This has come up here on a few occasions without any definate answer, so I'll ask those who know. Assuming I was building a drag race motor, at what stroke does an aluminum rod hit the pan rail and or cam. This would be using a commonally available crank and rod setup in an iron block. I'm a steel rod proponent, but may be swayed for the right reasons.
Also, roller cam bearings. Anyone used these on a drag motor and opinions on their benefit appreciated. Thanks!
I can't answer your question, but as often as you run your car, you'd......
November 10 2008, 5:47 AM
........be swapping them after run #150 NA, cut that in half if/when you use a PA. This is what was I told by someone I trust with alot of experience. Disregard this advice if the BMEs last longer than the Venolias, JMO, Rod.
"Smoky" Yunick wrote in one of his books about his efforts converting a SB Chev
November 10 2008, 7:45 AM
to roller cam bearings and he found no gain or loss in his dyno tests before or after all of his efforts and his conclusion was that it was a waste of time, money and effort. No one here has produced any conclusive dyno evidence regarding any gains in that area for "FE's" either.
This message has been edited by DEames on Nov 10, 2008 7:47 AM
Dale P Dale Roush did a 4 part article about chopping up an FE an installing rollerbearings for the camshaft. You also need to get a special roller camshaft for the correct rockwell hardness on the surface. It might also be a special core for the shaft itself. I will look and see if I can find the articles about this. He also had to groove behind the roller bearings for oil flow to the rockers. Not sure about the lifter galleys. He also improved the whole oiling system for his motor. Mike lefevers built a couple of shelby motors with roller camshaft bearings, Try him. As far as the aluminium rods and crankshaft setup, I would think if you are running a 1/4 mile motor, the 4.125 crankshaft and 6.8 rods would work fine for a 7,800 rpm limit. Anything more than this, I can only wish you luck. Rick L.
I know that the 4.25 and 6.7 rod set up will work fine, but thats in a Shelby block. Not sure about a factory block. As for roller cam bearings we use them in most of our race engines. If you're running a Jesel or T&D rocker setup all you need to do re groove behind the rear cam bearing. We use the roller bearings because they are stronger and last longer than a regular babbit bearing. With the spring pressures we use we would crush the other bearings. The roller bearings seem to make the engine more responsive, too. I don't think I would use them in a iron block though. You have to remove a decent amount of material and it would make certain areas very thin.
I never thought any HP was to be gained with a roller cam bearing, just wondered about increased durability with a big cam. Seems to be the case, but not without trade offs.
As for aluminum rods, I've heard more stories about frequent replacement than not, so will stick with my steel is better thinking at least with the RPM I run. I appreciate the input.
