'Bolters helping 'Bolters is a beautiful thing!
Restoring a Stovebolt to correct, original specs can be a formidible task -- especially when one gets down to the detail items that can make or break a run at Carlisle Gold. One of those details, the optional externally mounted oil filters, is one of those details that, because of a definite lack of comprehensive research, is often left to a "best guess." Well, no more! Your oil filter questions can be settled as Pat Doonan answers ...
It is important to note that oil filter assemblies were not standard equipment on pre-1963 Chevrolet cars and trucks. Chevrolet offered oil filter units as an RPO (Regular Production Option), or as a dealer installed item available through the GM Parts Division. In addition to the AC units supplied to Chevrolet, AC made many other styles and models available through AC distributors and United Motors Service. I will be discussing many of these AC units as they pertain to passenger cars and light / medium duty trucks. I will not go into the heavy duty units over two quarts, but if you need information on those units, please contact me and I'll be happy to share that as well.
In order to help with the identification of various units I will be covering, I have included pictures and references to those pictures throughout this article. To maintain as high a degree of accuracy as possible, all photographs of actual units shown are of NOS oil filters and fitting kits. None have been repainted or restored in any way.
If there's anyone out there with additional original literature that I don't have, or NOS units that they would like to share pictures of to help shed more light on this, please feel free to contact me so i can post it here for everyone.
All reference material used in this article was taken from the following sources:
1936, 1938, 1941, 1942, 1945, 1946, 1947, 1948, 1949, 1950, 1951, 1952, 1953, 1954 1955 1956 1957 1958 1959 1960 1961 1963 Chevrolet Master Parts catalogs:
Let us begin ...
L-1 Series (center opening type)
In that same 1936 book, it mentions another unit being used as a "replacement unit" for 1933-36 models CB, DB, O, P, EA, ED, EB, Q & R, but gives no part number.
The 1938 book lists part number 852902 as that replacement unit for 1933-36 models CB, DB, O, P, EA, ED, EB, Q, & R. From what I can determine from the books, the 601465 unit probably included all of the fittings, hoses and mounting bracket. No mention is made as to the AC model number of the unit supplied.
The only clue as to the model of this filter is that the AC oil filter manuals I have, list AC filter W-1 as being the original equipment filter for those 1933-36 models. It was then superceded by filter number W-21 (bottom left on this image).
S-1 filters were supplied in two different versions. The early version is shown here as the S-1 first design and here is another, listed with part numbers. It had a 9" shell length, nearly 12" overall length, and used gasket #130. The unit had a rounded neck at the bottom, and used a T-handle type cover bolt.
The second design type of the S-1 unit first appeared in the April 1, 1940 AC Oil Filter Service Manual, (image #5 ) but the instructions included with it (see Instruction Section below) still showed the first type. The second type had an conical bottom rather than the rounded bottom neck design used in the early version. It also used a different diameter gasket and the top cover was retained by a more conventional style bolt rather than a T-handle.
I would imagine that depending on inventory levels at AC at the time, and unsold units at the dealerships, it is possible that some first design units could have been used also on early 1941 models produced and sold in late 1940, especially since the first and second design units used the same part number, so stock could have been mixed.
The color (of both styles) was an aluminum gray lacquer, and had a black and silver waterslide decal on the side of the shell. Both the early and the late version used AC Kleer-Kleen type S-11 "igneonite" filter element. What is an "igneonite" filter you may ask? (See image #6 ) Well, the 1942 AC Oil Filter Service Manual states: "Igneonite is a mineral wool made from rock which is melted and blown into fine strands. This is mixed with a resin binder and molded around a perforated center core which is first covered with several layers of canton flannel or glass cloth. It contains no clay or fuller's earth." There. Now you know.
The element number changed to C-113 around 1944, and was a cotton type. Later, the element changed again to a more modern paper type and was sold under AC part number P-113.
Although the Chevrolet Master Parts books state the application as "all," its sales were undoubtedly targeted primarily towards trucks. The AC Oil Filter Installation sheets packaged with other smaller capacity models of the time (such as the L-1 & L-4) instructed the user to use the S-1 unit for truck applications.
The S-1 was the only filter offered through Chevrolet from 1939 to 1941. The 1942 and the 1945 Chevrolet Parts Books do not list a filter available through the dealership at all for 1942 models. However, AC still offered the S-1, as well as the L-1 and L-4 units for 1940-1942 passenger car and light truck models through AC distributors and United Motors Service (shown in the next 2 sections).
