You’ve got questions. We’ve got answers. We work with the Summit Racing tech department to tackle your automotive-related conundrums. This week, we’re talking about aluminum vs. steel roller rockers and rocker ratio in daily-driven, high-mileage fleet vehicles.
Q: I have some questions concerning the use of aluminum roller rockers on a street engine with a stock-type camshaft and valvetrain. We have shop trucks with Chevy small block V8s that routinely see 250,000 miles and do a lot of towing for several thousand miles at a stretch. The engines are 350 cubic-inch crate engine with we modify with headers, an aluminum intake manifold with a four-barrel carburetor, and an MSD HEI distributor with 8mm wires.
I know that the stock stamped steel rocker arms cause friction, which puts additional wear on both the rockers and the valve stems. I also know the roller rockers will reduce this wear considerably, plus we can gain some extra power by upping the rocker ratio from the stock 1.5 to 1.6.
What I don’t know is how long aluminum roller rockers would last in our engines. Are they up to the task? If I go with a 1.6-ratio rocker, would it give us some extra power without weakening the stock valve springs? Would we need screw-in studs, stronger pushrods, and guide plates? If the aluminum rockers will provide some extra power and less valvetrain wear without durability problem, I will definitely use them.
A: We don’t think aluminum roller rocker arms will deliver everything you want.
Used on a daily driven engine with a stock valvetrain, the rockers will last approximately 20,000-30,000 miles with regular oil changes. Since you run your engines for 250,000-plus miles, you would end up replacing aluminum rockers quite often.
As for power, a 1.6-ratio rocker will increase valve lift and power, but won’t affect duration (the time the valves are open) or the engine’s powerband. If you decide to run a 1.6-ratio rocker (aluminum or steel), you should check for coil spring bind.
The minimum clearance between the coils at maximum valve lift should be at least .060 inch.
So would steel roller rockers work for 250,000 miles?
So what’s the deal with the steel… Rollers that is?
Hell yes they will stand up for 250k. I’am gm guy but lets be fair when reporting
HEY, you didn’t cover if steel roller rockers would deliver on his needs. WHAT THE HECK!
I also noticed the very short non-answer that was given for a very good question. A question that I’m sure most of the people that enjoy reading AND learning from the replies given by an experienced staff which includes the expert technical staff at Summit Racing. I can think of a couple of reasons why such a question would be conveniently avoided but at that point things get really weird with the politics of competing manufacturers, the financial aspects if the buying public’s preference could actually be heavily skewed as the result of an honest answer.
I don’t think mass hysteria would be a problem. Despite claims that I was the grassy man in the mysterious knoll that fateful day in November of ‘63, I was in Dallas looking for the person that shot J.R.
It has nothing to do with vast conspiracies, Watergate, saving pennies and dimes to buy a four speed, dual quad, posi-traction 409, the ghosts that haunt Yellow River Trailer Park or alleged sightings at Area 51.
Just the facts about steel versus aluminum roller rockers in long term, high mileage applications. Pay no attention to the man behind the curtain….
Don’t know about that one. Crane’s die cast energizer roller rockers pedestal-type in 1.7 ratio was used by Ford on the 1993 5.0 Cobra. They had to pass all durability testing including testing under brutal conditions for well over 100,000 million miles, in fact I believe they were tested far beyond this.
100,000 miles, not millions
Passing a 100,000 mile test would certainly erase any doubts about long term durability. 100,000,000 miles….I’m calling Summit to inquire about a 1.73:1 set for my Cleveland.
i have a 6 cyc diesel with custom made aluminum roller rockers on it with over 750,000 miles, with no failure.
Comp cams steel roller tipped rocker provide a 1.54:1 ratio. Gave me 24 hp over stock, a quieter valve train, and another 700 rpm on to my recline, up from 5500, to 6200… easier starts too. Approaching 85k miles