Camshaft Gear Bolts

delling3 · Sep 18, 2020

Need some help here. I have a '96 GT. Stock NPI motor at present. Does anyone know the size (length, thread pitch) and bolt grade for the camshaft gear bolts?

I recall reading that if swapping PI cams into an NPI car, to make sure to get the camshaft gear bolts with the cams. From this, I assume that the camshaft bolts are different between the NPI and PI camshafts. But the gears are interchangable, so I have to assume that the difference in in thread pitch.

Now I have a set of aftermarket cams. I know the diameter and pitch of the bolts required, but don't know if my camshaft gear bolts I have will fit the new cams. If I need to source new bolts, I would like to order the appropriate bolts ahead of tear down, instead of having to wait for parts to ship once I have things taken apart. I am assuming that the bolt is a flange-style bolt, but is the bolt grade critical?

Fivestangs · Sep 19, 2020

I had to buy new bolts when I switched over to PI cams on my '96 GT. The PI cams have TTY bolts although some people re-use them. They are smaller bolts with the same size head. I used the gears off of my old cams.

The PI cams use 10mm bolts and the NPI cams use 12mm bolts. You have aftermarket cams though so it could be either I suppose. I've never done after market on a 4.6, only on earlier engines. I'm sure someone with more knowledge will chime in.

ARP 256-1002 bolts fit PI cams
ARP 256-1001 fit NPI

96blak54 · Sep 20, 2020

Good info^
Alot of the pre 2000 modulars were the 12mm bolt. Im not going to say this is 100% positive info, cause so much engineering changes going on, but as the nearing of 2000's and pi heads the bolts became smaller.

Although I havent seen a 10mm bolt npi cam yet.

delling3 · Sep 20, 2020

Well, thanks for the reply. They are Bullet cams, and they are 12mm threads. They were designed for NPI heads, so hopefully the will use the bolts from my original cams. I guess I’ll find out when I get it torn down.