Home » Public Forums » GMCnet » [GMCnet] 403 engine rebuild
| [GMCnet] 403 engine rebuild [message #99377] |
Sat, 11 September 2010 16:49  |
larry erd
Messages: 132
Registered: August 2010
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I am having the engine rebuilt (403 ) on the 1977 Kingsley I just purchased
and I need
advise. Is it worth while to install a new cam such as the CASPRO or ??. Do
i need to
do harden valve seats, my engine man thinks just do the guides. Are just
OEM type
pistons ok or is there a better choice. Is there any thing that we should
be doing
other than the std. quality rebuild? We will balance the new pistons & line
bore etc.
larry erd
'77 kingsley
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| Re: [GMCnet] 403 engine rebuild [message #99379 is a reply to message #99377] |
Sat, 11 September 2010 18:20  |
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jaholland
Messages: 565
Registered: June 2010
Location: Sweet Home Alebamy
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Larry erd;
I would go with the Caspro Cam/Lifters -
the Caspro Roller Timing Chain/Gear set
and a new Delco Water Pump ~
I would even consider the Rockwell Alum Intake ~
We blocked off the crossover on my 403
Installed Thorley Headers and 3 inch Exaust
~ Joe ~
/_]*[__][] *[__|] ~ * '73 TZE063V101887 "
"
O----------OO--]* ~ '78 TZE168V100234 "
"
" Joe & Lavelle " "
"
'sweet home alebamy'
[Updated on: Sat, 11 September 2010 18:25] Report message to a moderator |
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| Re: [GMCnet] 403 engine rebuild [message #99383 is a reply to message #99377] |
Sat, 11 September 2010 19:10 |
James Hupy
Messages: 6806
Registered: May 2010
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Larry, I have considerable experience on the Olds engines. The late 77 and
78 production 403 engines should have induction hardened valve seats. If
they need extensive machine work to restore the seat, some of the hardened
area will be ground away in the process. The guy on the scene doing the
grinding SHOULD be in the best position to make that call. If I were doing
the heads, it would be my preference to use the factory seats if possible.
There is not a lot of material around the valve seat pockets to machine away
to install replacement seats, but a competent machinist can do them. On the
guides, no tighter than .0015" on the intakes and no tighter than .002" on
the exhaust. I prefer to machine the tops of the guides to take teflon
inserted metal valve seals, but others use the umbrella type like the
factory. Make sure that the installed height of the valve stem ends is very
close to factory spec.as there is not a lot of forgiveness in the stock
rocker arm assemblies. If you go to a roller tappet camshaft, make sure to
install a thrust button or endplay plate with it. Mondello has what you
need. Use a true double roller timing chain set that has rollers that are
loose in the links. Cloyes makes a good one as do others. They are a lot
more money than some others. I would replace the factory oil pump with a
heavy duty one. I personally don't use high volume pumps, but a moderate
pressure increase doesn't hurt. Piston choice is all over the map but I have
used TRW matched sets for years with very good results. Keep the oversize to
a minimum and do not increase the compression ratio over stock. Don't get a
camshaft profile that makes max torque at higher rpm than about 2500 to 3500
RPM. These motorhomes ain't race engines, but they frequently see wide open
throttle at lower rpm. Also make sure that the new water pump you install
has the same impeller as what you take out. There are lots more tricks, if
you want more info., contact me off net at jamesh1296@gmail.com
Jim Hupy
Salem, Or
78 Royale 403
On Sat, Sep 11, 2010 at 2:49 PM, larry erd <1ljerd@gmail.com> wrote:
> I am having the engine rebuilt (403 ) on the 1977 Kingsley I just purchased
> and I need
> advise. Is it worth while to install a new cam such as the CASPRO or ??. Do
> i need to
> do harden valve seats, my engine man thinks just do the guides. Are just
> OEM type
> pistons ok or is there a better choice. Is there any thing that we should
> be doing
> other than the std. quality rebuild? We will balance the new pistons & line
> bore etc.
