HELP- Broken Valve Springs

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Oct 27, 2004 | 12:49 AM

motolust

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8th Gear

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HELP- Broken Valve Springs

Just got my truck back- had a rebuilt 390 installed- was runnng great for 100 miles- then it starts miss firing- back fire- take it to my installer- we open the valve covers and theres 2 broken springs. WTF. I'm pretty new to all this so can you guys tell me how fubared this is or what. Just not sure what else to look for after we replace the springs- should I replace all of them? Jeez.

Oct 27, 2004 | 03:21 AM

FFR428

Needsmorecoffee.

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From: CT

Yep I'd look at replacing all of them. You first need to determine if your cam's lift is too aggessive for the OEM springs. Most cam's have matching springs recommended. G.

Oct 27, 2004 | 03:24 AM

FFR428

Needsmorecoffee.

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From: CT

BTW check all the pushrods also. Some may be bent. Coilbind sounds like what caused the springs to break. This is when the cams lift is too big for the spring causing it to fully compress and bind...then break.G.

Oct 27, 2004 | 10:24 AM

Mike G

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From: Littleton, CO

..and hopefully the valve did not drop and hit the top of your piston. Have you pulled the head....

Sorry, --Mike

Oct 27, 2004 | 10:28 AM

elemint

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From: outback

JB-WELD is worth a try. Amazing stuff.

Oct 27, 2004 | 03:03 PM

krewat

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From: Long Island USA

I think if the problem was coil bind, the pushrods would bend before the springs broke...

That said, it is possible, I guess.

My machinist mentioned that when you reuse the old springs and shim them up to get the seat pressure back to somewhere reasonable - he said that the springs can break if you go too far and the spring is just plain worn-out. But then, he may have meant that they bind and break.

Pull the head, check the pistons, make sure the valves are straight, change those springs! Also, if it was coil-bind and it took out a pushrod or two, check the cam, you may have scarred it enough to cause problems later (look at the bottoms of the lifters, if they are scored or rough at all, the cam is probably going to toast itself soon too...

Oct 27, 2004 | 03:53 PM

motolust

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8th Gear

Joined: Jun 2004

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OK- Thanks- I spoke with Bob (mechanic)- he checked the push rods- all is straight- he is replacing all the springs on both sides- he is working on it now- not sure if he will pull the heads and check pistons- probably not. he assured me that if anymore problems arise it will be taken care of and that the guy who rebuild the motor stands by his one year warranty.

Thank you all for the info- If you can think of anything else please post it- this site is giving me a great education.