Aluminum intake and vacuum fusion snafu - now what?

[msg]

Thought I could reuse my vacuum port from my old 350 to my new L31 intake and messed up. Maybe its because I bead blasted the threads and caused some fusion to happen with the aluminum edelbrock intake. I checked the threads before I attempted it, wanted to paint the part after a fitting to make sure things went well and they just didnt. It was a bit of a snug threading to start and I did back of several times to avoid a cross thread. It finally did start to take and then it took a wrench to thread it a bit more. Then when backing it out it was jammed. Took a hammer to tap the wrench counter clockwise to loosen and some of the threading of the intake is now attached to the vacuum part. I tried to use a pic and no dice. The tap a die set I have isnt this big so from here I guess its buy a new vacuum port and try again? Now Im spooked.

[truckster]

I recommend using brass fittings with aluminum intakes.

[AcampoDave]

I think youll be o.k. it looks like it just affected the first few threads in the hole. Get a plastic or brass one and try again. What happened to you is called "galling". Aluminum (and stainless steel) can do that sometimes. Brass doesn't because it "plays nice" with dissimilar metals and of course plastic won't do it either. If you use a plastic fitting there will be minimal risk because the plastic threads will munch up before the aluminum ones in the event you get a cross thread situation. The manifold has what's called "national pipe thread" or NPT. Common PVC pipe fittings are also NPT you can buy a cheapo PVC fitting in the appropriate size and use it for a test mule to see if all will be well when you thread in the real deal. EDIT: ANY TAP YOU MIGHT USE ON THE MANIFOLD SHOULD BE NPT.

[msg]

Originally Posted by truckster

I recommend using brass fittings with aluminum intakes.

If I can find it in brass. These adapters might do the trick..

https://www.amazon.com/Legines-Brass.../dp/B07485XZN4

https://www.fastenal.com/products/details/440042-131280

and I can get a die set to correct the part I have?

Does this also go for bolts for the thermostat housing, carb , and all? I have anti-seize the permatex aluminum kind that I was thinking to use on bolts. But these fittings require teflon so I was just going to use teflon only.

Also, looks like I need to send these stainless plugs back for the ports next to the thermostat housing for heater hoses I think that I will not be using with the Vintage Air system Ive ordered.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

and instead get these

https://www.amazon.com/Brass-Fitting.../dp/B081YH9W42

Originally Posted by AcampoDave

I think youll be o.k. it looks like it just affected the first few threads in the hole. Get a plastic or brass one and try again. What happened to you is called "galling". Aluminum (and stainless steel) can do that sometimes. Brass doesn't because it "plays nice" with dissimilar metals and of course plastic won't do it either. If you use a plastic fitting there will be minimal risk because the plastic threads will munch up before the aluminum ones in the event you get a cross thread situation. The manifold has what's called "national pipe thread" or NPT. Common PVC pipe fittings are also NPT you can buy a cheapo PVC fitting in the appropriate size and use it for a test mule to see if all will be well when you thread in the real deal. EDIT: ANY TAP YOU MIGHT USE ON THE MANIFOLD SHOULD BE NPT.

Wouldnt plastic have trouble with the heat of the manifold? Ill pick up a pvc 3/8 npt fitting to test today.

Thanks to you both!

[AcampoDave]

Not sure about the heat. Modern cars have the whole intake in plastic though. It would need to be made for the job. I have galled up the waterneck bosses on an Edelbrock decades ago. I use anti sieze a lot more these days.

[Ziegelsteinfaust]

Always antiseize aluminum.

You should be able to use that fitting.

[AcampoDave]

msg, if you use a tap on the treads I think it best to remove the part. Because shavings and particles could fall into the intake tract. Maybe that goes without saying, but look at it this way...if it works it's still worth it.

[geezer#99]

That plastic is actually phenolic resin. Same stuff used for heat spacers on eddy carbs.
You can buy separate thread chasers. No need for a complete set unless you feel the need for more tools.
Are you gonna pull the intake to fix those threads?

[msg]

Originally Posted by Ziegelsteinfaust

Always antiseize aluminum.

You should be able to use that fitting.

But anti seize only on bolts right? Not when teflon is being added?

Originally Posted by AcampoDave

msg, if you use a tap on the treads I think it best to remove the part. Because shavings and particles could fall into the intake tract. Maybe that goes without saying, but look at it this way...if it works it's still worth it.

Removing the intake..well if its best to. Dang. If it were steel I could put a magnet in there. I guess what I need to do is invest in chasers for every port and do it all while its off the engine.

Originally Posted by geezer#99

That plastic is actually phenolic resin. Same stuff used for heat spacers on eddy carbs.

Which plastic parts do you mean Geezer?

Originally Posted by geezer#99

You can buy separate thread chasers. No need for a complete set unless you feel the need for more tools.

I may be buying this set at good ole HF

https://www.harborfreight.com/6-piec...BoC0iQQAvD_BwE

Id need a 5/16 and a 3/8 UNC chaser though as well to hit all of them.
Is chasing a better idea than tapping?

