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Engine doesn't like a lot of timing.

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AbandonedBronco
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Engine doesn't like a lot of timing.

Post #1 by AbandonedBronco » Tue Dec 03, 2019 1:10 pm

Hi all,
So, recently it came to my attention that I have engine damage due to detonation.
I will be pulling the engine apart here in a month or so to replace the pistons, rings, connecting rod bearings, rehone, etc. to repair the damage.

To keep this from happening again, I'm looking into why. I have a custom curved HEI style distributor from DUI.
I run it at the 12° base timing that they call for and have, in the past, checked and verified the timing curvy myself, so I know it was working properly.

Recently, since I have a Holley Sniper EFI setup (and to keep this from ever happening again) I converted it to use computer controlled timing.
While pulling it apart, I thought I had found my issue. The pegs that the weights rotate on were heavily worn. I thought that maybe they'd been binding/hanging up and keeping the timing advanced while it shouldn't have been. Look at the far left and far right pegs, they're about worn halfway through.

Image

Image

Image

However, now that I have computer controlled timing, I recreated the timing curve that I had mapped out from my DUI unit, and can hear pinging throughout. I also tried uploading a timing curve that Holley designed for performance applications, and again have pinging all throughout.

So, I've been dropping the timing gradually. As I'm driving, I can set "static timing" with the handheld unit on the fly, so if I hear ping I can tap a button and immediately drop it to something safe, like 15°. If I hear the rattle/pinging go away, I know the sound was caused by too much timing.

I have a curve now that doesn't produce any ping, but it's extremely modest.
Peak "mechanical" doesn't come in fully until around 4000 RPMs, and even then, it's only 32°.
The "vacuum" advance is only about 6°, for a total of 38°.
Base is 15°
15 base + 17 mechanical + 6 vacuum

Could something else still be going on? Or does my cam/compression just require less timing?

Specs:

9.1:1 compression
Enlarged S.I. valves with head P&P
Cam specs:

Duration @ .050: 220/220
Duration Advertised: 284/284
Gross Lift: .504/.504
Lobe Center: 110

Thoughts?
1985 Ford Bronco Eddie Bauer. 300 I6. 9.1:1 CR, roller rockers, EFI manifolds and 2.5" exhaust. DUI ignition. 3.55 final drive, 5 speed ZF5. Holley Sniper EFI w/Offenhauser C Intake. 32" BFG KO2 A/Ts.

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THE FRENCHTOWN FLYER
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Re: Engine doesn't like a lot of timing.

Post #2 by THE FRENCHTOWN FLYER » Tue Dec 03, 2019 4:05 pm

I commented on this topic before. If you increase cylinder pressure the optimum timing needs will decrease. That is because the burn rate will increase.
If you raised the static compression from stock optimum timing is lessened.
If you increased the volumetric efficiency through better manifolding optimum timing is lessened.
Suppose the max timing was 36 degrees at 4000 WOT on the stock engine. Your timing requirements with an improved more efficient engine will be less than that. Even if the DCR is less that does not necessarily mean you can handle more spark, if improved volumetric efficiency overrides a later closing intake valve.

Additionally, even if the optimum spark advance is less the octane rating of the fuel may prevent you from reaching it. Before you get to Minimum Spark For Best Torque (MBT) you may be borderline knock limited for the fuel being used.
It may be interesting to try running the engine in higher octane rated fuels - 91 ([R+M]/2)ON, 93 ([R+M]/2)ON, 100 RON (av gas), 110 RON (race gas), and see if it is indeed detonation you are hearing.

That is why I asked elsewhere what does a "performance curved distributor" entail?
Last edited by THE FRENCHTOWN FLYER on Fri Dec 06, 2019 6:36 pm, edited 2 times in total.
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Re: Engine doesn't like a lot of timing.

Post #3 by AbandonedBronco » Tue Dec 03, 2019 5:30 pm

Thanks for the answer.

