Front crankshaft threads

[CamaroAdam73]

Thanks for the info guys, yeah i'm having it towed over to my friends garage instead of driving it, and i'm going to flush the tank because I payed a pretty penny to have this holley custom built around what my new cam demands. And i'll deff be using a chaser and not a tap and dye, i thought about that the other day, i just want to restore the front threads, not make new ones.

 

[adumb]

Thanks for the info megaladon, Yeah the threads are only bent at the very front of the whole. btw whats a thread chaser???

It looks like a conventional 4 fluted tap with the exception of how deep the actual cutting is (sometimes a worn out tap will suffice) It may have a hex head on it rather than a square. FWIW you will be looking for a 3/8-24 NF tap or thread chaser. Hope this helps.

i believe the crank thread is a 7/16ths fine thread

just everything else on the motor is 3/8 24

 

[pontiacgp]

TYeah the threads are only bent at the very front of the whole. btw whats a thread chaser???

if the first few threads are damaged it'll be hard to repair since there are no threads to guide the thread chaser.

 

[CamaroAdam73]

Any advice on how i should go about doing this then?

 

[megaladon6]

carefully!
actually that's not a sarcastic response. you just have to go slowly, by hand and feel your way. on something like this i prefer a short socket on a 1/4 drive ratchet. this way you start and guide with your fingers, then you can add a little force w/out adjusting your grip. (the ratchet head is palmed) some people like to use one hand as the guide, and the other hand on a wrench, this allows them to control the "downward" (ie along the direction of the hole) force. i wind up twisting a little when i use this method myself. but if you don't have much room it can be easier than my usual method.

 

[Bonnewagon]

If you use a tap with a long taper, you might get past the bad threads and get a bite. I don't know if they are a special type, or what they're called, but I have several in my set. The first 1/2" or so looks like a pencil and the cutting threads are gradual.

 

[CamaroAdam73]

Thanks for the advice guys, BIG BIG help!

PS: megaladon, they need to change your status from royal smart person, to "the man"!

hopefully with this info the job should go smooth sailing, because removing a crank due to bad threads on the front is a really gay reason.

 

[uneek1976]

Ok, i just did that same sh** this summer with my and i thought that i would have to take out my crank. What i did was retapped the threads. I have the tool in my van, Its a 7\16 by 20 thread. I will take a pic of it now so you can see what it looks like.

 

[pontiacgp]

if the threads can't be repaired then you'll just have to install a heli-coil that was suggested

 

[uneek1976]

If you can save the threads use this.

Hope the helps you out to get you going.