OK, got my C4 blower installed. I spent about 3hrs making the spacer. I used two spacers that gave me a total thickness of 3/4". I was HOPING it was going to be enough because when measuring the two blowers side by side, there was a 1" difference in between them. When measuring the depth of the housing was a total of 3.5" and I measured my blower with the spacer to be 3 3/8". It was close to say the least but it doesn't rub from what I can tell.

Then I vacuumed out the junk from the evaporator core, at least as much as I could blindly get. Then I found the mysterious door in the plenum, its a little plastic door. It was free and the hose was still on the vac pod so I assume its working.

Now for the wiring. First I used the factory power wires to and from the high speed relay. They are thick gauge and there was less the .2v drop from the alt to the relay. I reinstalled the factory ground plug on the frame of the fan but it really was not needed. This particular fan needed the motor to be grounded directly, I tried to test run it by grounding the blower frame to an extra battery I have, the blower would not run with 12v going to the motor and just grounding the frame. So I ran a thick gauge wire(about a 10ga) from the blower motor directly to the frame of the car where the factory stainless braid ground strap attaches. Modded the cooling tube for the blower motor and started the car up.

IMPRESSION:

Well, from the get go I could "hear" the fan running a lot harder, I could hear it pulling through the cowl plenum strongly. Then I found a big air leak at the evap box where the upper tube comes out. So I plugged the leak and hopped in the car. To be honest, I am not that impressed with the C4 blower. I guess my original blower was in good shape. I mean I can tell SOME improvement on HI, but not THAT much difference..Definetly not enough difference to make it worth the work thats required. I mean I can sit in the seat and put my hands halfway between myself and the duct and feel it blowing which is decent but just not as much as I expected. No doubt I still have air leaks in the ducts though. I can put my hands up behind the dash and feel air seeping out of all the seams, even the ones I duct taped up. Its ok though because it needs cooling under the dash to, thats where a lot of heat is stored.

I am happy to report on my test drive, my AC was still blowing 41-42* while moving so if its gotta a freon leak, its not a major one. Ofcourse its only 70* outside but..

I guess we'll see how she does when it starts warming up here in the next few months.

THANKS FOR ALL THE HELP GUYS!!!!

 

Sorry you didn't like the fruits of thine labor.

 

HAHA, thats funny...

That lil bastard was a PITA to install. I tell you what, someone could make some jack if they started making and selling those spacers for the C4 blower. I tell you for f*ckin sure I won't ever make another one.

Its not that I am unhappy with the C4 blower, I just expected more I guess. I mean I thought my original blower blew pretty decent to start with, as far as feeling the air coming out of the ducts, I can BARELY notice an improvement with the C4 blower. I can hear it more, it seems that the more aggressive wheel on it makes more noise but.. Either way, it couldn't hurt and any gain is better then none. I am kind of wondering had I just added another ground wire to my original blower if it would have sped up more? Probably so..
Tomorrow I gotta go caulk around the blower/spacer to the AC box to seal a small leak, then reinstall my splash panel.

Actually I am gonna try to find the "pig tail" for the blower harness off of a 96 vette. I used insulated female spade connectors on the hot/neg terminals in the blower and they are a little loose for my taste, even after crimping them down some.

 

I'd sure like to do this to mine but I have no idea how to get them in and out - I can just barely see it. Is there a secret you aren't sharing? Oh yeah, I do have A/C - does that make it easier?

 

I had A/C on my car and I was able to lean over the fender, and reach in and get all the bolts and pigtails.

 

OK then, how do you get the motor and fan out - I honestly have a hard time getting my hand down in there.

 

To be honest I don't recall anything special about the process. I just reached in, disconnected the tube, wires, and removed the bolts. I didn't even really have to pry.

I will tell you that a cleverly positioned flashlight or drop light will help a lot in seeing what you're doing.

 

The trick to getting the blower motor out is to take it out from the bottom. Remove the first 3 screws in the rocker panel trim, behind the trim is 2- 1/2" bolts. Remove those, then look under the fender right behind the tire, there is 2 more 1/2" bolts. Those 4 bolts hold in the "splash panel" that is a triangular piece of metal with rubber weatherstripping on it. Just pull it out and look up in there, you can see the blower pretty easy. Its still a PITA, especially getting the spacer clocked correctly.

