US2686509A

US2686509A - Spark plug and ignition lead wire protective system

Info

Publication number: US2686509A
Application number: US262604A
Authority: US
Inventors: William E Drinkard
Original assignee: Chrysler Corp
Current assignee: Old Carco LLC
Priority date: 1951-12-20
Filing date: 1951-12-20
Publication date: 1954-08-17
Anticipated expiration: 1971-08-17

Description

Aug. 17, 1954 w. E. DRINKARD 2,686,509

SPARK PLUG AND IGNITION LEAD WIRE PROTECTIVE SYSTEM 2 Sheets-Sheet 1 Filed Dec. 20, 1951 41 I? I INVENTOR.

I! \d i /'am [In /07474.

14 J BY I if A m may Aug. 17, 1954 w. E. DRIINKARD SPARK PLUG AND IGNITION LEAD WIRE PROTECTIVE SYSTEM 2 Sheets-Sheet 2 Filed Dec. 20, 1951 M m .l|I|1|| l I l i I I l II V 0 "3 N\\ mi n W 7. l .w l|. M W I III 1..NII

Patented Aug. 17, 1954 UNITED STATES ATENT OFFICE SPARK PLUG AND IGNITION LEAD WIRE PROTECTIVE SYSTEM Application December 20, 1951, Serial No. 262,604

19 Claims. '1

This invention relates to protective or shielding systems for protecting the spark plugs and connecting ignition wires or leads of internal combustion engines from oil, dust, moisture, and gases, and more particularly to a combination spark plug and ignition lead protective housing structure for Vtype engines requiring submerged spark plugs.

Various devices have been suggested to protect the exterior portions of installed spark plugs and their immediate ignition wire connectors from moisture, dust, and oil. These have generally taken the form of plastic or flexible jackets confined to the spark plugs and the immediate Wire connectors. They have not been entirely successful as protectiv media since the lead wires constitute conducting paths for water and/or oil to the plugs within the shield and oil-laden gases emanating from the interior structure of the spark plugs or the mounting openings therefor have often caused the shields and connecting leads to be blown off the plugs. Moreover, shields of this character have been difiicult to handle especially where the spark plug was necessarily mounted in a well formed in the cylinder head of the engine.

The present invention provides a composite structure believed to better protect the plugs and lead wires of the ignition system.

An object of my invention is to provide a protective system for spark plugs and ignition lead wires that includes a spark plug shield which serves as a gasket.

Another object of my invention is to provide a protective system for spark plugs and ignition lead wires as aforesaid wherein these parts are the oil laden vapors emanating from the valve operating mechanism of the engine.

A further object is to provide a protective system as aforesaid, wherein the spark plug is ventilated so that blowby gases from the combustion chamber leaking through the spark plug interior or through the spark plug mounting joint may get out to the atmosphere without blowing oii any flashover shields provided on the spark plug and the lead wire connectors and wherein the ventilation provided in the system avoids any build-up of condensation'from blowby gases.

It is also an object to provide a protective system as aforesaid, which inhibits the condensation of external water vapor within the system especially during periods of high humidityand low temperatures, and wherein the ignition lead-wires emanate from the protective covering at a location permitting external water drainage away from the plug side ofthe leads.

A further object is to provide a protective sys tem for spark plugs mounted in a well of the engine cylinder head whereby drainage Water cannot get into the spark plug well.

Thes and other objects of my invention will become apparent from the following description and from the accompanying drawings wherein:

Figure 1 is an end elevation view of the rear or flywheel end of a V-8 overhead valve engine showing the ignition wire cover of my invention applied to each bank of cylinders and showing the manner of connecting the ignition wires to the distributor mounted on the engine;

Figure 2 is a top plan view-of one of the lead wire covers of Figure 1;

Figure 3 is an elevational view partly in section of the structureof my invention, the section being taken on the line '33 of Figure 2;

Figure 4 is a sectional elevational View through the spark plug and lead wire protective structure of my invention taken at 3-4 of Figure 2; and

Figure 5 is a sectional elevation taken similarly to that in Figure 4, of a modification of my invention.