>
> larry erd
> '77 kingsley
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] 403 engine rebuild [message #99392 is a reply to message #99377] |
Sat, 11 September 2010 19:56 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
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| larry erd wrote on Sat, 11 September 2010 15:49 |
I am having the engine rebuilt (403 ) on the 1977 Kingsley I just purchased
and I need
advise. Is it worth while to install a new cam such as the CASPRO or ??. Do
i need to
do harden valve seats, my engine man thinks just do the guides. Are just
OEM type
pistons ok or is there a better choice. Is there any thing that we should
be doing
other than the std. quality rebuild? We will balance the new pistons & line
bore etc.
larry erd
'77 kingsley
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Larry, my reply will be a lot less comprehensive than James, but part of the answer may depend on why you are rebuilding it in the first place. Certainly the timing chain and cross-over block off plates, but other than that I would stay totally stock. These engines are bullet proof, not so much due to strenght, but due to refinement.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] 403 engine rebuild [message #99420 is a reply to message #99377] |
Sun, 12 September 2010 00:20 |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
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Jim, You rebuild engines for "other folks"?
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: [GMCnet] 403 engine rebuild [message #99428 is a reply to message #99420] |
Sun, 12 September 2010 07:40 |
James Hupy
Messages: 6806
Registered: May 2010
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By "other folks", do you mean non GMCers? My wife's family are and were
commercial fishermen on the Columbia River and also in Alaska. Their gill
net boats were powered by 455 Oldsmobiles with Berkely Jet pumps. For years
I would do turnaround engines for them, so that they could quickly replace a
failed engine in the middle of a season if necessary. Mostly retired now but
I still have a couple of 455 engines and a whole shop full of Olds parts. My
personal GMC has a 403 and I currently am looking for a complete unmolested
403 to rebuild for a spare for me. I would consider doing one or two engines
a year for GMCers. The requirements for a Motorhome are different than for a
fishing boat. The boats run at a much higher RPM with a somewhat lighter
load. The motorhome runs at a slower speed but is under a heavy load with
frequent periods of full throttle operation. This is a challenge that is
difficult to master, because the heat load and lubrication load is greater
at full throttle, and further complicated by the slower speed of the engine
with subsequent reduced water flow and lubrication. I believe Jim Bounds has
spoken about this same problem as well as Dick Patterson and others. The
motorhome also has the heat load from the transmission and AC to contend
with, and a limited amount of coolant that has to transfer the heat to the
air. The boats have the whole ocean for cooling. I have to farm out some of
my machine work like crankshaft grinding and nitride coating and balancing
but there are very good technicians in the local area. I know this is a
lengthy answer but I would do an engine or two for fellow GMCers. I
presently have a complete 455 that is rebuilt but the cam is not appropriate
for a Motorhome. It has been started and run on a test stand for about an
hour with a pressurized cooling system to check for leaks. I have a toronado
oil pan for it, and some of the motorhome brackets for power steering and
alt and AC. I would take a complete 403 and $ for the 455 if someone was
interested, contact me off GMCnet at jamesh1296@gmail.com
Jim Hupy
Salem, Or
78 Royale 403
On Sat, Sep 11, 2010 at 10:20 PM, Chris Choffat <cchoffataz@yahoo.com>wrote:
>
>
> Jim, You rebuild engines for "other folks"?
> --
> -Chr$: Perpetual SmartAss
> 77 Ex-Kingsley 455, Power Drive, 3:21 FD, Quadra bag. The Engineer's
> Motorhome
> Scottsdale, AZ
>
> Photosite: Chrisc "It has Begun"
> _______________________________________________
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| Re: [GMCnet] 403 engine rebuild [message #99437 is a reply to message #99377] |
Sun, 12 September 2010 11:46 |
captjack
Messages: 271
Registered: February 2010
Location: Sebastopol, California
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Jim,
Do your recommendations on a 403 rebuild also apply to the 455? My recent oil analysis showed high lead and iron which suggests a bearing is about to go according to Blackstone.
