Which cam and which heads are probably the two most asked questions about an LS build, and the amount of info on the web can sometimes be daunting. Lucky for us, we have Richard Holdener who tests everything. I mean everything, that is LS related. So if you have a question, or want to know what performance you can expect from different parts on your combo, you can often find the answers in one of his videos. In this one it is going to be about cylinder heads, and specifically can you use “big bore” LS heads, ie rec port heads, on a 4.8 or 5.3. Here is the video you want to watch if this is a question you’ve had.
CAN I RUN FACTORY REC-PORT HEADS ON A SMALL BORE 4.8L/5.3L? CAN I REPLACE THE 706/862 HEADS ON MY 4.8L/5.3L WITH LY6/LS3 HEADS? WILL MY 4.8L/5.3L MAKE MORE POWER WITH HIGH-FLOW, FACTORY REC-PORT HEADS? HOW MUCH POWER ARE REC PORT HEADS WORTH ON A 4.8L/5.3L? WILL THE REC PORT HEADS EVEN FIT ON THE SMALL-BORE MOTORS? CAN YOU NOTCH THE BLOCK TO MAKE THE REC-PORT HEADS FIT? CHECK OUT THIS VIDEO WHERE I DIVE INTO THE INSTALLATION OF A SET OF FACTORY L92 821 HEADS ON A SMALL BORE 4.8L/5.3L? USING THE SECTIONED ALUMINUM BLOCK FOR VISIBILITY, WE CAN CLEARLY SEE THE INTERFERENCE BETWEEN THE BIG-VALVE 821 HEADS AND THE SMALL BORE 5.3L CYLINDERS. CAN WE MAKE THEM WORK?