Tapped Steam Hole Plug Size Model B block I recently purchased a 30 phaeton that came with a model B block. I took off the head and cleaned off the old copper gasket adhesive. I now have a clean block and head, however I read that you are supposed to fill the steam holes on the B block in order to avoid issues down the road.
I have searched on here and even purchased some model A manuals but can't seem to find a definitive answer as to what size hole I need to tap the steam holes to. I bought some 5/16" x 1/4" - 24 set screws and plan on drilling, tapping and screwing those in there (as long as this size is correct), then filling in whatever is left of the hole with JB weld and sanding it smooth. I plan on doing this in all 4 steam holes. Am I on the right track? Any advice for drilling into the block to get the straightest hole possible (minus pulling the engine apart and putting it into a mill or drill press)? I obviously want to get this done right the first time around to avoid ruining something and figured I'd ask on here to get a more knowledgeable answer, or see if there is anything I may have missed? Any advice or links to good articles on the matter would be greatly appreciated!! Thanks in advance, Gordy |
Re: Tapped Steam Hole Plug Size Model B block You are on the right track, a 1/4" set screw may be OK. Only tap part way in so the set screws will jam securely in place, or locktite them. The plugs must be flush on the deck as their purpose is to support the gasket. JB weld works fine and is easy to file flat although sand paper wrapped around a block of wood is better than a file as it won't flex.
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Re: Tapped Steam Hole Plug Size Model B block The issue down the road you are trying to avoid is that if you run a stock Model A head on a Model B block the holes will be too close to the edge of the gasket due to the shape of the combustion chamber and will probably leak. If you run a Model a Police head, a Model B head, or one of the aftermarket high compression heads that I have seen there is no problem and you can forget about closing the holes. I don't think I would ever build an engine and use a stock Model A head.
Charlie Stephens |
Re: Tapped Steam Hole Plug Size Model B block Your right, the holes are 1/4" in dia. the set screw is 5/16" x 24 tpi x 1/4" long, my chart says for 5/16 x 24, you can use a .272, .275, or 9/32 = .281 drill bit. I would use 9/32" because they are common. I don't think you will need a drill press unless you have one, a hand drill will work just fine. I would countersink them a little below surface incase it should ever need to be milled, these set screws are heat treated.
carry on nick c |
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As far as drilling 'to get the straightest' hole, I just changed heads...to keep busy, and drilled/plugged/filled as you indicate that you are into. My 'paws' are pretty messed up and shaky and I did the job with engine in and ready to run with different head. Simple job. IF you are lucky, you might have a whole quarter inch +/- of cast iron to drill thru. Even I could keep the bit approximatey vertical for a 1/4" or so. I ran the screws down just below surface and put JB smear with putty knife. The one 'tip' that I would give / do and did do...is to place a magnet around the drilled area. That way, I picked up ALL of the cut cast iron..easily. I was fortunate enough to have a DONUT shaped powerful magnet and it worked perfect. But, any magnet will do. My plugs were the 'pipe plug' shape/thread and tightened well the further screwed in. I used blue locktite also, but probably not needed. Good luck:) BTW...sometimes I'm overly cautious. I also taped over the cyl holes with masking tape..your choice. |
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I planned to run the original model A head at first, make sure it was running, and then switch an aftermarket head and some more banger speed equipment goodies after I could drive it down the road. If this will eliminate me tapping into the block, I'd prefer to just buy the head right off the bat (to save myself some work). I have a "Best Model B Gasket" I bought from Snyder's, if that helps. The engine does appear to be a fresh rebuild, as the original owner who abandoned the project had claimed, but I'm not sure why the head gasket leaked (I assume he never re-torqued the head, OR he never plugged the steam holes w/ his copper model A head gasket). The pistons have "0.080" etched on them, so I'm assuming theyre bored out, and the engine was indeed recently rebuilt. Quote:
Thanks so much for everyones help!! Really appreciate it! Gordy |
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Charlie Stephens |
Re: Tapped Steam Hole Plug Size Model B block Quote:
Any other recommendations? I'll check the top of the pistons in relation to the top of the block. Thanks |
Re: Tapped Steam Hole Plug Size Model B block Most, if not all, aftermarket, performance, heads are made for the Model A gasket, for better flow between the valves and cyl., thus the need to plug the B block.
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