[lfdsteve]

Is there an aftermarket "knock" or detonation sensor that can be added to a Pontiac? Between my mufflers, the wind noise, trany whine and being almost def I cant tell if what I hear is detonation or just the normal rattles of an older car.
Based on what I have read and the parts I have used, doesn't seem like I should have a detonation prone car but at 14* without vacuum advance hooked up, I am hearing "something" at cruise when I try to give it power to pass a car on the hiway.
thanks

[steve25]

Assuming your tune is right you should not have ping or knock issues with that Cam and Aluminum 87 CC heads.
Can you get the car on a Chassis dyno?

[lfdsteve]

Originally Posted by steve25

Assuming your tune is right you should not have ping or knock issues with that Cam and Aluminum 87 CC heads.
Can you get the car on a Chassis dyno?

Thanks, Like I said, I really tried to keep it way on the safe side based on all the advise on this board. Mapped and dialed up the timing this summer. really woke up the engine but just keep hearing "something". I will tell you that this Tremec is noisy as crap so it could be coming from inside that, or any other area that may be rattling. First car I have ever built so who knows what is too close,tight or loose.
Part of the plan is to get to a dyno at some point but with all of lifes tasks, it is a very low priority

[superdutybob]

Placement of a knock sensor system on an engine is a nightmare in itself. The OEMs go through this all the time. The placement is critical so as not to get false knock signals from alternate engine noises. The pinging of headers could be enough to send a false signal. I would think it would be more trouble than helpful.

[lfdsteve]

I'll be in Brighton tomorrow Bob. Just down the road here in Okemos.
Should meet for a coffee some day.
Steve

[Skip Fix]

I would think the normal noise for roller rockers, solid lifters would sure trigger it.

[Squidward]

Originally Posted by lfdsteve

Just down the road here in Okemos.

Small world. I was in Okemos a week and a half ago. Okemos was a rival where I grew up.

Sorry, and back to topic...

["QUICK-SILVER"]

Originally Posted by lfdsteve

Mapped and dialed up the timing this summer. really woke up the engine but just keep hearing "something".

Was the "something" there before timing got dialed up?

Originally Posted by lfdsteve

Part of the plan is to get to a dyno at some point but with all of lifes tasks, it is a very low priority

A man's gotta keep his priorities straight. But..engine damage from detonation would be high on my list.

What about trying a tank of race fuel, just to see if the "something" goes away.

If it helps AND you get a performance increase...It'll be time for a new thread about running 10+CR with a 108 LSA cam.

Just thinking
Clay

[chiphead]

A detonation sensor like used on LS engines is just a microphone of sorts. It picks up all the frequencies within its listening bandwidth and transmits them to digital electronics. The electronics must filter out the background noise and decide what is valid ping signature. Fitting the detonation sensor would be the straightforward part. Its the back-end electronics and digital signal processing that's the real trick. Aftermarket ECMs could do this, but you would have to teach it what is detonation and what is not in your application.

[lfdsteve]

Originally Posted by Squidward

Small world. I was in Okemos a week and a half ago. Okemos was a rival where I grew up.

Sorry, and back to topic...

I'll take that as a no on the coffee...

[lfdsteve]

Originally Posted by "QUICK-SILVER"

Was the "something" there before timing got dialed up?

A man's gotta keep his priorities straight. But..engine damage from detonation would be high on my list.

What about trying a tank of race fuel, just to see if the "something" goes away.

If it helps AND you get a performance increase...It'll be time for a new thread about running 10+CR with a 108 LSA cam.

Just thinking
Clay

Before? Don't know. That's part of the whole no time dilemma. Guess I was looking for an easy way out.
thanks
Steve

[Schurkey]

MSD "Knock Alert" #8964. Discontinued. Probably for all the reasons listed above.

[lust4speed]

Friend had detonation on his 462 with the 87cc heads with the Comp 240/246 HFT cam. It was close, and we had to dial back both vacuum and mechanical advance. Surprised us because this basic combo is being run by a lot of our club members with even somewhat smaller HR cams. Engine had to come apart for other reasons so we mike'd everything to the Nth degree and things was normal except for the heads being a couple cc's smaller than advertised, and the pistons a few thousandths out of the hole, the engine ended up at a true 10.6:1 when the smoke settled. Still shouldn't have been a deal breaker, but with our crap 91 octane, it was enough to cause pinging.

In this case, I'm wondering if either the springs are too light, or the weights are sticking creating an abnormal advance at mid range? For that matter, was total advance and the advance curve verified?

[lfdsteve]

@@@So, interesting information. I rechecked timing which was now showing 8* @ 850 (idle)
Not sure when that happened, must have been loose?
Anyway, got out my dial back light and got the following curve:
Idle 850=16*
1000=18*
1500=25*
2000=30*
2500=32*
3000=34*
3500=34*
All in.....
Steve @@@

That's my curve from a previous post. I will add that I can't guarantee it's repeatable. It's the original hei from way back. Planning on an upgrade this winter to remove that variable.
Weather looks is nice this week. May get it out and try to start with timing rolled back and inch up. I guess even though I can't hear it well enough to identify, if it goes away I'll know. Thanks for input and help as always!

[HWYSTR455]

Is that curve from when it was 16 initial? So it's 8 less now?

Is that at-idle reading with or without vacuum advance connected?

Is there a vacuum advance in use?

.

[HWYSTR455]

Is the 108 what's read on the cam card, or did you factor that in with the 4 degree key? Did you degree the cam, or just took a shot at it?

.

[lfdsteve]

Originally Posted by HWYSTR455

Is that curve from when it was 16 initial? So it's 8 less now?

Is that at-idle reading with or without vacuum advance connected?

Is there a vacuum advance in use?

.

It was at 8* when I checked so I set to 16* based on what I have been reading. That's with no vacuums advance. And it's still not hooked up. Trying to sort initial first. Really woke up motor but hearing the noises as posted. Probs will roll it back and road test if I can find time.

[lfdsteve]

Originally Posted by HWYSTR455

Is the 108 what's read on the cam card, or did you factor that in with the 4 degree key? Did you degree the cam, or just took a shot at it?

.

Cam card 108* set straight up and degreeed.

[harley3296]

This is what I have on my Pontiac 400. It's a knock sensor you can get on eBay and it's just the gauge that converts digital Signal into readable information. All you have to do is buy a knock sensor from any vehicle Chevrolet Volvo VW and hook it up into this device. It works well I asked my wife to look at the sensor while I took a ball-peen hammer and lightly tap on the engine block and sure enough and went into the red. I've been driving now for a year or so and it definitely works. I change spark plugs too cold ones and knock went lower then I switch to a different type of gas with no e 85 and knock was even lower

[harley3296]

I mounted it directly to the cylinder head and I tried several other locations close to where the Piston reaches top dead center but no matter where I put it at all comes out pretty much the same. The knock sensor is programmed to listen for 6400 Hz range, that's about where it sounds like when a hammer hits metal and it's very distinctive.