Got About 35 Hrs On The New Stroker.now I Have Devoloped A Light Knocking Sound.been Playing With Bbc's All My Life And Never Heard One Sound Like This.not A Deep Bottom End Knock,but Too Deep To Be Valvetrain.turns Out That Due To Extended 4500rpm Running(2-3hrs) With One Of My Valve Covers Vented To The Flame Arrestor Oil Was Steaming Into The Carb And Building Up On The Pistons.causing The Knock.hate To Pull The Heads And Now That The Valve Covers Are Vented To A Puke Tank W/breather It Won't Get Anymore.does Anyone Know Of A Chemical I Can Send Thru The Carb/intake With The Engine Running That Might Help Clean Out The Buildup?an Old Timer Said To Mist In Some Water With A Squrit Bottle To "steam Clean"the Cyl. Or Do You Think Carb Cleaner Would Be Better?i Know I Should Pull It And Do It Right ,but If I Can Avoid It I Would Rather Not Pull It,thanks.

How would that cause a knock???

Built Up Burnt Oil On Top Of Piston Slapping The Head,like A Carbon Deposit Knock In A High Mileage Car That Never Sees Any Rpm.

Try seafoam.

I agree. plus, with the amount you have you can shoot some carb cleaner in while it is running. when done you'll have to change the oil, then change it again after taking the boat out.

YUP,

Seafoam, follow the directions on the can.

well.......... i suppose... but what you are describing is, for all intents and purposes is what every PCV system in existance does... and every motor alive doesn't do this.

stop kidding yourself. if your motor pushes SO much oil out the breathers at 35 hours that you think you have this build up problem then you have some OTHER problem , far more important than the issue you are trying to address. do a leakdown. ill bet you have 40 % by the rings. and ill bet you are one of these guys that runs 150 deg of water temp and huge " marine" piston to wall clearences.....

and why do you capitalize every word when you write ?

Pour water down the carb while running at high idle , if it's carbon it will be blasted out after a while ..if the noise is still there it may be
a piston rocking...

This stuff works great on cleaning out Carbs.......

https://www.amsoil.com/storefront/apf.aspx

Its also a great degreaser for anything that you want to clean.

General Motors markets a product called TEC (Top Engine Cleaner). It does a better job then I can do with a wire wheel and piston in hand. Buy two pints, make sure the engine is up to temperature, and follow the directions. part number 105002

Wingnut