Aluminum Head Woes

Gene Fiore

Famous Member
After what seems like an eternity I was finally to the point of bolting down the aluminum head on my 250. Got the new head gasket and studs installed and torqued the head to specs. Installing the rocker assembly is where things went bad. Got the pushrods in place and rocker assembly in place. Start all rocker bolts by hand and snug down. Then torque them to 35 foot lbs and bamm...the threads in the head underneath the rocker stand at the back end of the motor pull out of the head. WTF! So I pulled everything back off and sure enough the threads are almost gone. :( I sure hope my machinest will be able to fix this. :banghead:
 
Gene Fiore":3920yeay said:
...and bamm...the threads in the head underneath the rocker stand at the back end of the motor pull out of the head. WTF! So I pulled everything back off and sure enough the threads are almost gone. :( I sure hope my machinest will be able to fix this. :banghead:
That'll B the easiest wont it?
The hard prt - to find a fasner that'll work after the machining?

Try'n figure Y it pulled up. I'd hate 2 C U get it fixed'n the others go...
 
HI Gene, this should be a very simple repair job using a Heili Coil thread repair kit from your local auto part store like NAPA ect. The kit comes with proper size drill and tap so you only need a hand drill with that kit, but (a drill press gives even better results). When finished the Heili Coil threads will be even stronger and last longer than the original threads in the Aluminum head and the current rocker hold down bolts can be reused if there's no thread damage. Good. Luck (y) :nod: Edited
 
gene, i agree with bubba and marco. a good helicoil install should cure the problem, which is probably what your machinist is going to do.
 
That's good news...I plan to give him a call first thing Monday morning. I'd rather have a professional handle this.
 
not a bad idea gene if you are not confident in your skills in doing such a repair, or dont have time.
 
like it as same fastener can B used...

Now, Y did it 'go''? U were not wrking on it @ the time.
Ur tq wrench is in accurate?
U did not follow the recommended procedure on tightening,
it's was a defective pour,
...or...or...or...
 
35# is probably overkill for the pedestals. That's around maximum torque for a grade 8 3/8" bolt. And being the aluminum head and the pedestals are aluminum or zinc/white metal 20-25# should do. With washers and locks 15# would probably be a plenty. A couple of the pedestals on my old 170 were distorted pretty badly from being over torqued.
 
Econoline":23lj29jr said:
35# is probably overkill for the pedestals. That's around maximum torque for a grade 8 3/8" bolt. And being the aluminum head and the pedestals are aluminum or zinc/white metal 20-25# should do. With washers and locks 15# would probably be a plenty. A couple of the pedestals on my old 170 were distorted pretty badly from being over torqued.
Thanks for the tip...once I get this fixed I'll back off to say 20#.
 
Gene, make sure your rocker shaft bolt goes far enough into the threads in the head??? Might need longer bolts. The problem with different bolts is oil supply to the shaft??
 
I tried to warn about keeping what you are doing in mind with your fastener torque,. but people kept saying no you have to use the torque that the fastener maker says...Some places you have to think about what you are doing...No blanket torque value.

There are even better inserts that will make the repair better than new...If it is in the budget I would go to studs,.easier on the threads..I have not done this yet but I think it would make installation easier,..slide it down the studs,.. keeping the push rods in place as you go..
Good luck,..get er done.. (y)
 
We have the same problem at the dealership with head bolts pulling the threads out of Northstar Cadillac blocks causing head gasket issues. We use a product called timeserts instead of heli-coils but it is the same principle. This is a factory approved repair, so don't feel bad about using a thread repair kit. I'm sure that your machine shop will get you fixed up. here is a link for the kits on Amazon if yoiu decide to go DIY: https://www.amazon.com/s/ref=nb_sb_noss ... s=timesert
 
ags290":2zwgtz0x said:
We have the same problem at the dealership with head bolts pulling the threads out of Northstar Cadillac blocks causing head gasket issues. We use a product called timeserts instead of heli-coils but it is the same principle. This is a factory approved repair, so don't feel bad about using a thread repair kit. I'm sure that your machine shop will get you fixed up. here is a link for the kits on Amazon if yoiu decide to go DIY: https://www.amazon.com/s/ref=nb_sb_noss ... s=timesert
That is the one I was thinking about (y)

Another problem that I heard about ,..is to much oil in the hole will hydraulic the boss off...That has never happened to me so it mght be hearsay.
 
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