Jack Christensen - K6ROW,
'76 Glenbrook/Clasco - "The Silver Bullet",
Sebastopol, CA
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| Re: [GMCnet] 403 engine rebuild [message #99443 is a reply to message #99437] |
Sun, 12 September 2010 12:42 |
James Hupy
Messages: 6806
Registered: May 2010
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Jack, what I said about the head and valve work also applies to the 455, but
some of the early 455 cylinder heads do not have induction hardening on the
valve seats. I would have to look up the year model info to tell you for
sure which ones are which. The 455 is blessed with a much smaller cylinder
bore with a longer stroke. This makes it more forgiving when it come to
reboring than the 403. The long stroke and somewhat heavier crankshaft limit
the torque curve somewhat in stock configuration, but that works to our
advantage in a motorhome. Many GMC owners opt for 3:50 final drive gearing
for the 455 when towing. Cam and lifter choices are similar to the 403, with
a lot of rebuilders using roller cams because of the loss of zinc and
phosphorous additives in the engine oils. This might account for your heavy
metal oil analysis. Newer bearing materials are supposed to have been
improved to account for this change, but flat tappet camshafts with high
valve spring loading can easily be damaged by lack of these additives,
especially during the break-in period. I have found engine balance to be one
of the things that the factory does not get spot on in these engines as well
as camshaft timing. When replacing pistons, a rebalance is highly
recommended. Also check the connecting rod lower ends for out of round and
oversize, as well as for twist. Goes without saying that the oil pump, which
has the same mileage as the rest of the engine, always gets replaced with a
new one. I am personally not convinced that a higher volume pump is what is
needed here, but higher pressure, especially at idle speed is beneficial.
Obviously a true roller timing chain set, one in which the rollers are free
to roll in the links, is one upgrade that needs to be included as well as
cam thrust button or plates to control endplay in the camshaft. This has the
added effect of taking out the slop in the distributor drive gears also. If
you do install a steel billet cam, then the distributor drive gear is harder
than the gear on the bottom of the distributor. I have seen some really
sloppy wear in the distributor shafts also on 455's. If I go into more
details on the GMCnet, they sometimes won't let it be posted, so if you want
more detail, contact me off net at jamesh1296@gmail.com
Jim Hupy
Salem, Or
78 Royale 403
On Sun, Sep 12, 2010 at 9:46 AM, Jack Christensen <captjack@sonic.net>wrote:
>
>
> Jim,
> Do your recommendations on a 403 rebuild also apply to the 455? My recent
> oil analysis showed high lead and iron which suggests a bearing is about to
> go according to Blackstone.
>
> --
> Jack Christensen - K6ROW
> '76 Glenbrook/Clasco
> Sebastopol, CA
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| Re: [GMCnet] 403 engine rebuild [message #99528 is a reply to message #99377] |
Mon, 13 September 2010 06:49 |
Gary Casey
Messages: 448
Registered: September 2009
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I read lots of good suggestions on engine rebuilding(not repeated here), but
sometimes people recommend engine rebalancing, which I don't think is worth the
money for this type of engine. I doubt than any rebuild has enough unbalance to
be noticeable when driving, and it has no effect on durability, reliability or
performance. I don't think I would spend the money. Three anecdotes:
Continental built some pistons with iron inserts for the top ring, used in
their aircraft engines. They approved replacing any number of pistons with
these and found the vibration to be not significantly effected. One of our sons
wiped out his turbo 4-cylinder Dodge engine and since I was in no mood to
contribute financially to the project, I acquired some misc. parts from
Chrysler. There was no complete set of any one type, so I mixed and matched.
Some rods were forged, some cast. Some pistons had different shaped dishes in
the top. Bearings were a mix of new and used with mismatched uppers and lowers.
Ran like a clock and for a long time until he rear-ended a truck. My friend in
Detroit built drag race cars for Chrysler, and observed the rules guys always
measuring the displacement of #1 cylinders. So, being the innovative guy he
was, he built multi-stroke crankshafts with the #1/2 Cylinders having a lower
displacement than the rest. Ran just fine. The benefits of a precision engine
balance are vastly overrated in my opinion.
