Intake bolt holes in head problem

[olddog]

The edelbrock heads have helicoil in the threaded holes that the intake bots go into. The second bolt in from the ends are the ones that are in the milled out spot between the intake ports. All four of these spots a bolt would only turn in 3 threads by finger. I can only get about a half turn more with a nut driver. You can twist the bolt in with a rachet.

So I tried running a tap down them. It felt like the tap was hitting the bottom, but I only gain a turn at best on a couple holes. So I tried a bottom tap. It felt like the tap was getting tight. I kept going back and forth, but it would not free any at all. I tried to go down a little further and it just stopped. Then when I backed up the helicoil backed out a couple thread. If I run the tap back in I can turn the helicoil back in, but then it backs out again. I cannot get it in nor take it out.

I tried tapping a second hole very easy, again the tap does not help to free up the threads. It acts to me like the tap cannot cut the helicoil. I suspect the hole the helicoils screw into are not tapped correctly causing a tight fit, who knows.

So what is the best method to remove the helicoils? I want to re-tap the holes and put new helicoils in.

[Jac Mac]

As a rule stainless bolts in heli coils tend to bind, I would also check that you are using the correct bolt thread match eg 5/16" UNC / NC in this case.

Running a tap thru a Heli coil is a recipe for disaster, if you are using the correct bolt thread you shouldnt need to do this if the HC was correctly installed.

To remove the Heli Coil from this 'Blind' hole location you have to grab & bend the top coil out into the hole and then wind it back out with a pair of needle tip pliers. '''IF''' the hole is not blind & the insertion tang is still present then you may be able to remove it out the bottom with the correct installation tool.

Bear in mind that a special tap for each size of Heli Coil is required, not just any old tap.

Jac Mac

[olddog]

Jac Mac,

The bolts are correct and the taps I used - 5/16 - 18.

The other eight holes, I can spin the bolts and the taps down with my fingers, with ease.

I agree something was wrong with these four holes. I suspect they were not right from the day they were new, as it is suspicious that it is the 2nd hole from the end both sides on both heads. A pattern makes me think a manufacturing problem, but since I have no history to back it up, I may be flat wrong.

I would guess the heli-coils are lock tight or other wise glued in. I'm concerned on how to get them out. Should I heat a bolt with a torch to loosen the glue before trying to get them loose? With out at IR gun to monitor the temp, I'm worried about the aluminum.

[Rick Parker]

Bear in mind that a special tap for each size of Heli Coil is required, not just any old tap.

Miss this and you'll ruin the bolt hole! Good point Jac Mac!

Put a little anti sieze on the bolt.

[Jac Mac]

Originally Posted by olddog

Jac Mac,



I would guess the heli-coils are lock tight or other wise glued in. I'm concerned on how to get them out. Should I heat a bolt with a torch to loosen the glue before trying to get them loose? With out at IR gun to monitor the temp, I'm worried about the aluminum.

There should be traces of glue/loctite in the hole if that is the case. I doubt that this is the case, but people do strange things!

If the oxy/acet flame tip was played on the top end of the helicoil for about 5 seconds MAXIMUM the helicoil should glow red hot & stuff any loctite or epoxy plus anneal it enough to allow you to bend in the top thread for removal as pointed out earlier. You wont affect the alloy with that time frame--- be real careful where you wave that torch though, especially down an intake port, could still be some fuel in there--use small tip & dont put the inner (blue) kernal of the flame on the heli coil- thats the cool part of the flame.

BE REAL CAREFUL ABOUT THIS, I would hate your next post to be

Jac Mac

[olddog]

Thanks guys.

I managed to get 3 of the Heli-coils out by screwing the bolt down until it tuned hard (1/2" rachet), then turn the bolt back out and the heli coil would back up a couple threads. Then I could turn the bolt in a couple more turns and I would hit the hard spot again and repeat. This would get about 8 threads up out of the hole, and then you could spin the bolt down with your finger and there was no hard spot any more. At this point I could grip the heli-coil with pliers and then turn the bolt. This got them the rest of the way out.

I think the factory did not run the tap down far enough, causing the bottom of the heli-coil to be tight (slightly smaller ID).

The fourth hole the bolt could be turned all the way in and it wouldn't get tight enough to move the heli-coil. So I ran a tapered tap down thinking it would bugger it up enough for the bolt to grip it. This time the tap actuall cut a fine piece out of the heli-coil. I ran the tap up and down a dozen more times and now the bolt spins free in it. So I'm leaving well enough alone.

I'll get a heli-coil kit tomorrow (correct tap) and put new heli-coils in. I ordered a stud kit. I'm going to try that route.