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Lazy Rocker Arm |
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Ken_Parkman 
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Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1814 |
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 Posted: Apr/15/2021 at 3:01pm |
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Yup that's tight. Intake clearance is much less critical than exhaust. Don't float the valves!
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799 |
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Posted: Apr/15/2021 at 10:51pm |
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Noted, I will try to avoid floating the valves. The good thing is I have just put now valve springs on it, so that might help.
It did start this morning and I was able to load it onto the trailer, so that is something
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I've finally given up drinking for good...........now I only drink for evil.
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73hornut
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Joined: Jul/03/2007 Location: Southern Oregon Status: Offline Points: 3130 |
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Posted: Apr/16/2021 at 7:23am |
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Why not just install the proper adjustable SBC studs and stock SBC length pushrods?
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71 Javelin
74 Gremlin 79 Spirit AMX Rogue Valley Rumblers Like Us on FB https://www.facebook.com/groups/1602825606650796 |
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799 |
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Posted: Apr/16/2021 at 9:11am |
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It had SBC studs in it, that’s part of the problem, really needs factory studs and the correct length pushrods to control the factory rockers properly.
Running SBC studs, proper roller rockers and the correct length pushrods is obviously the best option for what I’m doing. Anyway, did get about 7 runs in before something broke. New PB in the process, so some good and some bad. More details to follow.
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I've finally given up drinking for good...........now I only drink for evil.
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799 |
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Posted: Apr/17/2021 at 3:02am |
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All good in the end, that I thought was tap tap tap, turned out to be choof choof choof, blown header gasket. There might be a witness mark on one of the pistons from an intake valve, but nothing bent and no loss of compression.
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I've finally given up drinking for good...........now I only drink for evil.
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mbwicz
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Joined: Feb/20/2019 Location: Buffalo, NY Status: Offline Points: 1992 |
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Posted: Apr/17/2021 at 5:12am |
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Good to hear that you set another PB. Do you think you picked up anything from the front suspension upgrades this year, or mostly just other fine tuning?
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1970 AMX, one step forward, one step back. Both steps cost time and money.
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ccowx
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Joined: Nov/03/2010 Location: Yukon Status: Offline Points: 3510 |
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Posted: Apr/17/2021 at 10:21am |
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Just saw this now. I have had a similar issue for literally decades. I have one valve that insists on running cockeyed like yours does. #3 exhaust or #6 if I reverse the heads. I am not clear if the cast in guide wore out and that is the problem, or if that wear is only a symptom. Either way, it has worn a good 1/8" or so into the head.
I have swapped sides for the head and the problem followed it. I am running adjustable studs, .477" lift cam and stock rockers. I solved the issue by simply putting a guide plate on it and that keeps it running close enough. I can rev it to 6k, though I don't usually bother. I do a hot running valve adjustment on it, which makes it quiet, otherwise it ticks a bit.
I am looking forward to seeing what solutions come from this! Thanks! Chris |
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WesternRed
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Posted: Apr/17/2021 at 4:59pm |
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Chris, I think the root cause is already covered above, basically the slot in the stock rocker arm is too wide and allows too much freedom of movement on a non-shouldered aftermarket stud.
In my case, changing to a roller rocker greatly reduces the freedom of movement of the rocker tip on the valve tip. The rocker still runs a little off center (left to right) on the valve tip, so it really needs a slightly offset rocker arm to fully center the tip on the valve. Guide plates would also reduce the freedom of movement, which is why they work as a solution as would running the factory shouldered stud in the original non-adjustable arrangement. You could possible weld up the slot in the rocker arm to reduce it's width and even correct any misalignment, but that is probably just making a lot of work for yourself.
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I've finally given up drinking for good...........now I only drink for evil.
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tsanchez
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Joined: Jul/09/2007 Location: Arizona Status: Offline Points: 4303 |
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Posted: Apr/18/2021 at 3:27pm |
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Thats what happens when you dont use the shouldered stud, it is what guides the rocker along with the pushrod slot.
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