Valve Train Overhaull.
Posted in Valve Train Overhaul on April 21st, 2009 by SkipCaution, don’t attempt this overhaul if you don’t have some sort of experience. This is a long and vary demanding mod that should only be done by an experienced person. Done wrong this can cause extreme amounts of damage to the engine.. Just because you see me share it, that doesn’t make me the professional. Even myself find it important to have a professional head rebuild.
Below you see a couple of heads and some tools. Great, so what am I up too. Well you see I found that one of my boats had ingested some moisture before storing it, this moisture had rusted and caused the valve train to lock with exhaust valves slightly open. Ya the performance sucked. Even after fogging the SC I did not do the motor itself and found a huge drop in performance. Did Compression check and found #4 really low on compression. This low compression in my case was cause by the rusted Valves to not closing properly. Ok so lets overhaul the head.
Below is a shot of rusted up stuff that needs to be thrown away. Some might just clean them and reuse em. If not pitted on the seat side then you could reuse them but your running a gamble. Not here, no way. Rust will pit metal and fatigue it to the point it may fail and a failed valve is catastrophic.
Look at what a dropped valve is capable of doing to your motor. This is a pic of a dropped exhaust valve from rust and it sticking in the valve guide. Item in pic are all the items needed to be replaced due to damage.
This is a shot of the rusted valves that I want to discard in favor of new ones. Notice how the exhaust valves are so rusted on the valve stem that they cant shut all the way.
First thing was to get the head into pieces, removing the valves will show any valve seat or guide damage. I use a Deep 13mm socket on and extension and pop it with a rubber mallet to pop out the keepers holding in the valves.
Go ahead and grab the springs out. I use a magnet to catch the springs, keepers and collets. Be careful of the small collets. You need to reuse them so don’t loose any.
Here is a shot of the rusted valve seats. This type of corrosion if bad enough may need to be sent off to have valve seats re-cut. Some can do it but I at the moment cant nor care too. Mind you the rust is actually from the valve themselves as the head is made of aluminum.
Thankfully with cleaning in the parts cleaner and wire brushing the head really good, I was able to clean the surface well enough or at least good enough to continue on. When clean you must inspect the valve seat for pitting or damage.
Before washing the head you may want to run a reamer through the valve guides just encase some corrosion has accumulated in them. Valve Guide Reamer part # 57001-1204
Dirty Head verses cleaned head…..
I used a tool magnet to remove the valve spring seat before cleaning and to reinstall it during assembly.
Now for the boring part. The long slow process of Lapping a valve into a head. This needs to be done weather the valves or head is new or a combination of either being new. New head with old valves = Lapping or new valves old head = Lapping or new head and valves = Lapping. Getting the drift here, Lap it!.
OK start by laying out your work site. Get it organized now or you’ll find that you will be doing the job twice. What I do is lay the head on a towel with the timing chain cavity to my right hand side. This is then marking my #1 valve location. Notice my brand new valves in the picture and how I lined them up together in a row with Exhaust and Intake in order as the head sits. Keep them in order even as you work. Once a Valve is lapped to a seat then you want to keep them together. You just matched them together and moving then to another seat would not be matched any more.
Ok now watch closely.
First I used engine assembly lube to dip the valve stem into and set it in the valve guide to provide lubrication while lapping.
Add lapping compound to the valve and allow it to rest into the seat.
Allow it to drop and role in hands like your trying to make fire with two sticks. No pressure is needed to do this properly. Continue this till you hear that the grinding sound is getting quiet. You’ll here it when its ready to reload it.
Lift rotate and allow to resettle into the seat.
Again attempt to make fire and follow this routine for about five times per valve.
The valves should look like the pic below. The edge should be a dull grey color.
When your done then CLEAN IT GOOD. Part washer works good for me. DON’T GET THE VALVES OUT OF ORDER!!!!
Be sure to blow out your valve guides.
Now that she is all cleaned up its time to rebuild her. You’ll want to follow this method as it ensure a short rebuild time and less mistakes.
First you want to installed your cleaned Valve Spring bottom seat. Then the Valve seat seal. Once done with those two then insert your new lapped valves into the head in order they are suppose to go. Be sure to use some assembly lube or motor oil to allow the valve to gently push up through the seal without tearing it. When installed they look like this.
Now for the springs to be installed. Small springs inside the larger ones. Notice that these are red. Exhaust is red and intake is blue. Dont mix them up.
Next the top seat with collets.
Drop in over the proper valve. Remember blue is intake and red is exhaust. Once in place then use special tool for setting collets.
Tool in action!
Results of tool, one on right is set and one on left is waiting to be set by tool.
Once those are complete then you’ll want to install the head to properly gap the bucket shims.
Thats coming up next. Common I gotta keep you interested don’t I?
Break!
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The pump intake is off a 15F bored over to allow fitting of a Skat Trak Magnum pump.
