My hearing is terrible and I'm afraid I might not be hearing my motor detonating under power. Guess I could find a friend to ride along but I was wondering if one of those knock sensor dinguses could be hooked up? If so are they reliable for this sort of thing? What would be involved?
Sure just takes a bit of engineering, just match your bore with some OEM bore and buy their sensor. Knock Frequency = 900/(pi * 0.5 * bore in mm) Not really that simple as the frequency really needs to be empirically determined, but better than ears if done right
Once you determine the correct sensor frequency and mount it in the block, you will have to have the electronics to interpret the sensor signal and determine what its output will be. There are companies that make stand alone units usually marketed toward high boost modified late model motors. J&S Electronics, Knocksense, maybe MSD
Good advice from Yellow Dog. I have heard that the OEM sensors have signals that are only properly interpreted by the OEM computer/ECU. Hence the racer I talked to (I was interested in this too as after 40 years of drag strips, the old ears are lacking) recommended I look into aftermarket "knock" sensors like Yellow Dog recommended.
Look for tiny round shiny metallic looking balls or specks on the porcelain (you will need a magnifier), and exhaust lash clearance that closes up. If the exhaust lash clearance is closing, you are probably already in deep shit though.
The MSD unit pn 8964 looks like it could have been a simple installation with a lighted output panel. No longer available...I suspect it had issues....I suspect universal units are lacking. https://static.summitracing.com/global/images/instructions/msd-8964_frm29140.pdf
No, if combustion temperatures are really out of control, the exhaust valves can start to soften under load and start to "tulip". Before it gets to this stage, you will also see bluing around the stem where it flares up out of the valve head if you are doing regular tear downs. If I pull a race motor down and see loss of bearing crush, loosening of the main cap registers, or main cap brinelling, I will look at that as a confirmation as to whether the cause is detonation, or if I need to look for something else. As I alluded to its pretty serious shit and late in the game when you see the exhaust lash closing up, and really more something you are more likely to see in a race motor, but I figured I would throw it up there for information sake. But "fly shit" on the porcelain is a good early indicator.
This has been bothering me, I have been thinking about this, and realized its incorrect. Its the intake lash that will close up. The reason is the same, but it generally happens on the intake side.I don't know what to chalk that up to other than time, its been a while since I have been building race engines regularly.
So, how is the motor performing? What makes you think that you have a detonation problem? habe you looked at spark plugs, checked timing & air/fuel mixture? Sent from my VS985 4G using The H.A.M.B. mobile app
I've made some progress. What I thought might be the sound of detonation WAS detonation, diagnosed by tightening up the vacuum brake on the flathead's distributor, which limits advance under load. So at least now I think I can discern the sound over the other rattles and loud exhaust, and I've been easy enough on this fresh rebuild that I don't think any real damage has been done. I'm still intrigued by the knock sensor idea, however as yellow dog advised it might be hard to find one suitable for my v8-60's tiny 2.6" bore. Also hoped it might be a simple matter of hooking it to a warning light or some such, doesn't sound like it is. Thanks for the replies.
I know how you feel Blowby It's embarrassing when the car is making a bunch of noise, from detonation to brakes squeaking and everyone seems to hear it except the driver.
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