I'm curious why the curve that DUI created for me wouldn't be correct (and would cause enough detonation to cause engine damage). They built it off of my cam specs, vehicle weight, compression ratio, etc. It's what they do for a living so I would have figured it would at least be close.

For what it's worth, I run 91 octane regularly.

Otherwise, that all makes sense. I was wondering if it was something along those lines. I just generally hear about people getting more aggressive with their timing as they get into performance, not less. I don't think my build is that radical. But, as they say, "it likes what it likes".

For a "performance curve", it's one that Holley supplies with their software that's designed more for performance, as opposed to stock. Much like lighter springs on a mechanical distributor to bring the timing in faster.

Image

As far as your comment about it "indeed being detonation I'm hearing"... that's a problem I'm having.
I don't know what ping necessarily sounds like. I'm assuming what I'm hearing is ping, since it's a "rattle sound" from under the hood that doesn't sound much like anything else I've heard engine-wise, and it goes away when I lower timing.
As said above, I can drop timing by the touch of a button. So if I hear the sound, I can set the timing to a static 15°, feel the power of the engine change, but also hear the rattle sound go away. I'm assuming it's ping in that case.

I still could be wrong, as it could be a multitude of other things, like the way a more powerful cylinder fire sounds echoing through the exhaust, etc. but I don't think so.

I'm thinking of just making an obviously too aggressive timing curve and popping it into the computer, so that I can know it's pinging, and then know what the sound is.
1985 Ford Bronco Eddie Bauer. 300 I6. 9.1:1 CR, roller rockers, EFI manifolds and 2.5" exhaust. DUI ignition. 3.55 final drive, 5 speed ZF5. Holley Sniper EFI w/Offenhauser C Intake. 32" BFG KO2 A/Ts.

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Re: Engine doesn't like a lot of timing.

Post #4 by BigBlue94 » Tue Dec 03, 2019 5:47 pm

I can only throw in my experiences, since we have a similar engine. My compression is higher, but my cam is a touch smaller. 9.75 SCR, schneider 140h cam, 15cc step dish pistons, and larger valves.

I ran 89 octane all the way to moab without pinging. I have the DUI dizzy, but just the generic 300 tuned one from summit. Base timing is 14° BTDC. At one point I had to fill half the tank with 85 octane (!) and didnt notice pinging, but I was 7000 ft above MY normal altitude. I'm definitely not a pro at engine tuning, by any means. I'll be watching, carefully.
1985 Bronco. 309ci I6, NP435, 4.56 gears, Detroit locker and tru-trac, 4" lift, and 37" swamper tires. The 309 is 9.75:1 CR with a Schneider 140H cam, 4bbl, roller rockers, larger valves, and headers.

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Re: Engine doesn't like a lot of timing.

Post #5 by MechRick » Tue Dec 03, 2019 11:00 pm

It could be uneven mixture distribution.

Does the detonation sound like it moves around different cylinders or is it repetitive on one cylinder?
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

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Re: Engine doesn't like a lot of timing.

Post #6 by AbandonedBronco » Thu Dec 05, 2019 12:03 pm

BigBlue94 wrote:I can only throw in my experiences, since we have a similar engine. My compression is higher, but my cam is a touch smaller. 9.75 SCR, schneider 140h cam, 15cc step dish pistons, and larger valves.

I ran 89 octane all the way to moab without pinging. I have the DUI dizzy, but just the generic 300 tuned one from summit. Base timing is 14° BTDC. At one point I had to fill half the tank with 85 octane (!) and didnt notice pinging, but I was 7000 ft above MY normal altitude. I'm definitely not a pro at engine tuning, by any means. I'll be watching, carefully.


That's why I was bringing this up in the first place. It's not like I have some far out radical engine combination, and there are plenty of builds that are more so than mine. Your compression is a lot more than mine, too.
Plus, I run 91 octane regularly.

Lastly, as stated, DUI curved it specifically to my specs, which is something that's been done many many times for engine builders worldwide. It's nothing new. So why the detonation?

MechRick wrote:It could be uneven mixture distribution.

