Rebuilding Base 250HP Engine

[Ray C.]

I have just removed and disassembled the base 250HP engine form my 1965 restoration project. The miliage on the engine is 72,000. The previous owner must have wanted to increase the horse power. The engine had an Offenhauser intake with a 650 Holley carburetor. The cam is a Crane 296 Fireball, and the pistons are .30 over. I am trying to restore the car to original purchase condition for my wife, and it will be used for touring and outings. I have secured the correct dated intake and WCFB 3697 carburetor. The pistons, cam, lifters, rods and other internal parts look excelent. What would be the best aproach for the rebuild?

Thanks! Ray

[Duke W.]

Re: Rebuilding Base 250HP Engine

Replace the cam with the OEM 929. You can buy it from Federal Mogul, and you should, of course, install new lifters.

What is the condition of the bores - taper and out of round, and what kind of pistons are installed?

I would suggest magnafluxing the crank and rods. If they pass you can reuse them. New bearings and rings are appropriate. You also need to determine the condition of the valve guides and determine if they should be rebuilt and reseating the valves is normal on a major overhaul.

Duke

[Duke W.]

Re: Rebuilding Base 250HP Engine

Replace the cam with the OEM 929. You can buy it from Federal Mogul, and you should, of course, install new lifters.

What is the condition of the bores - taper and out of round, and what kind of pistons are installed?

I would suggest magnafluxing the crank and rods. If they pass you can reuse them. New bearings and rings are appropriate. You also need to determine the condition of the valve guides and determine if they should be rebuilt and reseating the valves is normal on a major overhaul.

Duke

[Pat Bush #35083]

Re: Rebuilding Base 250HP Engine

Ray -

Duke, as usual, is right on the money. I would add the following to his comments:

1) The bore taper should be no more .004 from top to bottom. If you have a ridge at the top of the cylinder in any bore, make sure the machinist checks taper. You can get another run with the .030 over bore if there is not too much wear. Replace the rings as part of the rebuild. Often, if the pistons are not in bad shape, you can simply clean the grooves with a ring land cleaner, tank them in Gunk, and re-use although most times we replace on rebuild for warranty sake.

2) Replace all the freeze plugs with either a brass or stainless steel set.

3) Replace the cam berings and make sure the machinist clears and cleans ALL the oil galley feeds for the cam and lifters.

4) Mike the crankshaft for egg-shape. Normally less than .001 is fine for a polish, fresh berings, and reinstall. If you have more than .002, the crank should be taken to the next undersize. Also, make sure the thrust on the crank is not worn and producing too much end-play.

5) ALWAYS replace the oil pump. Much discussion usually surround Hi-pressure/volume pumps, but if I were doing a motor, I would only put a stock or hi-volume style pump in.

6) Avoid putting seats in unless they are hammered or there is a real reason to do it. Running pump unleaded gas for your application does not, in my opinion, warrant new seats. Have done many older cars and never had one come back. Different story if you are racing it or driving it hard....

7) Have the rods checked for out-of roundness and REPLACE the rod bolts! Suggest Arp bolts

I would do all the guides and be done with it. Can't remember if this is BB or SB, but if it is BB -- they are just driven out and replaced. SB's require machining unless this was already done. When the machinist does them, have them machine the boss to accept PC seals on the intakes if this has not already been done. We use PC seals on the intakes, and umbrella type on the exhaust to make sure there is enough oil flow.

9) I usually replace springs,rockers, and pushrods as part of rebuild -- again for warranty issues. But, you can have the springs tested and if they are OK, use a spring shim to restore proper height.

10) Check the valves for excessive wear on the stem as well as the "edge". If it is razor sharp, this is an indication that several valve jobs have been done and it is time to replace your valves.

11) Again, just to reinforce, if you are replacing the cam REPLACE THE LIFTERS!

12) Make sure the balancer inner and outer rings do not move. BB's have an issue with this. If the balancer is hosed, you will need to have it rebuilt or replaced. Also check the shaft of the balancer -- there often times wear where the timing cover seals rides on the balancer. Kits are available to fix this. Believe it or not, it is cheaper to buy a TCS set rather than just the fix kit!

13) We use Felpro gaskets exclusively. They are the best. Bearings -- Sealed Power, Federal Mogul, and Clevite are preferred. Oil Pump - Melling. Pistons we use Zollner, TRW (Speedpro), or Keith Black depending on application.

Hope this helps you along your way.

Pat

[Pat Bush #35083]

Re: Rebuilding Base 250HP Engine

Ray -

Duke, as usual, is right on the money. I would add the following to his comments:

1) The bore taper should be no more .004 from top to bottom. If you have a ridge at the top of the cylinder in any bore, make sure the machinist checks taper. You can get another run with the .030 over bore if there is not too much wear. Replace the rings as part of the rebuild. Often, if the pistons are not in bad shape, you can simply clean the grooves with a ring land cleaner, tank them in Gunk, and re-use although most times we replace on rebuild for warranty sake.

2) Replace all the freeze plugs with either a brass or stainless steel set.

3) Replace the cam berings and make sure the machinist clears and cleans ALL the oil galley feeds for the cam and lifters.

4) Mike the crankshaft for egg-shape. Normally less than .001 is fine for a polish, fresh berings, and reinstall. If you have more than .002, the crank should be taken to the next undersize. Also, make sure the thrust on the crank is not worn and producing too much end-play.

5) ALWAYS replace the oil pump. Much discussion usually surround Hi-pressure/volume pumps, but if I were doing a motor, I would only put a stock or hi-volume style pump in.

6) Avoid putting seats in unless they are hammered or there is a real reason to do it. Running pump unleaded gas for your application does not, in my opinion, warrant new seats. Have done many older cars and never had one come back. Different story if you are racing it or driving it hard....

7) Have the rods checked for out-of roundness and REPLACE the rod bolts! Suggest Arp bolts

I would do all the guides and be done with it. Can't remember if this is BB or SB, but if it is BB -- they are just driven out and replaced. SB's require machining unless this was already done. When the machinist does them, have them machine the boss to accept PC seals on the intakes if this has not already been done. We use PC seals on the intakes, and umbrella type on the exhaust to make sure there is enough oil flow.

9) I usually replace springs,rockers, and pushrods as part of rebuild -- again for warranty issues. But, you can have the springs tested and if they are OK, use a spring shim to restore proper height.

10) Check the valves for excessive wear on the stem as well as the "edge". If it is razor sharp, this is an indication that several valve jobs have been done and it is time to replace your valves.

11) Again, just to reinforce, if you are replacing the cam REPLACE THE LIFTERS!

12) Make sure the balancer inner and outer rings do not move. BB's have an issue with this. If the balancer is hosed, you will need to have it rebuilt or replaced. Also check the shaft of the balancer -- there often times wear where the timing cover seals rides on the balancer. Kits are available to fix this. Believe it or not, it is cheaper to buy a TCS set rather than just the fix kit!

13) We use Felpro gaskets exclusively. They are the best. Bearings -- Sealed Power, Federal Mogul, and Clevite are preferred. Oil Pump - Melling. Pistons we use Zollner, TRW (Speedpro), or Keith Black depending on application.

Hope this helps you along your way.

Pat