I just saw a reply you made to another thread about large diameter lifters and I was wondering you said if the guy didnt change his base circel with the larger roller that his duarations would be off. I was planning on using isky red zone .903 lifters on a build im doing and was wondering if you could elaborate a little. will my actual durations change if i dont get a cam that was ground for the larger roller. I wasnt planning on haveing to get a custom ground cam but if you say I need to then I guess i do. would there be any ill affect if i used a cam that was designed to be used with a smaller diameter lifter roller.

any one

I've seen this discussed somewhere before but can't remember where. From memory, a roller lifter with larger rollers will have more duration than a roller lifter with a smaller roller. It's due to the geometry, make yourself a drawing to convince yourself. In the example this article gave, the difference was like 2-4 degrees more duration, not overly huge.