rebuilt atomic4

Aug 24, 2013
7
cal 25 Weymouth
I'm looking at a 1970 cal 34. the present owner has had the atomic4 engine rebuilt by a reputably shop that specializes in older motors of all kinds. when he had it rebuilt the shop stitch welded some cracks in the block. my question is should I trust this engine or put a new one in?
 
Jan 30, 2012
1,094
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
You need more information. Why welding was necessary. What is the location of these welds. What does the present owner or the shop mean by the phrase "stitch welding."

Apart from that you need to know the extent of the motor build including what machine work was done, what parts were renewed, and so forth. Start with the receipt from the motor builder.

Once you have all that information call and discuss the situation with someone at Moyer Marine.

Charles
 
Feb 8, 2014
1,300
Columbia 36 Muskegon
Do you know how many hours are on the weld repair? I've seen those run for years or fail the first day on car engines. I'd be pretty suspicious of a new repair, but an old one might last a quite a while longer.
That engine is likely 45 years old, you might be better ahead just planning on replacing it soon, and the purchase price should reflect that. I'd be thinking about a newer used diesel. Wouldn't consider a new one, that would certainly cost more than the boat.
 
Dec 3, 2013
169
HUNTER 29.5 PORT CHARLOTTE FL
You need more information. Why welding was necessary. What is the location of these welds. What does the present owner or the shop mean by the phrase "stitch welding."

Charles
"stich welding" is a technic used to weld cast iron w/o damaging the cast iron.

a bead of a short length is laid down in the repair and then a length of the repair is skipped and then another short length bead is laid, etc to the end of the repair.

the welder then returns to the first skipped area and lays down another short bead and continues this process until the entire repair is welded.
 
Jul 23, 2015
26
catalina 2-34 oregon
"stich welding" is a technic used to weld cast iron w/o damaging the cast iron.

a bead of a short length is laid down in the repair and then a length of the repair is skipped and then another short length bead is laid, etc to the end of the repair.

the welder then returns to the first skipped area and lays down another short bead and continues this process until the entire repair is welded.
I am a welder by trade. When welding cast material, it is important you have material know as wool (super wool is best). It is an insulation use to keep heat in or out. You can get it different thicknesses.
To weld cast, you would line up your cracked parts, use a rotery file and remove the material on either side of the Crack (open it up slightly) to cause a "V-groove". Making sure your gap has not changed. Once the Crack is gone, preheat the surrounding material. Then it gets welded. If it is iron, 7018. Depending on the size of the hole, 3/32 or 1/8 stick would probably work but, I have not looked up the material of you engine. I just saw the welding post and some info about welding and wanted to share. Then, fill the gap, just like you would with a test plate. Cover with the wool listed above and preheat just a little more. Let cool slow for a few hours. The slower it cools, the better chance you have of keeping it from cracking again.
I also would like to note, if you add heat to the engine and you notice the Crack get bigger, you have to "chase the cracks or make it go away. Sometimes you have to grind a "T" across the end of the crack to make it stop. Cast is hard to weld and do it right. Don't try it at home if you are not familiar with weld processes.
 
Jul 23, 2015
26
catalina 2-34 oregon
I'm looking at a 1970 cal 34. the present owner has had the atomic4 engine rebuilt by a reputably shop that specializes in older motors of all kinds. when he had it rebuilt the shop stitch welded some cracks in the block. my question is should I trust this engine or put a new one in?
Yeah, stitch welding is used to keep from warping the metal. You have to understand that when you weld, you are melting the rod/wire/stick and welding the parent metal together. You are basically superheating the materials to liquid form. Stitch welding spreads the heat out, otherwise warping can be extreme. Post pictures, I would like to see it. Still, you should be able to go to a weld shop and by the items to do a die penetrant test. You can do that with spray cans. Verify no cracks exist.
 
Sep 14, 2015
5
Cal 2-27 Lake Conroe
Since the Atomic 4 is very similar to the Model A Ford, i.e., flathead 4 with cast water jackets, the following technique would probably apply.

At both ends of the crack - or even 1/4 inch beyond - drill a stop hole, which will prevent the crack from propagating. Thread this hole 5/16-18. Screw a 5/16-18 screw into the hole, and cut it flush and pein it over to prevent rotation. Next, drill a #7 or 13/64 hole overlapping the filled stop hole by about 1/3 of it's diameter, and tap it 1/4-20. (When I've done this, I've started ALL of the holes using a small Center Drill. If you don't know what this is, you might not want to do this.) Thread a screw into the threaded hole, cut it off and pein it, as well. (A short piece of all thread rod may be used for this.) Pein the end over lightly to prevent it from rotating. Next, add a hole adjacent to the hole with the threaded insert, overlapping it by about 1/3 of the shank of the insert. Do this from one end to the other, connecting the two end holes, which will be threaded 5/16-18. As the screws are being inserted, you may also use Loctite Thread Locker to prevent rotation if you don't want to peen the ends over.

This was the technique mechanics used in the '30's & 40's to repair engines without removing them from the car, assuming the crack was in a location where the drilling & threading could be done. I used this technique in the '60's on my first car, a 1929 Model A Ford...

Take nice pics and post them here!