bradikus7
15+ Year Contributor
- 409
- 6
- Mar 8, 2008
-
Columbus,
Ohio
Well if you are reading this, I hope you're knowledgeable about drilling and tapping all aftermarket cams for 97-99 4g63 CAS.
I bought a set of brand new Kelford 272's, after much research I had all the info I need. The intake cam needs tapped to m8x1.25 1.37"deep. The cam already has a decent pilot hole so I grab my tap. Without thinking at all, I read the tap, it says requires 21/64 drill bit. So next I grabbed that bit, drilled it out flawlessly, tapped it no issues there, threads cut perfectly. I go to test out the bolt, hole is way to big!!
Turns out, I used a tap from my helicoil kit that I bought when I did my manifold stud.
So after I've freaked out a bit, I get to thinking. OK, so we have the hole drilled to big already, nothing I can do about that. It's already tapped, so I'll just hit up the hardware store, it's probably an M10x1.25. Definitely confirmed the thread pitch is 1.25 on the tap. Hardware store has nothing that fits. It's like the helicoil tap is some kind of special size between m8 and m10 like m9 or m9.5 
.
In conclusion, I am not sure what to do from here. Do I drill it out even larger and risk the structural integrity of the cam? Since the threads are already cut, do I run a helicoil into it, throw some red loctite and use the factory bolt? Is my cam no good now and I need to replace it?
I bought a set of brand new Kelford 272's, after much research I had all the info I need. The intake cam needs tapped to m8x1.25 1.37"deep. The cam already has a decent pilot hole so I grab my tap. Without thinking at all, I read the tap, it says requires 21/64 drill bit. So next I grabbed that bit, drilled it out flawlessly, tapped it no issues there, threads cut perfectly. I go to test out the bolt, hole is way to big!!
Turns out, I used a tap from my helicoil kit that I bought when I did my manifold stud.
So after I've freaked out a bit, I get to thinking. OK, so we have the hole drilled to big already, nothing I can do about that. It's already tapped, so I'll just hit up the hardware store, it's probably an M10x1.25. Definitely confirmed the thread pitch is 1.25 on the tap. Hardware store has nothing that fits. It's like the helicoil tap is some kind of special size between m8 and m10 like m9 or m9.5 .In conclusion, I am not sure what to do from here. Do I drill it out even larger and risk the structural integrity of the cam? Since the threads are already cut, do I run a helicoil into it, throw some red loctite and use the factory bolt? Is my cam no good now and I need to replace it?
