KA24DE mechanically locked timing tensioners
Posted: Thu Nov 20, 2014 7:08 pm
Hello all,
So some of you know I was heavy into all motor ITB's setups several years ago. After smashing through some goals, I set some goals that I could not acheive as I could not justify spending the kind of money in the head I was going to have to. During that time I went through some hiccups like everyone does. Mostly bending INTAKE valves, bending the snouts on the crankshaft, and blowing out the tensioners freeze plugs. After giving up on the all motor route, I planned to install an eaton M112 onto a ka and setup a 7:1comp motor for that with the monster port head some of you might remember. That motor sits in the corner waiting for me to hit the lottery to finish the blower setup. That motor also houses the version 0 of the locked tensioner. It required external adjustments(outside the covers) and was just a pain in the ass to work with.
Recently i came up with a way that the average person would be able to own/setup and enjoy the mechanically locked tensioner. But first lets discuss why I came up with this idea. Several times I would go to driving events or drift events and at the end of the day had a poor running car. Turns out most of the time the intake valves had tapped the pistons. HOW is this possible!? i thought.
In a normally and physically stable running engine, the intake valve is only close to the piston during opening events. The exhaust valve is only close to the piston near closing events. Whenever there is a valvetrain problem or float it ALWAYS shows up with the exhaust valve. So when I set cam timing and have nearly .040" to .060" of piston to valve clearance how is it bending intake valves.
I believed I found the problem years ago and finally mustered up to prove it as i believe it to be. The hydraulic (engine oil pressure supplied) tensioners were collapsing and allowing cam timing to be changed. This can happen 3 ways, first; during cranking with low oil pressure. The second, a rapid engine deceleration; standing on a revlimiter or a very hard gear change with a stiff clutch. The third is when the engine is cranking and for whatever reason as there are many, the engine kicks back hard on the starter. Basically the engine is being forced backwards counterclockwise rotation by a combustion event that started wayyyyy before the normal 30deg btdc to 0deg btdc.
So the tensioners are fed by the engines oil pressure, which is anywhere from 20-70psi depending on rpm, bearing clearances ect ect. The factory tensioners do employ a ball check valve to slow oil being displaced from the tensioners. However there are still openings that supply oil to the chain.
Now think about installing springs with 80 to 100lbs on the seat, much higher than factory. Then add a high lift high duration camshaft. Those tensioners are starting to hate life and without enough oil pressure to keep them tensioned, I believe they move.
So I setup a mockup engine with .060 thick copper washers to act as the thickness of a HG, built the tensioners and setup the camera. Heres some pics and some vids. While i've never bent any valves on stock springs and camshafts, i have with aftermarket stuff. There are a handfull of stories local and from the past that inspired me to act on this. All of them were intake valves and all of them you couldnt tell unless you put the valves in a drill. Tell me what you think!!!!
I built enough to sell extras if you want, they'll be posted in the forsale section when the stainless hardware I ordered comes in.
VIDEOS demonstration below on a mock up block
I tried to embed the videos. heres the direct links. help me if you can
http://www.youtube.com/embed/Zw7ZIKuYHh ... m70uj4htpQ
http://www.youtube.com/embed/UfCWfrd94x ... m70uj4htpQ
So some of you know I was heavy into all motor ITB's setups several years ago. After smashing through some goals, I set some goals that I could not acheive as I could not justify spending the kind of money in the head I was going to have to. During that time I went through some hiccups like everyone does. Mostly bending INTAKE valves, bending the snouts on the crankshaft, and blowing out the tensioners freeze plugs. After giving up on the all motor route, I planned to install an eaton M112 onto a ka and setup a 7:1comp motor for that with the monster port head some of you might remember. That motor sits in the corner waiting for me to hit the lottery to finish the blower setup. That motor also houses the version 0 of the locked tensioner. It required external adjustments(outside the covers) and was just a pain in the ass to work with.
Recently i came up with a way that the average person would be able to own/setup and enjoy the mechanically locked tensioner. But first lets discuss why I came up with this idea. Several times I would go to driving events or drift events and at the end of the day had a poor running car. Turns out most of the time the intake valves had tapped the pistons. HOW is this possible!? i thought.
In a normally and physically stable running engine, the intake valve is only close to the piston during opening events. The exhaust valve is only close to the piston near closing events. Whenever there is a valvetrain problem or float it ALWAYS shows up with the exhaust valve. So when I set cam timing and have nearly .040" to .060" of piston to valve clearance how is it bending intake valves.
I believed I found the problem years ago and finally mustered up to prove it as i believe it to be. The hydraulic (engine oil pressure supplied) tensioners were collapsing and allowing cam timing to be changed. This can happen 3 ways, first; during cranking with low oil pressure. The second, a rapid engine deceleration; standing on a revlimiter or a very hard gear change with a stiff clutch. The third is when the engine is cranking and for whatever reason as there are many, the engine kicks back hard on the starter. Basically the engine is being forced backwards counterclockwise rotation by a combustion event that started wayyyyy before the normal 30deg btdc to 0deg btdc.
So the tensioners are fed by the engines oil pressure, which is anywhere from 20-70psi depending on rpm, bearing clearances ect ect. The factory tensioners do employ a ball check valve to slow oil being displaced from the tensioners. However there are still openings that supply oil to the chain.
Now think about installing springs with 80 to 100lbs on the seat, much higher than factory. Then add a high lift high duration camshaft. Those tensioners are starting to hate life and without enough oil pressure to keep them tensioned, I believe they move.
So I setup a mockup engine with .060 thick copper washers to act as the thickness of a HG, built the tensioners and setup the camera. Heres some pics and some vids. While i've never bent any valves on stock springs and camshafts, i have with aftermarket stuff. There are a handfull of stories local and from the past that inspired me to act on this. All of them were intake valves and all of them you couldnt tell unless you put the valves in a drill. Tell me what you think!!!!
I built enough to sell extras if you want, they'll be posted in the forsale section when the stainless hardware I ordered comes in.
VIDEOS demonstration below on a mock up block
I tried to embed the videos. heres the direct links. help me if you can
http://www.youtube.com/embed/Zw7ZIKuYHh ... m70uj4htpQ
http://www.youtube.com/embed/UfCWfrd94x ... m70uj4htpQ