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What should I do about stripped threads in head

I bought a Chevy 350 1987. I was trying to put the intake bolts on and one of them stripped the threads. Is the only way to fix this a tap?

It’s one of the inside bolts and one that if it’s too long will push up against the push rod.


Or a Timesert.


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Motor is not in car? Ah, that’s easy. Or easier.


Yes… Helicoil is the way to go. It involves a drill bit, a tap and the Heli-coils… The repair is usually as strong if not stronger than the original setup (especially in aluminum) since the coil is stainless steel.

They sell everything you need in one convenient container…the properly sized drill bit…the tap…the coils, the coil installation tool… All based on the size of the bolt hole that you are trying to repair. With the engine out and apart it only gets easier…


Yes, indeedy! Works great and stronger than the original. Heck Heli-Coils (or generic inserts) are used in aluminum when repeated dis-assembly would be normal for that fastener.

Every single one of the tailshaft housing bolt threads on my T-5 transmission had to be done… and that bugger came apart regularly.


We use helicoils for high reliability assemblies all the time at work.


That bolt threads into the cast iron head. What’s the issue with stripped threads in aluminum?

That could be a very lengthy discussion, depending on which manufacturer you want to talk about . . .

Is that a Corvette engine?

New one isn’t, old one I have no idea all I know it was made between 1986 and 88

Is the OP dealing with stripped threads in aluminum?

Is the OP dealing with stripped threads on the bolt or the cylinder head?

There are rethreading taps that can often clean up damaged threads successfully.

Based on the picture, it seems like the threads in the cylinder head(s) are stripped

Notice that one missing intake manifold bolt . . .

That was my conclusion also @db4690. But somewhere “aluminum” got stirred in.

@mio.da.bomb_157143, you have a particularly pleasant situation there for repairing the problem. The engine is out and easy to work on and the problem hole is open and accessible from top and bottom.

And in case you weren’t aware of the problem with getting those intakes ‘nestled’ into position and hand threading the bolts several turns prior to using a wrench you will most likely not have such a problem again… Of course someone may have done the damage before you got involved. If you use rethreading taps I’d enjoy knowing if you were successful.


I was the one who stirred in the “Al-loo-minium” @Rod_Knox. I only mentioned it for informational type purposes, despite seeing they were talking about the mani bolts that go into the head. I’m silly like that sometimes…

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Well D&^$% @Honda_Blackbird, you know how easily us old people are to get confused. Is that the correct spelling for aluminum using the Queen’s English.

But as for that particular bolt I recall how Chevrolet often used torx bolts there for some reason and getting that intake into place seemed to work best by dropping those four center bolts into the intake and wiggling the intake until those four slipped easily into the threaded hole and turning them down several turns with bare hands and then working outward installing all the other bolts. And I likely tightened the bolts in 5 or more stages in the prescribed order before reaching full torque. I have seen so many leaking intakes despite the bolts being tight due to the intake being slightly cocked.

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In the USA it’s aluminum

In many other countries, it’s aluminium

I was trying to be British… Pip-Pip …Stiff upper lip and all that.

A cigar and bowler are all you need @Honda_Blackbird.

That’s good to know, I’ll keep that in mind when I put it back on

I’m picturing Blackbird looking like John Steed in “The Avengers” with a Bowler hat on.

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