In the drawings in which like reference numerals designate corresponding parts of the structure of my invention, I have illustrated, as seen in Figure 1, an 8-cylinder 'V-type engine of current manufacture to which my invention has been applied.

The engine, as seen in Figure 1, has right and left cylinder banks It and I2 respectively. The cylinder banks are arranged in a V relationship, each'having a cylinder head 14, the valve operating mechanism for which is enclosed beneath a cover It secured to the cylinder head, as seen in Figures 1, 2, and 3by bolts 18.

Each cylinder head has a plurality of spaced cylinders i9 each provided with a combustion chamber .Zt above which is a'liquid cooling space 2| defined, among others, by the chamber wall'22 and a top wall 24.

Connecting the Walls 22 and 2 5 on approximately one axis of the cylinders are walls 2550f 'circularformation'which define pockets, wells, or depressions 28 for receivin and substantially sub merging spark plugs as of'conventional character. The spark plug 30 is mounted upon a seat 32'by a threaded base portion M'which is'threadedly receivedin a threaded bore 36 at the bottom of the well which opens into the chamber tt'to permit the electrode .as of the spark plug to be exposed to thefuel-air mixture in the chamber 20.

Each-depression'23 preferablyhas its interior surface machined concentric with the axis of the spark plug for receiving a rigid cylindrical spark plug shield or tube 36 of suitable heatresisting and shape-retaining material, preferably steel, which is made a loose fit with the machined bore of the well 28. The lower portion of the tube 40 has an inturned lip 42 which is provided with an aperture 43 through which the threaded portion 3d of the spark plug may be inserted and whereby the lip portion 42 for the spark plug acts as a sealing gasket between the spark plug and the seat 32 and facilitates the removal and reassembly of the spark plug without the use of special tools.

The tube 48 surrounds the spark plug and extends vertically above the top wall it of the cylinder head cover l5, as seen at 45 in Figure 4, the said tube extending through a water and oil seal generally designated by the numeral as.

The tube 40 is of sufiicient size such that the spark plugs may easily be removed and replaced by an ordinary socket wrench, the tube 46 itself as will hereinafter be noted, serving as a tool to aid the removal and replacement of the plug. The upper end of the tube in Figure 4 is, moreover, preferably rounded or flared as at ll and all sharp corners removed therefrom.

The seal structure 48 comprises an annular cup-like depression 48 formed in the top wall of the cylinder head cover It and which provides an annular cylindrical wall 49 and an annular seat 50 having an aperture 5| through which the tube 40 extends; a pressure ring or washer 52 having an aperture 53 and which is of larger diameter than the depression as so that it may seat upon the top wall A l of the cy inder head cover; and a pliable annular or cylindrical sealing ring 56 of natural or synthetic plastic mate rial, for example, rubber or neoprene and which is preferably a shaped preformed ring of cylindrical section having an internal dimension slightly smaller than the external dimension oi the tube 40 and having at its opposite ends projecting lips 5'! and 53 forming shoulders with the adjacent portion 59 of the ring.

The projection 57 is intended to be positioned in the aperture 5! of the depression 53 and the projection 58 to enter the aperture 53 of the washer 52. The portion 55 of the ring is of somewhat greater depth than the depth of the depression 48 of the cover iii such that pressure may be brought to bear on the shouldered portions of the ring by the washer 52 when the structure is assembled as hereinafter described.

As seen in Figure 4, the insulated ignition lead wire 62 is provided with a spring contact clip 64 which snaps over the terminal end 58 of the spark plug 30 and is protected from flashover by a suitable tubular shield l forming no part of this invention which may be of ceramic or other suitable insulating material and which comprises an elongated tubular portion 72 embraclng the lead wire 52 and extending above the spark plug a substantial height of the tube 40 and having a lower outwardly flaring lip or portion M which extends over the terminal connection and over a portion of the insulating wall of the spark plug.

The lead wires 62 from the individual spark plugs are turned downwardly as they emanate from the tube 40 and are arranged, as seen in Figures 2 and 3, to extend longitudinally of the cylinder head cover H in the direction of the rearward end of the engine where they connect with the distributor generally designated by the numeral 18.