AC made two different versions of the top opening L-1 series. A drawn shell type, and a welded shell type were both sold under the L-1 series designation. The drawn shell type was one piece of stamped steel forced by a plunger through a series of progressively smaller drawing dies to form the bottom and sides as one unit. The lip under the top was the same diameter as the shell body. (See image #7)
The welded shell type (see image #8 ) was basically two pieces welded together where the bottom cap met the shell body, and the shell had a rolled lip under the cover.
Through my research, it appears that the welded type was used at first, and by the middle of 1940, the drawn cup style was the unit predominantly produced and sold. As with the mid-year change to the S-1 series, it could be entirely possible that some first design L-1 units could have been used on early 1941 vehicles.
The color for both versions was an aluminum gray lacquer, and had a black and silver waterslide decal on the side of the shell. The decals were not the same for both styles though. Looking closely at images #7 and #8 (above) of two NOS units shows the wording being different in reference to the gasket used.
Both versions were originally supplied with an "igneonite" element, #L-11. Around 1944, it was changed to a cotton element part number C-112, and was again changed to the P-112 paper type years later. Gaskets were different in all three versions produced of the L-1. (See image #9 which shows the different gasket part numbers.)
Unlike later styles of the 1940's and 1950's, this filter was not mounted to the intake manifold cross runner forward, or rear of the manifold heat stove. The Chevrolet Bracket and Fitting Kit (Kit 4) mounted directly to the face of the manifold heat stove. The top portion of the bracket had a single hole, and the bottom portion had two holes. The L.H. carburetor stud nut and the two bolts attaching the intake manifold to the exhaust manifold closest to the drivers side firewall were removed, the bracket attached in place, and the nut and bolts were re-attached. The bracket had a slot for a 1" wide strap which clamped the filter unit to the bracket. (See image #10 - part #'s 853534 & 853434 and the L-1 Instruction Sheet found at the end of this article.)
Although the S-1 unit was what was offered through the Chevrolet Parts Departments, the L-1 and L-4 series (discussed in the next section) were available through AC distributors and United Motors Service. Starting in 1941, AC offered a different style bracket for use on trucks only (except COE models) from 1937 to 1946 under part number 4-t (L-1/L-4 mounting bracket for truck -- image # 11 & image # 12) when using an L-1 or L-4 unit. It attached to the horn mount on the manifold in the front, and to the intake/exhaust manifold at the rear.
The original L-4 series shown in this picture was finished in aluminum lacquer and had a black and silver "Kleer-Kleen" decal on the shell with the "L-4" model designation and instructions on when to change the oil. The later type was painted with a gray lacquer rather than aluminum, and had a 2 ½" round black and yellow "AC Oil Filter" decal on the shell (see image #14).
Later versions appearing around 1946 were exactly the same in construction, but there was a slight change in the AC waterslide decal (see image #15).
Both of the later type units that were painted gray had an L-4 decal on the top. (Image #16 shows the L-4 second type color scheme.)
Unlike later styles of the 1940's and 1950's, this filter was not mounted to the intake manifold cross runner forward, or rear of the manifold heat stove. It used the same brackets as the L-1 which mounted directly to the face of the manifold heat stove. The top portion of the bracket had a single hole, and the bottom portion had two holes. The L.H. carburetor stud nut and the two bolts attaching the intake manifold to the exhaust manifold closest to the drivers side firewall were removed, the bracket attached in place, and the nut and bolts were re-attached. The bracket had a slot for a 1" wide strap which clamped the filter unit to the bracket. (See image #10 - part #'s 853534 & 853434)
The L-4 used an "igneonite" element, under part number L-14. The cotton version appeared around 1944 under part number C-110, and was finally changed to a P-110 paper element.
One thing is for sure though. The 1504439 unit is an AC model S-2 Filter Assembly, which was the replacement for the now discontinued S-1 unit. Although the books say "all except COE," it is geared more towards trucks I believe, rather than the passenger cars, simply because of the size of the unit. The S-2 unit is large, and in my opinion being nearly two quarts, is a little bit of an overkill for car use. It has a height of 11 5/8", which was a little taller than it's predecessor, the S-1, and the O.D. was 5" diameter, as opposed to the S-1's diameter of 4 5/8". The Chevrolet-purchased unit was mounted to the firewall with the two straps supplied with it. The standard version supplied by AC also mounted to the firewall with the two straps, or on the intake manifold runner by adding the correct bracket set, which was the same as the one used for the S-6 models described below.
