416 made horrible numbers!! What’s wrong?
10-19-2018, 08:05 PM
#141
I would contact whomever you bought from to discuss the issue. Me personally, i would replace all the rockers with genuion GM rockers, check to make sure the valve for that rocker opens and closes, as well as look at that pushrod to see if it's bent.
10-19-2018, 09:13 PM
#143
ModSquad
iTrader: (6)
Glad you found what you did. I’d pull all the rockers to inspect. Could be binding at the trunnions. Can’t say I’ve ever seen a GM ls rocker break. First time for everything. I just bought a nice take off set of ls3 rockers for $140 shipped. They are easy to find out there.
LOL at all of the stolen engine nonsense in this thread. Never ASSume anything...
LOL at all of the stolen engine nonsense in this thread. Never ASSume anything...
10-20-2018, 08:24 AM
#144
x2 Im betting on installer error. Those trunions are no upgrade imo they only create problems and I have yet to see one stocker fail over many many years now and almost no one abuses engines like I do. Check them all or better yet send them to Straub and get them bushed
10-20-2018, 12:12 PM
#145
JRickel, I'm glad you found the rocker issue. Personally, I would replace all of those rockers. I'd have no confidence in the those rocker castings or the trunnion install. There's could be another one with an issue or break in the near future. In any case, all of the remaining rockers should at least be pulled and checked for binding and other issues.
When my TA with 416 was stolen and had the engine damaged with a mechanical over-rev that broke several intake valves, damaged pistons, lifters, oil pump, broke intake runners and damaged two pistons - none of the GM BTR running rockers broke or cracked.
As others said trunnion install error and / or defective casting.
WS6 Store has an excellent GM rocker with trunnion upgrade. I have these on my 416 now. They also have a new rocker made by one of the OEM GM suppliers.
When my TA with 416 was stolen and had the engine damaged with a mechanical over-rev that broke several intake valves, damaged pistons, lifters, oil pump, broke intake runners and damaged two pistons - none of the GM BTR running rockers broke or cracked.
As others said trunnion install error and / or defective casting.
WS6 Store has an excellent GM rocker with trunnion upgrade. I have these on my 416 now. They also have a new rocker made by one of the OEM GM suppliers.
10-20-2018, 03:26 PM
#146
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Pushrod looked fine, the broke rocker went through the retainer so I’m assuming that needs to be replaced, is this easy to do?? And I bought them from Michigan Motorsports? Off eBay for $200. I just emailed them. So I guess I’ll wait to here from them.
Again, thanks for the advice!
10-20-2018, 03:46 PM
#147
Pushrod looked fine, the broke rocker went through the retainer so I’m assuming that needs to be replaced, is this easy to do?? And I bought them from Michigan Motorsports? Off eBay for $200. I just emailed them. So I guess I’ll wait to here from them.
Again, thanks for the advice!
10-20-2018, 04:23 PM
#148
Be sure to replace that valve spring. Nicked up it could snap easy. In fact I'd replace the entire valvetrain on that one valve aside from maybe the valve if its not damaged? Lifter, pushrod, rocker arm, spring keeper and lock and maybe the valve too if it was nicked.
10-20-2018, 05:43 PM
#150
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240/256 .625 .625 113 LSA cam?
That's a Howard's 190865-13 (or 190866-13 if its a single bolt cam).
The lift spec is for 1.7 rocker arms, yet you mentioned LS7 rocker arms which are 1.8 ratio.
That means you're using a cam with .662/.662 lift, probably on BTR .660 springs.
Not hard to see why a rocker arm was broken.
That's a Howard's 190865-13 (or 190866-13 if its a single bolt cam).
The lift spec is for 1.7 rocker arms, yet you mentioned LS7 rocker arms which are 1.8 ratio.
That means you're using a cam with .662/.662 lift, probably on BTR .660 springs.
Not hard to see why a rocker arm was broken.
10-20-2018, 06:38 PM
#151
Those aren't LS7 rocker arms.
But there could be binding to cause a failure like that. I'd replace the valve spring at least and the pushrod. But you have to worry about the lifter taking a **** if something was binding and broke a rocker arm... probably did some damage to the lifter and possibly the cam lobe.
But there could be binding to cause a failure like that. I'd replace the valve spring at least and the pushrod. But you have to worry about the lifter taking a **** if something was binding and broke a rocker arm... probably did some damage to the lifter and possibly the cam lobe.
10-20-2018, 07:48 PM
#153
TECH Senior Member
I would suspect EVERYTHING from the cam all the way to the valve. Not saying replace all, just check each and every one of those parts.
10-23-2018, 09:48 AM
#158
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10-23-2018, 11:05 AM
#159
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