Hi all
apparently there is a difference between a 4 and 6 cylinder cars' heater flapper boxes, but can't immediately tell what the difference is. Would a -4 work on a -6 ? I have a 3.2 engine and want to add heat exchangers
cheers.
Click to view attachment
Full Version: Heater Flappers for 914-6
The 4 doesn't have a hole on the cap where the 6 does.
See the pic. It's a 6 flapper box. I believe the hole is there to get rid of more heat/air from the heater boxes.
See the pic. It's a 6 flapper box. I believe the hole is there to get rid of more heat/air from the heater boxes.
QUOTE(Luke M @ May 31 2017, 05:37 PM) 
The 4 doesn't have a hole on the cap where the 6 does.
See the pic. It's a 6 flapper box. I believe the hole is there to get rid of more heat/air from the heater boxes.
huh....always learning something hanging around here.
All 914 6 flappers that I've seen are grey.
4 cyl. are black
The valves will mount on the 6 heat exchangers
The answer to your question depends on the position of the arms that operate the valves.
4 cyl. are black
The valves will mount on the 6 heat exchangers
The answer to your question depends on the position of the arms that operate the valves.
So apart from a hole and paint colour, is there any other difference?
Are the arm positions different? Look similar to me. What about pipe diameter? Can someone advise on OD diameter between the two please?
6 ones go for big $$$ and I can't see why -4 ones can't be made to fit.
Are the arm positions different? Look similar to me. What about pipe diameter? Can someone advise on OD diameter between the two please?
6 ones go for big $$$ and I can't see why -4 ones can't be made to fit.
Yes, the pipe diameter below the cap is different. But that is all I have noted.
QUOTE(IAA1963 @ Jun 1 2017, 10:33 AM)
Yes, the pipe diameter below the cap is different. But that is all I have noted.
interesting as I note in an old Pelican post that a 4 flapper will work on the 6 car
http://forums.pelicanparts.com/porsche-914...pper-boxes.html
QUOTE(Luke M @ May 31 2017, 01:37 PM)
The 4 doesn't have a hole on the cap where the 6 does.
See the pic. It's a 6 flapper box. I believe the hole is there to get rid of more heat/air from the heater boxes.
I did not know that !
My six has the non hole 4 flapper boxes and they fit and work just fine.
Phew...glad the /4 parts work for a 914/6 conversion with heat!
Running 4's on my six. They work normally. Thinking about opening holes on them similar to the six ones. Holes are there for a reason and I suspect that they flow some heat away from the exchangers/headers when the flapper is closed.
Good idea??
Good idea??
I also have used the -4 flapper boxes on my -6 conversion successfully, but now plan to drill the caps on the flapper boxes to increase the flow through the flapper boxes when the heat is closed off. I figure Porsche must have had a reason to design the -6 flapper boxes with a hole in the cap.
Get your hole saw out and make ANY -4 box into to a -6 box.
Do a search on this ....been talked about before by some of our knowledgeable experts...the 6 has the flapper with a hole in it like in Luke's post....apparently this is so more air runs thru the HEs to help keep the engine cool when closed...with out it the engine over heats....
QUOTE(GeorgeRud @ Jun 6 2017, 06:51 PM)
I also have used the -4 flapper boxes on my -6 conversion successfully, but now plan to drill the caps on the flapper boxes to increase the flow through the flapper boxes when the heat is closed off. I figure Porsche must have had a reason to design the -6 flapper boxes with a hole in the cap.
that's what i'll do with mine - being Porsche, they did these things for a reason !
Ok guys, we were wrong on this one.
Was mounting my 4 flapper valves and decided to add the six holes. Put in some holes and then decided to get my six flappers out to see how big the holes are supposed to be. While looking into the hole on the four flappers I noticed cutouts in the internal tube under the "mushroom" cap (they look like the cutouts on top of a castle tower). Then I looked at the six ones to compare. The castellated cutouts on the four version are twice the size as on the six version.
So it looks like the four version passes just as much air through these larger vents as the six version does through the smaller vents and the hole.
Maybe the engineers did this as a slight cost savings. While cutting the vents in the tube, might as well make them bigger and skip the extra step of adding the hole?
So now I have double venting flappers. Makes me wonder if I am robbing some air that would otherwise flow through the shroud to the cylinder fins? Oh the horror!
Was mounting my 4 flapper valves and decided to add the six holes. Put in some holes and then decided to get my six flappers out to see how big the holes are supposed to be. While looking into the hole on the four flappers I noticed cutouts in the internal tube under the "mushroom" cap (they look like the cutouts on top of a castle tower). Then I looked at the six ones to compare. The castellated cutouts on the four version are twice the size as on the six version.
So it looks like the four version passes just as much air through these larger vents as the six version does through the smaller vents and the hole.
Maybe the engineers did this as a slight cost savings. While cutting the vents in the tube, might as well make them bigger and skip the extra step of adding the hole?
So now I have double venting flappers. Makes me wonder if I am robbing some air that would otherwise flow through the shroud to the cylinder fins? Oh the horror!
Some pics of the different tube diameters of the /4 and /6 heater flappers ...
The one on the left is a /4 flapper box. The one in the middle a sandblasted unit from my original /6 and a new /6 flapper box on the right.
Click to view attachment
Click to view attachment
Click to view attachment
The one on the left is a /4 flapper box. The one in the middle a sandblasted unit from my original /6 and a new /6 flapper box on the right.