The original 1946 unit was gray, and had a 2 ½" diameter yellow and black "AC Oil Filter" decal on the shell. (See image # 17 - original gray color scheme used to July 1947)
By mid year 1947, the color scheme changed from all gray to yellow with a black top. (see image # 18 - S-2 yellow & black color scheme used from July 1947 through 1949; and image #19 - S-2 Kleer-Kleen decal used from 1946 through 1949)
The S-2 series was used up to 1962 as an alternative higher capacity unit to the S-6 for larger trucks and busses. In 1950 the color scheme changed, to having an orange lid and blue body.
The S-2 unit initially used a C-25 filter element, which was changed to a C-117, (cotton) and finally to P-117 (paper) element.
The 1947-48 version had the same decals, but the shell was yellow with a black top. (See image #21 - L-5 with yellow & black color scheme used from July 1947 through 1949; and image #22 - L-5 black top color scheme used from July 1947 through 1949.)
The L-5 series used a C-111 cotton element initially, and it was later changed to the P-111 paper type.
From its initial release in 1946 to mid-1947, the unit was gray with a yellow and black AC decal on the lid, and the 2" round yellow and black "AC Oil Filter" decal was located on the mounting bracket (see image #23 - S-6 original gray color scheme used to mid 1947; and image #24 - S-6 top). The AC designation for this unit packaged for installation on Chevrolet's was SC-646.
Starting in July of 1947, AC released the "5 Star Oil Filter Line." The S-6 unit remained the same as far as size, construction, and mounting brackets. The only difference was the color scheme. The S-6 unit was no longer painted gray as in the early models. The lid was now painted flat black, and the shell was a flat yellow (see image #25 - S-6 yellow & black color scheme used from mid 1947 through 1949).
The lid had the same yellow and black decal, and the yellow and black 2" diameter "AC Oil Filter" decal on the shell clamp as with the gray 1946 / early1947 units.
The element was a C-115 cotton element, later changed to P-115 paper type.
Through my research, i have found that there were three different coloring and wording schemes on the lid decal that took place between 1946 and 1949.All three versions are shown below. << click image for larger view >>
A note about "S-6" Series filters
An example follows:
Type SC-650 was an "S" line filter. The "C" denoted it was a tailored kit packaged specifically for Chevrolet applications. (Kits tailor made for Cadillac used a "K"; "P" for Dodge, Chrysler and Plymouth applications; "M" for Oldsmobile; "F" for Ford; "N" for Nash). The "6" denoted the line type. The "50" established what model year it was first put into service. So, SC-650 was an S-6 type, tailor made for Chevrolet, and first introduced in 1950. This same referencing applied to other types as well, such as the S-2 line.
The C-115 cotton element was still the replacement offered for this unit. The unit still mounted the same way as the earlier S-6 units with one bracket on the forward runner of the intake manifold, and one 2" high strap attaching the shell to the bracket. It also still retained the yellow and black color scheme that was used starting in mid 1947.
Starting in 1950, the Chevrolet Parts Book shows the P-115 paper element, and does not offer the cotton element, although they were still available through AC distributors.
The 1953 and 1954 Chevrolet Master Parts books for both years state that the unit was now an SC-653 unit. There were major changes to the unit once again, although the body itself was the same dimensionally as the 1950-1952 models. The spot welded bracket changed completely. The inlet hose connection was at a slightly different position in relation to the spot welded bracket than previous models. As far as package contents, the inlet and outlet hoses were each 1" longer than the previous model. The silkscreening on the lid was slightly different. Instead of having a block area to write the mileage in, it now had lines (see image #32 - 5573017/sc-653 top).
The year 1955 also saw the introduction of the soon-to-be-famous 265 cubic inch Chevrolet V-8. The Chevrolet part number was 5573607 for the 8 cylinder model filter used on vehicles without air conditioning. The AC model designation for this unit was SC-6558-1 according to the parts books. The V-8 filter used on models with air conditioning was Chevrolet number 5573919 and was marketed as an AC SC-6558-a unit.
It's interesting to note that the 1955 AC Oil Filter Catalog offers model SC-6558 to fit all V-8 except 4bbl, Corvette, or vehicles with air conditioning, and model SC-6558-x to fit 4bbl, except Corvette or air conditioning. The AC Filter Book makes no mention of the "a" suffix model described in the Chevrolet Parts Books.
The 1955 models were the first and only year the V-8 engine used an optional external oil filter. From 1956 on, all Chevrolet V-8's have used an integral cartridge type, or modern day spin on type, while the 6 cylinder still used the external bolt on S-6 exclusively through 1962, and some models to 1963.