FWIW
Gary Casey
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| Re: [GMCnet] 403 engine rebuild [message #99529 is a reply to message #99528] |
Mon, 13 September 2010 07:05 |
Jim Bounds
Messages: 842
Registered: January 2004
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While we can do what we want, America gives us this right, I have found maybe
because of how old out motors are, how many parts may have been installed over
the years that when we build up a motor we want all the same pistons-- balanced
to be all the same weight as much as reasonably possible. I have watched in the
side mirror as the RPM runs up a pesky small vibration at some certain RPM which
I would have to attribute that to something off balanced in the rotating
assembly of the motor. Wether it's because of all the older parts we must use
(heads, block, crank, rods, flywheel, etc.) I must respectully feel that
balancing the rotating assembly of a motor, any motor, is a good thing-- as long
as it does not coach a large amount to do so.
Just my opinion,
Jim Bounds
---------------------------
----- Original Message ----
From: Gary Casey <casey.gary@yahoo.com>
To: gmclist@temp.gmcnet.org
Sent: Mon, September 13, 2010 7:49:11 AM
Subject: Re: [GMCnet] 403 engine rebuild
I read lots of good suggestions on engine rebuilding(not repeated here), but
sometimes people recommend engine rebalancing, which I don't think is worth the
money for this type of engine. I doubt than any rebuild has enough unbalance to
be noticeable when driving, and it has no effect on durability, reliability or
performance. I don't think I would spend the money. Three anecdotes:
Continental built some pistons with iron inserts for the top ring, used in
their aircraft engines. They approved replacing any number of pistons with
these and found the vibration to be not significantly effected. One of our sons
wiped out his turbo 4-cylinder Dodge engine and since I was in no mood to
contribute financially to the project, I acquired some misc. parts from
Chrysler. There was no complete set of any one type, so I mixed and matched.
Some rods were forged, some cast. Some pistons had different shaped dishes in
the top. Bearings were a mix of new and used with mismatched uppers and lowers.
Ran like a clock and for a long time until he rear-ended a truck. My friend in
Detroit built drag race cars for Chrysler, and observed the rules guys always
measuring the displacement of #1 cylinders. So, being the innovative guy he
was, he built multi-stroke crankshafts with the #1/2 Cylinders having a lower
displacement than the rest. Ran just fine. The benefits of a precision engine
balance are vastly overrated in my opinion.
FWIW
Gary Casey
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| Re: [GMCnet] 403 engine rebuild [message #99568 is a reply to message #99528] |
Mon, 13 September 2010 10:44 |
James Hupy
Messages: 6806
Registered: May 2010
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Gary, In my personal experience, which involves both practical experience of
25+ years as a vocational instructor in Power technology and small engines,
Outboards, marine engines, motorcycles, Turf and Tillage equipment,
Hydraulics etc. and formal training and many service seminars and
manufacturers schools, I have had considerable opportunity to come across
problems with replacement engine parts of all kinds. I have found new
factory "matched" engine piston sets to be different in weights by more than
10 grams. I have lab scales and always weigh pistons, rods, pins in any
engine that I work on. I don't build any racing engines anymore, but have in
the past, both for me and for customers. Vibrations, both static balance
induced, as well as harmonic and dynamic ones, can and do break crankshafts
and main bearing webs. Doesn't take much imbalance to accomplish, either.
Connecting rods also are affected by imbalance. I know from experience that
engines that are in correct balance run much smoother, and last longer with
fewer failures from broken fasteners than ones that are not in balance. If
careful weighing of internal components proves that all rod and piston
assemblies are the same, then on a stock engine that turns less than 4000
rpm, the justification for expensive balancing is probably lacking. A sloppy
rebalance is probably worse than none, so it pays to verify results and
insist upon documentation of same on paper. It is just like dyno tuning,
some say they wouldn't install an engine without first running it on a dyno.
Pay your money and take your choice, I guess. I will just have to do what
life has been teaching me over all these years, and do what the Great
Communicator said. "Trust, after verification."
