keng2 wrote:
> "Roger M" <rnddmauck@[EMAIL PROTECTED]
> wrote in message
> news:4616C793.3BA39D67@[EMAIL PROTECTED]
> >
> >
> > keng2 wrote:
> >
> >> "Roger M" <rnddmauck@[EMAIL PROTECTED]
> wrote in message
> >> news:46145298.35CF5876@[EMAIL PROTECTED]
> >> >
> >> >
> >> > dcnisbet@[EMAIL PROTECTED]
wrote:
> >> >
> >> >> Hopefully somebody here knows where to look or possibly know of a
> >> >> newgroup like this that deals with Ford engines. I've got a 74
Ford
> >> >> F-100 with a 360 converted to 390 apx 10 years or 40,00 miles ago.
I
> >> >> did an in vehicle overhaul, having the heads rebuilt at a machine
> >> >> shop. I replaced rings, rod bearings and did not balance the rods.
I
> >> >> replaced the 360 crankshaft with a re-ground 390 crank kit with
> >> >> bearings. It still has decent compression with pump regular
knocking
> >> >> at acceleration. Usually a 50/50 gasoline blend eliminates the
> >> >> knocking.
> >> >>
> >> >> After apx 10,000 miles on the overhaul the engine started
vibrating
> >> >> about 30-35 mph or 18-2000 RPM. I get the vibration whether it is
in
> >> >> neutral or in gear. Having the older style rebuilt 3-finger
pressure
> >> >> plate and way to many miles on the clutch I suspect and out of
balance
> >> >> pressure plate might be where the vibration is coming from but
don't
> >> >> know for certain. The vibration is getting progressively worse. I
> >> >> replaced the vibration damper apx 5 years ago and the vibration
did
> >> >> not improve. The conventional ignition was changed over years ago
> >> >> prior to the vibration problem and I recently had it scoped and
there
> >> >> were no problems. Advancing and retarding the timing beyond the
books
> >> >> does not help with the vibration.
> >> >>
> >> >> Any suggestions on where to look next?? I'm trying to avoid the
> >> >> clutch. Being a 4X4 with a minor nuisance oil leak in transfer
case to
> >> >> deal with, changing the clutch is not an option until it wears
out.
> >> >> Dealing with the greasy transfer case and extremely heavy cast
iron
> >> >> drive train is no picnic and apx 5-700 $'s worth of labor if I
don't
> >> >> do it myself.
> >> >>
> >> >> The biggest problem is oil pressure. Normal in town driving the
> >> >> pressure is fine even at idle. After a short trip on the freeway
or
> >> >> high RPM's, the pressure drops the zero when it returns to idle or
low
> >> >> RPM's. After returning to idle after driving just a few miles on
the
> >> >> freeway I have to pick the RPM's up or I will get a lifter ticking
> >> >> from oil starvation if I sit at a stoplight for a few minutes. I
can
> >> >> drive around town all day and the oil pressure will remain normal
even
> >> >> at idle speed. If I take the truck on a long haul like an out of
town
> >> >> hunting trip I have to add a can of STP or Motor Honey to maintain
> >> >> decent oil pressure. I've pressure tested the oil pump via the oil
> >> >> sender outlet both hot and cold and it is doing it's job.
> >> >>
> >> >> I don't know if the vibration and oil pressure problem are related
but
> >> >> both problems are getting progressively worse. I've talked with a
few
> >> >> mechanics and naturally they try to sell an overhaul or short
block.
> >> >> None has been able to say where the problem is. At a shop that
uses
> >> >> wet back labor speaking through a translator one mechanic that
> >> >> exclusively rebuilds engines all day said main bearings most
likely
> >> >> fix the oil pressure problem but he had no idea on where the
vibration
> >> >> was coming from. His suggestion was to use 50 weight oil until the
> >> >> engine goes and live with the vibration.
> >> >>
> >> >> Any suggestions on where to look for the problem or a newsgroup
where
> >> >> I might look for answers are appreciated. With all the big-block
Ford
> >> >> engines I've owned since the 60's the easy fix to engine problems
was
> >> >> finding a wrecked Mercury, T-Bird, LTD or station wagon and using
the
> >> >> engine until it wore out. Good used 390's used to be a dime a
dozen
> >> >> but now finding a low milage wreck with an engine that is an easy
in
> >> >> and out to fit a 1974 drive train is near impossible to find.
> >> >
> >> >
> >> >
> >> > You lose oil pressure because the bottom end has a bunch of wear.
> >> > Likely
> >> > the source of your vibration also. When driving on the highway the
oil
> >> > gets hot and thins out causing the oil pressure loss. In town
driving
> >> > should net the same result but may require a lot of in town
driving.
> >> > Your
> >> > vibration is probably coming from a bunch of mismatched parts
wobbling
> >> > around in a bunch of loose bearings caused by poor assembly
techniques.
> >> > IE
> >> > poor quality parts (crank kit), no balancing, dirty assembly
> >> > environment,
> >> > etc.
> >> >
> >> > I would stop driving it, remove the engine, disassemble it,
measure
> >> > everything, replace parts as necessary then carefully and cleanly
> >> > reassemble it. I would also spring for a professional balancing
job,
> >> > professional crankshaft servicing and anything else that was
absolutely
> >> > needed to make it last. You got ten years so you did ok time wise
but
> >> > mileage wise you didn't get much for your rebuild money.
> >> >
> >> >
> >> > Roger
> >> I had a low oil pressure problem with my 390 which turned out to be
worn
> >> camshaft bearings!!
> >>
> >> KenG
> >
> > Great, glad you found the problem. How bad did it vibrate?
>
> >
> > Roger
> I don't remember having any vibration problems but the bearing wear
problem
> was caused by the professional engine rebuilder that failed to match the
> holes in the camshaft bearings with the oil holes in the block.
> keng
Sound like you mis-used the term.
Roger
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