Housing and protecting the ignition lead wires 62, is a still dished cover generally designate by the numeral which may be of heat-resisting and shape-retaining material, for example, a metal such as aluminum and which is secured to seat upon the seal washers 52, as seen in Figure 4, and to be secured to the cylinder head cover 16 through these washers 52 by means of countersunk head screws 82 received in suitable depressions as of the cover 813 and threaded into suitable shoulder posts 35 projecting upwardly through the cylinder head cover it of which three are illustrated, which posts are suitably held to the top wall 5 5 of the cylinder head cover H5 as by riveting, soldering, or spot welding.

The lead cover 3%! is relatively shallow in character and is of a width and length to extend O er the spark plug tubes to and provide adequate space to neatly confine the ignition lead wires without causing damage to them. A width slightly greater than the diameter of the posts 86 plus four lead wire diameters will generally suiiice for an 8-cylinder V-engine, there being four wires confined under each of the two covers provided on such an engine as is disclosed in Figure 1.

As further seen in Figures 2, 3, and 4, the cover 80 has a continuous right angled flange iii, 92, 93 which connects with the side walls 94, 55 and the end wall f the lead cover This flange portion may have, as seen in Figure 4, a slightly downwardly bent lip 97. The opposite flange portions s1, 82, as previously described, seat against top surface portions of the pres sure washers oi seals 55 and by means of the mounting screws 82, transmit compressive forces to the sealing ring 56 through the washers 52 to thus create a tight seal between the seat 50 of the depression d8 of the cylinder head cover it and the ring 5% and between the ring 55 and the washer 52 and between the ring 56 and the immediately contacting wall portion of the tube at. Unless the screws 82 chest a compression of the seal rings excessively, there Will generally be an edgewise aperture lei? formed by the lip ill of the lead cover and the top wall 44 of the cylinder head cover providing ventilation apertures between the adjacent pressure washers 52.

The end of the lead cover opposite the end Wall 9% is provided with a sloping wall 332 prolecting downwardly and outwardly from the top well tilt of the lead cover so as to project over the end portion of the cylinder head cover #6 and provide between this wall Hi2 and the rounded corner Hit of the cylinder head cover. an ignition lead outlet act. The outer edge or" the wall me has an additional outward dare to Provide a rounded lip Hi? to protect the lead wires from contact with any sharp corners.

Suitable clips or tubular confining members may be provided at the post or at other points between the adjacent spark plug tubes to hold the adjacent lead wires together in a compact group such that the lead wires will stay position after the cover 8d is removed and. lllOl over, to avoid sharp bends in the lead wires. These clips or tubular members may be of suit able heat resisting insulating material and if made of metal are preferably coated and have all edges rounded. If desired, the inner surface of the cover as may be coated with a suitable insulating and/or rust-resisting material such as a phenolic resin coating.

Between the outlet H38 of the lead cover 88 and the distributor 18, the ignition lead wires may be clamped at one or more places against the cylinder head cover It by suitable straps lfiZa, shown in Figure l, which are secured. by bolts or screws N33 to the cylinder head 14.

It will be evident that by providing a further metallic enclosure for the exposed portions of the lead wires in Figure l, a fully shielded enclosed ignition system to prevent radio interference from the ignition and other sources may be secured.

It will be observed that the ignition lead wire N38 is at the rearward end of the engine which end is generally lower than the front end when the engine is mounted on the vehicle chassis. By reason thereof any splash water getting under the cover 8% or on the ignition lead wires under the cover can readily run or drain off away from the spark plug chambers. Moreover, it has been previously noted that the spark plug tubes Ail project upwardly at 51 in Figure 4 above the cylinder head cover wall M. Hence, it will be apparent that any splash water getting under the lead cover 89 and on the wall M of the cylinder head cover it cannot get into the spark plug compartment it and cannot get into the valve mechanism compartment by reason of the seal 65. All this is true despite the presence of the apertures let described aforesaid, resulting from the method of mounting the lead cover as.