Jim Hupy
Salem, Or
78 Royale 403
On Mon, Sep 13, 2010 at 4:49 AM, Gary Casey <casey.gary@yahoo.com> wrote:
> I read lots of good suggestions on engine rebuilding(not repeated here),
> but
> sometimes people recommend engine rebalancing, which I don't think is worth
> the
> money for this type of engine. I doubt than any rebuild has enough
> unbalance to
> be noticeable when driving, and it has no effect on durability, reliability
> or
> performance. I don't think I would spend the money. Three anecdotes:
> Continental built some pistons with iron inserts for the top ring, used in
> their aircraft engines. They approved replacing any number of pistons with
> these and found the vibration to be not significantly effected. One of our
> sons
> wiped out his turbo 4-cylinder Dodge engine and since I was in no mood to
> contribute financially to the project, I acquired some misc. parts from
> Chrysler. There was no complete set of any one type, so I mixed and
> matched.
> Some rods were forged, some cast. Some pistons had different shaped
> dishes in
> the top. Bearings were a mix of new and used with mismatched uppers and
> lowers.
> Ran like a clock and for a long time until he rear-ended a truck. My
> friend in
> Detroit built drag race cars for Chrysler, and observed the rules guys
> always
> measuring the displacement of #1 cylinders. So, being the innovative guy
> he
> was, he built multi-stroke crankshafts with the #1/2 Cylinders having a
> lower
> displacement than the rest. Ran just fine. The benefits of a precision
> engine
> balance are vastly overrated in my opinion.
> FWIW
> Gary Casey
>
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] 403 engine rebuild [message #99615 is a reply to message #99603] |
Mon, 13 September 2010 17:09 |
Jim Bounds
Messages: 842
Registered: January 2004
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I have to side somewhat with the entleman who explained the differences you find
even in "matched" sets. Yes, we're not cranking the R's that will toss a pistom
next door but even at 3K you will get sympathetic vibrations which will
certainly reduce the life of the motor if not just annoying when you see the
mirror shake.
As an automatice along with the inspection of parts, checking their balance is a
good thing. Anymore, you cannot just depend on a new part to be "right". Just
does not happen these days and I think Joe Mondello covered that pretty well in
his motor talk at ES.
We line bore for the crank and have the rods and pistons checked for balance.
So far, that inspection has served us well.
Jim Bounds
-------------------
----- Original Message ----
From: Gary Casey <casey.gary@yahoo.com>
To: gmclist@temp.gmcnet.org
Sent: Mon, September 13, 2010 4:06:18 PM
Subject: Re: [GMCnet] 403 engine rebuild
Jim,
I certainly agree. I didn't mean to imply there was anything wrong with
balancing, just that for the GMC with an engine that rarely turns over 3,000 and
never over 4,000, there just isn't an economic justification to pay much for a
balancing job. Yes, the things that might suffer the most are the accessories
that are bolted to it.
Gary
Jim's post:
If careful weighing of internal components proves that all rod and piston
assemblies are the same, then on a stock engine that turns less than 4000 rpm,
the justification for expensive balancing is probably lacking.
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| Re: [GMCnet] 403 engine rebuild [message #99616 is a reply to message #99377] |
Mon, 13 September 2010 17:44 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
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Re engine balance. The "balancing" of an in-line motor is very different than balalcing a V eg V8 engine. On any in-line engine, the crank is balanced separately from the rods and pistons which are balanced against like pieces, eg, rod top ends and big ends and piston vs piston. On any V engine the crank has to be balanced considering the weight on the rod and piston assembly and there is some debate over the percentage of the appropriate rod/piston weight the crank should be balanced to.
I would expect that considerable "out of balance" on a hard working motorhome engine would not be a "good" thing.
Also re in-line "Chrysler" engines, some builders have found the factory crank balance on SRT4 engines to be spot on.
