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- USA
- CAN
Ships within 48 hours · Estimated delivery Jul 22 - Jul 27
Promo Codes Available:
For Your Every Summer RSVP, with Code: SUMMER15
Description
HP Copper Spark Plug - Shorty - 0437S-4Overview: ACCEL's patented race proven spark plugs in a Shorty configuration. The overall length has been reduced 3 16 in to 3 8 in (depending on the specific spark plug) to gain critical air gap between the spark plug boot and the exhaust manifold or header tube. This helps eliminate burning the spark plug boot or dimpling the header tube. The shorter spark plug length also can make it easier to install an remove the spark plugs in certain
Overview:
ACCEL's patented race proven spark plugs in a Shorty configuration. The overall length has been reduced 3/16 in to 3/8 in (depending on the specific spark plug) to gain critical air gap between the spark plug boot and the exhaust manifold or header tube. This helps eliminate burning the spark plug boot or dimpling the header tube. The shorter spark plug length also can make it easier to install an remove the spark plugs in certain applications where there is not a lot of room to fit a socket or move a wrench around. ACCEL Shorty Spark Plugs are made with a Copper core which is a better conductor than Platinum and Iridium. They deliver a stronger spark especially in high performance applications where high combustion pressures are present. Copper is much better at dissipating heat than other materials which lessens the chance of a misfire. ACCEL Shorty Spark Plugs are gapable allowing you to open the gap exposing a larger flame kernel or close it if needed for high boost applications. All ACCEL Shorty Spark Plugs have machine rolled threads allowing for a more precise thread engagement and torque retention.
Features:
- C-Cut ground electrode
- Resistor Shorty Plugs
- 14mm Thread - .375 in Reach
- Flat/Gasket Seat
- Projected Tip
- 13/16 in Hex
Application:
| Year | Make | Model | Submodel | Engine Size |
|---|---|---|---|---|
| 1969 | Oldsmobile | Delta 88 | Base | 455/7.5 V8 |
| 1969 | Oldsmobile | Delta 88 | Custom | 455/7.5 V8 |
| 1969 | Oldsmobile | 442 | 455/7.5 V8 | |
| 1970 | Oldsmobile | Cutlass | 455/7.5 V8 | |
| 1971 | Oldsmobile | Cutlass | S | 455/7.5 V8 |
| 1971 - 1973 | Oldsmobile | Cutlass Supreme | 455/7.5 V8 | |
| 1969 | Oldsmobile | Delta 88 | Royale | 455/7.5 V8 |
| 1970 - 1973 | Oldsmobile | Delta 88 | 455/7.5 V8 | |
| 1970 | Oldsmobile | F85 | 455/7.5 V8 | |
| 1971 | Oldsmobile | Vista Cruiser | 455/7.5 V8 | |
| 1970 - 1974 | Plymouth | Road Runner | 440/7.2 V8 | |
| 1970 | Plymouth | Fury | S-23 | 440/7.2 V8 |
| 1968 - 1974 | Plymouth | Fury | 440/7.2 V8 | |
| 1970 - 1972 | Plymouth | Fury | Custom Suburban | 440/7.2 V8 |
| 1970 - 1972 | Plymouth | Fury | Sport Suburban | 440/7.2 V8 |
| 1970 - 1972 | Plymouth | Fury | Suburban | 440/7.2 V8 |
| 1968 - 1971 | Plymouth | GTX | 440/7.2 V8 | |
| 1972 - 1978 | Chrysler | New Yorker | 440/7.2 V8 | |
| 1971 - 1978 | Chrysler | Newport | 440/7.2 V8 | |
