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Discussion Starter #1
Hi everyone, new guy to the forum.
I have been messing with this problem for a while now, I have a 410, it was a 351M, Internals are a 400 crank, .040 overbore TMyer flat top pistons, edelbrock 2172 cam, howards double roller billet cam, crower camsaver lifters, stock valve springs, but they were pressure tested and okayed by the machine shop, also everything is balanced, and the bottom end is all ARP.
The ignition is stock duraspark II, but it has a pertronix flamethrower coil, MSD 8mm street fire spark plug wires, and autolite racing ar25 spark plugs, and the timing is set to 10-11 BTDC.
Ok, the problem is no matter what the engine won't spin past 4,000-4,200rpm, the cam is rated for max 5,500rpm. I know before the engine was rebuilt when the throttle got stuck in April, that night that engine revved every bit close to 6 grand.
The transmission is the original FMX, is there a chance the trans is limiting the engine because its having nearly double the power going through it? - just a thought.
Let me know if you can think of anything. Thanks
 

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Valve springs are the first place I'd look. It's possible to float the valves with a STOCK cam, and it has less than 0.400" lift. An aftermarket cam not only lifts the valves further, but also faster. I'd say the valvetrain is completely out of control above 4k rpm. Look up the recommended valve springs, and MAKE SURE they are installed at the proper height. (compression) For a spring rated at 300#/inch... even installed 0.100" too tall takes 30# off the seat pressure.

Install the correct springs, and it should wake right up, unless there are other issues. Hopefully, you haven't gotten angry, held it wide open, and bent all the exhaust valves.

Good Luck
 

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Discussion Starter #3
Sorry for the late response, that had crossed my mind in the past, but the engine shop (Wilkersons in Springfield), said the factory ones were OK, so I went on and tried looking for other culprits, but everything checked out. I looked around and I'll probably-just for the ease of it, get the springs Edelbrock offers for the cam.
Also, no I haven't been rash with it, at most I held it open to see what the top RPM was, I've been lucky I guess, I was reading around on other forums and others have bent pushrods, valves, and even broken valve springs, she is my daily driver, so I'll just have to be careful until I can get the springs, and get them on, but keeping the RPMS down will be little bit of a task because of the 3.60 gears, at 60mph shes cruising at 2,700-3,000.

Thank you for the insight, I'll relay the results when I get everything together.
 

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You need 110-120 on the seat and 300-320 open to avoid valve float. Stock springs "might" be 80-90 if you're lucky.
The Edelbrock cam mentioned only measures 204/214 @ 0.050" with 0.484"/0.510" lift.
Rev range is from idle to 5500 rpm.

Seat pressure should be around 110 lbs, and 250-280 is fine for open figures.
Just use the recommended valve springs, and make sure they are installed at the correct height.

Good Luck!
 
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