The Stovebolt Site Forums The Shop Area Engine Shop manifold bolts

Trying to separate intake and exhaust manifold before assembly, '54 Chevy 235. 2 bolts on bottom of exhaust are bigger than 1/2" but smaller than 9/16". Cleaned up w/ wire wheel on drill, tried file
that I use to sharpen mower blades and won't even scratch it. OK - split the diff, look for 17/32 socket - no one stocks it. Anyone know what size they are?

Mine seem to be 9/16" but corroded down a bit in size. Maybe some metric socket will fit it perfectly. Not that they were metric in '54, of course.

Those bolt heads are rusty/worn 9/16", since the bolt diameter is 3/8" on the clamp bolts. 3/8" bolts have 9/16" heads. If a 9/16" 6 point socket won't grab the wrench flats, try using a cheap 12 point 13MM socket that you don't mind damaging, and hammer it on. 13MM is slightly bigger than 1/2". Soak the threads with KROIL or some other penetrating oil, and/or heat them before wrenching.
Jerry

`...then drill out the broken bolt in the box, and snap off an easyout in the hole in the bolt. Then see how far you can shotput that manifold across the shop and break something valuable
with it. (I laugh so that I won't cry.)
You don't have to follow what I usually do with these heat treated fasteners, but don't come unglued if they brake. It happens.

Heat the box with a torch. Soak in Kroil. hit the top of the bolt with a hammer to help the Kroil get into the threads. Next day, carefully turn the bolt clockwise, feeling for the slightest bit of movement, then stop! Then try to back it out. I don't know why tightening a bolt breaks it free better than loosening, but it does.
If you don't get any movement when you carefully tighten it. Start from the beginning and do it all over.

Someone told me to try to tighten a stuck bolt or nut first because that was the last direction the bolt or nut was turned.

I have a set of Craftsman bolt extractors that are spiral hex that grab a rounded head as you turn it to loosen it. They might work on rusted heads. Here's a link to various similar extractors. Link

If you want to try a metric socket, I would try a 14 mm first, as 13 is REALLY close to 1/2 inch (0.512"). 14mm is 0.5512" while 9/16 is 0.5625". Whatever you try would definitely have to be 6-point rather than 12 point.

52Carl is right on, except he missed on very important tool. PATIENCE!

In this case an abundance of patience is required and of course a 6 point socket. Don’t attempt it with a 12 point as you will round it out. Heat the area surrounding the bolt threads to two - three hundred degrees then douse it in your favorite penetrant. I like Kroil, followed by PB Blaster. Now tap the head of the bolt. Try to remove but don’t get too forceful. More penetrant. Let it cool, try to remove but again, don’t get to forceful. Douse it in penetrant and let it sit a day. Repeat!

If after three or four days of doing this, cut the head of the bolt so you can separate the two manifolds. This will leave you with the end of the stud sticking out. Find a nut that just fits over the stud and weld it on. The heat of welding usually breaks the rust bond. Douse and repeat the above procedure.

Good luck!

52 Carl You dont weld onto them ?? Once you break something hard off in there weld is about the onlt choice !!

I guess you missed the part about the throwing of the part across the shop and breaking something else.
I suppose I would look for the aforementioned thrown-with-extreme-prejudice part some time later and try something else such as welding.
Perhaps my description of how I operate can be held as an example as to how not to proceed when the going gets tough.

Something that seems to work better at loosening seized/rusty threads than oil is paraffin- - - - -the oldtime sealing wax that's available in big blocks at the canning supply department of most grocery stores, or candle wax. Heat a stuck bolt or nut until it's almost red, and apply the wax liberally. I use chassis grease, beeswax (toilet bowl seal rings) and paraffin to make cast bullet lube, so I always have a couple of boxes of paraffin blocks around the gunsmith shop.
Jerry

Got it off - thanks for all the ideas. Used 14mm socket (a bit loose), several days of Liquid Wrench + tapping, finally heat from MAP gas torch and tightening a bit before backing it out.

Good to hear!

OK, I guess it would be advisable to listen to some of what I recommend.
Just pay attention for when I start to go off the rails, exhibiting intemperance.

52 Carl Saw that part about fireing stuff across the shop do it here too !! I usully weld a lever on problem bolts then heat the casting carefully,once it moves just walk it along if it squeeks little more heat if lever hitscut it off put on endo so you can vise grip it. Have several manifolds saved that way.

52 carl On one thats able to be drilled thru have taken the sharp torch and blown the center out of it let it cool then unscrew.