercsrus51]

spark plugs

choke is working fine...after start up it starts up fine one hour two,, no problem,,even 4-5 hrs later....seems like the next day is when its hard starting...chioke closes after first touch of the gas peddle,,, opens right after it warms up,,,,

 

[dq409]

choke is working fine...after start up it starts up fine one hour two,, no problem,,even 4-5 hrs later....seems like the next day is when its hard starting...chioke closes after first touch of the gas peddle,,, opens right after it warms up,,,,

Thats my point. You can`t test the choke on a warm engine. Even 4 or 5 hours later it still is not a cold engine.

Try backing it off a bit and see how she starts first thing in the morning.
If it`s better back it off a bit more for the next morning,,, and so on.
This is a simple test that might work.
If the choke is fulling closing or closing too far it will cause this problem.
Then if that doesn`t help try what jester says.

IMO,,, These engines don`t need much choke if the carbs are jetted and adjusted right.
My dual carbed 409 never needs the choke. Even bone a** cold after weeks of storage,,,, dq

 

[Fathead Racing]

Plugs, choke.

R44s are the stock plug as I remember. One of the best improvments I made on my engine was to install an electric choke. I also thought my old Rochester choke was ok, but when I put the electric choke on I was amazed with how much better the engine behaved! As far as the black wet plugs are concerned, curb idle adjustment, advance at idle, vacuum at idle and cruise, jetting. A lot of things can contribute to rich condition. If it burns your eyes when your in the garage with the engine running right away then you have a problem. 348 with three twos should show 18-22 dgs of timing advance at idle @ 650-750 rpm and I'd like to see 16 to 22 inches of vacuum. Run your idle air bleeds in, engine should lose rpm, stumble. If it doesn't you are out of the idle circut, throttle blades open to far. makes for very rich idle! Check your vac at idle. Vacuum advance should be hooked to manifold vacuum.

 

[bobs409]

I have to agree with DQ on the need for chokes. I don't even use mine at all. I've started it when it was 20 degrees many times with absolutely no problems. Fires right up and idles with no stumble. I can start it up and drive right away if I wanted.

Mine always burned your eyes and nothing I ever did would cure that. I got to hear another members 409 "65impala409" and it too had very strong exhaust.

Both of our engines plugs have a black sooty outer ring on the plug but no wetness.

I'd be suspicious of the wetness on the plugs, that's not normal. Sounds like it's flooding to me.

Ever try to start it without using the choke??? Maybe yours doesn't need it either?

 

[bowtieollie]

Hi Merc,

Throw away the Splitfires - they are worthless.

The factory plug depends on which heads you are using.

AC made a nice spark plug in their day - but as with anything GM touchs lately - they are not what they once were. Also, they are not plated and they rust in a short period of time (ugly to me)

NGK is the only plug I will recommend.

348 heads (non watercooled plugs) XR 4
348 heads (watercooled plugs) GR 4