It will also be noted that any vapor emanating from the internal structure of the spark plugs 35 or through the threaded connection 34 between the spark plug well 28 and the combustion chamber 26, can find escape through the apertures 106 between the flange portion c1 of the lead cover and the top wall 4 1 of the cylinder head cover or through the lead wire opening H38. Moreover, fresh air can get under the lead cover throughout its periphery by reason of the aforesaid apertures to ventilate the spark plug compartments as well as the under space of the lead cover 80. The described structure, moreover, is of a character wherein it has been observed in actual use that practically no condensation forms on the under side of the lead cover 80 even under conditions providing low ambient temperatures with high humidity.

As previously indicated, the above described structure lends itself to very easy assembly of the spark plugs and of the seal structure. In actual asembly, each of the tubes 48 is provided with a seal ring 56 adjacent its upper end following which a spark plug is inserted in the tube with its threaded end 34 projecting through the aperture as at the bottom of the tube. A socket wrench is inserted over the octagonal portion l 22! of the spark plug after which these elements are lowered into the spark plug well 28 after inserting the tube through the aperture in the cylinder head cover M if the same is then in place. The tube li! helps center the spark plug 3 3 with the threaded bore 38 and the spark plug may then be screwed in place by the wrench very rapidly. It will be observed that since the lip d2 of the tube serves as a gasket for the spark plug, there are no loose washers which may fall off the end of the spark plug in assembly or which may become lost. After the spark plug is in place, the seal ring 55 is pushed into position against the seat 5% of the depression 48 in the cylinder head cover [6, and a pressure washer 52 is placed over each ring 56. Thereafter, after the lead wires are properly arranged, the lead wire cover 88 is positioned over the wires and 6'. tubes upon the pressure washers 52 and is secured in place by the screws 82.

It will be understood that in assembly or disassembly, the cylinder head cover It may be positioned after the spark plug tube 40 and spark plug are in position. In that event, the seal rings 56 must be positioned after the cover I6 is seated and must be forced over the fiared end of the spark plug tube 40. Since. however, the rings 55 are very pliable, there is no difiiculty in forcing them on the tube 40 over the fiared lip, or to remove them from the tube in disassembly.

In Figure 5 I have illustrated a modified form or" the structure of my invention wherein an 0 ring type seal is employed between the spark plug tube 413 in this figure, and the depression 48' in the wall Aid of the cylinder head cover [6' and wherein the lead cover seats in face-toface contact with the top wall 44' of the cylinder head cover.

As seen in Figure 5, the upper end. of the tube it has rigidly secured thereto as by press fitting, soldering or spot welding, a right-angled sectioned pressure ring 522 having an annular cylindrical portion I23 secured on the tube and having an annular flange portion H4. The depression 48' has an annular cylindrical wall 49 and a seat 5!).

In assembling the tube and spark plug, the seal ring 5% which is preferably of pre-formed O shape section and has a somewhat smaller internal diameter than the external diameter of the tube '30 and a somewhat larger external diameter than the internal surface of the cylindric wall @9 of the depression 48 is forced over the tube 40 and against the flange 12d of the pressure ring I22. The tube 40' is then dropped through the aperture in the depression as and the O ring seal permitted to rest upon the seat 50' of the depression 48'. The location of the ring H2 is such that it is necessary in mounting the spark plug to force the ring I22 downwardly against the seal to effect a compression thereof between the flange I2 3 of the ring E22 and the seat 50' such that the seal ring also spreads laterally to produce an efiective seal between the outer surface of the tube 40 and the inner surface of the annular portion 49 of the depression to thereby create an effective vapor seal. No gasket is required between the flange portions 9!, 92 of the lead cover and the top wall 4 5 of the cylinder head cover any unevenness between the mating surfaces serving as further means for ventilating the interior of the lead cover and the spark plug tubes.

Although it will be apparent that the illustrated embodiments of my invention are well calculated to adequately fulfill the objects and advantages of my invention described above, it will be understood that my invention is susceptible of variations, modifications and changes within the spirit and scope of the appended claims.

I claim:

1. In an internal combustion engine having a cylinder head, a spark plug relatively submerged in a well in said head, valve mechanism carried by said head and a dished cover enclosing said valve mechanism and said well; a protective structure for said spark plug and the ignition lead therefor comprising a tubular member surrounding said spark plug in said well, said tubular member having a mounting portion thereon whereby said member may be secured in said well by said plug, said member having an end open and extending through the top of said valve mechanism cover, means forming a seal between said member and said valve mechanism cover and an ignition lead cover straddling the open end of said member and mounted on said valve mechanism cover.

