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From: Merryweather, George
Sent: Monday, January 06, 1997 10:06 AM
To: 'David Deutsch'; mgs@autox.team.net
Subject: RE: Engine Machine Shop services ??s - Long Post!
This is a fairly lengthy post. It is an accumulation of a number of =
years and a number of rebuilds of experiences, both good and bad. I =
started of by doing things quick and easy, and using my 'machine shop on =
the corner'. They were interested in piece work, not quality. They may =
have been cheaper, but I ended up paying for it elsewhere, later. The =
opinions, ideas, suggestions noted below are my own. There are a lot of =
different way to rebuild an engine. As was noted in a post last week, =
opinions are like 'armpits' (I hadn't heard that variation either), and =
for you, my opinions may not be worth the paper there not printed on. =
FWIW.
There are a number of thing to consider. A number of things you can do, =
and a number of things you can have the shop do.
Magnafluxing - I have been a 'participant' of two different types. The =
quick and dirty involved a large electro-magnet and iron filings. Very =
inexpensive, if not free. The other was what the shop called an =
'aviation type' flux, which actually used a similar process, but the =
using an x-ray type device, looked for cracks. (I think they use this =
process on jet engine turbine blades). The second is more costly, and =
more time consuming, but very reliable. The shop I use only sends out =
stuff in batched. Reduces cost but increases time. Have fluxes - Rods, =
Crank, and Head. If there is reason, have the block checked as well.
Cleaning - remove ALL the oil gallery plugs. Depending on the engine, =
they are all over. Remember, (write down), where they all are, so that =
upon replacing, you get them ALL back in the right place. There is an =
area on the bottom of the block that has numerous holes, some of which =
take plugs, some don't! You may want to make appropriate marks with a =
small punch to identify the holes. There are plugs on the end of the =
block, bottom, sides, Get them all. I drill a small hole and use a =
slide hammer to get them out. The shop I use builds racing engines, so =
he plans on taking a motor back apart, therefore he taps/threads each =
hole, and puts a set screw in, so that the next removal is easier. That =
might but good for the racers, but I think it is a little overkill for =
typical driving. Remove the freeze plugs. (NOTE! I am assuming that =
before you start any of this, you have completely disassembled the =
engine. Mark/tag/bag the bearings your pull out as to where they go. =
This can be useful if there is any abnormal wear.) You may want to =
pressure wash the block to get the major gunk off, (You may want to do =
this upon engine removal) Your shop should hot wash the block. IF YOU =
HAVE AN ENGINE ID PLATE, YOU MAY WANT TO REMOVE IT. THE HOT WASH USES A =
CAUSTIC SOLUTION WHICH CAN DESTROY THE ID PLATE. To be very thorough, =
you should remove the oil restrictors in the crank. This allows for =
better cleaning. If you are having the head done, let the shop take it =
apart. It is pretty tough to do with out the right tools. The same =
goes for the Cam bearings. Let the shop mess with their removal and =
refitting.
OK, so everything is clean, and fluxed, now is the time to check =
tolerances for the bearings, pistons, etc. No sense pre-ordering =
bearings for a crank that may need to be replaced. Once you get the =
parts in, I recommend that you get the appropriate components balanced. =
Your shop may be able to do this. To do this properly, the shop will =
need the pistons, rings, rods, crank, pulley/balancer, flywheel, clutch =
disc & pressure plate. The MGA flywheel can be lightened considerable at =
this time if you want. About 25% can be removed.
Make sure everything is clean. Re-tank the block. You may want to bead =
blast it. Make sure everything is clean. Did I say that again? Flush =
out all the oil passages, double check it. Make sure every thing is =
clean! Use lint free rags! Red shop rags are NOT lint free! Once =
everything is ready, then have the shop install new cam bearings. They =
will need your cam as well to do this properly. =20
Now comes the time that you need to decide who is going to build the =
engine. If you are going to do it, take your time. Short cuts are =
expensive. You should pick up some 'Plastigauge' (sp?) or equivalent. =
This is a precisely measured 'string' of plastic that you place between =
a bearing and the moving surface prior to assembly. You torque down the =
bearing cap appropriately, which flattens the plastigauge strand. Since =
the original size of the strand is known, then the flatten strand =
corresponds directly to the bearing clearance. Check your clearance as =
you assemble. The appropriate clearance are listed in your shop manual, =
as are the right torque settings. (Never go to full torque first time =
out! step up to it with 10 lb. increments, alternating bolts as you =
go. Check the shop manual for head bolts!)