 

remember, the newer fan is about 1" longer and has more blades. if you install with a spacer you get the benefit of the additional blades but not the extra 1" length. to get both, you need to modify the housing . . . that must make most of the difference???

 

Sorry I been outta th loop for a while, I dunno about for sure what blower assy was in your car directly....OR IF there are any differances between a '72 and a late shark fan/motor.....

Slick glass work there, and IF I was to take it out and do over again, I would do the same thing, but not with engine in there.....

I cut the fender liner up for two reasons....an overflow tank install without going crazy....and that blower motor, without going crazy...older I get the lazier I get....

When I got this car 12 years ago, first thing I noticed was the blower did't put out nearly as much as the A&B body GM cars....so I went with my DVM checks and found that inadequate ground wire....also noting that the voltage dropped through that crapacitor by about a volt or more....SO make damn sure that POS is outta there....it's for supression of motor sparks in AM radio....last time I heard AM radio it was stereo....the hi freq buzz in the left channel and the lo freq buzz in the right channel.....( olde tyme stereo tech joke).....

so in fact my '72 some 12 years ago had about 10 volts MAX going to the blower motor, that like about second gear maybe third....in reality...

 

MR Vette, I measured the volts before and after the capacitor and it had no detectable drop. I have not measured the volts with the new blower installed and running. When I did it with my original blower I was losing 2-2.5v across the motor. With the new C4 blower, I ran a 10ga ground wire from the neg post of the blower motor, directly to the frame of the car where the stainless braided ground strap attaches. I also reinstalled the factory ground connector and wire on the blower frame. The blower runs hard, I can really hear it on high speed but the air flow is not SIGNIFICANTLY increased, some yes, major no.

Yesterday evening I was able to drive the car in about 75* ambient temps with the AC on MAX and the fan switch on the 2nd speed and still stay comfortable, I could still feel air lightly hitting my face so...it moves some air.

 

I wonder how much that in-dash leaking is affecting your air movement. I'd bet that a few stretches of duct tape would really hit you in the face with air.

 

Yeah its definetly leaking some. WHen I reinstalled the dash, I duct taped up with passenger side duct where it ties into the main box with aluminum type tape. Then on the driver side duct where it meets the main box I used regular black duct tape(because you can see it) and it still has air leaking out. I also know there is an air leak where the defroster duct connects to the main box.

There is definetly a few leaks in there but nothing MAJOR. I figure hell, its just helping cool my feet anyway so...All in all, my car is pretty damn cool with all the triple insulation, I get basically NO heat through the floor board any more. Any heat thats getting in is coming through the AC system but when the AC is on, its nice and frosty.. I am gonna try to seal up some leaks and see what it does.

I got new t-top seals and window weather stripping coming in to seal this baby up.

 

Batman - is this what you meant when you said "This has the added advantage of unshrouding the A/C evaporator."?
If so - I agree - w/o the extension on the housing, there is no area for the fan to grab air from. Good comment. So what year housings would be good to cut from and glass to the existing housing (in my case 1969).

I will check into AutoZone PM105 (Extended blower motor $35) and Advance Auto 35603 (extended Metal Fan Cage). I assume this cage is 1/8" smaller in diameter? - if so - I will try to contact Zip.

Let me know on the fiberglass section

 

It's hard to describe without a picture, but cutting the box so the fan sits around 1" further towards the front really opens up the air passage between fan and evaporator. In stock form, it's quite constrictive.

 

study the last pic in post #26 and you will see how much "unshrouding" the mod makes.

 

Mine has the same plug. Did you find a pigtail and connector, or just use spade terminals?

I forgot that those pics are in this thread. How much space did you add to the box?

 

it turned out to be about 1". if you have all the parts and cut tabs like are shown in the pics (i'm sure there are other ways too), then you can use little clamps to trial fit the housing sections and fan to get the fan clearance just right.

 

So what year evaporator assembly did you use for the add-on? I realize 77 +, but what if you could go much later??? BTW - nice job as well !

I have seen those cutting boards warp - thought it was my bad housekeeping skills

 

If you need a '77 evap, I have a very nice one for sale.