Rhoades pioneered what they call "variable duration" lifters. He puts a groove in them so they bleed down at low RPM and "pump up" by 3500 RPM. They take out about .025" lift and 15° duration at idle and give the full lift and duration of the cam by 3500. They are also anti-pump up. The Rhoades variable duration lifters work better than the others. He patented his groove design which works the best...
Here's their main page:
http://www.rhoadslifters.com/
Part numbers, you want 2018:
http://www.rhoadslifters.com/Pages/PartNumber.html
Here's the page with articles on how they work. The second one is the better one to read.
http://www.rhoadslifters.com/Pages/Articles.html
I've used Rhoades lifters for years. It took me 3 years of looking into them to even try them and now it's all I use. They give better low end torque and horsepower, better fuel economy, without sacrificing the top end. They work with large or small cams and std./high volume- and/or high pressure oil pumps.
I installed a MP .484/284 cam in my 68 340. It barely idled at 1100 RPM at 10-11" vacuum. After installing Rhoades lifters, I had it idling smoother at 800 RPM and 13" vacuum. I'm running a stock 340 with the MP .484/284 cam, stock converter, and 3.91 gear, Holley spread bore Mechanical secondaries and it doesn't bog off the line...
I put them in a 318 with 9.2 compression, stock 340 cam, 360 heads, 4 bbl, dual exhaust and it idled at 22.5" vacuum and got just under 18 MPG highway. I drove it over 300k miles with a set of Rhoades lifters in there.... They last and Rhoades stands behind them.
I got a new one with a pin hole where it didn't machine, back in the 80's. I called Rhoades and described the defect and they sent me one without even asking for the old one back.
They work. Some people don't think that they do, but if you ask people who have used them, they work...
Here's a link to them at Summit Racing:
http://www.summitracing.com/search?S...rhoades 2018