Detonation?

[MTBRider]

Finally purchased a borescope and this is what I saw. I assume this is due to detonation which I’ve been struggling with occasionally.
Can anyone confirm by this pic?

 

[PurpleBeeper]

Probably detonation. When I've had it in the past, the pistons looked like they were shot point blank with bird shot BB's

 

[zyzzyx]

Does anyone make a detonation sensor for adding on to our cars????

 

[MTBRider]

Does anyone make a detonation sensor for adding on to our cars????

Not sure, I could hear it occasionally. I picked up an AFR gauge for better tuning this summer to hopefully use it with some timing adjustments solve the problem.

 

[MTBRider]

Not sure, I could hear it occasionally. I picked up an AFR gauge for better tuning this summer to hopefully use it with some timing adjustments solve the problem.

Search “old car knock sensor” and you’ll see some options for aftermarket units.

 

[snake]

would riching up the carb help with ping.

 

[Geoff 2]

Yes it can. So can cold air induction, getting the engine to run cooler.

 

[Slap Stick]

Cold air holds more oxygen, leaning the AF ratio.

 

[dvw]

Less ignition timing or better fuel is the answer.
Doug

 

[MTBRider]

It’s a basically stock engine with a lot of miles and I think compression is down a bit. I put in a limiting plate to reduce total timing and I run 92 pump gas.
Going to install the AFR gage soon as try to tune better this spring.

 

[Rebelrouser]

View attachment 1604192Finally purchased a borescope and this is what I saw. I assume this is due to detonation which I’ve been struggling with occasionally.
Can anyone confirm by this pic?

View attachment 1604193

I use an engine software to generate an advance curve, and then recurve the distributor to eliminate detonation. Performance Trends makes the software, and I have a distributor machine, but if you have a buddy and some paper you can have them rev the engine at 200rpm increments and record the timing on some paper connect the dots and produce an advance curve. Then changing weights and springs until your real curve matches the predicted one from the software. Most of the time wide open throttle is not the problem part throttle under loads is where the most damage is done.
Only issue is you have to put good numbers into the software to get good results. https://www.performancetrends.com/Engine-Analyzer.htm

And the software also provides a bunch of other numbers like idle vacuum, cranking compression, etc. If you are planning a cam swap or other upgrades it is worth it just in the money you can save.

 

[MTBRider]

I’m considering sending my distributor out for someone with the ability to verify condition and rebuild/recurve if needed.

 

[RJRENTON]

Does anyone make a detonation sensor for adding on to our cars????

All, or most of the new vehicle offerings, are equipped with Piezo Electric detonation, or knock sensors. These devices are basically accelerorometers, which "listen" or feel for the internal vibration waves, produced by the detonation effect. The devices are connected to the vehicle's on board computer to RETARD the spark trigger point or slightly delay the ignition point to reduce the detonation point (retarding the spark slightly). All this assumes that the on board computer has the engine management function.....both fuel and ignition operation. It does this seamlessly.....without any driver intervention. The location of the knock sensor will vary engine to engine family to the point where the detonation vibrations are maximized (physical location) to provide the most accurate effect. Its not a simple function of buying an device and connecting it to the spark/ignition control box.....its an integrated component...a "feed forward" philosophy. Just my opinion of course......
BOB RENTON

 

[c.moo]

I’m considering sending my distributor out for someone with the ability to verify condition and rebuild/recurve if needed.

Halifaxhops might be able to help you with that. He is a member here.

 

[zyzzyx]

I understand the workings of a knock sensor system, I was just wondering if someone makes a system that will notify you of the condition!
I don't want to put an ECU on my old car, just want to know if I'm having a problem. With all the noise going on under the hood, I probably
wouldn't hear a grenade go off.

 

[Geoff 2]

Post #8. No, not more oxygen. The volume of air [ containing 19% oxygen ] ingested by the engine for a given rpm does not change. It's density does; & density also changes with temp.
One of the causes of detonation is auto ign of the mixture from a superheated mixture. Cold air reduces the the temp of the incoming air & can reduce &/or eliminate det.