Stripped valve cover holes on ported head

[Shadowjake]

I have a used Menegon ported head I bought. I just installed the valve cover on my engine build last night and realized 3 of the valve cover holes in the head are stripped out. I tried to torque them to 105 inch pounds like the FSM says and some just let go before getting there.

How do I repair this? Should I just re-tap the holes for a size larger (what size?) and use different bolts? is there a rethread insert in the right size that would work in the head?

Please help. I'm sure the valve cover will leak with these bolts loose. Thanks!

[shmedley]

I have used helicoils in those bolt holes with good success.

[RoadWarrior222]

I'da just grabbed the taps and tapped it bigger (after inspecting for nearby oil and water) ... though I guess that's why my car now has a mixture of metric, imperial, british standard whitworth, national pipe thread and phonecian war chariot hub nut threads on it now...

["Top Fuel" Bender]

I'd heilcoil or nut-sert them
gotta be careful especially going bigger ,
seen my fair share of cracked off corners on the heads
I'm a big stickler for torquing things properly but the valve cover is a feel thing
make sure you run them down evenly

[supercrackerbox]

I have used helicoils in those bolt holes with good success.

As have I. The old head on my Charger had probably 1/2 of the manifold and valve cover bolt holes Heli-Coiled.

I even successfully Heli-Coiled one of the flywheel bolt holes in the crank in my old Daytona.

[cordes]

You'd be surprised to see how few of them you really need to stop a leak.

I would helicoil it if you are going to fix it. When you tighten them down next make sure to do a little at a time across all of them. That helps to lessen the stress on each one because it isn't trying to mush the gasket all by itself.

[GLHNSLHT2]

We just heli-coiled 7 out of the 9 bolts on a friends car. Some hillbiilly used different threads on 2 holes, the rest just stripped out. Used heli-coils on them. works great.

[black86glhs]

I like to drill them out and use larger bolts. You can get to the 105 in lbs without stripping them out. No it isn't really that important, but i don't have any valve cover leaks. The heli-coils are nice, though.

[RoadWarrior222]

I tried to torque them to 105 inch pounds like the FSM says and some just let go before getting there.

BTW that usually means someone has fugged them up before you... I had a hella time of it with the trans pan on my used tranny, was using a deflecting beam torque wrench on it, and practically every bolt I'd get it to about 9 or 10 ftlb (Spec 15*) and then it would just drop off, and I'd get that feeling in the pit of my stomach...

Edit: * or was it 12 ftlb... was using the right spec at the time, numbers used for illustration, not reference.

[Pat]

Helicoil then install studs.

[135sohc]

Helicoil then install studs.

Ditto...

Your past posting about doing such on a T3 head convinced me to do the same for my 8v head.

[chilort]

Helicoil then install studs.

Ditto...

Your past posting about doing such on a T3 head convinced me to do the same for my 8v head.

What they said. I'll never use bolts in aluminum heads again for the valve covers.

[22mopar]

NEVER tap it out and use bigger bolts, that's what backyard hacks do. Just install helicoils. that's the correct way to repair.

[RoadWarrior222]

Sorry to break it to you, but helicoils are also a hack, real, real way is to to plug it, redrill and retap back to original size.

["Top Fuel" Bender]

Sorry to break it to you, but helicoils are also a hack, real, real way is to to plug it, redrill and retap back to original size.

how do you figure?
Heilcoils are stronger then the original thread even in steel
How would you recommend "plugging" it?
can't just drill a bigger hole , press a chunk of alumn. in there

[RoadWarrior222]

Well obviously a home shop (and a lot of machine shops) aren't set up for the possibility of successfully friction or ultrasonic welding a plug in there, or managing to TIG fill a smaller hole. It could be preferable though to use a solid threaded insert, preferably harder or hardened. Those are substantially stronger than "original" tapped hole, but sort of only as strong as a bolt of the same external diameter, with the original fastener as a fuse. With a helicoil it's stronger than the "original" hole somewhat, but not quite as strong as a bolt the same size, because it is possible for the coil to spread or turn over inside the hole. But if there's enough room to put a helicoil in there, there's enough room to use a larger bolt... unless there's some pressing reason to preserve thread size such as spark plug holes, even then, to get a guaranteed pressure seal a solid threaded insert would be better.

[tryingbe]

Take a valve cover bolt to napa or aceshardware, they would have the heli kit you need. (drill, tap, and heli-coil)

[black86glhs]

Well obviously a home shop (and a lot of machine shops) aren't set up for the possibility of successfully friction or ultrasonic welding a plug in there, or managing to TIG fill a smaller hole. It could be preferable though to use a solid threaded insert, preferably harder or hardened. Those are substantially stronger than "original" tapped hole, but sort of only as strong as a bolt of the same external diameter, with the original fastener as a fuse. With a helicoil it's stronger than the "original" hole somewhat, but not quite as strong as a bolt the same size, because it is possible for the coil to spread or turn over inside the hole. But if there's enough room to put a helicoil in there, there's enough room to use a larger bolt... unless there's some pressing reason to preserve thread size such as spark plug holes, even then, to get a guaranteed pressure seal a solid threaded insert would be better.

That is my point of view. If your worried about cracking the head, don't helicoil it either. It can be done either way. I don't care if it isn't factory correct, so i will drill and tap for a slightly larger bolt.

[GLHNSLHT2]

The problem with using a larger bolt is you're still twisting and pulling on the threads when tightening the bolt down. With a stud, or a heli-coil that doesn't happen. You just pull on the threads which allows the bolt or stud to be clamped tighter. Using bolts in aluminum is fine but make sure it's heli-coiled. On our fixtures at my job that we machine parts on it's not practical to use studs to hold the parts down. So we have to use bolts. All the holes are heli-coiled and I've removed and replaced the bolts so many times with an air drill that the heli-coils wear out on the bolt side. But they NEVER strip the aluminum.

[22mopar]

I've got 4 MP factory ported heads. Over the years I've been racing them, I've helicoiled just about every hole and never had a problem. I'm no machine shop, just a backyard mechanic but I'm set up to do it right.... infact you can be too if you have patience to do it right. bigger bolt is totally lame and hack work.