Made an extreme rookie mistake drill/tap Kelford cams!!!

[bradikus7]

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!!WTF

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?

 

[vingasoline]

You either need a m10x1.25 bolt, or run a helicoil in it and use the original bolt. I would put a helicoil in it.

 

[bradikus7]

You either need a m10x1.25 bolt, or run a helicoil in it and use the original bolt. I would put a helicoil in it.

No sir, already have the m10x1.25 bolt. Does not thread in. The bolt feels slightly too large.

 

[snowborder714]

If you've already used a tap made for a helicoil, I'd just throw one in and run the stock bolt.

 

[BogusSVO]

^^^^^ what he said... just install the heli-coil and rock it

 

[SonySlave]

The tap that heli-coils use has a proprietary pitch designed only for threading the inserts into. Once the inserts are installed, it provides the proper pitch for the bolt. You won't find a bolt that will properly fit the hole tapped with the heli-coil tap. Throw one of your inserts in there and you're good to go!

 

[talonalex92]

Especially since all its doing is holding the trigger wheel for the cam sensor, it will be fine.

 

[bradikus7]

Alright guys, I was honestly leading towards just throwing a heli coil in it but wanted some expert opinions. Red loctite sound good too? I know this thing is going to be spinning 8k RPMs.

 

[BogusSVO]

Doubt that sensor will ever seek 8k RPMS.... Cams spin half crank speed,

 

[Jward5]

Sorry to hear about that. Id use the loctite for an extra safety measure

 

[synthetek]

I had a similar problem, I just switched to a 1g cas

 

[HIGHPSI4]

Yes, thread locker and use the heli-coil.

 

[Exxxel]

Use a 1g CAS, there is no need for a bolt!