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Fri Nov 04, 2016 2:29 pm

I purchased a pair of IDF intakes from a reputable vendor. When I took a good look at them I was a little disappointed.
The seam between the castings seems kind of porous. Also the flange surface is a little un-even as seen the in the image below.

The real disappointment was one of the intake flanges to the head has a built/machined in vacuum leak.

Is it acceptable to have the intake to head flange machined down, lets say .050" without effecting the performance of the intakes?
Both of the images above are of the same intake manifold.

Fri Nov 04, 2016 3:16 pm

They have been alittle rough lately. Do you have a decent belt sander? I took .050 or more off mine. I did the carb mounting faces too, although they did not need as much. Chalked it up to the usual "Making aftermarket parts fit right" game.

Fri Nov 04, 2016 4:48 pm

If you don't have a belt sander you could use sandpaper on something flat. Or if you know how to use a file it would be faster.Aluminums soft so it should go quick. It would be cheaper to return them then pay somebody to machine them.

Fri Nov 04, 2016 5:20 pm

Yeah, about average. The important thing is the ports can be match ported without making them too large, and the flanges are thick and strong, and the carb fits where you want it to be. All of the rest is do it yourself.
Also you need to machine the spot where the nuts will sit, most it is only 'as cast"

Fri Nov 04, 2016 5:41 pm

dont use no effing belt sander. it needs to be flat. either leavce it alone it's fine. or have it machined right....or left ...or if you need to move the carbs this way or that way then add a tuch of angle, but calculate it first so you dont screw it up an the tops will need it too.

Fri Nov 04, 2016 6:09 pm

Belt sander is not perfect, but it will work fine. Not everyone has a mill in their closet.

Fri Nov 04, 2016 7:15 pm

I have a mill. And honestly, I would just clean it on a belt sander.

Sat Nov 05, 2016 4:27 am

Thanks guys. A belt sander is not precise enough IMO. And a file is out of the question. They tend to get clogged with aluminum shavings in the teeth.
I'll find a machine shop near by and have them do the work so I get good sealing surfaces. I didn't think to have a look at the carb end of the manifolds. I'll have to do that and see what's up.
Have a great day.

Sat Nov 05, 2016 9:34 am

67rustavenger wrote: Thanks guys. A belt sander is not precise enough IMO. And a file is out of the question. They tend to get clogged with aluminum shavings in the teeth.
I'll find a machine shop near by and have them do the work so I get good sealing surfaces. I didn't think to have a look at the carb end of the manifolds. I'll have to do that and see what's up.
Have a great day.

I would look at both ends carefully and think about angles.

I "think" part of what Modok was getting at is that being raw castings and starting with thick flanges....you have enough room to machine the mating surfaces at both ends to set proper mounting angles.

I would mock them up to make sure that:
A. spacing between carbs for linkage purposes is good

B. so that the angle they lean or stand outward/inward when bolted to the heads gives adequate clearance.

Ray

Sat Nov 05, 2016 9:51 am

Its important not just for the original poster, but for everyone reading this and buying intakes, to check and clean them up as needed.

However,
I have purchased 2 sets of CB big beefs and 1 set of ICT intakes in the last year and they all needed facing (looked just like original posters intakes). I wanted to show the results of 5 mins on a flat top belt sander, using a 400 grit belt. I think when some people say "belt sander" they think of some belt sanders that do not have much flat backing behind, or underneath them. When your sanding on a perfectly flat surface, and not taking off much material, it faces nicely.

With all of these intakes possibly needing some facing, I would hate to see the whole VW community returning their intakes or taking them to machinists to have them milled when its not necessary.

Sat Nov 05, 2016 11:42 am

Don't forget the 12" disk sander.
Large disk and belt sanders are not just for wood, they are for manifolds too.

I don't know if these are CB's manifolds or the chinese copys of them, and you don't have to say, don't ask don't tell.
I've been very pleased with the CB manifolds. I even was in an accident and broke one, and it broke 1" above the flange. :D

When parts are CAST using simple methods, it's common procedure to let the parts sit for weeks, or even months, to let them age and the stresses release. Or, perform some type of stress relief procedure. If this is not done and they are finish machined right away, they may warp. That's how your empi finned oil pump cover is not flat right out of the package even though you can see the machine marks on the surface. :roll:

I do not see a feeler gauge showing the low spot, just a area that didn't clean when it was surfaced, and that area will not cause a leak, but in any case they will benefit form some work, and I (and probably a lot of people) consider them semi-finished.