2. In an internal combustion engine having a cylinder head, a spark plug relatively submerged in a well in said head, valve mechanism carried by said head and a dished cover enclosing said valve mechanism and said well; a protective structure for said spark plug and the ignition lead therefor comprising a tubular member surrounding said spark plug and having one end loosely interiitting said well, said member having a mounting flange thereon whereby said member may be held therein by said spark plug, said. member having its opposite end open and extending through the top of said valve mechanism cover, means forming a seal between said member and said valve mechanism cover and an ignition lead cover straddling the open end of said member and mounted on said valve mechanism cover.

3. In an internal combustion engine having a cylinder head, a spark plug relatively submerged in a well in said head, valve mechanism carried by said head and a dished cover enclosing said valve mechanism and said well; a protective structure for said spark plug and the ignition lead therefor comprising a tubular member arranged in said Well and surrounding said spark plug, means on said member interengaged with said spark plug whereby the latter may mount said member in said well, said member having its other end open and extending through the top of said valve mechanism cover, means forming a seal between said member and said valve mechanism cover and an ignition lead cover straddling the open end of said member and mounted on said valve mechanism cover.

4. In an internal combustion engine having a cylinder head, a spark plug relatively submerged in a well in said head, valve mechanism carried by said head and a dished cover enclosing said valve mechanism and said well; a protective structure for said spark plug and th igmtion lead therefor comprising a tubular cylindrical member loosely interfitting the wall of said well, one end of said member having an inturned lip positioned intermediate the base of said well and said spark plug and serving as a mounting means for said member by said spark plug, the other end of said memer extending through the top of said valve mechanism cover, means forming a seal between said member and said valve mechanism cover and an ignition lead cover straddling said member and car ied by said valve mechanism cover.

5. In an internal combustion engine having a cylinder head, a spark plug well in said head provided with a spark plug seating face, a spark plug substantially submerged in said Well and mounted on said seating face, valve mechanism carried by said head, and a dished cover enclosing said valve mechanism and said well, a protective structure for said spark plug and the ignition lead therefor comprising, a cylindrical bore in said well substantially coaxial with said plug, a substantially rigid, hollow cylindrical member in loose te1escoping relation with said bore, a mounting washer for said spark plug integral with said member at one end thereof and secured by said spark plug against said seating face, said washer serving as the mounting means for said member, the opposite end of said member extending through said valve mechanism cover to a position above and adjacent the top wall thereof, means providing a seal between said member and said valve mechanism cover wall, an ignition lead cover straddling said member and means mounting said ignition lead cover on said valve mechanism cover.

6. In an internal combustion engine having a cylinder head, a spark plug on said head, valve mechanism carried by said head and a dished cover enclosing said valve mechanism; a protective structure for said spark plug and the ignition lead therefor comprising an elongated tubular member surrounding said plug and secured in said head by said spark plug, said member extending through the top of said valve mechanism cover, an annular seal mounting seat on said valve mechanism cover surrounding said member, an annular seal ring on said seat, an annular washer on said seal, and an ignition lead cover straddling said member and seated on said washer.

T. In an internal combustion engine having a cylinder head, a spark plug on said head, valve mechanism carried by said head and a dished cover enclosing said valve mechanism; a protective structure for said spark plug and the ignition lead therefor comprising an elongated tubular member surrounding said plug and secured on said head by said spark plug, said member extending through an aperture in the top of said valve mechanism cover, an annular seal mounting seat carried by said valve mechanism cover surrounding said member, a compressible seal ring on said seat, an annular washer abutting said seal, an ignition lead cover straddling said member and seated on said washer and means securin said ignition lead cover to said valve mechanism cover, said means adapted to apply sealing pressure to said ring through said ignition lead cover and washer.

