Swapping a newer head to older AMC V8

[Stangerize]

Well, we assembled most of my 407 last night and when we got to the point of trying to get the alternator on we were having fits. The brackets and bolts were driving us nuts. We had what we believed was the bolt that went on the top of the alternator but it was too big for the hole in the head. It fit the hole just above it. No, that's not it. So I had a revelation and remembered this was the head from the 1983 360. I went to the back of my original head since they are all symmetrical and voila, the bolt we were trying to install fit the hole we were trying to put it into on that head. It appears AMC changed that hole somewhere between 1976 and 1983 from 7/16" to 3/8"-16. Oh well back to the hardware store for a Grade 8 3/8-16 x 6.5" bolt. Just thought I'd let you guys know.

[Bob Barry]

I just posted on this point; I found out that the break year for downsizing that bolt is 1979; up to '78 used the 7/16" bolt, while '79 and later used the 3/8" bolt.

Good luck finding a 6.5" bolt; I had to go with all-thread cut to length.

[ibnfe]

I used a grade 8 bolt, 8" long. Couldn't find anything else from anywhere, and truthfully, I don't know where I got this bolt. It was in my "goodie bin" from some bygone project as a left over. I ran a die down it to extend the threads, and then whacked it down to proper size. If you don't have a die to run the threads, you can always stack a bunch of washers/shims on it. I know my rig has enough belt clearance for that.

[Stangerize]

<BLOCKQUOTE>quote:</font><HR>Originally posted by ibnfe:
I used a grade 8 bolt, 8" long. Couldn't find anything else from anywhere, and truthfully, I don't know where I got this bolt. It was in my "goodie bin" from some bygone project as a left over. I ran a die down it to extend the threads, and then whacked it down to proper size. If you don't have a die to run the threads, you can always stack a bunch of washers/shims on it. I know my rig has enough belt clearance for that.<HR></BLOCKQUOTE>

Thanks, I had gone to the Hardware store that usually has a plethora of bolts. The largest they had was 6" in grade 8 and stainless. I am going back with all SST hardware anyway from a kit I bought for it.

I bought the 6" SST bolt in hopes that it would work. But doubting that it would I bought a 3' piece of SST 3/8"-16 allthread and a SST nut.I wacked it to just under 6.5" with the chop saw, ran a die down it to smooth the threads, put the nut on it about halfway, MIG welded it with SST wire, ground it smooth with the bench grinder and voila. 6.5" SST bolt fully threaded. Only thing missing is the stamp on the end but oh well. At least it won't rust.

Then I find out the header bolts on the 1983 head are 2 different sizes on the same head. We're havin' fun now. The guy at ARP knew about it when my bro called them. He said they changed that in '82. Now I get to wait for them.

[Bob Barry]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Stangerize:
Then I find out the header bolts on the 1983 head are 2 different sizes on the same head. We're havin' fun now. The guy at ARP knew about it when my bro called them. He said they changed that in '82. Now I get to wait for them.<HR></BLOCKQUOTE>

My '79 had the 5/16" outer bolts for the exhaust, while my '78 had 3/8" bolts all across. So the switch may have been made in '79.

[Stangerize]

Hey, let's bring back a post from over a year ago. I am about to the point where I can put my Thorley headers on and I'll need 1" long header bolts. The bolts I have on my Heddmans are too short because the flange is so thin. The Thorleys came with bolts but they're the black steel ones that rust in no time. To save from pulling my bolts out and measuring them all, I wanted to clarify what I'll need to get.

8) 3/8"-??x1"
4) 5/16"-??x1"

Right? What is the thread pitch? Anybody have that handy?