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Diesel of the Week

Work Stock/Pro Street 6.7L Cummins Engine

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For as long as Jeff McCord can remember, he’s had an interest in motorsports. Since the age of four, Jeff would attend drag races and truck and tractor pulls with his dad. His first taste of motorsports action being behind the wheel himself was mud racing four-wheel-drive trucks.

Jeff carried that passion into a career, which started at a Chevy dealer, then progressed to heavy equipment and then becoming a field mechanic before opening a shop of his own called LinCo Truck and Tractor Repair.

“I got into diesels between working on heavy equipment and tractors,” McCord says. “The diesel performance side just kind of came along with it.”

Jeff started LinCo Truck and Tractor Repair in 2010. The shop, which is located in Troy, MO, worked on heavy equipment, ag equipment and diesel trucks. However, it wasn’t long before diesel performance overtook the shop’s other work.

“Not only my passion for diesel performance, but the industry grew and the demand for our work on diesel performance grew to where in 2015 we started LinCo Diesel Performance and got out of the heavy equipment side altogether,” McCord says. “Ever since we started the shop we’ve done diesel performance, but people didn’t realize it. That’s why we started the performance business was for the name. We always did it, it just wasn’t as well known.”

The secret of LinCo Diesel Performance didn’t stay quiet for long, and today the shop focuses primarily on Duramax and Cummins engine work for all kinds of applications, as well as transmission work and some parts manufacturing.

“What we’re most known for is Duramax work,” he says. “However, our experience and preference is to work on Duramax and Cummins. We work on common rail mostly, but we have roots in 12-valve stuff too. We also manufacture a lot of parts for 12-valve trucks.”

Manufacturing parts, doing complete transmission work and keeping all engine and machine work in-house is easy since LinCo Diesel Performance has a brother company in LDP Machine, a full engine machine shop.

“We’re currently building a new facility for LinCo Diesel Performance,” McCord says. “The machine shop is in a brand new 8,600 sq.-ft. space. We’re building a 15,600 sq.-ft. building right next door for LinCo Diesel Performance. When it’s done, we’ll have about 25,000 sq.-ft. total on six and a half acres, so we have plenty of room to expand more.”

That latest expansion is underway now and has been the culmination of many years of saving and flipping trucks. One such engine build that LinCo Diesel Performance recently completed was a 6.7L Cummins for a Work Stock/Pro Street application. The customer, who has a 7.5 crew cab, short bed Dodge, is also having LDP do work on his transmission and chassis. This 6.7L Cummins engine is a brand-new build with the exception of the customer-supplied block.

“Everything else was brand new for this build,” McCord says. “The engine utilizes a Hamilton cylinder head that we got as a bare casting and we worked it over in-house. It has a Hamilton crank, Wagler rods and S&S is going to build a custom injector setup for it.

“The engine has stock pistons with reliefs that were done in-house. The pistons also have gold PTFE ceramic coated tops and Teflon-coated skirts. We sent the rings to Total Seal and had the gapless second conversion done. It’s got a Hamilton cam, tappets, pushrods, and valve springs to accompany the Hamilton head. The build also features a Beans Diesel girdle.”

According to Jeff, the girdle required some extra machine work, but it is also a limiting factor when it comes to horsepower potential.

“We spent a lot of time on the Beans girdle and had to line hone the block,” he says. “The block and head were also fire ringed in-house. We also weight matched the engine and balanced it in-house. The girdle is holding us back more than anything. It could see 1,200-1,300 horse, but that would be pushing it. If it had 14mm mains, it could go to 1,500-1,600 hp.”

As it stands now, the 6.7L Cummins is being tested with several different turbo setups and LDP is shooting for 1,050-1,100 horsepower out of the build.

“We’re shooting for 1,050-1,100 horsepower on a work stock turbo, which is like a factory appearing turbo,” he says. “We’re going to dyno a few other setups too for something like the cheater stuff and 2.6 stuff and hope to hit 1,200-plus horsepower. We also have the customer’s truck here too because we’re doing chassis work and swapping to a manual trans.”

A few other parts that are essential to the 6.7L build are XDP billet valve bridges, Hamilton rocker arms, a Jegs electric water pump, a G&R Diesel billet grid heater delete intake plate, Keating Machine billet freeze plugs, a Fluidampr balancer with full power retention kit, a Fleece Performance coolant bypass, a Steed Speed manifold, ARP hardware, and a D&J billet valve cover.

With this 6.7L Cummins all wrapped up, the customer is ready for 2021 competition in the Work Stock class.

“In the Midwest, the Work Stock class is a very large, very serious class featuring 900-plus horsepower engines,” McCord says. With nearly 1,100 horsepower on hand, this Cummins engine build should have the customer right in the thick of the competition.

Diesel of the Week is sponsored by AMSOIL. If you have an engine you’d like to highlight in this series, please email Engine Builder Editor Greg Jones at [email protected]

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