What do you guys think of these photos of a few of the water jacket holes in my old L-Head? I planned on getting it milled anyway. Sent from my iPhone using H.A.M.B.
Any idea how to check the valve clearance to see how much I can mill? Anyone know how far away I should stay with the head from valves? I’ve been told I can go ten thousands off but would like more compression increase if possible, they only had 6.25 factory. Sent from my iPhone using H.A.M.B.
Take children's Modeling Clay & put a marble sized ball on each valve on the edge closet to the head, spray the combustion chambers in the head with WD-40(keeps the clay from sticking to the head) then carefully so as not to knock them off, set the head WITHOUT the head gasket on the motor(use 2 head bolts for alignment, but no need to tighten them), rotate the engine through 2 revolutions, remove the head & note how much the clay has been deformed. if there is at least .060" clearance on the intake valves & .090" clearance on the exhaust valves, you'd be "good" milling up to the thickness of the head gasket( ask your machinist for his recommendations), but at least .060" removed is usually "safe", & will raise compression 1 full point(in your case, up to 7.25). Only going .010 doesn't do much of anything, except "pass money" to the shop.
BJR & Sunbeam: I was able to locate (code for found it in all my crap) a head gasket for it so I have an idea how it will fit around the holes. It’s kinda surprising to see how some gasket holes are right on & others are quite a bit off. drtrcrV-8: excellent idea I will give it a go today! I’m sure I still have some play dough around here. Do you think I should do only one cylinder, a few or all incase of variances? The good thing is the valves were just adjusted so they are at least where they should be. I have a button on my starter to rotate the engine & my remote starter switch arrives today so I’ll get a chance to use that too. At least I assume I can turn the engine over this way vs by hand. Sent from my iPhone using H.A.M.B.
By hand is how it should be done. One stroke is all that is needed. Another thing. Solid or hydraulic lifters in your engine?
Play it safe : it only takes a few minutes to do it right., so do them all. I recommend 2 revolutions( Johnny Gee : 4 stroke motor turns over 2 times to activate all the valves!!) Machining .060 should take care of the erosion around the water holes to give you a nice clean surface.
Why don't you just ignore it and put the engine back together. What problem could it cause? If you want to mill the head to gain compression that is fine (I never liked that approach) but don't mill it just to clean up the eroded area. Charlie Stephens
Johnny Gee : On an L-Head it's not about the valves "chasing the pistons", but rather valves "hitting the underside of the head", which is why I suggested "claying" as a quick & easy way to determine valve to head clearance.
Thanks for the great help! I did some initial measurements and was quite surprised at what looked to be a great deal of room over the valves. Not knowing the thickness of the valves, I have some dismantling & work to do to determine if new valves are needed. If they are it will change everything I’ve measured thus far. With that said, I made a couple balls of play-doh & placed them on both the valves in cylinders 1 & 2, after applying some WD40 to the valves to keep them from sticking. Great suggestion BTW! Since I didn’t use WD40 in the combustion chamber they came off with the head after turning the engine over a few times. Gently removing & measuring them I came up with the following values. Space above valves: Cyl 1: Ex- 0.367” In- 0.419” Cyl 2: Ex- 0.371” In- 0.414” Like I said I was rather surprised at just how much room was above the valves. After I determine if these can be reused or if new valves are needed I will redo this with more Play-doh to see how much room there is at edges of these valves as well as on the top. I guess the next question would be just how much to remove to raise compression approximately 1 point? Here are some photos: Current image of block: Play-doh valve test: Block after Head removed & a little piston top clean up to read markings: Photo of valves from a couple years ago when I had one stuck valve. Easily resolved then but it gives an idea of what they look like in this old Hudson Engine. Since she has side valve cover & I’m not really wanting to remove the intake & exhaust manifolds again, is there a valve tool which may work on the side valves? Sent from my iPhone using H.A.M.B.
This is the spark plug installed in the head. I don’t know how far they are supposed to go into the combustion chamber but it surprised me how little it came in. Also the spark plugs are placed directly over the exhaust valve. Does anyone know if that placement effects how much I’d want to mill or how much to not mill the head? I assume I have so much space even taking off 60 thousands isn’t going to effect things but need to ask. Sent from my iPhone using H.A.M.B.
Remove one spark plug & measure from the flat where the plug seats (outside the head) to the bottom of the hole (inside the head) & you could use spark plugs of the same heat range that have a thread length of 3/16" to 1/4" less than the distance measured. This would definitely "unshroud" your spark.
In the case of the plug over the exhaust I think it would be well worth "Indexing" the plugs when you install them to make sure the open side of the electrode is pointing towards the intake valve. Easy to do with the plugs right on top of the engine.
At the machine shop I worked at we would cut Model A heads up to .090. I don't think the erosion is a problem but I would cut the head for compression.
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