Assembly lube - If the engine is going to sit for any length of time =
before running, don't use Lubriplate. It actually hardens over time! =
Use a good quality black moly assembly lube for your bearings. Every =
where else, I recommend a 50/50 mixture of STP and 20/50. Mix it up in =
a squeezable ketchup bottle. Put it all over the cam, the oil pump, =
pistons as you insert them, etc.
Misc. thoughts....Use new nuts and lock washers where available. If the =
mains are held in with 'lock nuts', use new ones. Replace the cylinder =
head studs and nuts. They stretch over time. DON'T FORGET TO PRIME THE =
OIL PUMP! If you are using lock tab washers, replace them. (Some shops =
won't use them) Make sure everything is clean!. Are the restrictors =
back in the crank? Are all of the oil plugs in the right place? Use a =
quality gasket hi-tack compound. A little goes a long way. Use it =
sparingly. Freeze plugs. Make sure the seating surfaces are clean and =
smooth before you tap them in place. I've seen JB WELD used as a =
sealant. A little goes a long way here, too. If you keep the =
antifreeze level appropriate, you should have to worry about freezing. =
The JBW make the plugs a little harder to get out next time, but =
hopefully, next time isn't anytime soon. Something that I forgot =
above.....Have the top surface of the block, and the mating surface of =
the head, checked for flatness. That is the time to find any problems, =
rather than later. Decking a block is a simple procedure. Timing =
chain, sprockets, and tensioner. Check for wear. Depending on the =
length of time since the last rebuild, I would replace all of the above. =
Follow the manual for all clearances, i.e. the shims at the front end =
on the crank.
Cylinder head - Let the shop do this. They will need to do most of the =
work anyhow, and they have the tools, so let them do this. Stellite, =
bronze alloy, hardened seats, etc., is a subject for another =
dissertation.
The rest of the assembly is straight forward. Keep it clean! Now is =
the time to replace marginal parts, i.e. motor mounts, (you did take =
your NEW clutch down when you got everything else balanced, didn't =
you?), hoses, pressure relief spring, thermostat, etc. Oil cooler? =
FLUSH IT OUT! And the hoses! Don't get engine paint/overspray anywhere =
it doesn't belong. The radiator is out, so why not get it flushed? Oil =
pump condition? Check it!
You did prime the oil pump? When the time is right, and the engine has =
been filled with oil, (to the right level Carol), crank the engine, =
without spark plugs, until you get oil pressure. Don't burn out your =
starter. 15-20 seconds at a time is adequate. Oil goes from the pump, =
past the oil pressure relief valve, through the cooler, through the =
filter, and then to the gauge and bearings, so be a little patient. If =
the needle hasn't flickered at the end of a minute, stop and =
re-evaluate. Is oil coming from the pump? That's why you primed it. =
Loosen/remove the oil pipe/hose at the right rear of the block. Does =
oil come out of here when you crank it. If so, then tighten, and crank =
some more. If not, pour a few ounces of oil down the fitting in the =
nd resurfacing? Aside=20
from the head crank and connecting rods what other parts should be=20
Magnafluxed (one of my favorite words)? Where do they stop and I begin?
=20
I also hope this stops the rediculous comparison of me to, one of the=20
most knownledgable MG professionals, Mr John Twist. I'm just a guy with=20
a love for these cars and the people who feel as I do. I'm very=20
faltered by the comparison but at the same time I do not wish to have=20
John thinking I'm putting myself on his level in any way, shape or=20
form.
John Twist also offers a seminar each winter on several topics=20
including O/D transmission rebuilding and Engine rebuilding. You can=20
call 616-682-0800 fax 616-682-0801 or email VRHS43A@prodigy.com for=20
info on this =20
I'm hoping that after I complete these two projects I can use the newly=20
acquired knownledge of my experiences in helping as many of you as=20
possible.
There is a Tech Session coming up in Feb on the fifteen at:
Modern Machine and Parts
228 North Henry Street=20
Alexandria, VA
9 AM
I hope to have most of my questioned answered there, but am sure that=20
I'm not the only one who wonders these things. =20
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