Exhaust, Spark Plugs, Ignition Coil & Oil Filter Spacer

First job was to connect the old exhaust pipes to the manifolds.  I am going to build a new exhaust system in the future, but this will do to get it running.


The engine gasket kit came with exhaust gaskets, so I used them to install the pipes.  It was simply a matter of placing the gasket over the studs and then bolting up the flanges.

IMG_2854  IMG_2856

Spark Plugs

Another simple job which signals that an attempt to commit combustion is just around the corner is the installation of spark plugs.  My research came up with the NGK B6S as being an equivalent plug to the original.  The plugs which I removed were NGK B4 which are a couple of steps hotter than standard.

The spark plug gap required for the 390 engine is .035″.  When I checked the new plugs ( you should always do this) I found that they only had a gap of .025″ so I had to open each plug gap out by .010″.

I placed a small dab of grease on the thread and then screwed each one on by hand.  Once the crush washer made contact, I gave them another 1/2 to 2/3 of a turn as per the instructions on the box.

Tip: NEVER over tighten spark plugs – they don’t need to be very tight.  The same also applies to wheel nuts.

IMG_2872 IMG_2873

Ignition Coil

Mounting the ignition coil turned out to be a little bit more involved than normal as the fuel rail passes straight through the coil in its original position.  The mounting bosses are either side of the rail, and are at different heights.

IMG_2857 IMG_2859

After looking at a couple of options, I decided to mount the plate for the coil as a cantilever using a couple pieces of steel tube with bolts running through them into the bosses.  I found a tube which was a good fit over the bolts.  A couple of minutes measuring and I worked out that the tubes need to be 42mm and 70mm long.

IMG_2861  IMG_2862

I cut the tubes 1 or 2mm longer than needed, and then filed them square and to length.  Once finished, a quick sand followed by a coat of VHT Cast Iron Engine Enamel saw them finished.

IMG_2863  IMG_2868

I installed the plate using a flat washer between the tube and the boss on the manifold, and a flat & spring washer on top of the coil mounting plate.  Once it was all tight, it was nice and solid – actually better than I expected.  Even better, I can still access the fuel pressure regulator if needed.

IMG_2869  IMG_2871

Oil Filter Spacer

Another job I have been putting off is the oil filter spacer.

The 1959 Cadillac was fitted with an AC Delco S-6 bypass oil filter.  This filter was used on most GM engines of the time, and although not a perfect solution, is better than having no filtration.  It uses a filter insert which slides over the central shaft.  When the engine is running, a small amount of oil is allowed to ‘leak’ into the oil filter cannister and flow through the filter and back into the sump.  In 1960 Cadillac changed the design of the 390 to have a full flow spin on filter which ensured 100% of the oil was filtered before it entered the engine.  This spin on full flow design is still used today on modern engines today.

There is a spacer which slides over the shaft of the cannister and sits under the filter to hold it up off of the tapered sides.  You can see the cut away which shows how the filter assembly should look – note the thin T shaped spacer at the bottom.  I also have included a picture looking down into the bottom of the oil filter cannister.  The spacer was missing on my engine, which is quite common, so I need to make one.

oil filter section  IMG_2874


I bought some steel tube which has an inside diameter approx 2mm larger than the shaft, which makes it an easy fit.  I installed a new filter and measured how far it went down the shaft before it hit the tapered sides at the bottom of the cannister.  I then measured the length of the filter and added 2mm.  I worked out that the minimum length should be 15mm, and proceeded to cut a piece of pipe to suit (less the thickness of the washer I need to attach).  Once I had squared up the ends of the pipe and filed it to length, I gave the washer a light grind with my Dremel on one side to take off the zinc coating so I can weld it.

IMG_2876  IMG_2877

I set it all up in a G Clamp and MIG welded the two pieces together.  I didn’t have the MIG set hot enough to start with, so the welds don’t look the prettiest, however you will never see them, so job done…..

IMG_2878  IMG_2879

….well, maybe not.

I did a trial fit of everything and found that there was almost no pre-load on the spring in the lid when it was all bolted together.

I went back to the bench and did the whole process again, and made a spacer 22.5mm high.  The bonus was this time the welder was set correctly, so the welds were much tidier.


This time when I did a dry fit, the spring compressed when I installed the lid.  Happy days!

IMG_2882  IMG_2884

I tipped in just under a quart of engine oil into the cannister and closed it all up.  Winner winner chicken dinner!  🙂



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