Train Rail

stock bottom end,226/591/112 gtp cam, 4.8 gtp heads dual valve springs.

i have probably 2,000 miles on these heads and i was driving the other day and it started missing a little. i did not think it was a big deal, so i was driving along and got on it a bit and all of a sudden it was knocking bad, so i shut it down and got towed. the next day i took the valve cover off and one of the springs were broke to ****. the inner spring looked ok but the valve had to be hitting the piston as loud as it was. ( and here i thought the inner spring was there to keep the valve from hitting the piston! ? ) guess i was wrong. i guess i will be pulling the head soon!!!

has this happened to anybody else and is this something that is common!

jmX

Can't say I've heard of many dual springs breaking. Were they the larger diameter 1.4" springs or were they one of the smaller types?

I have duals on my GTP's, but Thunder Racing did them and they used the larger style springs (comp 987 I beleive).

LS1x2

iTrader: (11)

Has nothing to do with the head. Has everything to do with the spring.

Dave Carney

The second spring will keep the valve from dropping but it's not going to keep the lifter on the cam while you get on it a bit.....if you shut it down right after it starts missing you have a much better chance of not doing significant damage.

Gary Z

Dual valve springs provide several advantages over single springs but they can not guarantee that valves will not contact pistons. They will usually prevent a valve from falling into the cylinder in the event of a broken spring. Nevertheless, neither one of the dual springs alone is equivalent to a healthy single spring and one of two springs broken is a serious problem. I can understand your “getting on it a bit” if the problem seemed like a misfire but it is also easy to see how a bad condition was made worse. I am sorry about your misfortune.

-Gary

Train Rail

should i go ahead and take the head off,or is there another way of checking things out so i do not have to go to the trouble? thanks for any help!!!!

robertbartsch

I suppose you could replace the bad spring with the head on the car and then do a compression test to see if the valve is bent, the piston has a hole in it or both...

...If it was my car I would take the heads off, inspect everything and replace all the springs with a new set...