8. In an internal combustion engine having a cylinder head, a spark plug relatively submerged in a well in said head, valve mechanism carried by said head and a dished cover enclosing said valve mechanism and said well; a protective structure for said spark plug and the ignition lead therefor comprising an elongated tubular member surrounding said plug in said well, said member having an annular mounting flange at one end thereof whereby it is secured to said cylinder head by said spark plug, said flange also serving as a sealing gasket for said plug, the other end of said member projecting a short distance through an aperture in said valve mechanism cover, an annular seal mounting seat carried by said valve mechanism cover juxtaposed said aperture, a compressible seal ring having a central body portion and end lip portions, one of said lip portions being received in said aperture, said body portion being positioned on said seat, a seal compressing washer abutting said ring and received over the said other lip portion of the said ring, a flanged ignition lead cover straddling said member and having its flange seated on said washer and means operating between said ignition lead cover and said valve mechanism cover for compressing said seal.

9. In an internal combustion engine having a cylinder head, a spark plug on said head, valve mechanism carried by said head and a dished cover enclosing said valve mechanism; a protective structure for said spark plug and the ignition lead therefor comprising, an elongated tubular member surrounding said plug, said member having an annular mounting flange at one end thereof whereby it is secured to said cylinder head by said spark plug, the other end of said member projecting through an aperture in the top wall of said valve mechanism cover, an

annular, depressed seal mounting seat carried by saidvalve mechanism cover and surrounding said member, a com-pressible'seal ring on said seat, a

seal compressing washer carried by said ring,

said washer being larger than said seat and overlying said wall, an ignition lead cover straddling said member and seated on said washer and means securingsaid ignition lead cover to said valve mechanism cover whereby said ring iscompressed and air slots are formed between said covers adjacent said washer.

10. In an internal combustion engine having a cylinder head, a spark plug relatively submerged in a well in said head, valve mechanism carried by said head and a dishedcover enclosing said valve mechanism and said well; a protective structure for said spark plug and the ignition lead therefor comprising an elongated substantially rigid cylindrical member surrounding said plug, said member having an annular mounting flange at one 'end thereof'whereby it is secured to said cylinder head by said'spark plug, the other end of said member extending throughthe top wall of said valvemechanism cover to a predetermined point adjacent thereto, and said mem ber having an internal transverse dimension sufiicient to enable insertion therein of a socket wrench for removing said plug, means providing a seal between said member and said valve mechanism cover adjacent the top side of said top Wall, an ignition lead wire within said member having a terminal clip engaged with a terminal on said spark plug, a fiashover shield surrounding said lead in said member and adapted for facilitating connection and disconnection of said lead terminal clip with said plug terminal, said lead wire having a portion thereof extending over said member and arranged to be adjacent said valve mechanism cover, a shallow ignition lead cover straddling said member and ignition lead and in face-to-face relation with said top wall of said valve mechanism cover, and an aperture at one end of said ignition lead cover providing a lead outlet and ventilation port.

11. In an internal combustion engine having a pair of cylinder banks forming a V with each other, said banks being pitched downwardly longitudinally from the fan end of the engine when the latter is assembled in a vehicle, a plurality of longitudinally spaced cylinders in each bank, said cylinders having overhead valve mechanism, a plurality of spark plugs relatively submerged in wells in said heads, one being over each cylinder, and a dished cover secured to each head and covering the valve mechanism of that head; a protective structure for said spark plugs and for the ignition lead wires thereof comprising an elongated substantially rigid cylindrical member surrounding each spark plug and secured in each well by a spark plug therein, said member having an annular mounting flange at one end thereof positioned beneath said spark plug and having its opposite end extending through the top wall of said valve mechanism cover, means providing an elastic seal between each said member and said valve mechanism cover at a position within the lattercover, a detachable ignition lead wire connected to each said spark plug and extending over the tube in which it is connected, said lead wires being arranged to extend toward the low end of the cylinder bank in which they are connected, an elongated ignition lead cover secured to said dished cover and straddling all said members of one bank and the lead covers emanating from the 10 spark plugs therein and a lead wire aperture at the longitudinal end of said "lead wire 'cover which is at the low-end of the cylinder bank.

12. A protective structure as claimed in claim 11 wherein the apertured end of the ignition lead cover is located attheend of the dished portion of said valve'mechanism cover and has'a downwardly sloping wall extending over the lead wires and over the end of said dished portion.

