[Chambers]

I'm wondering at what point would one need lifter bore braces? What causes problems in this area of the pontiac block? Is it the lobe lift,lifter ramp speed, rpm? Could this area of the block be filled with simular material as block filler opposed to bolt in plates?

[Chambers]

I'm wondering at what point would one need lifter bore braces? What causes problems in this area of the pontiac block? Is it the lobe lift,lifter ramp speed, rpm? Could this area of the block be filled with simular material as block filler opposed to bolt in plates?

[Big Injun]

There is really no need for lifter bore bracing until you go to a roller cam with lobe lift of greater than .417 or .626 with 1.5 rockers. Based upon the base circle of the Pontiac cam, lift greater than this causes for the lifter to be pushed out instead of up.

If you are going to a big roller cam with duration of better than 285 it is a good practice to reinforce the lifter bores. Dave Bisschop of SD Performance, gtoracing@aol.com has an excellent product in his MegaBrace product.

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www.PontiacDragDays.com
Dave "Big Injun" Anderson

[Old Man Taylor]

The problem relates to the ramp rate of the cam lobe. Solid roller cams over about 270 or 275 duration @ 0.050 need to be reinforced. There is actually a duration at 0.200 lift that is identified, but I don't recall the number for sure. I believe it was 190.

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Jim