Click to view attachment
Click to view attachment
Click to view attachment
Interesting... I have been running 4 banger ones with factory heat exchangers for 20 years with no problems. I just upgraded to mb911 heat exchangers and they still work fine.
cheers for posting - useful to know. I was going to adapt the ones I've bought, but seems like no need
Ok guys, we were wrong on this one.
Was mounting my 4 flapper valves and decided to add the six holes. Put in some holes and then decided to get my six flappers out to see how big the holes are supposed to be. While looking into the hole on the four flappers I noticed cutouts in the internal tube under the "mushroom" cap (they look like the cutouts on top of a castle tower). Then I looked at the six ones to compare. The castellated cutouts on the four version are twice the size as on the six version.
So it looks like the four version passes just as much air through these larger vents as the six version does through the smaller vents and the hole.
Maybe the engineers did this as a slight cost savings. While cutting the vents in the tube, might as well make them bigger and skip the extra step of adding the hole?
So now I have double venting flappers. Makes me wonder if I am robbing some air that would otherwise flow through the shroud to the cylinder fins? Oh the horror!
QUOTE(gereed75 @ Jun 27 2017, 01:55 PM)
Ok guys, we were wrong on this one.
Was mounting my 4 flapper valves and decided to add the six holes. Put in some holes and then decided to get my six flappers out to see how big the holes are supposed to be. While looking into the hole on the four flappers I noticed cutouts in the internal tube under the "mushroom" cap (they look like the cutouts on top of a castle tower). Then I looked at the six ones to compare. The castellated cutouts on the four version are twice the size as on the six version.
So it looks like the four version passes just as much air through these larger vents as the six version does through the smaller vents and the hole.
Maybe the engineers did this as a slight cost savings. While cutting the vents in the tube, might as well make them bigger and skip the extra step of adding the hole?
So now I have double venting flappers. Makes me wonder if I am robbing some air that would otherwise flow through the shroud to the cylinder fins? Oh the horror!
The diameters measured by IAA1963 are the diameters of the inner tubes. These do not effect fitment. Mount diameters appear to be the same.
Note the depth of the castlellated cutouts. The four cutouts are almost twice as deep as the six
Not sure I could disassemble my six flappers like this as the tabs appear to be welded. Maybe not, I'll check later
Note the depth of the castlellated cutouts. The four cutouts are almost twice as deep as the six
Not sure I could disassemble my six flappers like this as the tabs appear to be welded. Maybe not, I'll check later
The taps on the /6 flappers are not welded. The cover is quit easy to remove.
But the cover on the /4 flapper was welded and is difficult to remove. The second flapper of my /6 was damaged too much, so I wanted to mount the cover with the hole of my /6 to a NOS /4 flapper. But after removing the welded spots on the /4 flapper I have figured out that it does not fit due to the different tube diameters.
Meanwhile I have a second grey NOS flapper to complete my set.
But the cover on the /4 flapper was welded and is difficult to remove. The second flapper of my /6 was damaged too much, so I wanted to mount the cover with the hole of my /6 to a NOS /4 flapper. But after removing the welded spots on the /4 flapper I have figured out that it does not fit due to the different tube diameters.
Meanwhile I have a second grey NOS flapper to complete my set.
Curious if it's just a VW parts bin versus Porsche parts bin thing or is there a technical reason of one over the other? Do the concours judges look for this?
QUOTE(gereed75 @ Jun 27 2017, 05:55 AM)
Ok guys, we were wrong on this one.
Was mounting my 4 flapper valves and decided to add the six holes. Put in some holes and then decided to get my six flappers out to see how big the holes are supposed to be. While looking into the hole on the four flappers I noticed cutouts in the internal tube under the "mushroom" cap (they look like the cutouts on top of a castle tower). Then I looked at the six ones to compare. The castellated cutouts on the four version are twice the size as on the six version.
So it looks like the four version passes just as much air through these larger vents as the six version does through the smaller vents and the hole.
Maybe the engineers did this as a slight cost savings. While cutting the vents in the tube, might as well make them bigger and skip the extra step of adding the hole?
So now I have double venting flappers. Makes me wonder if I am robbing some air that would otherwise flow through the shroud to the cylinder fins? Oh the horror!
The purpose of the vent holes is to prevent a high temperature build up of trapped air in the heat exchangers that would be sent to the cabin when the flappers are first opened. I doubt you are losing any significat amount of cooling air to the cylinders with added venting.
Discussed this with Wayne Dempsey recently.
Bruce
It has a VW part number sourced from Volkswagen, but probably marked up since it has a Porsche sticker on it.
http://www.aircooled.net/vw-part-numbers-explained/
http://www.aircooled.net/vw-part-numbers-explained/
QUOTE(Steve @ Jun 28 2017, 06:12 PM)
It has a VW part number sourced from Volkswagen, but probably marked up since it has a Porsche sticker on it.
http://www.aircooled.net/vw-part-numbers-explained/
I believe the VW Bus and 914 flapper boxes differ on the clocking of the lever. Amoung the crate of flappers I have there are at least four variations on the lever clocking.
Bruce
Thanks Bruce!! Learn something new every day. I didn't know there was 914 specific VW part numbers. I heard stories about how some of the parts are interchangeable with VW, such as the window winders. Assumed that included the flapper boxes.
If you have the fuel pump in the stock location, I'd take the cap off the right valve and run a Beetle pre-heat hose over and away from the pump.
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