Suggestion for steel bolts in aluminum

[3v0]

I have two projects where I have steel threaded into aluminum that is seized.

One is the screws holding a vacu-jet carb to a 8ci briggs from the 60s. Up to now I have only seen the pulsa-jet carbs which use hex head bolts to attach the carb. This vacu-jet is held on by screw head fasteners. This is as much of an access problem as it is with seized threads but another bolt on this engine was seized and the head bolts were not easy. I have tried a #3 phillips but it is not a great fit with everything in the way and I did not want to mess up the heads. If possible I would like to save these screws to keep the engine as authentic as I can.



The second is a 3 cylinder speedair (champion) compressor I want to rebuild. Two of the three heads are off. On the remaining head 2 of the 4 bolts are out. I have been doing the penetrating oil and rapping routine for a week or two on these two bolts with no joy. I am thinking of heating the bolts with oxy-propane, or would one be better off heating the aluminum around the bolt?



Any suggestions ?

3v0

[bgsengine]

for the briggs "cross Slot" Screws - use a plain slotted screwdriver that fits the slot - which is what they were designed for, Briggs has a (very expensive at $30) special angled driver (Part number 19305) for these - that tool allows more torque to be applied than a typical screwdriver.

For the other bolts, you can lightly heat the Jug (cylinder) around the head bolts where they thread in to the cylinder (not the head) *if* the bolts themselves seem to have a little "twist" when attempting to loosen - they could be galled in either the head (along the shank) or on the threads (in the cylinder) , and it takes some experience and practice (Zen: Become one with the Bolt) to develop the feel for what a bolt is doing, but an experienced tech can usually tell where abouts the bolt is binding , and usually can tell when it is about to break, in which case 95% of the time the bolt is gonna break anyway and it'll have to be drilled out.

[KE4AVB]

Don't look like it be that hard to make one out of some tool steel that would work. Of course if the bolts are corroded in then even it won't work. Takes a lot of gentle persuasion to even get one out without it breaking and it can still break. It just one those things we techs just have to deal with when we are working on old engines.

[3v0]

Thanks I followed your suggestion and drug out the torch to use on the compressor. The last head is off. The last bolt stuck in the head and they turned off together. The good news is it looks like the head bolt holes will be ok after chasing with a bottom tap.

After reading your post I gave the top carb bolts a try with a flat screw driver but it is not going to come easy. I have a right angle screw driver around here someplace. Just need to find it. I expect getting these out will take some time.

Thanks

[okie]

This has always worked for me if you can get to the slot.




Travis

[3v0]

An update.

Please keep in mind like the fellow fixing the old weed whip I am mostly doing this to keep busy. Every engine or device I am working on has been junked by others because it was cheaper to buy new then repair.

While hunting for another tool I found the right angle screwdriver I needed to get the carb off. I got the screws to budge a bit then soaked em for a day with pb blaster. The screws were not nice looking when I finished and they convinced me to replace them with bolts if possible.

It is going to take more coaxing to get that compressor torn down further. It is soaking with pb blaster now.

Thanks for the encouragement and suggestions.

[Arkie]

For seized head bolts and exhaust manifold bolts, etc, I have a muffler cutting tool rigged with a homemade mushroom end punch, slight concave end like this so as the punch stays on the bolt head and a air regulator located right on the air input of the air chisel so as the air pressure can be readily easily adjusted while operating the tool. I place the air chisel onto the bolt head and start with zero or low air pressure while holding the tool tight against the bolt head and start slowly turning up the air pressure and you will reach a air pressure usually around 30# where the punch will start a very fast stinging type vibration and almost sting a finger when feeling the metal. ((this applies high speed vibrations to the bolt head) Then if it's a 6 point bolt head I use a 6 point box end wrench so as I can see and feel for bolt movement. A socket hides the bolt head and usually result in a twist off. You can also do a test run by placing the air tool blunt punch onto a bench vise or anvil for initial feel and adjustment of the air pressure. The air pressure can be adjusted so as the tool does not damage the bolt head, just a high speed vibration.

[38racing]

I know thread is 6 years old. Still if you have to get steal bolts out of aluminum google until you find procedure for submerging them in a heated alum solution. Eats the steel and no impact on the aluminum.

[KE4AVB]

Which one of the several Alum compounds is it? Potassium alum, Sodium alum, or ammonium alum? Of course there other versions too; like chrome alum, aluminium sulfate, and aluminium hydroxide gel. I think you mean potassium alum but I need know which it is to get so I can try it.

Sulfuric acid works but it extremely slow at the battery strength.

[38racing]

Not sure. Just went to the bulk food store and bought the alum that they sell for pickling.