Water pump - timing chain cover bolt sets

[pyroman]

I have what I believe to be all the bolts I need to put both the timing chain cover on and the water pump to attach. However when I look at a kit like this one from ARP

ARP #154-1504

I count 15 bolts. I also have 15 bolts but there seems to be 16 bolt holes, I'm always left with one vacant spot and it makes guessing and checking as to what goes where frustrating. What's the deal?

Also, why is there distinction between a bolt set for an aluminum pump and an iron one? What is the difference?

On one site they were selling a timing chain cover "for aluminum water pump"? Is there any reason for this?

 

[pyroman]

I feel a bit like an idiot after reading a few pages down. Ok so I get the aluminum pump/iron pump thing. I have a 67 with a 289 originally, does the #154-1504 match?

 

[pyroman]

The bolts I have look like an assortment of different styles. I believe they should all be 5/16-18 but am not sure. Does anyone have the specs on these?

 

[pyroman]

Anyone? Are the water pump and timing chain cover bolts from a fox body the same? MY guess is the lengths are different....

 

[j69302]

I ordered the same waterpump/ timeing cover bult kit as you..

I have a 69 302 with an aluminum cover but iron pump.

Ill let you know how it works when I get my cover and pump on in a couple days.

I didnt count my bolts, but I noticed I had a hole that didnt have anything in it too.

 

[l1k2gadd]

I don't know a timing cover on a small block Ford that isn't aluminum from back in the 60s and early to mid 70s. Having an aluminum timing cover and a cast iron water pump is common. As for the bolts, I have two 289s and a 70s 302 in a few of my vehicles. Remember, some timing cover bolts hold just the cover in place. Two hold the top behind the top lip of the timing cover,under the thermostat area of the intake. Two hold each side of the bottom front of the cover, two hold each bottom oil pan edge of the timing cover down against the oil pan. I believe all of the others go through the water pump and bolt to threaded ends in the timing cover and/or they go through to the motor in a couple of places. I recommend using an anti-seize compound on all of the threaded ends of all of the bolts. Don't tighten the bolts for the water pump to the timing cover so tight that you strip the threads out of the timing cover rear water pump edge. Yes, I believe ALL but two bolts are 5/16"-18. There are two bolts that are 1/4"-20 that go in the oil pan edge, 2nd from the front on both sides.

(edit) Fox Body bolts ARE NOT the same. The Fox Body bolts are designed to hold the brackets for the serpentine belt assemblies and components. The 5/16"-18 thread I believe is the same, but the upper bolts are different. The four in the oil pan surface should be a close match though and I believe the two top bolts, under the thermostat housing may be a close match. The water pump on the Fox Body is also different to the best of my knowledge. (end edit)