22350 Posted April 19, 2023 Report Share Posted April 19, 2023 So I have a new engine, new radiator, rebuilt carb, electronic ignition timed correctly, and running 91 octane gas. Why am I still getting pinging under load? Timing set to 10 degrees and advance working Quote Link to comment
datzenmike Posted April 19, 2023 Report Share Posted April 19, 2023 Timing sounds about right for compression and single plug per cylinder and 91 should tame just about anything. Try dialing back the timing bit by bit and see if pinging stops. If it won't go away it may not be pining at all. May not even be pinging. Might be mistaken for something else... 1/ Could be exhaust leak which is louder under heavy load. Cracked exhaust manifold? Bad gasket at head or to the down pipe. 2/ Check the valve clearances. A tight valve will not fire correctly and sound differently. Possible other pinging causes... 1/ Wrong heat range of spark plug. Use only NGK that are not bought from Amazon. Acts like a glow plug causing pre-ignition under load.. 2/ Pull all plugs. Are they sooty dry from carbon build up? Is one different from the others? Over rich from choke not shutting off? Carburetor may be flooding from incorrect float height? Built up carbon becomes a glowing hot ignition source. 1 Quote Link to comment
stevecar Posted April 20, 2023 Report Share Posted April 20, 2023 19 hours ago, datzenmike said: 1/ Wrong heat range of spark plug. Use only NGK that are not bought from Amazon. Acts like a glow plug causing pre-ignition under load.. How are the NGK plugs bought from Amazon different than others with the same part number? Quote Link to comment
Stoffregen Motorsports Posted April 20, 2023 Report Share Posted April 20, 2023 1 hour ago, stevecar said: How are the NGK plugs bought from Amazon different than others with the same part number? There have been known knock-offs. Total scam. Amazon is the worst. 1 Quote Link to comment
stevecar Posted April 21, 2023 Report Share Posted April 21, 2023 Sorry to sidetrack this conversation. But I want to say thanks to datzenmike and Stoffregen Motorsports for the heads up. Just last week I bought a set of NGK laser iridium spark plugs from Ebay. I had no idea there were fakes out there and they can cause some damage, let alone a much shorter life. I did some research and ended up contacting NGK. They wanted some pics of the plug and just informed me that they are genuine. So I guess I was lucky. But I will only buy from known distributers in the future. 1 Quote Link to comment
datzenmike Posted April 21, 2023 Report Share Posted April 21, 2023 Remember (well you may not) when Iran held Americans hostage? Well a seal team was sent in and besides just bad luck one of the helicopters broke down. It was later found that a counterfeit part had gotten into the supply chain. There are fare more stringent inspections now. Counterfeit parts are a problem. You can guess where most come from... 2 Quote Link to comment
Stoffregen Motorsports Posted April 22, 2023 Report Share Posted April 22, 2023 Yeah, I was 9 years old, but I remember the Iran thing. Counterfeit parts is a huge issue worldwide. A handful of people I know, including my brother, have parts made overseas and it's an entire job just staying on top of the production facilities so they don't sell out the back door. Even with constant supervision, the factories always find a way to make a bit on the side. Glad to hear you contacted NGK and that they confirmed the parts were genuine. 1 Quote Link to comment
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