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VALVE LIFT LIMIT |
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JERSEYJOE
AMC Addicted Joined: Oct/23/2008 Location: TUG HILL NY Status: Offline Points: 1716 |
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Posted: Dec/08/2022 at 9:22pm |
What is the valve lift limit with factory bridged pivot rockers? I'm thinking less than .500 so like .480?
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1985 J-20 PLOW TRUCK
1977 CJ 7 360 T-18 D 300 1970 AMX ex-SCCA car SPEED COSTS MONEY HOW FAST DO YOU WANT TO GO? |
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6884 |
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Most will say 0.500", including myself. Erson states 0.510":
Not all the stamped bridge rockers are the same, so caution is in order if going to the limit. And never reuse aluminum bridges!
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ericdowneast
AMC Apprentice Joined: May/08/2021 Location: Maine Status: Offline Points: 70 |
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I wonder what the lift limit is for the new Scorpion lifters? Probably about the same I would guess.
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Sonic Silver
Supporter of TheAMCForum Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7950 |
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merr6267
AMC Apprentice Joined: Aug/22/2013 Location: Ravenna, MI Status: Offline Points: 69 |
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On the factory bridged setup I've been running what is allegedly a .488 cam on a haphazardly assembled, worn out junkyard motor with mismatched bridges and rockers for almost 20 years.
It's been WOT for minutes at a time at 5000+rpm without an issue related to the valvetrain. Now, the rockers had wear marks in them before I ever assembled it, and I didn't intend on keeping the engine together for any length of time so I just assembled it. It was obvious that the rockers had to skip, or jump over their wear pattern, but I just went with it. They were noisy at first, then I stopped paying attention. I eventually upgraded the valve springs to avoid float at 4500 and they still looked in fair condition. That was 18 years ago, but the poor old Jeep has been mostly parked awaiting another restoration for the last 12.
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ericdowneast
AMC Apprentice Joined: May/08/2021 Location: Maine Status: Offline Points: 70 |
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Yes it does seem like a lot. I read the specs too but was wondering if some one knew more about it from experience. I guess they are pretty new to the market so maybe we don't know that answer yet.
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6884 |
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Scorpion bridge mount rockers have different lift and spring pressure limits:
Realistically, anyone building an engine with valve lift over 0.550" is not going to be using bridge rocker heads as is, if at all. The heads would need professional porting just to support the flow for that lift. Your getting into race motor territory and money will be spent on better components for longevity and specific goals. IMO, these support the gap between 0.500" and 0.550" lift that stamped bridge rockers are not made for. They can also be used at lower lifts, but not necessary.
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Heavy 488
AMC Addicted Joined: Apr/27/2019 Location: In the Status: Offline Points: 3553 |
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If you're going to a high lift cam, are you going to trust a stamped piece of tin to be an actual 1.6 ratio?
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6884 |
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Up to 0.500" lift, have for many years with no issues.
Highly doubt "tin" is the best description as the OEM ones can be cleaned up and reused and show little wear after tens of thousands of miles if proper maintenance is done.
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