Originally Posted by geezer#99

Are you gonna pull the intake to fix those threads?

Ugh, looks like it unless I can rig up a catch block under and vacuum out the shavings.

Im attaching a screen grab of the specs, the installation instructions I got in the box doesnt have it. In fact the water pump inlet isnt listed or the thermostat housing so I need to look those up.

[geezer#99]

Dave mentioned plastic fittings.
A tip for you.
Use grease on the threads of your tap when you chase the threads. The grease will catch the shavings.

[msg]

Ah, so would I be ok to not pull the manifold and use the grease?

[geezer#99]

I would but I’ve been wrenching for 50 years.
I’d suggest you pull it.
That way you’re sure nothing snuck in.
New Gaskets are cheap Insurance.

[truckster]

I'm not sure if you got an answer to your question about other bolts on the manifold. Use stainless steel with aluminum anti-seize. This is the one I use:

https://www.permatex.com/products/lu.../?locale=en_us

[msg]

Originally Posted by geezer#99

I would but I’ve been wrenching for 50 years.
I’d suggest you pull it.
That way you’re sure nothing snuck in.
New Gaskets are cheap Insurance.

Ill pull it, but I just put on that expensive gasket set last month and never fired this engine up. At this rate I wonder if I ever will.

Post 20 and 21 in that thread shows what I did. I was hoping top remove the rtv and reuse the gaskets.

https://67-72chevytrucks.com/vboard/...d.php?t=811362

Originally Posted by truckster

I'm not sure if you got an answer to your question about other bolts on the manifold. Use stainless steel with aluminum anti-seize. This is the one I use:

https://www.permatex.com/products/lu.../?locale=en_us

Thanks Truckster, Ive got the stuff just need stainless bolts then.

[geezer#99]

Like Mr. Eastwood used to say. Feeling lucky!
Once you’ve compressed intake gaskets they’re wasted for reuse.
At least that’s my opinion.

[msg]

Thats kind of you to ask, I am definitely running short of luck these days.

[garyd1961]

Isn't that pipe threads? You don't want to tighten it to tight or you will crack the intake. I would start with another fitting preferably brass and if you can get 3 of 4 threads it should be good. Maybe a little pipe sealer would help also.

[geezer#99]

Originally Posted by msg

Thats kind of you to ask, I am definitely running short of luck these days.

Don’t mean to be unkind!
I’ve known people who reused gaskets and had no problems they were aware of but I never trusted using used gaskets.
Easier to do it right Now than later once you’ve got the whole top end bolted togethor.

[msg]

Originally Posted by garyd1961

Isn't that pipe threads? You don't want to tighten it to tight or you will crack the intake. I would start with another fitting preferably brass and if you can get 3 of 4 threads it should be good. Maybe a little pipe sealer would help also.

Yep its NPT, I ordered a 3/8 NPT male to 3/8 NPT female brass fitting to attach to the manifold this time and I have die for the 3/8 NPT vacuum 3 port part I have to clean out the threads and reuse it. I hope. Definitely teflon tape will be used.

Originally Posted by geezer#99

Don’t mean to be unkind!
I’ve known people who reused gaskets and had no problems they were aware of but I never trusted using used gaskets.
Easier to do it right Now than later once you’ve got the whole top end bolted togethor.

No i meant asking if I felt lucky was putting it kindly. Im having a bout of the blunders lately. I appreciate the advice Geezer as always.

[geezer#99]

I’ve got some liquid Teflon tape that’s much easier to use than regular tape.

Some like this.


https://www.shop.evcohardware.com/LO...N-LOC56747.htm

Just need a little dab on the threads. It spreads nice and fills the threads as you screw it in.

[AcampoDave]

Originally Posted by garyd1961

Isn't that pipe threads? You don't want to tighten it to tight or you will crack the intake. I would start with another fitting preferably brass and if you can get 3 of 4 threads it should be good. Maybe a little pipe sealer would help also.

I was kind of along these lines too. If the plastic PVC fitting starts well and threads then I would see that as a positive sign that a brass one would too. Then there would be "no muss no fuss" and you'd not have the expense of tap and die tools, intake gaskets, etc.

[garyd1961]

Be careful with the teflon tape, too much will make it easier to crack the intake. You want it snug not wrenched down tight.

[geezer#99]

Originally Posted by garyd1961

Be careful with the teflon tape, too much will make it easier to crack the intake. You want it snug not wrenched down tight.

Precisely why you should use liquid tape!

[truckster]

I use Permatex Aviation Form-A-Gasket on the threads. A little denatured alcohol on a rag will wipe off anything that squeezes out.

[msg]

Thanks guys, Ill start with a pvc first to see then some liquid teflon on the brass and start first without the tap and die on the intake. Ill snug it not overtighten. Didnt know that only a few turns is all that fittings need in a manifold.