DAVE KING
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
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| Re: [GMCnet] 403 engine rebuild [message #99633 is a reply to message #99377] |
Mon, 13 September 2010 20:06 |
Gary Casey
Messages: 448
Registered: September 2009
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Certainly an interesting discussion about the benefits of balancing. Yes, there
can be resonances induced in in some components, or even the dishes in the
cupboard, but one always has to weigh the benefits of anything with the cost of
doing it. No one will argue that balancing is bad, but rather are the benefits
worth it? Just to put it in perspective, once I calculated the inertia loading
of the reciprocating components. Turned out for a typical engine (can't
remember the details) at what would be considered a "peak" engine speed of
something like 7000 rpm the inertia loading in tension (piston trying to pull
itself off) was about equal to the pressure loading during combustion.
Combustion pressures at full throttle are something like 800 psi, and on a 4
inch piston that is close to 10,000 pounds. The inertia loads are proportional
to the square of rpm, so at 3500 rpm the inertia loads might be something like
2,000 pounds or so, a quarter of the combustion loads. Then someone said that
he found pistons that were 4 grams different from each other, which is less than
1 percent. Does the engine really care if one inertia force is 2,000 and
another is 2,020? I don't think so. The combustion pressures can be multiple
percentage points different from each other because of variations in air and
fuel delivery, certainly masking the effects of mechanical unbalance.
Yes, balancing the crank of a V8 has to consider the big end rod weights,
because a V8 has an inherent rotating out-of-balance couple that has to be
balanced out by putting weights at the ends, often in the torsional absorber at
the front and the flex plate at the back. To get these right, the equivalent
weight has to be added to the crank throws. An inline 6 is inherently balanced,
so only the weights of the various parts have to be matched. Without a
secondary balance shaft an inline 4 is so bad that I don't think anything would
be noticed. Production Ferrari V8's are another example of an inherently
unbalanced engine and while they certainly aren't smooth, they seem to satisfy
their customers. Of the commonly used configurations, I think only inline and
opposed 6's are the only inherently balanced engines.
Now, line boring is a different matter. If the bores in the block and the
journals on the crank aren't straight there will be a big bending load imparted
on the crank through the bearings. But when one does a line boring job, how
crooked is the typical block found to be? I have no idea.
Thanks for the discussion.
Gary
ps: My posts come back with question marks scattered about. I wonder why.
I have to side somewhat with the entleman who explained the differences you
find
even in "matched" sets.? Yes, we're not cranking the R's that will toss a
pistom
next door but even at 3K you will get sympathetic vibrations which will
certainly reduce the life of the motor if not just annoying when you see the
mirror shake.?
As an automatice along with the inspection of parts, checking their balance is
a
good thing.? Anymore, you cannot just depend on a new part to be "right".? Just
does not happen these days and I think Joe Mondello covered that pretty well in
his motor talk at ES.
We line bore for the crank and have the rods and pistons checked for balance.?
So far, that inspection has served us well.
Jim Bounds
-------------------
Re engine balance. The "balancing" of an in-line motor is very different than
balalcing a V eg V8 engine. On any in-line engine, the crank is balanced
separately from the rods and pistons which are balanced against like pieces, eg,
rod top ends and big ends and piston vs piston. On any V engine the crank has to
be balanced considering the weight on the rod and piston assembly and there is
some debate over the percentage of the appropriate rod/piston weight the crank
should be balanced to.
I would expect that considerable "out of balance" on a hard working motorhome
engine would not be a "good" thing.
Also re in-line "Chrysler" engines, some builders have found the factory crank
balance on SRT4 engines to be spot on.
DAVE KING
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| Re: [GMCnet] 403 engine rebuild [message #99640 is a reply to message #99377] |
Mon, 13 September 2010 20:33 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Don't forget to address the oiling. Some like restictors to the top half. I remember somthing about the squirter hole orientation from the Patterson speech and that has to be right to lube the chain and dist gearset.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] 403 engine rebuild [message #99647 is a reply to message #99646] |
Mon, 13 September 2010 21:23 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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| philipswanson wrote on Mon, 13 September 2010 20:20 |
Don't mess with it, upgrade to a 455.
Phil Swanson
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Well that took longer than I expected 
Bob de Kruyff
78 Eleganza
Chandler, AZ
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