Loud ticking when engine running

[Maximus Gladius]

Run 89 cuz your engine is pings with 87?

Our pumps in Canada say, at the gas pumps (87 clean), (89 cleaner), 92+ cleanest).

It SHOULD say, (87 really dirty), (89 less dirty), (92+ least of the dirty).

But between you and me, I think the numbers mean the burning speed of the octane from slow to fast or maybe it’s fast to slow, (someone else more knowledgeable than me can clarify) to mitigate the pre ignition pinging. If you don’t have pinging at 87, any octane number higher is just a waste of money.

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[ShadowsPapa]

Our pumps in Canada say, at the gas pumps (87 clean), (89 cleaner), 92+ cleanest).

It SHOULD say, (87 really dirty), (89 less dirty), (92+ least of the dirty).

But between you and me, I think the numbers mean the burning speed of the octane from slow to fast or maybe it’s fast to slow, (someone else more knowledgeable than me can clarify) to mitigate the pre ignition pinging. If you don’t have pinging at 87, any octane number higher is just a waste of money.

Octane is resistance to self-ignition under heat and pressure, not burn speed or cleanliness.
The pinging you typically might hear in some engines isn't pre-ignition, it's detonation.
Detonation happens as the unburned part of the charge is cornered and compressed by the advancing flame front and happens AFTER the spark plug fires.

Preignition is lighting the charge before the spark, thus the "pre" bit.
Preignition is typically caused by hot spots, incorrect spark plug heat range, carbon buildup and so on.
Detonation is caused by heat and pressure and takes time to occur.
Higher RPM engines seldom have any detonation issues - they burn the charge too fast for the remainder to reach a self-ignition point.

Octane resists self-ignition with more complex molecular chains.

The only reason to use "premium" in these MAY be because some companies add different additives and detergents to the more expensive gas (often to justify the cost and get people to buy it rather than the cheaper stuff)

I've always put in whatever is recommended except for a couple of times I experimented for a while - and found no justification in the form of better performance or better mpg. It was pretty much a wash. I did notice a slightly different engine sound in my 2020 using 93 for a short time, but that can be explained by the PCM adjusting the valve and ignition timing to allow for the higher octane fuel - less likely to detonate, so pressures and timing can be increased, but it wasn't any real measurable gain (mpg) or anything I "felt" in the butt dyno.

Also - a few people will jump and shout - but...but...but 11.3:1 compression!!!!!

Yeah, ok, that's theoretical static ratio.
Operation compression or dynamic compression and compression pressures can be modified by cam/valve timing, lift and so on.
Static assumes you fully fill that cylinder to the point that's all the air it will hold at atmospheric pressure.
Dynamic can be higher or lower depending on many factors.
So you aren't necessarily operating at that static number or pressure when running - it's capable of that, but isn't always running there.

I wanted to lower the compression of my 1970 390 as they were known for detonation issues.
I put on larger chamber heads, figured I'd dropped it by a good half point.
The problem is - I also stuck on free-flow exhaust manifolds, a Comp xtreme energy cam and a performance intake - in the end raising the dynamic pressures quite a bit.

 

[Stan H]

Run 89 cuz your engine is pings with 87?

Not on the blacktop but did notice e that on steep inclines it would so started running 89 no ping .

 

[Sandman 4x4]

It would be quite interesting if there were Isky cams for these engines.

Oh yea! I remember back in the day I would replace a stock cam in my SBC, add headers and fat dials. The sounds were glorious! For the time the low end response, especially on the beach or boat ramp was fantastic. Along with the extra passing power.

 

[Verne]

Seafoam. That's the direction I'd go these days. There are other good ones, but I still have yet to see anyone make negative comments on it.

For me it's just for my 4.0 (in my car) with SHORT DRIVES and infrequent drives and sticky used/rebuilt injectors.
I've seen a number of folks comment about "quieting injectors". For my 4.0, it smooths idle on those old rebuilt injectors. I bet they have 150,000 miles on them.

Would you recommend filling the tank up and then dumping in a can or should I use a higher concentration. 50K miles. Never done before.

 

[ShadowsPapa]

Would you recommend filling the tank up and then dumping in a can or should I use a higher concentration. 50K miles. Never done before.

I put it in the tank, then fill. I don't trust just driving to mix it well but the force of the gas going in should do a good job.

Results of course will vary with the condition of the engine, injectors and other things.

 

[Stan H]

Would you recommend filling the tank up and then dumping in a can or should I use a higher concentration. 50K miles. Never done before.

Yes on a Full tank

 

[Stan H]

I put it in the tank, then fill. I don't trust just driving to mix it well but the force of the gas going in should do a good job.

Results of course will vary with the condition of the engine, injectors and other things.

It hasn't been an issue for me since that gas get jostled around alot .

 

[MPMB]

I've always put in whatever is recommended except for a couple of times I experimented for a while - and found no justification in the form of better performance or better mpg. It was pretty much a wash. I did notice a slightly different engine sound in my 2020 using 93 for a short time, but that can be explained by the PCM adjusting the valve and ignition timing to allow for the higher octane fuel - less likely to detonate, so pressures and timing can be increased, but it wasn't any real measurable gain (mpg) or anything I "felt" in the butt dyno.

Same. No noticeable difference between gas types. The only thing that has made a difference in MPG (other than weight) is altitude and flat land, like in Jackson, WY. Get 18mpg without much work.

 

[ShadowsPapa]

Same. No noticeable difference between gas types. The only thing that has made a difference in MPG (other than weight) is altitude and flat land, like in Jackson, WY. Get 18mpg without much work.

I noted a fair difference in mpg between our home area, even driving east to IL, the once in IL where things really flatten out, I get a jump in mpg. Same in FL - mpg went up. Can say that for the JT and JLU.

 

[JTGuy]

I run nothing but 91 as it protects the cam and trans better,,, LOL

 

[Apothum]

Update: Took it in. The service guy and the head mechanic listened to it for a minute and confirmed it’s just loud injectors and it’s common on the latest 3.6 to just make a lot of noise. They said if it was the lifter/cam issue it would sound like a wrench tapping metal and would be much louder. So totally normal, glad it’s nothing and good on jeep for not taking it for a whole week to tell me nothing is wrong. Got a lot of time left on my warranty so they said I’m good.

 

[RHINO79]

What I figured it was.

 

[Batterycap]

It is a gas, sorry should have included. So does this mean a dealership trip is in my future

Yes, on the back of a rollback.

 

[imallcrawl]

Update: Took it in. The service guy and the head mechanic listened to it for a minute and confirmed it’s just loud injectors and it’s common on the latest 3.6 to just make a lot of noise. They said if it was the lifter/cam issue it would sound like a wrench tapping metal and would be much louder. So totally normal, glad it’s nothing and good on jeep for not taking it for a whole week to tell me nothing is wrong. Got a lot of time left on my warranty so they said I’m good.

Very good to know!

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