CRANK bolt help please help

ok for a friends motor bbc
had a lunati bbc crank
ordered a new blower crank supposed to be the same but it has new upgrades

heres the problem we run a hemi bolt 3/4x16 with 1/2x20 threads in for mandrl http://www.rbssuperchargers.com/Store_Detail.cfm?ID=145015&InfoID=3921


lunati new crank has the threads 4 inches deep (they start at 3.5 and end 4.65 almost at the main bearing no joke)

i need a bolt thats 4.4 or so inches long that has a 1/2x20 threads in it
like this one ( but with threads in center)
http://www.rbssuperchargers.com/Store_Detail.cfm?ID=145021&InfoID=3921
but with threads on inside for mandrel
this blot has ben lightend so we cant just drill and tap it

the only thing i can come up with is a pice of round stock press it into the lighten hole tig weld and tap ????
any ideas
lunati told me they dont know where to get a bolt
i called arp and they told me good luck

 

Chris

Hey bud, a std 1/2" bolt is 13 Coarse and 20 Fine. Even a pipe tap is 1/2-14. Is Kenny sure his is 1/2-16" I can bring a bolt gage over to his place if it helps. 1/2-16 is a British imperial thread.

http://www.britishfasteners.com/index.php/products/bsf-hex-bolt-12-16-x-2-1845
See, you could call these guys in NY and see if they would sell a tap or custom make a bolt but I would just buy the tap as I'm not sure how familiar they are with this application.

First I would try RCD at 530-292-3133. also try the person that made his dry sump system or maybe JR at RBS and see if he knows of someone.

RCD PN

358875-75 3/4-16 4.4 LONG 1.43 FLANGE CRANK BOLT $57.00

Doesn't say gun drilled so possibly just drill and tap, If the dry sump system was made by Autoverde or someone the mandrel could be metric, Can't remember who made his so its a thought.

Let me know when hes going to be at the house and I'll swing over with my magic bolt tool.

Trev

 

You probably read the pitch wrong. Can't imagine Lunati coming up with something that odd ball, not even by mistake. The cure in the end would be either bore and tap the crank for the 3/4-16 or make a stud to work it out. Studs always worked better for me anyway.

 

the crank is 3/4 16
and the threads in the bolt tip (for mandrel need to be 1/2 20)
i found a bolt that will hold the crankhub on but i cant put the drive on for oil pump mandrel
the second rbs website shows bolt i can use but cant run a drive off it

 

ok i read the bolt right but i typed it in wrong
all fixed
but still need a bolt

 

Ok, You are describing one of those offset bolts (meaning it's impossible).
Make a stud or bore out the hub.
Dave Koehler
http://www.koehlerinjection.com

 

try RCD I think leach makes one..Dave

 

they make one but it is lightend head on it so i cant run drive for oil pump