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#1
10-21-2025, 10:25 AM
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Many times Tim will suggest using a profile with less acceleration on the exhaust side for street longevity, that is another alteration that can be done. For instance that cam would probably look like 290/303 at .006” instead of 290/298, but the .050” spec is the same.
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| The Following User Says Thank You to Jay S For This Useful Post: | ||
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#2
10-21-2025, 02:21 PM
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Jay's example...
Lobe HR303/3532 303 244 157 0.3532 .
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) Best time 5.13 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
| The Following User Says Thank You to Steve C. For This Useful Post: | ||
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#3
10-21-2025, 04:11 PM
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Using Harland Sharp 1.65 rockers ?
If so, keep in mind their actual ratio when calculating the valve lift. We have seen it stated the Harland Sharp Pontiac 1.65 rocker arm ratio to be 1.7, 1.72, etc. One example. Years ago Ken Crocie used Harland Sharp 1.65 ratio rockers on a build. The cam had 0.3600" lobe lift and based on 1.65 ratio it suggested a theoretical 0.594-inch valve lift. Yet when measured on this specific build it netted an actual 0.606-inch lift at the valve. Here the actual ratio of the Harland Sharp rocker seems to be closer to a 1.684 ratio. This was a static measurement A running measurement 'at the valve' could be different. .
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) Best time 5.13 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE Last edited by Steve C.; 10-21-2025 at 04:38 PM. |
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