13. A protective structureas claimed in claim 12 wherein said seal comprises a preformed O ring member seated on said valve mechanism cover and held under compression by apressure ring mounted on said" member.

14. In an internal'combustion engine having-a cylinder head,'a spark plug relatively submerged in a Well in said head, valve mechanism carried by said head and a'dishedcover enclosing said valve mechanism and said well; a protective structure for said spark plug and the ignition lead therefor'comprising an elongated tubular member surrounding said plug and secured in said well by saidplug, said member extending through the top wall of said valve mechanism cover, an annular seal mounting seat on said valve mechanism cover surrounding said'member, an 0 sectionedseal ring on said seat, :an annular pressure ring secured to said member and in pressure abutting relation tosaids'eal ring, and an ignition lead cover straddling said member and seated on said Valve mechanism cover.

15. In an internal combustion engine having a cylinder head, a spark plug relatively submerged in a well in said head, valve mechanism carried by said head and a dished cover enclosing said valve mechanism and said well; a protective structure for said spark plug and the ignition lead therefor comprising an elongated tubular member surrounding said plug and mounted in said well by said plug, said member extending through an aperture in the top of said valve mechanism cover, an annular seal mounting seat carried by said valve mechanism cover surrounding said member, a compressible O ring seal on said seat, an annular pressure ring abutting said seal and secured to said member, an ignition lead cover straddling said member and seated on said valve mechanism cover, and means securing said ignition lead cover to said valve mechanism cover, said member being secured in place by said spark plug and as an incidence thereto adapted to apply sealing pressure to said seal through said pressure ring whereby said seal is compressed and caused to spread laterally.

16. In an internal combustion engine having a cylinder head, a spark plug carried by said head, valve mechanism carried by said head, a dished cover enclosing said valve mechanism; a protective structure for said spark plug and the ignition lead therefor comprising a tubular member surrounding said plug, one end of said memher having an inturned flange portion positioned intermediate said spark plug and head and serving as a mounting means for such member by said spark plug, the other end of said member being open and extending through the top of said valve mechanism cover, means forming a seal between said member and said valve mechanism cover, and an ignition lead cover straddling the open end of said member and carried by said valve mechanism cover.

17. In an internal combustion engine having a cylinder head, a spark plug on said head, valve mechanism carried by said head and a dished i1 cover enclosing said valve mechanism; a protective structure for said spark plug and the ignition lead therefor comprising an elongated tubular member surrounding said plug and carried by said head, said member extending through the top of said valve mechanism cover, an annular seal mounting seat on said valve mechanism cover surrounding said member, an annular seal ring on said seat, and engageable with said member, an annular Washer on said seal, and an ignition lead cover straddling said member and seated on said Washer.

18. In an internal combustion engine having a cylinder head, a plurality of spark plugs spaced apart on said head, valve mechanism carried by said head and a dished cover enclosing said valve mechanism; a protective structure for said spark plugs and the ignition leads therefor comprising an elongated tubular member surrounding each said spark plug and carried by said head, said members extending through the top of said valve mechanism cover, an annular seal mounting seat on said valve mechanism cover surrounding each said member, an annular seal ring on each said seat, an annular washer on each said seal, and an ignition lead cover straddling said members and seated on said Washers there being an air slot formed between said covers intermediate said washers.

aeasoe 19. In an internal combustion engine having a cylinder head and a plurality of spark plugs mounted on said head in spaced relationship, each plug including a body portion and an ignition lead; a protective structure for said plugs and leads comprising tubular members surrounding the body portions of said plugs, said members having inturned flange portions at one end thereof positioned intermediate the spark plug bodies and said head and serving as mounting means for said members by said spark plugs and said members having their other ends open, and cover means carried by said head in spaced relationship to said members and straddling the open ends of said members and said leads.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,933,423 Forsyth Oct. 31, 1933 2,118,673 Green May 24, 1938 2,478,128 Peters Aug. 2, 1949 2,625,146 Stephens Jan. 13, 1953 FOREIGN PATENTS Number Country Date 556,790 Great Britain Oct. 21, 1943 977,954 France Nov. 22, 1950