Does the detonation sound like it moves around different cylinders or is it repetitive on one cylinder?


I suppose anything's possible, but I would think the EFI setup I have would provide a pretty even mixture. More so than a carb.
As for moving around, I honestly have no idea. I've had to train myself to hear it over the engine and tires as it is.


Either way, I have my timing curve getting pretty close to fully eliminating all the ping. I cranked it up greatly for a drive (basically increased the whole thing by 25%. So, 25 became 32. 40 became 50. Etc. And all the noise I thought was pinging increased and became much more noticeable. So, I'm pretty confident what I'm hearing is pinging.

I have a few spots that need to be dropped a little bit, and it should be gone.

The hardest part to eliminate has been at 1700 - 2000 RPMs. Even at light throttle, it really doesn't like much timing. 25° is too much. I can run more than that at idle and it won't complain, so that's definitely odd to me.
1985 Ford Bronco Eddie Bauer. 300 I6. 9.1:1 CR, roller rockers, EFI manifolds and 2.5" exhaust. DUI ignition. 3.55 final drive, 5 speed ZF5. Holley Sniper EFI w/Offenhauser C Intake. 32" BFG KO2 A/Ts.

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Re: Engine doesn't like a lot of timing.

Post #7 by pmuller9 » Thu Dec 05, 2019 1:08 pm

I know you have done this before but would you just one more time verify that the TDC timing mark is actually TDC with the piston location.

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Re: Engine doesn't like a lot of timing.

Post #8 by AbandonedBronco » Thu Dec 05, 2019 1:12 pm

pmuller9 wrote:I know you have done this before but would you just one more time verify that the TDC timing mark is actually TDC with the piston location.


Yeah, this one keeps going through my head too. It seems like the timing mark is off.
However, recently, when I converted to computer controlled timing, I lined it up by putting a camera scope down in the cylinder and rotating the engine until I could visibly see the piston reaching its highest point. The timing mark was pointing at 0 when I did.

I'm going to triple check though. I'll also confirm again when I pull the head.
1985 Ford Bronco Eddie Bauer. 300 I6. 9.1:1 CR, roller rockers, EFI manifolds and 2.5" exhaust. DUI ignition. 3.55 final drive, 5 speed ZF5. Holley Sniper EFI w/Offenhauser C Intake. 32" BFG KO2 A/Ts.

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Re: Engine doesn't like a lot of timing.

Post #9 by MechRick » Thu Dec 05, 2019 2:01 pm

AbandonedBronco wrote:I suppose anything's possible, but I would think the EFI setup I have would provide a pretty even mixture. More so than a carb


Sometimes throttle body injection can behave very strangely. Airflow around the partially open throttle blades can move fuel and air around in very unpredictable ways. It can be worse than a carb, because most carbs are set up a bit fat everywhere. In that situation, even the leanest cylinder in an engine is richer than stoichiometric. A throttle body setup with an O2 sensor is going to average out all the cylinders leaving some lean and some rich with the exhaust combining to stoichiometric air/fuel at part throttle.

Also, carbs at part throttle have fuel exiting the transfer slots *below* the throttle plates. All fuel in a throttle body injection setup exits above the throttle plate.

Even multiport can have air distribution issues. The longer and more convoluted the intake runners, the higher chance of this happening.

I'm battling a ping on my big block multiport truck. If I set the timing where the truck runs best, I get a single cylinder knock. Back timing off to make the ping go away and I lose 20 HP. It could be an injector not putting out as much fuel as the rest, or 1 cylinder getting more air than the rest. One of these days I hope to figure it out.

Are you running a wideband? If so, you can set closed loop to run a bit rich, say 13.9:1 to see if your ping goes away. If it does, the problem is likely distribution-related. Changing the plenum volume or installing a baffle or two may fix it.
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

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Re: Engine doesn't like a lot of timing.

