RE: valve job update

["Eppinger.Michael" <Eppinger.Michael@domain.elided>]

This is one of the best examples I have seen of project creep!  You start
out with replacing the carb, and end up with rebuilding the whole motor.
"Let's see, while I have this off, I might as well do this, and if I do
that, then I better do this, etc. etc.  <grin>

In all seriousness, I do agree with John 100 % on these suggestions, you
might as well do it once, the first time.  If you have the heads off, you
might as well do everything that would require new head gaskets, and intake
manifold gaskets, etc  (like replacing rings, etc), otherwise you will start
spending a lot of money in gaskets alone.  When you add up all the costs of
doing each job individually, a rebuild is quite cheap.  John is also correct
that fixing one problem will sometime cause or reveal other problems.  So do
it all once, and at the same time, it is cheaper, easier, and a lot less
frustrating.

Side note, have the shop check to see if you have hardened valve seats,
don't go by year alone!  That alone can save you a some major cash.  As far
as the 3 angle valve job, can someone out there confirm that you don't see
any improvements over a single angle, until you get up into the higher rpms,
and higher airflows?  ie, for an IH engine you won't be running in the rpms
to get any benifit from a 3 angle.
Anyone want to touch this one?

Epp

> -----Original Message-----
> From:	jlandry@domain.elided [SMTP:jlandry@domain.elided]
> Sent:	Wednesday, December 02, 1998 11:42 AM
> To:	Kurt McDowell
> Cc:	ihc@domain.elided
> Subject:	Re: valve job update
> 
> In a brilliant stroke of genius, Kurt McDowell <gmcd@domain.elided> blurted
> out:
> 
> >He says I should put in new original sixe mains in on the crankshaft
> without
> >machinineing it to get the oil pressure up. This sound pretty dangourus
> to me.
> 
> This is not a completely bad suggestion with a few a few very important
> precautions are observed.  First, let me say that the mains are not the
> only cause of the oil pressure dropping on a high mileage engine.  Don't
> forget you have a bunch of bearing surfaces (six?) on the camshaft and
> eight connecting rods spitting out oil.  So this procedure may not help
> all
> that much.  That being said, you just don't want to go slapping in new
> main
> bearings without taking some measurements first.  As a minimum, you should
> mic the crankshaft journals to see if they are within acceptable factory
> tolerance specs for size and out-of-round condition.  Then, if you do find
> them acceptable, you should be sure and verify the crank journal to new
> bearing surface gap with Plastigage.  Too much gap means low oil pressure,
> too little can mean insufficient lubrication.
> 
> >He also thinks I might as well replace my rings while im in there.
> >If I do that, Then I have to worry about the rings seating properly.
> >I dont burn any oil except at start-up.
> 
> Again, you just don't put in rings without getting the preliminaries out
> of
> the way.  In order to put in new rings, you have to pull the pistons.
> This
> *will* require you to ream the ridges out of the cylinders.  Then you need
> to take careful measurements of each cylinder to check for wear, out of
> round, and taper.  If by some miracle the cylinders still fall within
> factory tolerance limits (and I seriously doubt it), then you'd need to
> break the glaze on each cylinder with a hone.  Then you can fit new rings
> to the cylinder walls and then install them on the pistons, etc.
> 
> Sheez... by this time you've darn near rebuilt the engine, so why not go
> all the way???
> 
> >My oil presssures not bad, Its about 5 or ten psi  at hot idle (depending
> >onn how fast its idleing) and its at about 30psi on the highway. I'm
> using
> >10-40oil.
> 
> Personally Grant, I wouldn't waste my money on trying to do the things you
> mentioned unless I were going all the way with a full blown "pull the
> motor" rebuild.  You'll be back having to mess with it again in a few
> years.  Fixing one part of an old engine can cause unexpected problems in
> another area.  For example, just doing a valve job on an old engine can
> lead to *increased* oil consumption as the valves now seal better creating
> more suction and blow-by around worn piston rings.
> 
> >Also I rember sombody saying that if you
> >replace the lifters, then you must replace the cam. is this true? TIA
> 
> Absolutely correct!  You run a *great* risk of quickly wearing out a new
> set of lifters by using an old cam and vice-versa.  The cam will have
> certain odd wear patterns on the lobes which will not properly mate with
> the new faces of the lifters.  The lifters will likely not properly rotate
> either, which leads to rapid wear of both it and the cam lobe.  You could
> wind up in a much worse situation in a few thousand miles than you started
> with.
> 
> Just my $0.02, and I'm sure others will chime in too.
> 
> Take care,
> 
> John L.
> --------------------------------------------------------------------------
> 
> jlandry AT halcyon DOT com      |
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