Right now I just have an after market flex fan and spacer. Fan doesn't even go into the shroud. I want to go to a seven blade clutch fan arrangement for AC equipped cars. What fan diameter do I get? I see 17" - 19.5". Don't want to hit the shroud. What clutch should I use? How is this mounted? Do I need to get certain length studs? Is a spacer required? Sorry for the dumb questions.

Only dumb question is one never asked!

If you have the stock shroud, measure that and I believe it should be about 20" and therefore the 19.5" fan would be the one... and yes, the stock units had a spacer, but it may depend on the water pump shaft length. (long pump or short pump)

But if you measure from the snout of the pump/pully to the edge of the shroud, this will give you a rough idea of the length of spacer you'll need. There should only be a couple for a stock application to choose from, so you should be able to determine it that way.

The fan should go into the shroud, but just to the point where the back of the blades are about at the edge of the shroud...

I'm sure some of the others will have some more difinitive info for you.

Brett - 67 Drop Top 455!

My clutch fan does not have a spacer; it goes halfway into the shroud. Any farther and it would hit the shroud.

I am pretty sure the stock fan clutch was designed to place the fan at the right position w/o a spacer.

Right. No spacer for fan clutch is what I've always been told. Mine had that same set-up

- Jake

Thanks for the info. I think I'm going to use a Hayden #2747 HD Thermal Fan Clutch. How are the fan and clutch attached to water pump? Studs or bolts - or does it matter? Guess it would be obvious if I had them sitting in front of me Just don't want to go buy a fan and clutch and then have to go back and buy the correct bolts/ studs.

Mine is connected with bolts through the fan hub, through the water pump pulley, and into the water pump flange. I'm sure studs would work fine too, but I'd use threadlocker on them.

You can still buy the GM clutch from your local
dealer.The part number has changed many times
but I bought one for my ride.Part number is
22075085.Mike

Right you are... been a while since I've worked on one with the clutch fan still on it.

B!

I installed a pontiac seven blade clutch fan I bought off of ebay on my '67 w/ a 400. I don't think I used a spacer but the fit is perfect, and I used bolts on mine. I would have prefered to use studs, but I couldn't find any that were the right length. Even the ones I ordered from Ames weren't the right length. And when I talked to their tech guy he didn't have any answers for me either. I used bolts w/ loctite and no lock washers. I think the bolts had to be about 1.25" long or so(I can't remember for sure). So far so good--it hasn't gone through the radiator yet, and the bolts haven't moved either. Studs would be SO much easier. Getting everything lined up and putting the first bolts through the holes and started in the threaded pump flange is a major PITA--seriously it really sucks. Also with bolts they can't protrude through the back side of the water pump flange too far or you'll have clearance issues. Good Luck

Bruce

Ordinary carb studs would probably work perfectly. The threads in the water pump flange are 5/16-24 UNF (Fine). Summit sells a kit for $4 with 1-3/8" long studs. (They also carry 1-3/4" and 2" and 2-1/4" and 2-1/2" and 2-3/4" and ... if they end up too short.)



Obviously you'd want to lock them in the flange, but a nut on the back side of the flange would work, too, if you get them the right length

Carb Stud Kit

Vikki, what is that cable running along the AC and heater hose in your picture above?

That's the battery feed for my 200 watt subwoofer. It's routed (none too neatly) through an existing firewall grommet and is fused just after the battery connection.