Post #10 by AbandonedBronco » Thu Dec 05, 2019 2:10 pm

Very interesting info. That makes sense, too.
Yes, the Sniper system comes with a wideband, and I can see the readout on my handheld display, which I have mounted on the dash.

Image

Image

Good idea about richening it up and seeing if the pinging goes away. Fortunately, I can save multiple tunes with pure ease, so I can modify one, upload it and test, and the reupload the original. Pretty slick.

Now, I don't know what caused my initial engine detonation damage, but it was all 6 cylinders. They all have lost compression, and all failed miserably when I did a leak-down test. I'm thinking that was the wear on the weights (as in my original post).

But do you think that with the cylinder compression compromised, even though all of them are still above 100, that some getting higher compression than others, or more seeping past the rings, could cause a distribution issue?
1985 Ford Bronco Eddie Bauer. 300 I6. 9.1:1 CR, roller rockers, EFI manifolds and 2.5" exhaust. DUI ignition. 3.55 final drive, 5 speed ZF5. Holley Sniper EFI w/Offenhauser C Intake. 32" BFG KO2 A/Ts.

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Re: Engine doesn't like a lot of timing.

Post #11 by MechRick » Thu Dec 05, 2019 7:17 pm

AbandonedBronco wrote:do you think that with the cylinder compression compromised, even though all of them are still above 100, that some getting higher compression than others, or more seeping past the rings, could cause a distribution issue?


Not with a TBI or a carburetor. If it were a multiport-injected setup or a diesel, I could see it.
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

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Re: Engine doesn't like a lot of timing.

Post #12 by AbandonedBronco » Fri Dec 06, 2019 12:48 pm

I think part of the problem I'm facing is I just don't know if what I'm hearing is spark knock / pinging.

I've been looking at YouTube videos for about an hour, and 99% of them are only explaining what detonation / pre-ignition is, but not what it sounds like or how to know if you're experiencing it.

So, I *think* the sound I'm hearing is pinging, as it goes away with less advance, but how do I know for sure?
I've heard all the tell-tale sounds people give, like shaking a paint can, marbles in the cylinder, BBs bouncing off a tin roof, etc... but engines make lots of different noises for different reasons.

I'd just like to know what it actually sounds like, so I'm not chasing some phantom sound that's not really ping.

Does anyone actually know of a source that lets you listen to what ping sounds like?
1985 Ford Bronco Eddie Bauer. 300 I6. 9.1:1 CR, roller rockers, EFI manifolds and 2.5" exhaust. DUI ignition. 3.55 final drive, 5 speed ZF5. Holley Sniper EFI w/Offenhauser C Intake. 32" BFG KO2 A/Ts.

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Re: Engine doesn't like a lot of timing.

Post #13 by pmuller9 » Fri Dec 06, 2019 1:11 pm

Detonation in a 4" bore has a frequency around 5.7 khz.
The best way to detect that frequency is to use a Knock sensor.
It will not respond unless it sees the high frequency signal and will distinguish between noises providing there aren't any background noises creating harmonics across that frequency.
Last edited by pmuller9 on Fri Dec 06, 2019 1:18 pm, edited 1 time in total.

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Re: Engine doesn't like a lot of timing.

Post #14 by AbandonedBronco » Fri Dec 06, 2019 1:17 pm

I was asking about that a little while back on the Sniper forum.
The 4.9 does come with a knock sensor in later years (although it seems to be quite difficult to find anyone who makes a replacement).
The Sniper has custom inputs that I can record and display on the data logging.

I was wondering if I could hook up a knock sensor and then look back over the data and see if it ever goes off, and if so, lessen the timing in that area.

I was told that that wouldn't work, and was really just a shot in the dark. The best way to set the timing is on a dyno and time each part of the curve for optimal horsepower.

However, I'd love to go the knock sensor route if that's an option. Get one installed, run a wire from it to one of the custom input wires on the Sniper, and record the data as I drive.

