FEATURE ARTICLES

1937 Buick Special Business Coupe: A Restoration Journal — Part 19

By Chris Ritter

So here we are, it's March 2015. The garage is getting slightly warmer, pressing work commitments have been satisfied, family flu and sickness has been defeated and some winter woodworking is now complete. There are no more excuses, it's time to get dirty. One small task remains before I can rebuild my engine and that task is overhauling my oil pump. It is a task that I've delayed for nearly two years and it is a task I need to tackle now.

The oil pump in my engine is pretty typical for late 1930's automobiles. A gear on my camshaft drives my distributor and oil pump shaft. The oil pump shaft in turn spins two gears that create the pressure used to deliver oil throughout the engine. In addition to the shaft and gears, my oil pump has a pressure relief mechanism and a floating oil pickup tube.

In many earlier engines the oil pickup tube was fixed in position and often surrounded by screening to keep large debris from entering the oil pump. In 1937, Buick had a nifty floating pickup that stayed floating on the top of the oil reservoir's surface. This floating assembly pulled only the best oil from the top but should any sludge or debris find its way to the surface it was kept out of the pump by a small screen on the assembly. My oil pump assembly was pretty sludgy so I completely disassembled it and soaked everything in a degreasing solution of...well...it's a homemade blend and pretty nasty so I won't give all the details. I will say that it cleaned my pump up quite nicely.

After a thorough de-sludging, I inspected the pressure relief mechanism for free travel and then installed a new shaft and gear set. Before I could close the assembly I had to resurface the pump body face with its mating face plate. The faceplate was made of cheap pot metal and had a tendency to warp and become uneven. When this happens the pump leaks and you lose oil pressure. Needless to say, this is very, very bad.

To resurface the plate and assembly I placed a fine grit sheet of sandpaper on top of glass and then worked the pieces in a figure-8 pattern. High spots were quickly discovered using this method but I continued until everything was clean and flat.

Once the mating surfaces were ready I had to check the end play between the gears and the faceplate. I did this by placing a straight edge over the pump assembly and then tried to slide a .0015" feeler gauge underneath. The 1937 Buick Shop Manual states that acceptable end play ranges from .0005" to .004" so I then put the faceplate on, spun the shaft and the gears did not scrape the plate. Since I didn't have a feeler gauge thinner than .0015" I finished securing the faceplate and finished the job.

With a tight pump and my relief valve working properly I now expect to have good oil pressure at both idle and regular driving conditions. I didn't have any problem with oil pressure before but an oil pump overhaul was definitely in order considering I had my engine all apart.

As I said earlier, there are no more excuses. I've spent many months slowly acquiring necessary components and it will be a real treat to start putting things back together. Let's get to work!

Saturday, March 7, 2015. A major day in my '37 Buick project — the day I would start rebuilding my engine! A day I dreamt about for years, a day I spent hours researching and a day where two years' worth of accumulating parts would be put to use.

My final preparations for March 7th started three days earlier when I hoisted my engine block on to my sturdy saw horses. Parts, including my ridiculously heavy crankshaft and cylinder head were walked out to the workshop in 6 different trips. I had everything laid out beautifully from nitrile gloves to assembly grease and oil to every last nut, bolt and washer that would be needed.

I laid down to sleep on March 6th like a little kid full of excitement. That excitement woke me up around 6:00 am but I played it cool, ate a good breakfast and headed out to the shop at 7:00.

My plan of attack was pretty straightforward:

• Install main bearings
• Check main bearing/crankshaft clearance with Plastigage and shim as needed. For this step the crank and bearings would be dry.
• Remove crankshaft and lube the shaft and main bearings with assembly oil.
• Reinstall crankshaft
• Install camshaft
• Install two pistons, place assembled head on case with no gasket and check for domed piston interference on valves.

That was all I wanted to complete on that first day — anything else was a bonus. So, I grabbed my main bearings and started to install them. To my horror, I discovered that the very first bearing that I installed protruded from the bearing journal by 3/16"! "Oh no!" I thought, "They must have sent me bearings for the larger Buick engine from 1937!" To add to the mystery was the fact that my rear main bearing fit perfectly. At 7:26 am my big day of engine building came to a screeching halt.

My day wasn't a total loss as I directed my attention to some woodworking instead. On Monday morning I called the Terrill Machine in Texas to tell them about their error. The man who answered the phone is a man I talked to every time I've called Terrill. He is helpful, patient and unbelievably knowledgeable. When I told him about the situation he gave a little chuckle and asked which bearing I was inserting into each journal. He patiently pointed out that in 1937 the circumference of the main bearings is different in every single position! The smallest circumference is found up front and as you proceed to the rear they get larger. He told me to flip the bearings over and look for an etching...sure enough, there it was! Ten minutes later my main bearings were all in the correct positions fitting perfectly and I felt a little foolish for neither the first nor the last time with this project.

With my main bearings in their proper place, it was time to set my crankshaft in place and then install the bearing caps. Cap clearance could then be checked with Plastigage and the acceptable clearance range according the '37 Buick Shop Manual is .0007" - .0022". When you consider that the thickness of a piece of paper is about .003" you quickly realize how small the space is between crank journals and bearings. Naturally, when the engine is running this small gap is filled with oil and the crank rotates with tremendous ease and virtually zero friction.

In 1937, Buick engines came from the factory with shims between main bearing caps. Factory shims were .0015" thick and could be found in stacks as thick as .006" — the width equivalent of two pieces of paper. These shims were in place because if a car's main bearing clearance increased through wear, a shim or two could be removed and the clearance would be back within limits. However, once all of the shims were removed and the clearance was out of range it was time for new bearings. Naturally, when these cars were in service, mechanics didn't pull the engine to check clearances so they had to either crawl under the car and lay on a creeper or put the car on a lift. It is much nicer to do all this work with the engine out of the car and at waist height — here I lucked out.

