--- Imperial59crown@xxxxxxx wrote:
> Also, how hard is it to do a valve job? Remember, I failed carburetor
> 101 by
> not removing the metering rods before putting back together the two
> halves of
> the carburetor, so we're talking very novice mechanic here.
> Bill '59 Crown
>
Jump in and do it as a novice, but be prepared to learn, and maybe learn
the hard way. Getting a little help during the process from someone
that's already been there could make all the difference in the world.
"Doing" a valve job is probably several rungs up the ladder from novice.
The parts involved are a lot more brutish than the little carb parts that
you dealt with on the last round, but there are a number of ways to do
things incorrectly if attention to detail is not paid.
You didn't mention why the valve job was needed, and I'll assume that you
have your reasons. If you're not sure, one thing that you can do is a
compression test. There is a tool with a brass threaded fitting at one
end and a dial gauge at the other end of a soft hose that threads into the
spark-plug hole (you do one, by one, cranking the engine and then writing
down each cylinder's value and then replacing spark plugs as you go to
each cylinder).
http://www.imperialclub.com/Repair/General/charts/1960-Page1.jpg
This page for a 1960 413 engine (click to enlarge if not legible) shows
the firing order and lots of other helpful reference items. The
compression tolerances are there, too, and can give you an idea how far
away from stock your engine is once you take your reading. The numbering
of the cylinders and firing order is there too, for when you need to
explain to the machinist which cylinder is bad and which spark-plug wire
goes where if you don't label them ahead of time....
Using one of these compression gauges on a V8 that I had that was lumpy
led to me figuring out that #8 cylinder was the one that was bad, and it
got special inspection when things came apart. Turned out to be both a
fried valve and a bad cam lobe.
Engines have a "top" and "bottom" end. The heads that contain the valves
are the top. The cam is sort-of in the middle, as it is located in the
block, but since it operates the valves, a cam that has worn and is "flat"
can fail to open one or more or all valves all the way, directly affecting
the "top" end.
To strictly answer your question about what's involved in a valve job:
The intake manifold that the carb sits on is unbolted from the engine and
lifted out. The exhaust manifolds are removed, laying the exhaust aside
in the engine compartment. The valve covers come off, revealing nuts or
bolts that when loosened, allow you to lift the heads off. I fell into
owning the tool that takes the valves out of the heads by compressing
their springs, but I doubt that I'll ever use it. I'd just take the whole
head over to the machinist. When he's done, you'll have heads that are
ready to bolt back onto your engine with a fresh "valve job" done at the
machine shop for you. You'll need a bunch of gaskets, so ask what you
need before going home with your newly redone heads.
OK: You took your heads off and are re-doing the valves. Had you done
the compression test, you'd know how closely grouped the cylinders are to
each other and how far away from stock measurements they are. If one or
more are significantly low, is the valve really the culprit? Is the cam
lobe that actuates that valve not doing its job due to wear? Are the
piston rings still sealing correctly (or broken?)? All three work
together to create compression and the cam is supposed to hold the valve
open far enough, long enough to allow the cylinder to draw its breath into
the combustion chamber during the cycle.
You'll doubtless get other opinions about the technical details on your
valve question and the merits of doing just that procedure in other
emails, but I'd be inclined to do the entire engine all at once if you
have the money. Doing the heads and refreshing the seals on the valves
and then mating the newly redone heads to the used and broken-in engine
could create more stress on the lower-end, as well as more blow-by where
the rings don't seal like new (but the valves do) and gas gets past them
during the compression stroke (this is called "blow-by" by some).
Blow-by's consequence is removing oil from the cylinders and accelerating
cylinder wear and gas getting into the oil in the pan in the process in a
worst-case scenario.
The "bottom end" of the engine is the crank, the piston rings/pistons,
connecting rods, and all of the bearings in there. Fresh valves mean that
you could accelerate the wear via less leakage at the valves/higher
compression pressure and create a situation where the already used engine
gives out at some sooner point in the future due to higher compression
forces, after all of this work that you just did on the upper end. You'd
have to pull all of that work partially apart to redo the bottom end at
that point anyway. I'd rather wrench once and drive than re-wrench later
if avoidable.
The other side of the coin here is that the V8's are plenty beefy, you
just want to freshen things up, and what the heck, you'll rebuild later if
needed - you just need to solve a problem in the valve-train for right
now. Don't get sore if other things need attention sooner or later due to
the fact that the engine's been around the block already and worn
together. Upsetting that "worn together" balance can unmask other items
that are worn and then cause a progression of frustrating failures that
are neatly escaped in a complete engine rebuild the first time around.
I'd suggest doing very thorough investigation of your options and their
consequences so that you can weigh things properly and know what to expect
out of your proposed maintenance. If you've never seen what's under the
intake manifold and how an engine works, it's a really revealing
experience that will put all of the vocabulary that you've heard into
perspective, so that's a good aspect to doing this yourself.
If you haven't been through this before and proceed, be certain to read
the FSM carefully and to ask advice from people, especially your
machinist, as you proceed. Extra points if you can lift the hood and have
someone point to what each step will involve. It CAN be done by you. I'd
suggest having a buddy along who has done it before and might be able to
point out some of the things that aren't obvious till you go there, like
the fact that when reinstalling your heads, there is a torquing sequence
laid out in the manual that you should go by when tightening down the
bolts that hold the heads on to avoid warping the head as it is tightened
down.
Not a complete story, but I hope that this helps give a better picture of
the road ahead on doing your own valve job. Good luck.
=====
Kenyon Wills
6o LeBaron - America's Most Carefully Built Car
73 LeBaron - Long Low & Luxurious
San Lorenzo/SF Bay Area
__________________________________________________
Do you Yahoo!?
Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop!
http://platinum.yahoo.com
Back to the Home of the Forward Look Network