Do you think it could be as simple as that? If so, do you have a recommendation on a sensor?
1985 Ford Bronco Eddie Bauer. 300 I6. 9.1:1 CR, roller rockers, EFI manifolds and 2.5" exhaust. DUI ignition. 3.55 final drive, 5 speed ZF5. Holley Sniper EFI w/Offenhauser C Intake. 32" BFG KO2 A/Ts.

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Re: Engine doesn't like a lot of timing.

Post #15 by guhfluh » Fri Dec 06, 2019 1:21 pm

pmuller9 wrote:Detonation in a 4" bore has a frequency around 5.7 khz.
The best way to detect that frequency is to use a Knock sensor.
It will not respond unless it sees the high frequency detonation signal.

That only works if using a narrow band sensor tuned to the specific frequency of the specific bore size(still with filtering) or a wide band sensor with filtering specific to the bore size as well. Even then, the tuning is problematic.

I'd suggest trying some race gas. Keep the timing high (not crazy) where you think you hear it with the 91 octane, then throw in a good mix of race gas that will certainly quell the knock. If you still hear it, you know it isn't knock. You can use an additive instead, such as "Boostane" or similar that may be a little cheaper than a few gallons of race fuel, or easier to get.
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

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Re: Engine doesn't like a lot of timing.

Post #16 by pmuller9 » Fri Dec 06, 2019 1:22 pm

Can you find one on a 4.9 in the wrecking yard just to try it?

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Re: Engine doesn't like a lot of timing.

Post #17 by guhfluh » Fri Dec 06, 2019 1:28 pm

The only two knock modules I'd consider trying would be from Plex or Link.

Knock sensors need electronic circuitry to handle the small mv signal the sensor outputs and convert it to something useable. The sensor is basically just a microphone. I have wired a wide band sensor to a microphone input on a laptop and used headphones to listen to the noise before, but you're still using your ears and brain to discern knock from noise. It's not much different than using a normal mic and "det cans".
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

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Re: Engine doesn't like a lot of timing.

Post #18 by pmuller9 » Fri Dec 06, 2019 2:10 pm

Most knock sensors contain a piezoelectric element (crystal) that is tuned for the specific frequency that is produced by a particular engine and is a narrow band device.
Output is in tenths of a volt, the amplitude depending on the intensity of detonation and can be used directly with the Holley EFI systems.

There are wide band acoustic sensors but are mainly used to research the frequency of detonation and require a special interface.

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Re: Engine doesn't like a lot of timing.

Post #19 by guhfluh » Fri Dec 06, 2019 2:44 pm

pmuller9 wrote:Most knock sensors contain a piezoelectric element (crystal) that is tuned for the specific frequency that is produced by a particular engine and is a narrow band device.
Output is in tenths of a volt, the amplitude depending on the intensity of detonation and can be used directly with the Holley EFI systems.

There are wide band acoustic sensors but are mainly used to research the frequency of detonation and require a special interface.

I somewhat disagree.

Narrow band "resonant" sensors were used in the 80s and 90s and we're marginal at best even when used with factory control systems. Most every manufacturer has started using the common Bosch wide band sensor since the turn of the milinneum.

Please show where the Holley Sniper EFI system can take a direct knock sensor input signal and do something with it.
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

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Re: Engine doesn't like a lot of timing.

Post #20 by AbandonedBronco » Fri Dec 06, 2019 3:01 pm

guhfluh wrote:Please show where the Holley Sniper EFI system can take a direct knock sensor input signal and do something with it.


On second look, it appears that only the Super Sniper can do that. Bummer.
But, it comes with 3 input wires which can be configured. Basically, just showing between 1 and 5 volts. Not sure what the knock sensor puts out, but I imagine it converts whatever signal its getting to a voltage.
1985 Ford Bronco Eddie Bauer. 300 I6. 9.1:1 CR, roller rockers, EFI manifolds and 2.5" exhaust. DUI ignition. 3.55 final drive, 5 speed ZF5. Holley Sniper EFI w/Offenhauser C Intake. 32" BFG KO2 A/Ts.

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Re: Engine doesn't like a lot of timing.