Both the 6 cylinder and 8 cylinder units are shown in image #33. The P-115 paper element was used on both 6 and 8 cylinder versions of the filter.
The cap was now slightly shorter in height (see image #35 ; and image #36 - - 5575218/SC-659 top) and the stamped depression extending to the sealing lip surface was not as deep or pronounced. The top retaining bolt was also different, as there was no shoulder under the head as in previous versions. The silkscreened lettering was moved to the angled portion of the top rather than the flat surface right above the gasket sealing area. An area to write the mileage when the filter was changed was also eliminated.
This unit still used the P-115 paper element as in past models.
The SC-660 filter type was used on the 1960, 1961, and 1962 Chevrolet 235's as well as the two quart SC-260 unit described below. They were both discontinued for 1963 since the newly introduced Chevrolet 230 cubic inch 6 cylinder engine now used a spin on type element, eliminating the need for this bolt-on type style. The one exception to this is the 1963 Chevrolet 4 wheel drive trucks which retained the 235 engine until mid-year 1963. Once the 235 was finally phased out, so were bolt-on oil filter units for use on Chevrolet cars and trucks from that point forward.
Many of the units I've described here are all fairly close in style. When looking on eBay, or scrounging around at junkyards or car shows trying to find your correct unit, it's easy to get one style mixed up with another. Many of them look identical. The only way to tell them apart is by size. Image #38 shows many of the one quart units discussed here, grouped together to give you a better idea of the physical size differences between the various types.
Which oil lines are technically correct is just about as confusing as the filters themselves. AC changed materials and colors quite often, as you will see in the example pictures. Image #39 and image #40 show hoses from the original Kleer-Kleen line prior to 1947. For the hoses prior to 1947, the part number did not match the hose length. For example, hose number 27 was 20" in length. Also, the two NOS samples shown are encased in different materials. Image #39 is the early style cloth braided type hose, and image #40 shows the later style which had a gray rubberized or neoprene casing. During that same time period, AC also supplied completely black hoses, too.
Starting in 1947, the part number of the hose was also the length of it. Some hoses supplied were gray, black neoprene, or yellow (see image #18). Most late 1940's hoses came with a plastic band around the hose indicating the part number along with a yellow and black AC circle logo (see image #41). By the 1950's, all of the hoses were black and the logo band was still black and yellow. The only difference is the box packaging had changed to the double bulls eye logo (see image #42). Starting in 1959, they changed from a plastic band to a sticker with a red and white AC logo around the hose showing the part number (see image #43). Replacement hoses supplied through GM dealerships in GM packaging rather than AC packaging did not have the band or sticker with the part number of the hose.
Below are some original oil filter Instruction Sheets.
I hope this has been of use and value to some of you out there. My goal in researching and writing it was that this information should clarify what is and is not correct for our vehicles for those of you like me, who are sticklers for authenticity. It would also be nice to see this used as an ACCA and VCCA judging aid, as there is no definitive standards out there as to what is and is not correct or acceptable.
Another reason I was motivated to do this type of research was the fact that many vendors out there are telling people what they have for sale for your vehicle is what is correct for it. EBay sellers and swap meet vendors are the world's worst at this. Whenever you find an oil filter for sale with these folks, no matter what type, they will usually say that it's correct for your 1930's to 1950's car or truck when in most cases, nothing could be farther from the truth. In all fairness to these folks, they are not always trying to intentionally deceive you so you'll buy from them. They are just going on what they think is correct or by instructions included with items they're selling. For example, the S-6 units i have described above, that were not introduced until the 1940's, have instructions that show installation back to the 1930's. Although these instructions show this, the units are not correct for the 1930's applications since they didn't even exist then. The way I see it, if you know what's right, you won't waste your money on what's wrong.
The other problem is that reproduction places perpetuate this thinking. Decals sold through the repro places don't always give the correct year usage or application. Not because they're purposely trying to deceive you, but because they honestly don't know all the facts. I hope this article gives you those much needed facts.
On the other hand, despite my arguments on correct vs. incorrect, the one thing I need to stress is that one of the most important things you can do for your restored Chevrolet Stovebolt 6, is put an oil filter on it. When it comes down to it, whether it's the correct one, a different year, style, or another aftermarket brand, ultimately it really doesn't matter. Just put one on to help protect your engine, and we'll all be able to enjoy each other's vehicles for many years to come.
Questions? Comments? Arguments to the contrary of what's written here? Email me. I will also be happy to email copies of the oil filter Instruction Sheets for various AC units for many GM models and years free of charge.
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"It's not a wreck ... it's a natural resource!" ~ Doc Bob