Tap a hole
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Racer
Joined: Mar 2009
Posts: 251
Likes: 1
From: Windsor Connecticut
Tap a hole
I just snapped the head off one of the valve cover bolts on my 1984 Corvette the good thing is the bolt is on the outside of the cover the question is can those holes be tapped and I never done it before so all suggestions and good advice will be welcomed. This Snapped boat is easy to get to not sure if I need to remove the valve cover or not and I hope to hear from someone soon
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 764
I just snapped the head off one of the valve cover bolts on my 1984 Corvette the good thing is the bolt is on the outside of the cover the question is can those holes be tapped and I never done it before so all suggestions and good advice will be welcomed. This Snapped boat is easy to get to not sure if I need to remove the valve cover or not and I hope to hear from someone soon
Le Mans Master
Joined: Sep 2004
Posts: 6,019
Likes: 568
From: Conroe Texas
or a bottom tap to straighten the threads and to cut new threads at the bottom of the hole if the drill depth will allow it.
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
curious - how do you snap the head off a VC bolt at 50-75 INCH pounds? doesn't matter, what's done is done. personally, i'd remove BOTH valve covers. grab what's left of the bolt with a pair of vise grips, remove, and clean out the hole, as well as the other bolt holes using a 1/4-20 thread CHASER. i'd also replace existing VC bolts with 1/4-20 studs (try moroso #97020), nuts and washers, fel-pro #1628 gaskets, and TORQUE TO SPEC.. now, this is just what I would do - plenty of experts here will have different opinions-
Last edited by GregMartin; Aug 11, 2020 at 06:27 PM.
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
If the bolt was over-torqued, but didn't bottom in the hole, it should screw out with a just a little ice pick grabbing the nub of the broken bolt.
If the bolt bottomed in the hole then snapped off, it's going to be a bitch to get it out. I'd begin with reverse-rotation drill bits, which are intended for broken bolt removal.
You will have to remove the valve cover either way. If you have to drill, put up a little barricade of cardboard or stiff paper to keep chips out of the valve springs and other hard to clean areas.
I over-torqued and broke off a center-bolt valve cover bolt in one of the later engines with plastic valve covers. I panicked as I didn't see a good way to deal with it without removing the head. My machinist of 40 years calmed me down and said it will come out with a pick, because it didn't bottom in the hole. He was right. I called the right guy for advice.
If the bolt bottomed in the hole then snapped off, it's going to be a bitch to get it out. I'd begin with reverse-rotation drill bits, which are intended for broken bolt removal.
You will have to remove the valve cover either way. If you have to drill, put up a little barricade of cardboard or stiff paper to keep chips out of the valve springs and other hard to clean areas.
I over-torqued and broke off a center-bolt valve cover bolt in one of the later engines with plastic valve covers. I panicked as I didn't see a good way to deal with it without removing the head. My machinist of 40 years calmed me down and said it will come out with a pick, because it didn't bottom in the hole. He was right. I called the right guy for advice.
