Converting A Tried-and-True Small Block Chevy from a Flat Tappet to a Roller Camshaft
Words and photos: Tommy Lee Byrd
There aren’t many cutting edge ideas associated with the small block Chevy, as it’s been in the hot rod rotation for 60 years now. However, it still stands at the most popular engine platform, whether you’re dealing with a street rod, a drag car or a rowdy street machine. Although the platform has remained the same, a lot of the internals are leaps and bounds ahead of the original equipment. For instance, camshaft and valve train technology has allowed gear heads to use parts and pieces that were once considered hardcore racing components in their weekend cruisers.
It’s quite common for a mild mannered small block Chevy to have a roller camshaft and valve train. We want to illustrate the necessary steps involved in converting a hydraulic flat tappet camshaft to a hydraulic roller, using the common small block Chevy as an example.
Our project car drove into the shop under its own power, but had developed some excessive valve train noise. The car is a 1964 Corvette, and the engine is a 350ci small block Chevy with a mild mix of modifications, which made for an excellent street car with a little more pep than your average weekend cruiser.
With flattop pistons, Dart Pro1 Platinum 200cc heads and a Dart dual plane intake, the engine had a mis-matched camshaft profile, due to previous plans that never materialized. The camshaft in question is a COMP Cams NX274H camshaft, which is designed for use with nitrous oxide and features a 230/244 duration split at .050-inch lift, and a max lift of .487/.501-inch. Along with the big split in duration and valve lift, the nitrous-ready camshaft features a 113-degree lobe separation angle. It is a flat tappet design, with High Energy hydraulic lifters, hardened pushrods and 1.6 Ultra Gold rocker arms, all from COMP Cams.
With plenty of miles and abuse on the combination, it was time for a mild overhaul, which included pulling the cylinder heads and removing all of the valve train to replace it with a new COMP Cams hydraulic roller setup.
The goal is to free up a few horsepower with reduced friction, while also matching the camshaft profile to the engine’s current specifications.
While a camshaft swap seems pretty simple, it’s important to note that it’s more than just sticking a new camshaft in the block and re-assembling the engine. There are a few additional parts, as well as additional assembly steps required to make sure the roller camshaft lasts a long time in our small block.
When we decided it was time to refresh the engine, we consulted the folks at COMP Cams to determine the correct parts for the job. We didn’t want to go too radical on the camshaft, and we obviously didn’t want a lot of maintenance, since the car sees quite a few street miles. The answer is a COMP Cams Xtreme Energy 282 hydraulic roller camshaft (XR282HR), and the guys at COMP supplied us with all of the related part numbers, and other suggested parts to get our engine back on the road. And though it was a pretty time-consuming job to convert our small block from flat tappet to roller, we could see the time, effort and money was worth it as soon as we fired the engine.
Now, we have a freshened engine with a new attitude, thanks to a better match-up on the camshaft and valve train components. We’ve highlighted the necessary steps to convert your small block from a flat tappet camshaft to a hydraulic roller, so follow along with our build and consult the tech guys at COMP Cams for further advice on camshaft selection. We’ve also included a parts list at the end of the article.