I am putting together a 360 and need water pump advise. I currnetly have a new aluminum water pump. That problem is that the timing cover is from a 318 with iron pump. When I put the w/p on, the pulleys are way off. I put the old iron pump on and it all lines up. So, I need to get a new iron pump. Do I want 1 for a/c or no? Does it make a difference? Crank pulley o/d is 6.25 and the w/p pulley o/d is 6.5. This will allow the 318 timming tab to be used, but what about the marks on the balancer? What needs to be done there? All help is appreciated.

iron pumps are thinner but you can space the pulley back out & use slightly shorter mounting bolts. I'd find exact TDC w the ten dollar tool & make a new paint mark across the dampener & a piece of sharpened rod as a pointer. .0632683" is (1) degree i.e. 12 deg initial is 3/4" (.759") and 2&1/4" is 35.5 deg. MP (& others) have an iron pump w a pass side inlet if needed but they are pricey. EDIT and their iron pumps flow more than a parts house replacement one and I would tack weld an anticav plate on. Get one for non AC app as at least on the alum ones they have more vanes (8) which flows more & cools better

id use the a/c pump.. but if you have a choice use the alu pump, and as mentioned before there are spacers avail.. or get the whole set up from a later LA

A/c and non A/c have different diameter pulleys to spin the pump at different speeds. Mixing and matching pumps and pulleys may get you unhappy (overheating) results. If your car is non-a/c, I'd recommend a non-a/c pump. Go with a FlowCooler type pump, it will circulate water much more efficiently than a stock LA water pump (whether early iron or later aluminum)

Thanks so far. The motor previously had an 8 blade iron pump. When I bought the new pump I was not aware of the spacing differences. The pulley sizes I listed are what I have. I am going to be buying a new iron pump. Can you tell which pump I will need? Thanks again.

you need the iron pump that has the nipple on the correct side as your rad obviously. The aftermarket ones flow more. I think parts house iron ones are 6 vane/dr inlet and aftermarket ones are most likely 8 but I'm not positive on that & 8 is the way to go if avail. I agree w Stewart the Nascar water pump people that the faster the water speed the better up to a max pump speed of 5800-6000 (my max not theirs) so I overdrive the pump esp as the eng is way below 6K most of the time. dont forget the anticav plate & you can mill the FRONT of the timing cover to reduce the vane to flat clearance to .040" (including gasket thickness)

Are there pics of this anti-cavitation plate?

Mancini may sell them but a round piece of 1/8" steel plate tack welded to the vanes then mockup & measure the distance from the plate to the recessed flat then add in the gasket thickness & decide if you want to mill the timing cover. Also in the timing cover cooling ports on each side is a casting parting line that can be removed in seconds w your die grinder. That improvement is minor but they all add up

first lets be clear. the 6 vane is an a/c wp.
8 vane is the non-ac pump.
the a/c pump spins faster due to the pulley size being smaller.

next, I was pretty sure the inlet changes sides when you go for the newer aluminum vs the older cast iron.

did you find an aluminum that was the same side?

That's the other reason I need to go back to the iron pump. The nice, pretty alum pump inlet is on wrong side. Its a new GMB pump if you know anybody looking.