With a little help from my son, I cleaned off the crankshaft journals and summoned tremendous strength to lift and gently set the crank in place. After that I installed the bearing caps and snugged things up. I tried to move the crankshaft by hand and couldn't — I knew then that I would be making shims!

Apparently the art (loose term) of making shims is practically extinct because it was very difficult to find brass or any other shim stock. I visited three local NAPAs, one Advance Auto and even the local tractor repair shop and struck out at each place. I wasn't going to cut corners and use aluminum foil so finally I called the local MSC Industrial and, while they didn't have any brass shim stock on site, they could get it delivered to my house in a day. I ordered stock that was .001" thick and it came in a roll 6" X 100". Needless to say, that will be enough to shim about 75 engines!

When I disassembled my engine back in 2013 I learned that only one of my main bearings had any shims remaining. I used these originals as a pattern to cut 20 shims. With my Sack-o-Shims by my side, I started the not so scientific process of stacking shims and checking clearance. That process involves lining up shims to accommodate the bolt hole and ensuring that the shim doesn't extend past the bearing and rub on the crankshaft. Repeat as needed.

You may remember from an earlier post that Plastigage is a "plastic-ish" material that looks a lot like angel hair spaghetti when you remove it from the package. You place a little length of Plastigage on a surface, compress it to specifications and when you remove your cap you "read" your findings by comparing the flattened piece to samples illustrated on the packaging. It is absolutely essential that you don't move the crank while checking clearance because it will simply rub the Plastigage off and you will have to start all over.

I found a fairly effective approach to shimming by starting with a stack totaling .006". From here I could peel a layer or two off as needed based on my clearance readings. I was shooting for .0015" clearance on each bearing and I was able to do that by using shim stacks that ranged from .003" to .005". See my handwritten chart and notice that my bearing clearance is in the center of the box while my shim stack thickness is listed on each side of the bearing.

Shimming my bearings wasn't difficult but it was definitely time consuming. Many years ago, the FIRST time I overhauled a tractor engine I was in a hurry and I never checked bearing clearance. That tractor taught me a fast and expensive lesson on ruined bearings and it (thankfully) instilled a bit of patience that sure helped with future engine rebuilds!

Perhaps the biggest mystery for me leading up to my engine rebuild was the issue of my pistons. About 18-months ago I bought a new set of oversized pistons from Egge Machine Company in California. They are pretty much the leading piston and engine rebuild supply house for American cars older than 1980 and they are staffed with very experienced professionals.

When I ordered my pistons I talked to their top piston guy who told me I could use domed pistons in my engine with no modifications. Now understand, the pistons in all 1937 Buicks came from the factory with flat tops. In 1938 and beyond Buick went to domed pistons but they changed their cylinder head shape. See my issue?? I explained everything I knew and read about a possible conflict but the Egge Man assured me that "We do this all the time with '37 Buicks, it's a well-kept secret!" Still sensing my apprehension and doubt, the salesman said "Here is what you do. When you put everything back together place the head on top of the case with no gasket in between. No gasket will simulate carbon buildup. If there is no interference you will be in the clear and you will have higher compression and a small increase in horsepower." I executed the order and promised to report back. After my crankshaft was properly shimmed it was time to check the pistons. I installed the #2 and #7 pistons with no piston rings and rotated the crank until the two pistons were at their apex. In this position the pistons rise above the case by 9/16". I measured the space inside the cylinder head and the math worked with plenty to spare.

Holding my breath, I gently put the head into position and...holy cow, Egge was right! No interference! I directed my flashlight into the combustion chamber through the spark plug hole and found plenty of clearance as well.

Naturally I felt pretty good (and relieved) about my findings. Before I can say that the use of domed pistons is 100% possible I still need to install the camshaft, lifters, and pushrods and assemble the cylinder head/valves as well. On the exhaust stroke the exhaust valve will be fully depressed. Once I can confirm there is no interference between piston and valve (with no gasket again) I can tell the world about my findings. You see, while Egge may believe this domed piston use "happens all the time" I could find no published or verbal confirmation of such a switch.

When the preliminary piston issue almost resolved I now had to make sure that my rod bearing to crankshaft clearance was within appropriate limits. Connecting rods on pre-1950 Buicks were babbit-lined and, as a result, the connecting rods were originally shimmed just like the main bearings. In late 1949 Buick adopted modern, insert bearings. Relining babbit bearings requires complete removal of the connecting rods and then shipping them to a shop equipped to service them whereas new insert bearings can be inserted with minimal effort.

I decided to have my connecting rods machined to accept insert bearings around the same time that I bought my pistons. Terrill Machine in Texas did the work and sold me the insert bearings as well. Their connecting rod and insert bearing set installed with .0015" clearance for every rod and I did not have to shim any of them. Acceptable rod bearing clearance is .0008" - .0018" and I am well within that range.

Now that I went through all of the effort to install my crankshaft and connecting rods, it was time to disassemble everything and prep for the final install. Remember that during my main bearing clearance check I installed everything dry. Now it was time to lube everything with assembly grease and oil.

I installed my resurfaced flywheel onto the crankshaft, making sure to line up the markings I etched into each just before I dismantled things for the first time. While the crankshaft was still out I installed the flywheel housing. I lubed and installed my camshaft then lubed all of my main and rod journals. With the help of my wife I gently placed the crankshaft into position, placed all of the shims in their proper location and installed the main bearing caps to proper torque specs.

In the next few days I will install my rods, pistons and oil pump assembly, then get the oil pan back on for the first time in over two years. The head will get my attention after that and I will soon be ready to paint the entire engine. Stay tuned for more progress!!!