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It's been a long time since I've been what you'd call 'active' in FSJ circles. I remember over on the IFSJA there used to be a fair bit of chatter about wanting to shrink the heater box for clearance reasons. Sadly, it's very quiet over there these days... Anyway, for what it's worth, here are the 'before' pictures. I'd appreciate it if someone would let me know if they're showing up or not.

I can see them.

I can see them.

I've always thought it would be great if the heater could double as an additional engine radiator, which it can but it dumps the heat into the interior. Not good when it's already too hot outside.

The stock radiators are right around 410 sq/in of surface. The heater core is a very dense 6X9 or 54sq/in, which would net an additional 14% of area and perhaps more than that in cooling. Chances are pretty good I'm going to add an air dump door, and probably use a vac motor to drive it. Hummnn... Down side to that is high power = 0 vac = door no work. I could set it up so default is dump, and when the heater is on... yeah, I think I like that better. Excuse my rambling.

Any updates on this?

I'm still glueing the puzzle pieces together but today I did look at it as far as putting in the dump door. It's looking like the surface area on the bottom of the box may wind up too small, which leaves the forward facing surface. I'll post an update when I make significant progress. Thanks for the interest, MadMax.

Cool. I understand. Work, the holidays and family get in the way of our hobbies sometimes. What would we do without them. LOL

fsj1978 wrote:I've always thought it would be great if the heater could double as an additional engine radiator, which it can but it dumps the heat into the interior. Not good when it's already too hot outside.

The stock radiators are right around 410 sq/in of surface. The heater core is a very dense 6X9 or 54sq/in, which would net an additional 14% of area and perhaps more than that in cooling. Chances are pretty good I'm going to add an air dump door, and probably use a vac motor to drive it. Hummnn... Down side to that is high power = 0 vac = door no work. I could set it up so default is dump, and when the heater is on... yeah, I think I like that better. Excuse my rambling.

Also could just put in a vac reservoir so it'll stay closed on acceleration

I've got the stock vac reservoir and even changed over to electric solenoids instead of the rotary valves the factory used. What I don't know is how long the vac will hold? 2 min? 5? 10? 20? I guess I could put a gauge on it and check.

fsj1978 wrote:I've got the stock vac reservoir and even changed over to electric solenoids instead of the rotary valves the factory used. What I don't know is how long the vac will hold? 2 min? 5? 10? 20? I guess I could put a gauge on it and check.

If it's not long enough if you can find a 70s ford car in a junkyard you'll find some huge football sized vac reservoirs

fsj1978 wrote:I've got the stock vac reservoir and even changed over to electric solenoids instead of the rotary valves the factory used. What I don't know is how long the vac will hold? 2 min? 5? 10? 20? I guess I could put a gauge on it and check.

Unless there is a leak, it should hold indefinitely.
Ever pull the booster hose on a rig in a boneyard? Most good ones will give a whoosh if still holding a vacuum.