By Manley Performance

Manley Chevy LT-1 6.2L 1.590in Head Diameter Pro Flo/Severe Duty Exhaust Valves (Set of 8)

Regular price $636.95
Regular price Sale price $636.95
Shipping calculated at checkout.
Availability: In stock
SKU: MAN12347-8
Regular price $636.95
Regular price Sale price $636.95
Proven Fatigue Tests: The Severe Duty? Valves have undergone rigorous fatigue tests. In normal operation, valves experience 20,000 to 25,000 lbs of applied stress. When valves bounce on the seat, this stress soars to 40,000 to 60,000 lbs. Manley exhaust valves, tested at 40,000 psi and 1400?F, impressively endured up to 100,000,000 (one hundred million) cycles. In contrast, competitors' offerings failed after just 100,000 cycles, showcasing a staggering 1000 times better fatigue life.Designed for High Temperature Gasoline Engines: Engineered for superior performance in high-temperature gasoline engines.Chrome Stems and Hard Tips: Incorporating chrome stems and hard tips for enhanced durability and longevity.Optimized Combustion: Swirl polished under head areas and fully machined combustion faces for improved airflow and combustion efficiency.XH-428 for Exhaust: No competitor worldwide offers the exceptional XH-428 as exhaust valve material. It boasts nearly double the ultimate tensile strength at 1500?F compared to the competition's EV-8.NK-844 for Intake: Our intake valve material, NK-844, is equally unmatched, displaying over four times the ultimate tensile strength of the competition's best intake valve material at 1000?F.

What clients say


  • Really fast and high quality customer support, my order got to me faster than the quoted time too. No complaints

  • The team took a mostly broken car after some work done elsewhere, and have systematically made it reliable and fast for a fair price. The staff are invested in the work they do which also makes a big difference.

  • Jeff was extremely helpful in assisting me with my exhaust. Always kept me updated and answered any queries in a timely manner. Will definitely be coming back for my future mods

  • Justin and his crew is amazing! Always ready to help and service with a smile. Trusty, friendly and reliable! Had my car sent in for repair twice and it’s fixed on time, at a reasonable price and with no issues. Highly recommended!

  • Easy to deal with and part was ordered quickly

Fitment & Compatibility


How do I know if this part fits my car?

We recommend checking your vehicle's make, model, year, and variant carefully. Most product listings include compatibility notes, but if you're unsure, contact us before purchasing.

Can you confirm fitment before I place my order?

Absolutely. Send us your VIN or Rego and we’ll confirm fitment for you.

Do you offer installation at your workshop?

Yes, we offer installations for most parts at our Ringwood workshop. Contact us to book or get a fitting quote.

Shipping & Handling


How long will it take for my order to arrive?

Most in-stock items ship within 1-2 business days. Delivery time depends on your location and shipping option chosen at checkout.

Do you ship internationally?

Currently, we only ship within Australia. For international enquiries, please contact us directly.

Can I pick up my order in person?

Yes, local pickup is available from our Ringwood workshop. Simply select ‘Local Pickup’ at checkout and we’ll notify you when your order is ready.

Please note: Some items are stored offsite and may need to be transferred from our warehouse, which can add a few business days before pickup is available.

Returns & Warranty


Can I return a product if it doesn’t fit?

Returns are accepted within 14 days if the item is unused and in original packaging. Please see our full Returns Policy for details.


What warranty comes with your products?

All products come with the manufacturer’s warranty. If you experience any issues, contact us and we’ll assist with the claim process.