spark plugs?

[ggaagg57]

i have a 74 350 ,motor work has been done . block was milled and heads.compression don,t know what it is but has to be over 8.5 to 1 it pings if timing is at 8 that s where it says to set it.if you set it a t 4 it want run right . would a colder plug help or a hotter plug help? which one? additive 104 didn't help.

 

[Bullitt]

Hmmm... I'm not exactly sure which way to go on the plugs, as I haven't messed with the ranges that much. Are you sure that your ignition is working correctly? I'm just grasping at straws here. I wish I could be more help, so I'll look for some advice, later on today.

--Bullitt

 

[Eric]

I'm with Bullitt on this one. You may want to play around a little more with the timing. I too had problems that continued after replacing the ignition, plugs, and wire - a timing adjustment cured it.

- Eric

 

[ggaagg57]

it has a duel point distr . it get about 22 to 24 degess at full advance at 4 up at tdc it will ping and lower it want run good .

 

[Buckskin7T7V]

It should be 8 degrees with the vacuum advanced plugged and at 700 rpm.
If the idle is to high, the weights in the distributor kick in and you get a incorrect reading. A richer carb jetting could help. Timing and jetting first. If you can use a timing light that allows you to see what the timing is at different rpms, that will tell you if you are getting too advanced. They are worth the money.
I am running a 77/350 block with 69 heads. 9 to 1 compression and comp cam. Holly 7501/650cfm spread bore. No ping on regular gas in the heat of central California.

 

[ggaagg57]

i do have a light that show rpms and timing advance. it has a mallory dual point im going to put the stock one back in to see what happens. i would still like to know what a colder plug or hotter one would do. george

 

[Buckskin7T7V]

To see the way the plugs are coloring, you have to do a power shut off run. Drive a couple of miles to burn away the idle coloring. Then in 3rd gear, run it at about 4000 rpm and turn the key off. As you put in the clutch. DO NOT TURN THE KEY TO LOCK THE STEERING WHEEL!!!!!! This will color the plug as it is really burning and Not the idle coloring most people read. The color of the plug, is deep inside of the insulator. Not the tip. Number 2 or 4 plug is the easy ones to get at.

 

[Rowdy1]

Timing

I'm running 12:5 to 1 with a radical cam and 64cc aluminum heads on 94 octane straight from the pump with no ping or detonation. I don't even have a timing mark on my timing cover, it's done by ear.

 

[ggaagg57]

i will try to put in a stock dist, in the next few day . any thing you can think of that would make it ping.?it really spark knocks when it shifts and you r getting on it a little more than normal. i was told they put a new timing chain on it not to long ago??? if it were a tooth off i dont think it would run as good as it dose

 

[ggaagg57]

found problem not plugs. took out mallory dual piont distr , put in stock one runs great so far,

 

[Stingray72]

I would highly recommend getting rid of the points. Points can lead to all kinds of annoyances, especially when engine work has been done.

 

[Jack]

/ggaagg57 ... it has a mallory dual point im going to put the stock one back in to see what happens.

Just a guess ... does your mallory dp dist have ONLY mech/cent advance ??? And No Vac can? Most carbed street motors need vac advance too.
JACK:gap