Pure Diesel Power’s Cummins 6BT cylinder head

Cummins 6BT 12-valve engines are becoming more and more popular, thanks to their near-indestructible nature. Unfortunately, these engines (commonly found in ’94–’98 Dodge Rams) are two decades old, which means chinks in the armor are showing up.

One of the most common issues with these engines centers around the cylinder head. After 20 years, many of these heads are cracked, warped or both. A blown head gasket is also a common problem. Either way, this means the head is coming off the truck.

Our good buddy has an 1,100 hp Cummins that ran headlong into the cracked cylinder head issue after a couple of passes where the water injection didn’t turn on. There were numerous cracks between the valves and even at the exhaust ports after some outrageous EGTS.

A new cylinder head was needed—but where to find one? After three attempts with used stock heads, it was found that one was rusted, two were cracked, and all three were unusable.

Fortunately, there was an answer in the form of a fully loaded head from Pure Diesel Power. They say there’s no truth in advertising anymore, so we were very surprised to learn that PDP was up front about the cylinder head being cast in China. Truthfully, virtually every Cummins head that

isn’t a $1,700 reman from the factory is most likely a China head, but most companies just won’t admit it. Score one for honesty for PDP, because that is the head we went with!

Pure Diesel Power did have some suggestions for us when it came to cylinder head prep. One was to get the head checked out by a reputable machine shop.

Vintage Hot Rod Design and Fabrication and Pro Machine in Chico, California, works on everything from blown alcohol race engines to vintage 409s—and everything in between. They said they’d be more than happy to check out our head for us to make sure everything was A-OK before we went racing. They checked valve spring rates, lapped the valves, checked the seats and then checked the head to ensure it was flat.

At the end, the results were pretty surprising, so we can honestly say Pure Diesel Power’s head is definitely a good bang for the buck.

The valves checked out fine, so Beck then removed the valve springs and valves from both the intake and exhaust side of the cylinder head—being careful to keep them in order.

We ordered the Pure Diesel Power head with 60-pound exhaust springs, which have a higher spring rate. Here, you can see the difference in height between the two.

Engine builder extraordinaire John Beck was the one who would be doing the work (if needed) on the cylinder head. The head came fully assembled, so John checked a few things before taking it apart.

The first thing Beck checked was the installed depth of the valves. More than anything, he was looking for inconsistencies from valve to valve that could indicate shoddy craftsmanship.