INTERNAL ENGINE MODIFICATIONS Valvetrain |Heads | Strokers | Design | Assembly

Single valve springs

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Old 01-30-2020, 05:12 PM
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Default Single valve springs

I broke a PAC beehive with only a couple of years use. It bent the valve just enough so that it wouldn't seal when I replaced the spring. Never again will I put single springs in an engine that turns faster than a Briggs and Stratton.

My idea to run it and keep changing the oil to fix it didn't work.




How the heck did pieces get into the other cylinders? The part in my hand is the intake valve, it was the exhaust valve that bent. I imagine what is left of the valves is in the exhaust pipe. But how the heck did pieces get into the other cylinders? They would have had to travel to the collector in the header and back to the next cylinder. That's a long way. Or back through the intake runner, into the intake manifold plenum, and through the next cylinder's intake runner into the cylinder. The valve broke at less than 3000 rpm, which makes it all the more confusing as to how the pieces traveled so far.
Old 01-30-2020, 05:37 PM
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I would say it got pushed up into the intake. Sucks.
Old 01-30-2020, 05:42 PM
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I better wash out the intake manifold pretty good before I put it on the next engine.
Old 01-30-2020, 07:18 PM
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My guess would be back through the intake. No way it was via the exhaust. Just 3 cylinders damaged? Shake the intake around and see if anything’s in it.

i only use dual springs also.
Old 01-30-2020, 07:22 PM
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Oi! Was that your 408?!

I think Texas Speed has the cheapest dual wound kits, but bear in mind that most guys suggest replacing the dual wounds at 50k ish. Don't really understand that myself, but that's what the folklore says
Old 01-30-2020, 08:32 PM
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Yep, no more 408. I bought springs when the beehive broke. They are already in the replacement engine. A very used 2003 lm7. I also put valve seals and an o-ring for the oil pick up tube. I'm getting ready to replace the head bolts with the studs from ol' 408. Pin the crank.


What else am I forgetting to get this new engine boost-ready?
Old 01-30-2020, 09:18 PM
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That's awful.

Just the usual gaskets. Oil pump maybe?

Makes me want to replace my beehives now.

Old 01-31-2020, 04:15 PM
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man that sucks on so many levels

i used them a while back on a 383 stroker had valve float any thing over 6200rpm's engine was forged and full arp built for nitrous but since the springs sucked i never even hooked up the nitrous

id do a timing chain and oil pump on the replacement
Old 01-31-2020, 04:23 PM
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sucks, ran my pac springs for about 45k miles and 7k+ rpm.... never had any issues but i also had them on with ls3 hollow valves/ .600 lift
Old 01-31-2020, 05:31 PM
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I always do good lifters, timing set ( not stock) and springs and pushrods. Basically the valve train stuff.


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