Here is a Plenum Pan DXF, STEP, Drawing, and printable Template. (UNTESTED!!!)

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Max78

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Just to be clear!
THIS HAS NOT BEEN TESTED YET


For those of you that dont want to pay out of the nose for a small plate of aluminum, here you are. Take this to a metal shop (water jet being the cheapest I have found) and ask them to cut the DXF.

Holes are drawn at Ø.275 because that's what the gasket measures, if I can figure out the bolt size used to attach the plate I can shrink the holes to better fit the bolt.

I traced the plenum gasket and drew up a plenum plate. I have plans to get one cut at a local shop as I can get a good price.

I figure I would share my work with others so everyone has more options!

The Plenum Pan Scale.pdf is on 11x17 paper and make sure scaling is off if you plan to use it as a template, I included a 15" line to check against so you can verify it printed to the correct scale.


One Drive Plenum Pan Link



If someone gets around to doing this before me let me know how it works out as I have NOT made one yet.

Enjoy!

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Plenum Pan.jpg
 

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dudeman2009

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The gasket holes are a pretty tight fit to the bolts if memory serves. The bolts are 3/8 thread size. Most machine shops will be perfectly happy if you give them the center point and tell them the size clearance holes you want.

For example, in this situation, you just need to mark the center point with a circle that has a cross through it, then specify 3/8ths clearance or if you want to make their job easier, you can use the clearance dimension for that bolt size, which is an X sized drill or .3970 inches.

You can use just about any metal you want, aluminum or steel as long as you use the proper thickness gasket.

The problem you'll run into if you don't dimension everything (and I mean everything) something in the process of getting it from your file to the gcode required to cut the part, the sizing will be messed up. I've used multiple professional and free programs to convert cad files to gcode. At least half the time, when I check the part dimensions after conversion, something is wrong and I have to go back and scale something. With all machining, you have to take into account the width of the bit, it you want a 1in hole and have a 1/2in end mill, you need to trace a hole that is 1/2in to get a 1in hole. to get a 4in hole with a 3/4in bit you need to cut out a 3 5/8in dia. hole. If you had a 3/4in end mill and wanted a 4 in hole so you had the machine trace a 4in circle, you'd end up with a 4 3/8 diameter hole.

There is a lot to consider when making technical drawings, I only outlined the importance of specifying the exact hole diameter on paper and not relying on the cad file to tell them what the size needs to be. There are a ton more things to consider. Many machine shops won't accept anything but paper schematics due to all the problems with trying to convert and scale cad files. Many shops also have a policy that if a part was spec'd in cad and it came out wrong, its on the cad designer not the machine operator.

Whatever you decide to do, I strongly suggest talking to a designer or machine operator at whatever shop you goto and bring something simple like this and have them go over it with you and mark it up with pen in order to show you exactly what they will need to make the part correctly.
 
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Max78

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The bolts couldn't possibly be 3/8 as the gasket hole is .275 in diameter, I corrected my text in the first post as I said mistakenly typed .175.


Machining this part should be last resort honestly, that would probably be one of if not the most expensive routes to take. As stated the most affordable option would be water jet. However I included a .stp file if that is the route someone wanted to take.


Being that this part is dead nuts simple and I did it in my limited free time I opted to not produce a technical drawing but if you really feel there is a need for one feel free to contribute. Out the thousands of parts that I have sent to Machine shops and Laser shops the only scaling issues we dealt with were user error on one end or the other, the 3 dimensions provided are enough of a sanity check for any operator worth their salt to get the scale correct.


I'm not sure if you still live in this world with current technology but every machinist I have dealt with and currently deal with ask for a .stp file and use that as the master over the technical drawing so it better damn well be correct. Every laser/water jet house we use asks for both a .dxf and .stp. If they cant import it to the correct scale and need a technical drawing to redraw it they will charge you a fee, usually $100 minimum from what I have dealt with, at that point you would be better off buying a kit.


As for machining large diameter holes that don't apply at all in this case there are a hand full of ways to go about it depending on what you are trying the achieve.
 
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dudeman2009

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The bolts couldn't possibly be 3/8 as the gasket hole is .275 in diameter, I corrected my text in the first post as I said mistakenly typed .175.


Machining this part should be last resort honestly, that would probably be one of if not the most expensive routes to take. As stated the most affordable option would be water jet. However I included a .stp file if that is the route someone wanted to take.


Being that this part is dead nuts simple and I did it in my limited free time I opted to not produce a technical drawing but if you really feel there is a need for one feel free to contribute. Out the thousands of parts that I have sent to Machine shops and Laser shops the only scaling issues we dealt with were user error on one end or the other, the 3 dimensions provided are enough of a sanity check for any operator worth their salt to get the scale correct.


I'm not sure if you still live in this world with current technology but every machinist I have dealt with and currently deal with ask for a .stp file and use that as the master over the technical drawing so it better damn well be correct. Every laser/water jet house we use asks for both a .dxf and .stp. If they cant import it to the correct scale and need a technical drawing to redraw it they will charge you a fee, usually $100 minimum from what I have dealt with, at that point you would be better off buying a kit.


