🔧 High-Quality GM Parts 12499224 Valve Spring for LS1 Engine - Optimal Performance Guaranteed! Review

Advertised as GM Performance parts, no markings to prove this. Not marked as a GM factory part. I don't want to install without knowing who did it. No guarantee if they break and drop the valve

My master said you need this and he was right. I can rev my 4.8 at over 6500 rpm with stock rockers and a soft cam. Before that there were float valves at about 5800.

The springs in this kit are the correct size but were purchased to fit a sanctioned racing engine and do not pass engine validation without GM blue powder coating as stated on the purchase page? site. Only useful for non-racing applications.

OEM GM parts are brand new in individual packaging. These are the same springs used in the LS6 engines and that's why I bought them. This is a great budget source for LS heads. I am installing an LS6 cam in LS1 and need an additional valve lift rating for the LS6 cam's .550 inch lift.

These are good springs and correct for your order. They are individually marked with P/N 12713265. This part replaces P/N 12625033. The pack of (16) 12625033 has GM P/N 12499224. So this is the correct spring set but the genealogy needs to be sorted out. They're not blue either, but that's typical of these sources.

I have paired this with: 787-16 Competition Cams GM Parts Steel Holder 12499224 Valve Spring 648-16 Competition Cams 7 Degree Racing Locks Removed standard springs and detents from my Vortec heads and added them for more Lifting force between valve stem seal and spring plate. I have about .505-520 lift with this combo and could get a little more by replacing the valve stem seals. The valve springs fit without reworking and are significantly better than the original springs when it comes to…