Like to try another spark plug on my little pinging 440 cui with iron heads

[Moparjack 489]

Hi guys , I still fighting with my 440 cui in my 73 coronet station wagon about timing and pinging problem .i run the auto lite 85 spark plugs Now my question ;
I like to try one step colder spark plug , what I can use ?
I have also in my storage brand new AR 73 race plugs from auto lite , but I read they have no resistor .... what this means ? What you need ( or not need) to run a non resistor spark plug ?
I have a firecore race distributor and the Rev-anator box + coil .
The pinging is not at total advance , the pinging just came under load in high gear if the water temp raise over 180 F and I speed up from about 2500-3000 the ping will mostly came on about 2600-2800 rpm’s, if I full throttle from 3000 rpms up there no problems

 

[hunt2elk]

Have you tried putting stiffer springs in your distributor?

 

[Moparjack 489]

Have you tried putting stiffer springs in your distributor?

I put already two black spring inside , is the stiffest what came with the distributor

 

[steve340]

Spark plugs if they are around the right heat range will probably not be the answer to your problem. If they are too hot it may help - if you go too cold it will foul plugs.
Detonation can be the combination of engine parts not working well together.
As hunt2elk has said you will probably have to slow down the timing curve.

 

[Bee1971]

Firecore race ? I would assume no vacuum advance ?

I run a Firecore distributor with vacuum advance

Anyways your Autolite Spark Plug heat range is 5

You could switch to NGK plugs in a 6 heat range , that would bee colder per NGK


Like he mentioned with the black springs distributor , the advance curve is very very slow

 

[Bee1971]

One more thing to add

Carb jetting , lean condition off idle ?

 

[hunt2elk]

One thing I was told as I just went through this whole detonation issue is that these motors were designed for a NGK5 or similar heat range. Rule of thumb is every 75 to 100 hp over stock you can go one heat range colder. This is according to IMM Engine out in CA.

 

[WP29440SE]

back off the timing and add a little curb idle. I think you'll be wasting money on another set of plugs

 

[RJRENTON]

IMO...
spark plugs are relatively inexpensive, ~ $ 2.50 each. The recommended Autolite is 85. I've used Autolite AP85, which have platinum tip. They are a resistor plug, which wss done for radio noise suppression. Is a resistor plug needed ? Some say yes, others no. You could also use AC R44S, one step colder or AC R43S, 2 steps colder. Or Champion RJ-12YC or the NGK equal l
Many factors determine the engine's spark plugs heat range.....compression ratio, spark advance characteristics, cam, intended use, rear gear ratio, fuel mixture. Can you answer how your engine/car was set up? How about fuel mixture, what carb is in use, how much you can afford to do or want to spend? Or, you can do what others suggested, go one step colder on the spark plug and then check spark plug's coloration, to establish a reference or starting point. There is no one thing fixes all problems but perhaps a little of all suggestions.....it just takes a little time to get things sorted out Others will suggest NGK plugs are best others will have their own opinions and preferences. Just my opinion of course.
BOB RENTON

 

[Moparjack 489]

Fuel mixture it’s fine , I switch from a 800 AVS to a 650 AVS 2 and makes everything much better , car runs good , just the very short pinging appears only under load in high gear ( specially hill up ) between 2600-2800 rpms more or less . It’s a heavy station wagon and I have a 3.53 gear in back , but want switch back again to 2.94 or 2.76 .
maybe I will measure Zylinder pressure again, before we switch the head gasket to a thicker one I had about 200 psi pressure what is to much I think .

 

[Moparjack 489]

back off the timing and add a little curb idle. I think you'll be wasting money on another set of plugs

Add a little curb ?

 

[Moparjack 489]

One more thing to add

Carb jetting , lean condition off idle ?

No , I not think this my problem , but thanks

 

[Moparjack 489]

Firecore race ? I would assume no vacuum advance ?

I run a Firecore distributor with vacuum advance

Anyways your Autolite Spark Plug heat range is 5

You could switch to NGK plugs in a 6 heat range , that would bee colder per NGK


Like he mentioned with the black springs distributor , the advance curve is very very slow

Yes no vacuum advance , before with my original distributor I try with vacuum advance canister , it was horrible and ping as hell

 

[steve340]

If the engine is burning oil you can get some detonation.
Is the engine sound? Not burning oil or any other issues?
If it is OK I would try adding some octane booster to the fuel.

Also what is your initial and total timing numbers?
Some of the timing figures people are saying to use are to high in my opinion.

 

[Moparjack 489]

If the engine is burning oil you can get some detonation.
Is the engine sound? Not burning oil or any other issues?
If it is OK I would try adding some octane booster to the fuel.

Also what is your initial and total timing numbers?
Some of the timing figures people are saying to use are to high in my opinion.

No oil burning no other issue , engine not eat any oil or so .... air fuel ratio perfect too. Octane booster I used too before we rebuilt it and reduce compression ratio from 10,5 to 10.0 :1 . It was helping a little when I race it on the quarter mile . But is also my daily summer driver , not like to put octane boost each filling , the engine is not a race engine , just a 440 cui with small goodies , but the build shop was not so good , because my pistions looking over the deck height ..., we see this when my friend and me open the engine after rod bearing damage ..

 

[Moparjack 489]

Total timming about 34-35 max . Today I reduce to 32 , but I had the total before also one time on 30 and it’s pinging under load in high gear from about 2600-2800 rpms half Second

 

[steve340]

If you only have a very mild camshaft with 10 to 1 static CR your dynamic CR could be very high which could give you this problem.
However when I have experienced this problem slowing down the timing curve cured the problem.
Unfortunately does not seem to be the fix for you.

 

[Moparjack 489]

But interesting what you say. Yes cam is mild