As for machining large diameter holes that don't apply at all in this case there are a hand full of ways to go about it depending on what you are trying the achieve.

Perhaps the wrong bolt size was listed, I don't remember what it was and pulled up intake bolts off summit racing.

As far as scaling, i'm not saying it shouldn't be easily caught, most of the time it is user error, but having dummy checks is always a good idea. How often does one forget a single small bolt, for whatever reason, only to get a couple steps down the line before remembering. No one is perfect, the point is to put enough checks in place so any slips of the mind can be easily caught.

Most of what I said was not specific to your drawing, but to getting your own parts made in general. Any amateur designer that wants to have a part made is best off doing both a CAD file and technical drawing (which can be easily made from the CAD program in a half hour or so) just so there is a physical copy to pour over to check for errors. Professional designers don't always do that simply because they have spent the large number of hours checking it on the computer that it's easy.

As for the holes bit, no it doesn't really apply to your case at all, as far as the designer is really concerned, the hole size they spec is whats important, its up to the machinist to get it correct from there. But its important to know the differences between clearance and threaded holes when making your own part, something an amateur might not think about, and it doesn't hurt at all to have some background knowledge of the process involved. Its like knowing why having the correct air to fuel ratio is important as opposed to knowing its just got to be within a set of numbers.

I don't claim to be a professional, I probably did make some errors, but the basis is still there, check your work and save yourself some money, whatever the application. I mentioned all the scaling issues i've ran into in the past on my CNC machine and printer, almost every single time its because I forgot to change a number or switch the tool the program was set to use. Its clear you have more experience having professional shops do your work, mostly, all the stuff I do is personal or for the Robotics team, so I would defer to your judgement on a lot of things, I just hate seeing people waste money on simple mistakes.
 
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goodtodoo

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So what is the root cause of failure with these? Here a pic of 2 pans I have and you can see failure at the same place on both.
 

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goodtodoo

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So I just looked at an intake I have. The plenmum bolts are 1/4". So here,s a ? How thick does this new piece need to be? Cause I can make 1 of those, easily.
 

dapepper9

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So what is the root cause of failure with these? Here a pic of 2 pans I have and you can see failure at the same place on both.

****** gasket. If you look at your pic you'll notice the gasket bowing on multiple other places. For whatever reason it's particularly weak in that one spot. Gasket gets oil soaked and weak over time. Mopar even came out with an updated gasket to use. Updated gasket and quick shave of 2 threads and i haven't heard of em failing again with steel pan
 

goodtodoo

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OK, but how thick does the plate need to be. I,m thinking 1/4" should do it.
 

EvilSpirit

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Not sure exactly what you are trying to accomplish here. The plenium gasket failures in naturally aspirated engines have never really been due to cover design. Most, if not all of the failures have been from the bolts bottoming out in the manifold, which results in poor clamping pressures and eventual gasket failures. Reseal a stock plenium cover correctly with a premium gasket, proper sealants and the correct length bolts and it will never fail again. At that point a better cover is unnecessary. The only real need for a stronger cover is for boosted engines, or possibly one running NOS and may see a NOS backfire. For stock engines 16ga aluminum with a couple of beads rolled across the cover would be plenty - again, sealed correctly. Boosted engines? I guess that depends on the boost, but a 1/4" plate should hold a metric poo-ton of boost.
 

dapepper9

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Not sure exactly what you are trying to accomplish here. The plenium gasket failures in naturally aspirated engines have never really been due to cover design. Most, if not all of the failures have been from the bolts bottoming out in the manifold, which results in poor clamping pressures and eventual gasket failures. Reseal a stock plenium cover correctly with a premium gasket, proper sealants and the correct length bolts and it will never fail again. At that point a better cover is unnecessary. The only real need for a stronger cover is for boosted engines, or possibly one running NOS and may see a NOS backfire. For stock engines 16ga aluminum with a couple of beads rolled across the cover would be plenty - again, sealed correctly. Boosted engines? I guess that depends on the boost, but a 1/4" plate should hold a metric poo-ton of boost.
This. Bottoming bolts and a very poor gasket material. For more thsn 8-10psi i would just weld an aluminum pan on just to eliminate it
 

Basslicks

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This. Bottoming bolts and a very poor gasket material. For more thsn 8-10psi i would just weld an aluminum pan on just to eliminate it

Out of curiosity, does anyone know what the purpose of having the removable pan to begin with, rather than a 1-piece cast anyway?
 

Basslicks

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No just cost. Aluminum cost more than steel. Plenty of factory manifolds that are fully cast aluminum and early manifolds from the 60s are cast iron.

Kinda figured as much. So, based on your experiences, getting the Hughes kit with the aluminum plate is unnecessary? Just shave the bolts down and reinstall with thread locker and better gasket or what?
 
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