Sat Nov 05, 2016 12:21 pm

The manifolds are from CB. It's just at .007-8" off at the deepest point when measured with a feeler gauge. The image that I posted was with the manifolds on top of my welding table. So that surface is not so precise. But I did notice this issue while they were sitting on my desk at work.
It turns out that there are not many machine shops in my county. So I may have to resort to the belt sander route to resolve the issue. I did check the carb mount ends and they are tolerable as any misalignment can be covered by the thick gaskets supplied with the intake and linkage kit I purchased.
modok, that's good information regarding the manufacture and and machining time.
Thanks for all the input

Sat Nov 05, 2016 1:07 pm

Get a piece of flat glass, a sharpie, and various sanding paper grits and mark the bottom with a sharpie then have at it sanding in a crisscross pattern-enjoy the workout!

Sat Nov 05, 2016 1:19 pm

74 Thing wrote: Get a piece of flat glass, a sharpie, and various sanding paper grits and mark the bottom with a sharpie then have at it sanding in a crisscross pattern-enjoy the workout!

Is the Sharpie idea for an indication that all is even when using this method? Kinda like the Bluing used for machine shop layout?

Sat Nov 05, 2016 1:29 pm

Yep. Works. Can of layout dye is good for large surfaces like a block dekc, but for small areas, I use sharpie marker 50 times a day.

Sat Nov 05, 2016 1:42 pm

jpaull wrote: Its important not just for the original poster, but for everyone reading this and buying intakes, to check and clean them up as needed.

However,
I have purchased 2 sets of CB big beefs and 1 set of ICT intakes in the last year and they all needed facing (looked just like original posters intakes). I wanted to show the results of 5 mins on a flat top belt sander, using a 400 grit belt. I think when some people say "belt sander" they think of some belt sanders that do not have much flat backing behind, or underneath them. When your sanding on a perfectly flat surface, and not taking off much material, it faces nicely.

With all of these intakes possibly needing some facing, I would hate to see the whole VW community returning their intakes or taking them to machinists to have them milled when its not necessary.

yes that type of belt sander will do the job add a fence and it's a lot eazer. Ive seen sopme that were done with a 1" belt sander or a hand held made for wood work 3x21 belt sander used the result was a intake that wonr seal. personaly I think his are fine for most apps.

Sat Nov 05, 2016 1:42 pm

Thanks again.
Just to be clear. I'm not dumb when it comes to mechanical things. Just ignorant(not knowledgeable) to Dual/Dual carbs. I'm just trying to get this right the first time.
Although my left foot is resting on a 4X5" glass coffee table. I think that I may go to HD and buy a smaller piece of glass to sand the manifolds a bit. I'm in no hurry as the carbs are in transit and not expected until later this month.
Just trying to get all of the things in my control out of the way ahead of the carb arrival.
Then the fun begins. Disassembly, cleaning, setting the float level, reassembly, syncing the linkage, syncing the carbs, jetting,syncing the carbs jetting,syncing the carbs, jetting, syncing the carbs ect. It should be loads of fun :shock:

Sat Nov 05, 2016 1:59 pm

I wouldn't sand them until mock up, if you're using a doghouse shroud you might need to angle the big beefs a bit so the carbs/air cleaners don't hit.

Sat Nov 05, 2016 4:46 pm

So I went to HD and bought a piece of glass to use as backing for a sanding surface. Used the Sharpie to cover the flanges, Then I sanded the manifolds with 220 grit first pass. After the black Sharpie was sanded off both ends of the manifolds. I moved onto the 400 grit paper. After blacking the flanges again, I sanded them until I had a uniform surface.
Regarding the "doghouse shroud" comment. The manifolds that I bought, are the standard CB offsets so I hope that they are going to be bolt on. If I have to make mod's to the shroud, that will be fine. I have the tools to make some mod's.

I'm still bothered by the casting. But I'll get over it.
Thanks for the input. Keep it coming. Someone will benefit from this thread. Besides me, that is.

Sat Nov 12, 2016 11:11 am

this is a great post

jpaull wrote: Its important not just for the original poster, but for everyone reading this and buying intakes, to check and clean them up as needed.

However,
I have purchased 2 sets of CB big beefs and 1 set of ICT intakes in the last year and they all needed facing (looked just like original posters intakes). I wanted to show the results of 5 mins on a flat top belt sander, using a 400 grit belt. I think when some people say "belt sander" they think of some belt sanders that do not have much flat backing behind, or underneath them. When your sanding on a perfectly flat surface, and not taking off much material, it faces nicely.

With all of these intakes possibly needing some facing, I would hate to see the whole VW community returning their intakes or taking them to machinists to have them milled when its not necessary.