Post #21 by pmuller9 » Fri Dec 06, 2019 3:27 pm

guhfluh is correct.
I made too broad of a statement in both cases.

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Re: Engine doesn't like a lot of timing.

Post #22 by guhfluh » Fri Dec 06, 2019 3:56 pm

AbandonedBronco wrote:
guhfluh wrote:Please show where the Holley Sniper EFI system can take a direct knock sensor input signal and do something with it.


On second look, it appears that only the Super Sniper can do that. Bummer.
But, it comes with 3 input wires which can be configured. Basically, just showing between 1 and 5 volts. Not sure what the knock sensor puts out, but I imagine it converts whatever signal its getting to a voltage.

You may be able to use a standalone knock monitoring system that can output a 0-5v analog signal, or even a ground at a desired amount of knock and use one of the Sniper inputs to retard a certain amount based on the input. It could be done on a "nitrous input" signal, but I'm not sure the base Sniper firmware allows it, or any timing change based on any input. At any rate, it would be fairly involved and either require a lot of tuning of the external knock signal circuit, or a big expense, or both.

At the low cost end of the spectrum, hose type or electronic mic type "det cans" really can't be beat, though you do need to learn what it sounds like.
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

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Re: Engine doesn't like a lot of timing.

Post #23 by guhfluh » Fri Dec 06, 2019 5:08 pm

Speak of the devil...

https://www.facebook.com/groups/megasqu ... 6&sfnsn=mo

Link G4 knockblock just posted for sale on Facebook MSEFI group.
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

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Re: Engine doesn't like a lot of timing.

Post #24 by AbandonedBronco » Mon Dec 09, 2019 5:03 pm

Makes sense.

I was looking at the Sniper software, and it was a cakewalk to set up the input to respond to a custom voltage signal, and perform actions like lower the timing, etc. However, I'd have to upgrade my Sniper ECU to support it. So that idea's out.

However, I've been doing some reading and research on detonation, and everything that I find states that it is more prevalent when the engine is under load. I find I'm getting worse pinging noises when I'm at light load (timing increases due to low load). Could there be something else making this noise? It DOES reduce / go away with decreases in timing, but it just doesn't seem to make sense.

The other thought that I had. I am using EFI era spark plugs in a non-EFI era cylinder head. It was never really an issue before, and I had someone recommend it to me about 10 years ago, and have use them ever since. But could there be a compatibility issue with their design/heat range, etc. that were fine for a stock engine, but not with a high compression, high performance setup? Maybe I need to use carb era plugs? Or a different plug altogether that better matches my engine?
1985 Ford Bronco Eddie Bauer. 300 I6. 9.1:1 CR, roller rockers, EFI manifolds and 2.5" exhaust. DUI ignition. 3.55 final drive, 5 speed ZF5. Holley Sniper EFI w/Offenhauser C Intake. 32" BFG KO2 A/Ts.

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THE FRENCHTOWN FLYER
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Re: Engine doesn't like a lot of timing.

Post #25 by THE FRENCHTOWN FLYER » Mon Dec 09, 2019 6:30 pm

AbandonedBronco wrote:...I am using EFI era spark plugs in a non-EFI era cylinder head. It was never really an issue before, and I had someone recommend it to me about 10 years ago, and have use them ever since. But could there be a compatibility issue with their design/heat range, etc. that were fine for a stock engine, but not with a high compression, high performance setup?

No. I doubt it. I use them in a 12.5:1 race engine.
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guhfluh
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Re: Engine doesn't like a lot of timing.

Post #26 by guhfluh » Tue Dec 10, 2019 6:43 pm

I haven't looked up the info, but as far as I can tell looking at them, they are around the same "heat range" plugs, just the EFI plug electrodes are much longer. I can see it creating a hot spot for preignition in an extreme scenario. I think I'd want to run a cooler plug in a forced induction application. I have wanted to see if it made a difference in my truck, as I get ping and dieseling with low grade fuel and I run EFI plugs as well.
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

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