Heater Fan Motor Mod for Added Engine Bay Clearance

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Longgone

John/68 Barracuda & Dart
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Longgone submitted a new Article:

Heater Fan Motor Mod for Added Engine Bay Clearance

Many of you know that when you install a 440 or RB block in our A-bodies that there is often trouble getting the right valve cover off if the car is equipped with any cover other than a stock stamped steel cover. There's a great mod that is covered step by step over on BigblockDart.com. It involves moving the heater motor in on studs so that it doesn't interfere with the valve cover. I had very little room on my car and it's a solid cam car so I did the mod and it turned out great. Although I don't have pics of the install yet, I do have some of the parts as modified. The original mod has screws welded to the back side of the mounting studs. I just removed the studs and used threaded rod to go through the mounting plate and secure both the motor and the heater box. I also found some of that black cardboard from hell (at the upholstery shop) to make up the back of the box. Here's a few pics of the mod and a comparison with an original box.

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I finally got a picture of the installed motor/heater box to show you the difference it made. There`s now plenty of room to remove the valve cover without having to remove the box first. There is one thing to keep in mind when doing this mod, as you move the assembly back you reduce the amount of heater core tubing protruding from the firewall. There`s only so much tubing for the heater core to connect your hoses to once the mod is done. With mine I had about 3/4" behind the flare on the tubing but it was just enough to get a hose clamp in there.

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Longgone, Great job on the motor modification. Please post some pictures of it when you get it installed.
 
Jeff, thank you so much for the clips. Between you and BWDart I was able to put two boxes together with 2 clips left over. I`ve done the modification, just haven`t gotten a photo of the finished product yet. It should be nice tomorrow so I`m going to try to get out there and snap a picture or two. I was almost ready to toss one of the boxes when the parts just started coming together. First I found a good heater core and right fresh air door. Then (thanks to FABO) I found a blower wheel and the clips. Now I`ve got a good factory piece and a modified version.
 
Glad to help. I think the blower wheel on mine is metal.
 
It probably is, I had a metal one and a plastic one. The metal piece is 24 blades while the plastic one is 32. Since I lost a little of the efficiency of the fan by moving a section of the fan blade out of it`s duct I thought the 32 blade wheel might help bring it back. The plastic wheel came out of a `70 box, I don`t know if it was stock or not.
 
Awesome tech write up John!!!!!!!!!!!!!! I love it when you guys post these useful step-by-step procedures. THANK YOU for contributing some great information !
 
I moved this thread to the tech archive because it's that good..... 8)
 
I moved this thread to the tech archive because it's that good..... 8)

Thanks John, this probably is a better place for it but I can`t take credit for coming up with the idea. The real play by play is over on BigblockDart and was started by BBD member Dart67. For those that want a detailed description of the mod check it out over there.
 
I'm getting ready to mod my heater box for my 68 Cuda with a 505 RB , Anyone have any pics and tips using the Siemens fan, P/N PM360. It looks like that combo would give me max room around the valve cover .
I have a new heater core , and a heater box gasket kit from Detroit gasket . The heater box is currently torn apart on my bench
I'll post pics of mine as I do it.
Donnie
 
I`ve heard of people trying to use the rear defroster motor in place of the heater blower motor for this mod but the rear defroster motor has a smaller diameter shaft and the case is not sealed, making it unsuitable for exterior use.
 
Got the Blower Motor from Napa BK 6551087 . This is a blower motor for a dodge truck , 68-73 I think
,Shaft is same diameter, but will need to be cut to correct length .
The motor housing is same diameter as factory, 3" , and only 3 1/2" long
Next will be to do some trimming so the fan can be moved closer to the heater core.


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That looks good Donnie, that motor may be a viable option. The only thing I see that may present a problem is, the case appears to be unsealed and the wires exit the motor on the opposite end. It may not be a problem but if water gets in the hole where the wires are fed through or at the end cap it will probably kill it rather quickly. I imagine your car will never see rain but I`m sure it`ll get washed, so assuring a good seal on the exposed side is something you might consider before installing everything. This is a great alternative to using a stock blower motor. Please keep us posted on your progress with the mod.
 
Its a replacement blower motor for a dodge truck , it looked sealed to me.
The wire is on the wrong end , but some close work with a dremmel tool and some black silicone should do the trick...... I hope :).
Wish me luck , I hope it turns out as nice as yours
Pics to come as time , money and weather allows..............

Donnie
 
Its a replacement blower motor for a dodge truck , it looked sealed to me.
The wire is on the wrong end , but some close work with a dremmel tool and some black silicone should do the trick...... I hope :).
Wish me luck , I hope it turns out as nice as yours
Pics to come as time , money and weather allows..............

Donnie

Sounds like some good insurance, a little RTV and you should have no problems. That motor looks short enough that you may not have to clearance the box for the squirrel cage. Keep us updated.
 
I started putting the heater box back together , The Cuda is still in Body Shop Hell.....
It looks like the factory blower motor sticks out about 2 3/8 " from the firewall . The shorter motor sticks out 1 5/16"
About an inch shorter without any heater box mods.
Is this enough clearance , or do I need to cut the box to move the motor in some more ?
How far away is the head from the firewall on the BB A bodies?
Cant wait till warm weather here in Ohio .
Here's some progress pics
I also see some differences between the 67 and the 68 Heater boxes , both are off non AC fastback Cudas' . The cable attachment points are different as seen in the pics
Donnie

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