Engine pre ignition knock

[Oldcarbuff]

Is this forum still alive? 
My engine when warm seems to have a pre ignition knock doesn’t do it when cold could it be a carbon build up?

[rocketraider]

What engine? 70s Ford engines were prone to that.

 

What weight oil and what is your oil pressure? Just to make sure it's not a wrist pin or rod knock.

 

If determined it is a detonation problem, make sure engine is not overheating. If it's an EGR engine, make sure the valve functions.

 

What octane fuel are you using? 87 octane in an engine over about 9.5:1 compression can cause it.

 

Run a couple cans of SeaFoam or Chevron Techron fuel system cleaner thru the tanks. Sometimes that will clean up carbon buildup. 

[Oldcarbuff]

This is on a 1909 single cylinder Brush engine 

[edinmass]

Nope.......could be lots of things..........check your base timing. Running too much advance will pound on it..........also check fuel.

Edited December 23, 2021 by edinmass (see edit history)

[Mark Gregush]

You might go back and edit your title, would help get more eyes on it.

Like the car.

Oh! There is a Brush forum way down the list; https://forums.aaca.org/forum/126-brush-automobiles/

Edited December 24, 2021 by Mark Gregush (see edit history)

[Akstraw]

I agree that checking timing should be the first step.  I recently looked closely at the timing on a 1909 2-cyl Maxwell using the setup shown.   I used a ‘whistler’ to find TDC for each cylinder, and setup a pair of plugs on a piece of angle iron bolted to the engine so that I could see exactly when the spark was occurring for each cylinder.   Then with the working plugs removed, I was able to turn the engine by hand thru the cycles and mark just where each spark was happening relative to TDC (at a fixed position of the spark advance.)  What I learned was that my timer was imbalanced, so to speak:  There was an offset of about 7 degrees of timing between the two cylinders.  I was also able to mark on my spark advance lever exactly where is TDC.

[Akstraw]

By the way, it could be carbon buildup as you say.  Carbon retains heat, sometimes enough to ignite the air/fuel mixture prematurely.  I have noticed that many of the very old owner’s manuals recommend once-a-year removal of the head to scrape away the carbon.

[Gary56]

Check the valve clearance,  also check the cap for cracks

[Oldcarbuff]

Thanks next week it will get in my shop to remove head and check things out. 

[Mark Gregush]

It would not have a head to pull.

[jim43]

     I have an old  head carbon cleaning outfit which resembles dentist hygienist tools, only heavy duty. Enough different shapes so scraping could be done through the spark plug hole. Probably a must for non-detachable heads.  It all folds up in its metal box. I have used it in the past on non-detachable head Chalmers and others.  If anyone is interested in it get in touch.   JIm43

 

[edinmass]

Do you want to remove carbon from a single cylinder engine, just use a spray bottle with water in it. Running at 2/3 throttle fully warm, just keep spraying the water into the intake until you put two or 3 ounces through it. It’ll be perfectly clean in minutes. 
 

The odds of it being carbon causing a early fire are about zero.

 

10 to 1 says it a lean burn misfire or timing issue.

Edited December 24, 2021 by edinmass (see edit history)

[Frank DuVal]

Yep, water poured with proper precautions through the carburetor works on many engines, even Chevrolet V-8s. Always a good idea, but never remembered in time, to do the water trick before disassembling an engine. Makes the heads cleaner during disassembly. It also cured the spark knock of my aunt's '65 283 PG Chevelle that was just city driven.😉

[Hans1]

In the 50's and 60's 

 

Used pop bottles as applicator method.

Liked straight side bottles from orange crush,  as curvy sided bottles, you know,  did not apply the the same amount per degree of tippage.

Did not want to put the fire out.

Edited December 27, 2021 by Hans1
spelling (see edit history)

[JFranklin]

We used the hose with the nozzle at a fine mist. watered the carb for a minute or so until it (the cool engine) stumbled and quit. Only do on a cool engine. Then we went one step farther and let it sit over night. Dont stand behind the car when it is started the next day. I learned this in auto shop from a good mechanics teacher!

Edited December 27, 2021 by JFranklin (see edit history)

[Mark Gregush]

It is a single cylinder 1909 Brush.