Why is this 360 pinging

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Snake

Snake

Mopar Nut
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Ok got a buddy that does not know two much when it comes to tuning.he has a dodge truck with a rebuilt 360 with the KB 107 pistons,stock intake,stock heads,stock exhaust manifolds,and the edelbrock carb,727 tranny with 323 gear,cam he has forgotten what the spects are.He has had pinging from day one he runs 91 octane gas.So he turns to me for help,goes and gets a new dizzy with no vacuum can this has been re-curved.I installed it for him ,set is timing at idle 13 degrees ,rev to 3 grand and we have 31 degrees total witch in my books is great.Well it still pings,for the life of me why what do we do next?
 
George R said:
Too much initial for me. I would start at 8 BTDC if it was my car.

George
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I would say timing except that 8 degrees is not the standard for canadian vehicles; most have a sticker saying 12 degrees before top dead center
 
without knowing the cams specs were just guessing. Have him do a compression test and see what his cranking pressure is.
 
Run more octane thats the cure for all, you should try 93=94.
 
Well...too much squeeze is more than likely the culprit.
Like Adam said, do a cranking comp test and report back.
Egr, if it has one is another place to look for function.
The 1406 has always been too lean ootb for all my experiences using it, so if its just surging...its it need a rod change, if its punting under load and not due to timing 'which btw 31 isn't too much"...then it needs bigger jets.
 
timing or oil in the combustion chamber, Ive also seen em knock when run without a pcv valve
 
Ok I turned him back to 9 degress at idle and no pinging now but he says down on power a tad.
 
what is the compression ratio of his set up? Could be pinging because too much squeeze with an open chamber iron head. Also The distributor, if it is re-curved with too light of springs can bring the timing advance on too fast, causing pre-detonation as well. Like mentioned above, going up a jet size to make it more rich can help too.
 
hey Don...if you went to 9 initial and you were 13 and 31 does that means you're now at 27 or so total?
sounds like too much compression and not enough cam duration for 91
 
ir3333 said:
hey Don...if you went to 9 initial and you were 13 and 31 does that means you're now at 27 or so total?
sounds like too much compression and not enough cam duration for 91
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I agree AL,good thing he brought his timeing light mine died shortly after words lol,now I know what will be under the tree this year.
 
Mopar367 said:
what is the compression ratio of his set up? Could be pinging because too much squeeze with an open chamber iron head. Also The distributor, if it is re-curved with too light of springs can bring the timing advance on too fast, causing pre-detonation as well. Like mentioned above, going up a jet size to make it more rich can help too.
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he has almost no clue what he has,I felt like saying you need to pay attention to what your buying and how to work on therese things,but me being as i am I just shut up.
 
If he can't get it to stop pinging, tell your buddy to rip it apart and blueprint the engine properly. It it sounds like the guy who he bought it from sold it for a reason.
 
NEED more info. It is very tricky to build a truck engine that performs well on pump gas. You really need to reign in the compression ratio if you are going to cam it properly-especially with stock exhaust manifolds-they are not very forgiving.

Jet up, try colder plugs, much better fuel (AV gas would be a great test) or dial back timing and live with it. Me? I would remove heads and add some cc's or get other heads with a larger chamber. Oh and carefully examine the piston tops while the heads are off-those KB's HATE pinging. J.Rob
 
Those 107s in a .030" 360 with the common fel-pro .039" head gasket will end up at 10:1 even with a 70cc chamber.

With a small street cam in the 220 @050" range your gonna to much cylinder pressure for pump gas
 
Could be as simple as running too hot. I fought the timing for days before I noticed there was no ping even under a severe load when starting from stone cold.
In the end , a new radiator cured it.
I felt foolish too because I had replaced everything under the hood except the 30 year old radiator. Lesson learned.
 
this is all just guessing until he does a compression test to find out cylinder pressure. He has close to 10:1 compression with a cast iron open chamber head in a heavy truck with high gearing. He probably wont be able to tune it out.
 
TrailBeast said:
Nobody mentioned the heat range of the plugs.
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Good mention.

I'm with the fellas here starting with the above first. A stock plug or 1 step cooler is what I would run. I have had that short block combo before and it does like 93 octane better.

Next would be looking at the damper. If it moved at all. Then re time it.
If it was built properly, at zero deck height for the slugs w/a 72 c. Head, it is going to want 93.

Lastly, but not least importantly, look at the plugs for a rich lean condition. Re-check/jet carb, check for vacuum leaks at the carb, intake to head areas.

I would stick with the vacuum advance set up and limit the vacuum advance while keeping as much intimtiming as possible.
 
Your probably right Adam. Not via the carb at least. At the distributor, it can be done. Though he won't be happy.
 
I dont consider taking a bunch of timing out of the motor fixing it.
 
LOL, me either. But it won't ping and he can drive it.
 
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