Different size timing cover bolts?

[StangYellow]

All 8 of my ARP timing cover bolts are the same size, but the bottom 4 holes are larger than the bolts. I haven't been able to find my ziplock baggie of original bolts yet to check them out. Needless to say... I'm stuck. Anyone experienced this before?

[drdano]

Sounds about right, 4 of the bolts are a larger diameter on the bottom of the cover.

[cjshaker]

Typical for ARP. Very few of their "engine specific" kits are 100% correct, so you have to spend more to get the correct ones. Often times they need modified (shortened) also. Their intake bolt kits are often wrong length on a few,  header bolts are too long, flywheel bolts are often too long, front cover bolts as you found out, etc.

[StangYellow]

Oh boy, so I have a lot to look forward to with this complete set. I didn't pay much attention to the cover bolts when removing them, so I didn't notice the difference. Looks like I will be tearing the garage apart for my original ones

[StangYellow]

Does anyone happen to know the length/thread/pitch of these bolts? Seemed to have misplaced these during the disassembly. I called ARP to see if they happened to know about this, and they didn't. I need to call in and order the correct ones from ARP

Block and cover are a '66 390....

Thanks!

[Nightmist66]

The bottom 4 bolts are 3/8-16 thread and the others are 5/16-18 thread. As far as lengths, I don't know off the top of my head and am not sure when I could measure mine. If you need the measurments right away and no one else jumps in, figure on a good 1/2" thread going into the block, another 3/16" for the washer and gasket,and whatever else the timing cover measures. Good luck.

[thatdarncat]

The original Ford spec for the bolts are 3/8"-16 x 7/8" long and 5/16"-18 x 3/4" long. Also just as a bit of trivia, the originals were a "locking" bolt, they have a small nylon pellet imbedded in the threads to keep them from backing out.

[StangYellow]

That's a huge help guys. Much appreciated!

[cjshaker]

Does anyone happen to know the length/thread/pitch of these bolts? Seemed to have misplaced these during the disassembly. I called ARP to see if they happened to know about this, and they didn't. I need to call in and order the correct ones from ARP

Come on, you called to find out what type of bolts it uses, from the guys who got it wrong the first time?...lol

Just razzin ya, but I thought that was humorous