| 1975 - 1978 | Dodge | B200 | 440/7.2 V8 | |
| 1974 | Dodge | M350 | 440/7.2 V8 | |
| 1970 - 1976 | Dodge | Monaco | 440/7.2 V8 | |
| 1970 - 1973 | Dodge | Polara | 440/7.2 V8 | |
| 1975 - 1978 | Dodge | B300 | 440/7.2 V8 | |
| 1977 - 1979 | Dodge | CB300 | 440/7.2 V8 | |
| 1970 - 1976 | Dodge | Coronet | Base | 440/7.2 V8 |
| 1977 - 1978 | Dodge | Monaco | Base | 440/7.2 V8 |
| 1977 - 1978 | Dodge | Monaco | Brougham | 440/7.2 V8 |
| 1970 | Dodge | Challenger | Base | 440/7.2 V8 |
| 1970 | Dodge | Challenger | R/T | 440/7.2 V8 |
| 1970 - 1971 | Dodge | Charger | Base | 440/7.2 V8 |
| 1970 - 1971 | Dodge | Charger | R/T | 440/7.2 V8 |
| 1970 - 1971 | Dodge | Charger | 500 | 440/7.2 V8 |
| 1971 | Dodge | Charger | Special Edition | 440/7.2 V8 |
| 1971 | Dodge | Charger | Super Bee | 440/7.2 V8 |
| 1972 - 1974 | Dodge | Charger | 440/7.2 V8 | |
| 1968 - 1973 | Plymouth | Fury I | Base | 440/7.2 V8 |
| 1968 - 1974 | Plymouth | Fury II | Base | 440/7.2 V8 |
| 1968 - 1974 | Plymouth | Fury III | Base | 440/7.2 V8 |
| 1972 - 1975 | Plymouth | Gran Fury | Base | 440/7.2 V8 |
| 1970 | Dodge | Coronet | Deluxe | 440/7.2 V8 |
| 1970 | Dodge | Coronet | R/T | 440/7.2 V8 |
| 1970 | Dodge | Coronet | 500 | 440/7.2 V8 |
| 1975 - 1978 | Plymouth | Fury | Base | 440/7.2 V8 |
| 1977 - 1978 | Plymouth | Fury | Salon | 440/7.2 V8 |
| 1970 | Dodge | Coronet | 440 | 440/7.2 V8 |
| 1970 | Dodge | Coronet | Super Bee | 440/7.2 V8 |
| 1975 | Plymouth | Gran Fury | Custom | 440/7.2 V8 |
| 1975 | Plymouth | Gran Fury | Sport | 440/7.2 V8 |
| 1975 | Plymouth | Gran Fury | Brougham | 440/7.2 V8 |
| 1976 - 1977 | Plymouth | Gran Fury | 440/7.2 V8 | |
| 1976 - 1978 | Plymouth | PB200 | 440/7.2 V8 | |
| 1976 - 1978 | Plymouth | PB300 | 440/7.2 V8 | |
| 1974 - 1978 | Plymouth | Trailduster | 440/7.2 V8 | |
| 1975 - 1977 | Dodge | Royal Monaco | 440/7.2 V8 | |
| 1974 | Dodge | B100 Van | Base | 440/7.2 V8 |
| 1974 | Dodge | B200 Van | Maxi | 440/7.2 V8 |
| 1974 | Dodge | M300 | 440/7.2 V8 | |
| 1974 | Plymouth | Satellite | 440/7.2 V8 | |
| 1970 | Plymouth | Superbird | 440/7.2 V8 | |
| 1970 - 1971 | Plymouth | Cuda | 440/7.2 V8 | |
| 1970 | Plymouth | Fury | Sport | 440/7.2 V8 |
| 1967 - 1969 | Pontiac | Executive | 428/7 V8 | |
| 1967 - 1969 | Pontiac | Grand Prix | 428/7 V8 | |
| 1967 - 1969 | Pontiac | Bonneville | 428/7 V8 | |
| 1967 | Pontiac | Catalina | Base | 428/7 V8 |
| 1967 | Pontiac | Catalina | Safari | 428/7 V8 |
| 1968 - 1969 | Pontiac | Catalina | 428/7 V8 | |
| 1965 | Dodge | Monaco | 426/7 V8 | |
| 1963 - 1965 | Dodge | Polara | 426/7 V8 | |
| 1965 | Dodge | 880 | 426/7 V8 | |
| 1965 | Dodge | Coronet | Base | 426/7 V8 |
| 1965 | Plymouth |
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.7 ★★★★★
Based on 22 reviews
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Product Reviews
★★★★★ 5
Top quality
Model: SLH20025
This Siless Hybrid 3-in-1 sound deadening mat is easy to work with and feels high-quality. The butyl material is thick and pliable, making it simple to cut and fit into doors, floors, or panels.
