401 Block damage/problem?

This can be repaired and must be repaired. welding brazing or even a insert would work. EZ fix. Most likely cause would be the wrong cam bolt. (To thick) or someone may have put a washer under the cam bolt. How does the original timing cover look and is the cam stop look ok. Main thing is that you don't want the cam to walk. I think .003 is normal(not sure without checking specs) and .009 on top of that could spell disaster for the distributor gears. (premature wear) On another note, good picture of the oil gallery going to the mains thru the cam journals. now just imagine installing the cam bearings and closing off 30% or more of the flow to the main bearings. This is why I all ways take new cam bearings and champher the outside of the cam bearings to match the flow of the oil passageways. never have had a oil concern since doing this procedure. Also get a 5/16 10 inch long drill bit and clean out all the oil galleries while you have the engine apart. Pay close attention to where the main oil gallery passageways meet the lifter galleries you will get some casting flash from that area. Just don't go to far you can see the drill bit through the open lifter galley. No need for a oil bypass line, it never worked anyways and usually caused other concerns. last note if you don't mind, don't want to be preaching but I've been around AMC engine all of my life, and that includes my terrible two's. When installing the front lifter gallery plugs make sure that they don't block off the oil flow to number 1 cam bearing. If you note from your photos that the oil passageway leading to the number one cam bearing is drilled rate into the threads. I usually clock the plug and then grind that area so there is a smooth transition then I also radius as many of the 45 deg bends that can be accessed in all the oil galleries. time consuming but also piece of mind. Good luck 

Have a steel shim made to compensate for the loss of material. Next it would be a Rollmaster timing chain and gear set. When you see this set you will understand why most of us recommend using it. Good luck with your build......Jim

Hmmm Cam walk has been a concern with AMC engines and other manufacturers. Distributor gears seam to be the first thing to go in most cases. Once the groove or wear mark is remedied and the timing cover is to be installed it would be wise to use a dry gasket on the cover, put some silly putty on the cam bolt, a slight bit of petroleum jelly on the timing cover cam button and torque the cover down. this is to check the end play of the cam. Oh make sure the cam is back as far as possible first and that the rear cam core plug isn't set to far in and pushing on the back of the cam. Personally when rebuilding a AMC V8 engine I machine the cam bolt head so there are no markings and then polish so it is smooth and crowned slightly. Then use a Delron inserts epoxied to the timing cover to limit cam walk. Yes I can be annul but 20 years on my 401 and still running strong. I only had one problem with the engine and that was the cam didn't have a groove cut into the front bearing journal and after years of heavy footed driving it took out the disco gears. ended up machining a groove in the cam and no concerns since. 

The thrust bearing race sits against the block surface, so the needles don't run on the block.

http://theamcforum.com/forum/uploads/119/AMC-RollMaster-Cam-Sprocket-Backside.jpg

Hope this helps,RD.

Oh! In that case the block is toast/unrepairable/How much will you pay me to take it off your hands . Oh! torrington is a bit overkill but they are encapsulated by a heat treated shell so the bearings would not contact the block surface nor gear, then you'd have to machine the bearing also to compensate. A must for Helical cut gears. If the timing set has a larger footprint then problem solved.

Edited by WARBED - Jul/30/2015 at 12:19pm