I am getting ready to glass bead my intake and exhaust manifolds. Why type of tape should I use to prevent the beads from getting in the ports?

 

one layer of regular masking tape so its easy to get the goo off afterwards and two layers of duct tape. Always works for me.

 

I have to ask.
1) Why tape off the exhaust manifolds? Unless you are planning to mount a carb on the end, the glass will never enter the engine.
2)Why not blast the intake the same way? After all, it started out life as a sand casting. You will want to clean it out afterwards anyway. 1 grain of sand past the tape, and it's cancel Christmas. Blast it in and out, followed by lot's of clean air, and soak in laquer thinner for a final bath, followed by more air.

 

If you have an intake that contains a "heat cross-over" under the carb and want to glass-bead OR sand-blast it, make certain you block off that section. If any sand/beads get caught inside there it could come back to haunt you on a new unit!

The only time we "peen" any intakes is after they've gone through the "Bayco". In other words, they get "cooked" first to make sure there is absolutely no contaminants left behind from the original unit. By this I mean "caked" oil inside. This "leftover" oil can contain some of the media and cause much damage. This has happened to a number of my customers over the years. Very similar to cleaning an oil pan with welded baffles inside. These we will not use ANY media to clean whatsoever.

The exhaust manifolds are usually not an issue! Thanks, Gary in N.Y.

P.S. Just recently on the dyno I had a customer's unit fail from the media that remained inside the intake. He did the build, we did the test. No matter how good you think you clean it, it's not worth the risk!

 

It's the stock intake. Maybe I should just spend the $100 at get a Edelbrock 2101? Is the 2101 a direct cross?

I am using the original quadjet carb.

 

I hope we have not scared you. We both have our points. If you are going to paint it, just have it hot tanked , paint it, and put it on. Be sure to check it for warp.
If you want to play it safe, or like the bare alum finish, get a new manifold. I did just because it is not worth messing with over a couple bucks.
Or,I can sell you my old edelbrock after I blast it .

 

Yep...you scared me. I like the aluminum look and would rather be safe then sorry. I will still bead the exhaust manifolds.

 

Get a new one. Mine was so corroded inside it just wasn't worth it. Nothing beats new.

 

Will do....Thank you for the help.

 

The purpose of the tape is to protect the sealing surface. Blasting can and will distort the surface ever so slightly on cast and a great deal on aluminum. It might not cause problems but when it heats up this distortion gets bigger and usually does cause problems on aluminum. Also, air can push the abrasives into the little surface irregularities inside the manifold (intake) and no amount of solvent will get it out. But the heat and airflow when running will always loosen it up and then... well, bad news. Sealing surfaces should always be cleaned with a soft material like a scotchbrite pad and by hand as to prevent damaging the surface.

 

I do mine all the time, just use lots of water and a bottle brush to push thru the runners to clean it, never had a problem

 

Why can't the sand/glass beads get in the ports? When I do an intake I do everything. But you must remove any coverplate on the underside.
Don't worry about masking anything. Just blow it out really well afterwards and again you can NOT leave any coverplates on the intake.

 

based on what others say...I won't be able to get all the sand out.

 

Go shesd snd blast the thing and be done with it. Its easy and it sure cleans up nice. Getting all the media out has never been a problem for me, and I have done this many times over the years and never a failure. Some of these guys act like these cars are the most hi tech complicated vehicles in the world, but they are just a car with a high cool factor. Its not a thermonuclear reactor. Just be sure and clean itout inside very well and run it

 

I don't read other's replys before answering. I just read the question and answer from experience. Intake passages are not difficult to clean out afterwards. Other then the metal pan on the bottom everything else is easy to clean. I do alot of intakes for guys and it is nothing special. I do insist on removing the pan but everything inside and out is blasted. As for cleanup afterwards it blows out easily with shop air.

 

Lots of people bead blast stuff, it's just how you clean up afterwards. There shouldn't be a problem if your careful.

 

I didn't quite understand some of the above. My interpretation is that the exhaust gas crossover on an intake manifold has a steel shield riveted on the bottom of the intake manifold. This is to prevent crankcase splash oil from hitting the extremly hot exhaust gas crossover section of the manifold and carbonizing. When you glass bead the manifold, you don't want glass bead particles to collect inside the shield. So duct tape off the shield.

That being said, for a new engine rebuild, if you are going to re-use your manifold, you really want to clean out whatever has collected inside that steel crossover shield. A lot of nasty stuff lurks inside there. Pop the rivets and clean the underside of the shield. I think GM still sells the tiny replacement rivets. At one time I had the part number, but I've since lost it.

A good solution, for a performance or specialty driver engine, is to remove the shield - so you don't have to worry about cleaning it - and block off the exhaust gas crossover with a intake maniforl/cylinder head gasket that has the blockoff.

 

 

What negative effect does the exhaust crossover have on performance? My 79 has the hot air choke and I'm considering a new manifold, but without the crossover, my choke wouldn't work.

 

The overall cleaning method is not an issue. The heat shield if used, this is not on all intakes, must be removed. The ports are very simple and straight-forward to clean. It's where you cannot see that is the whole issue. If you can't see it you can't know if it's clean or not!

The main problem is inside the heat cross-over. This is NOT a straight-shot design, it's made as a figure "S" inside. There's a good possibility of getting the media, whether it's sand or glass, caught in this area and you CANNOT see inside their to determine what if anything is still there. We've lost a couple of units on the dyno from "outsiders" who swore they had it cleaned.

The inside gets like a "gum" coating through the years and retains the media. Especially true on units that were burning a considerable amount of oil before the rebuild. Baking the intake turns this "gum" to powder and enables it to be pretty much "blown" out with air. It can be blasted with anything as long as it's "baked" first. We do ALL intakes now using this procedure. There's too much at stake to risk the proper cleaning method.

You're talking about possibly $30.00 to both "bake and steel shot" this part on cast iron or "bake and peen" the aluminum's! Cheap insurance, nothing survives the "Bayco"! Thanks, Gary in N.Y.

P.S. I would like to take this time to wish ALL up here a very "Merry Christmas" and a healthy and "Happy New Year". And by all means DO NOT drink and drive!