After installation, road noise and vibrations are noticeably reduced, and it also seems to improve the overall cabin feel. No bad smell.
At 25 sq ft per roll, it’s a good value for anyone looking to dampen noise and improve car acoustics. Overall, a solid, effective option for automotive soundproofing. Used on a Fiesta ST.
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Reviewed in the United States on February 15, 2026
★★★★★ 5
Made a big improvement in cabin noise—highly recommend
Model: SLH20025
Siless Hybrid made a huge difference in reducing noise in the floor of my truck cabin. In some areas, there was basically just bare sheet metal between the inside and outside, so adding this really helped the truck feel more solid and noticeably quieter on the road.
I used Kilmat on the doors, and honestly I wish I had used Siless Hybrid there too, but it was too late by the time I realized the difference. This material is very sticky, easy to cut, and simple to apply, which made the install pretty smooth.
Just a heads-up: the tacky side gets messy and will bond to clothing really easily, so be careful during installation. Overall, I’d definitely buy it again—great product with real results.
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Reviewed in the United States on December 2, 2025
★★★★★ 5
Very good product at a fair price
Model: SLH20025
Very good sound deadener and heat shield, it is a bit sticky to work with, but easy to shape and cut
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Reviewed in the United States on April 19, 2026
★★★★★ 5
I wish I had Siless 20 years ago!!!
Model: SLH20025, Model: SLH20025
I have installed all kinds of insulation in vehicles over many years. I only needed to purchase 2 boxes to complete the entire interior siding of my 2025 chevy express, what a great value! I wanted to insulate my locksmith van for sound and heat. The sound reduction virtually eliminated the road noise. These panels also look amazing. It got up to 110F in the sun with the doors closed. After adding Siless insulation the temperature maxed out at 97F. That is a massive difference. Plus, I didn't even finish with the roof before testing. Siless Hybrid 3in1 was extremely easy to cut and adhere onto metal panels. I'm impressed with the quality of the individual panels and the adhesive is not toxic smelling compared to some others. My favorite thing about these panels is you can actually take them off and readjust them before they finally stick and they do not leave any black residue behind when you pull them up to adjust them. All I needed was a heat gun, knife and a roller to complete this job. The size of each panel is perfect, you can handle them with ease. I probably won't need your product again for a while, but when I do I will definitely be back.
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Reviewed in the United States on September 21, 2025
★★★★★ 5
Works well and is easy to install.
Model: SLH20025, Model: SLH20025
I was sound and heat insulating a generator bay in my class A RV so I did three tests before and during material application: I did a sound level test to see how effective the material was for my application, a "stickiness" test, and a flammability test. This was indoors on a dry 78°F day. From beginning to end, the entire process, including testing, took 5 hours to install 25 sqft or material in a very complex area. One hour for cleaning, 3 hours for installation, and 1 hour for test setup and testing.
Using a sound meter, I took before and after readings and determined that I reduced the sound level by 2.2 db (40% energy decrease) with a noticeable decrease in sound and frequency. The generator bay is located under the master bedroom in the aft portion of the coach. The sound went from a rattling, vibrating generator noise to a more tolerable low level rumble.
The material was easy to apply. I did some testing prior to application and determined that surface preparation is key. I cleaned my painted metal surface and then degreased with acetone and the material stuck well. Be careful and purposeful when you apply the material because once it was stuck to the metal, it was quite difficult to remove or reposition.
Since it was going to be installed into a gasoline powered generator bay located under our sleeping quarters, I did some flame testing to determine the level of risk. Although not highly flammable after installation, my testing revealed that the PE used will catch on fire under certain circumstances. In order to reduce the risk, I used aluminized duct tape to ensure that all the edges were sealed and the PE was not exposed to direct flame in the event of a fire. I also decided to install an automatic fire extinguisher as an added precaution. In all fairness there should be one installed in the generator bay anyway.
All in all, I am very satisfied with the product and the results. I have recommended this product to my other RV owner friends.
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Reviewed in the United States on April 13, 2025