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#21
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both
I recall a test in hpp via Pete Mcarthy where an engine improved a lot using 1.5 on the intake and 1.65 on the exhaust.
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#22
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Do you remember if it was a single or dual pattern cam.
I would think that on a single pattern cam you would not use 1.65 only on the int, but on either both or none or possibly just the exhaust. Especially on lower flowing heads to.l make up for a poor int/exh flow ratio. |
#23
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I like mechanical cams where you can adjust the lash and get an idea of what the combo is wanting. If it picks up HP or ET with tighter lash on intakes, exhaust or both, it probably will like bigger rockers. . Not to often do you find an engine that responds to tight lash on the exhaust side, but finding HP with loose lash on the exh, it likely will respond well too a smaller rocker on the exh. Last edited by Jay S; 10-25-2023 at 10:39 AM. |
#24
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My thanks to Skippy597 for starting this informative thread and thank you to all who have posted here. I have several different cams on my garage shelf and now think I should also carefully think about rocker arms and their ratios in determining which cam to use.
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"No replacement for displacement!" GTOAA--https://www.gtoaa.org/ |
The Following User Says Thank You to 1968GTO421 For This Useful Post: | ||
#25
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Quote:
Stamped-steel OEM rockers? Roller-tip aftermarket rockers? Full-roller aftermarket rockers? What brand/model? Contact at the valve tip reasonably centered? What pushrod length did it need? What heads are those on? Need to grind the pushrod hole for clearance? |
#26
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Since BBC rocker bodies are 0.120 longer trunnion to rocker stud hole than a Pontiac I would also. I have Crower 0.090 offset 1.8 rockers on my pump gas motor and I had to use a lash cap and a 0.200 shorter pushrod than the HS rockers to get a decent pattern on the valve tip.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
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