Posted by Vaughn on Thursday, May 31, 2001 at 9:39PM :
In Reply to: flathead rebuild tips? posted by charlie on Thursday, May 31, 2001 at 8:58PM :
Well, if it were mine, this what I would do doing the tear down and reassembly
After tear down, take the engine block to a machine shop for reconditioning:
- New block plugs or freeze plugs;
- Upgrade to new hardened valves and seats. Talk to your machinist about a 3 grind angle on the valve to give you a boost in performance;
- Have them replace the water distributor tube;
- Check cylinder wear and rebore if needed. If they have to bore out to .080 or more, consider sleeves to back to stock piston. The farther out, the hotter they run.
Have check you crank for flat areas and scoring. If you slide a penny across the journals and it leaves a deposit, its time for a regrind. You may want to have a nitride treatment (hardening) on the crank journals for extended wear.
Ok, everythings back and ready for assembly. Lets start:
- Take an air hose and blow out all water passages to get rid of any loose rust. Do the head also because you will stand a good chance for a piece of rust to fall out of the head onto the head gasket and causing an oil leak into the cooling system. Since I started doing that, I no longer have experienced that problem.
- Take some warm soapy water and wash the cylinders to remove any remaining hone grit, but have someone ready to dry the cylinder when you move to the next one. That's the only way to get it all out. Once you do, it will take longer to seat your rings, but you'll get many more miles. This is a practice most machinist and home mechanics do not do.
- make a mixture of 50% oil/STP as an assembly lube to lube all moving parts as you assemble.
- For piston rings, place the oil ring gap parallel to the piston pin. This gives you maximum oil control. The remaining rings, place 125 degrees from the oil ring gap. If you looked down from the top of the piston, you would have three gaps 125 degrees from each other. That gives you maximum compression.
- When installing the main and rod bearings use plastic gauge to check the clearance to make sure you are in tolerances
For the rest of the assembly, I assume you rebuilt engines before. Use a non-detergent for the breakin oil. good luck!
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