Well I have been collecting nailheads and parts for a while to build a fresh motor for the company hauler. I have come to the realization that it takes about 2.5 401's to have enough parts to build a fresh one. We wont talk about the expense right now. I have a good running 401 with factory 2-4's in the war wagon right now but its plenty loose. It came out of a 65 wildcat that the PO had rebuilt about 10000 miles before parking it for 15 years. Only problem is the rebuild he paid for was only a ring and bearing job. It must have at least 15-20 thous. clearance in the cylinders. I didn't want it down for the duration so I started rounding up stuff to build a good fresh one. Bought this 401 with turbo 400 off of a CL ad, got it home, tore it down, and although it was locked up from condensation in the cylinders it still made a good .030 with only a hint of a ring grove left in the top of one cylinder. Man I have heard nailheads are made from some good high nickel***** but this the first time I have created smoke while boring a block and I took two cuts not one. Please ignore the hammer, I dont know what the hell I was doing with it at the time. Nailheads have a hellofa lot of casting flash around the lifter bosses. Actually the first item on the adjenda before boring was to remove this unsightly and potentially fatal mess. Ah much better I hate those expansion type oil galley plugs so I always put screw in plugs in the chevys I have worked on in the past. It's not as easy with the nailhead. The oil passages are pretty close to the plug sealing surface. Care must be taken not to block them off if tapping for screw in plugs. I had already started tapping before taking this pic but here is an example of the problem. Since the overall length of the plug exceeds the depth of the oil passage in the front of the block some trimming has to be done. I chucked the plug up in my lathe and since this is not a rocket engine I just took a grinder to it for some speedy length reduction. Plus chucking the plug up tight enough to cut it down with tool steel would mangle the threads pretty good. Now you can only take off so much on the bottom end of the plug so some has to be taken off of the hex socket end too. I used a 3/8" brass collar to hold the plug this time since its getting kinda short. Then the same grinding action. Just have to remember that this is the end the wrench goes on so cant take off too much. Heres the finished product after some beveling on the bench grinder. and heres a pic of the front three installed after some carefull tapping to get the threads just the right depth. Damned thats a lot of typing for an old fart and its past my bed time so I'll add some more later. ZZZZZZZZZZZZZZZZZZZ
Love those nailheads. Had a 66 Gran Sport 401cu, super turbine 300 trans, posi-rear. Fun car. Great engines.
Round two: Here is another galley plug you have to hunt for. Its hidden behind a plug on the back of the block. I already cut some threads in it in this pic. Again dont thread it to much at first as some fitting has to be done to keep the plug from screwing in too far and blocking the oil hole. Here is the installed plug peeking down through the distributor hole. This plug does not have to be cut down as it can stick out the back of the galley without interfering with anything. just thread the galley so that the plug doesnt go in too deep and block the oil passage. On to another problem easy to miss. After disasembling the rocker****emblies you will probably find substantial wear on the rockershafts and rocker arms. This is where many may cut corners to save money but running worn parts here puts undue side loads on the valve guides causing them to wear faster. Plan on spending about $300 to replace the shafts and all the rockers. The stands and springs can be reused. Oh by the way, remember the pic of the nasty casting flash around the lifter bores? Here is a pic of what I knocked loose before getting out the die grinder. What kind of damage do you think some of this could cause if it came loose in the engine?
Thanx for starting this thread and for the excellent photos! I'm just starting a build on a '54 roadmaster 322 that will be a spare engine for my '37 truck. That engine has all the same issues that you've gone over so far.
Good info there..................I'm rebuilding a 401 as we speak. So far everything looks very good, though I did have to replace the cam and everything it touches. Bytheway, who sells the rocker arm "tips" for the Nailhead??
Ive got a 322 that I want to start tearing into maybe this thread will get me off my**** and do it. There is nothing like the sound of a good rumble that a nailhead makes. Subscribed!
Well I didn't get much done on the nailhead today. After getting my bill paying business done I called on a CL ad on yet another 401 and SP400 about 90 miles from me. Struck a deal and went and picked it up. I'll try to get back on this tomorrow after work and unloading and finding room in the shop for the stuff I brought home today.
Put the crank in dry and torqued all the mains to check the bearing clearance with plastigage before****embly. If you have never used plastigage its some cool stuff. I used to use inside mic's on the bearings, outside mic's on the crank then subtract the i/s dim from the o/s. As this will work too there is the posibility of one or both mics being off a little or maybe not gettign a true reading with the mic and not getting the correct answer. Got a good 2 thous clearance on the crank. Put a piston and rod in with out rings and checked the clearance on the rod bearing the same way all was good so out came the piston and crank and cleaned the plastigage off the bearing surfaces. Well my camera battery died and I was all geared up to put this thing together. so instead of putting the camera battery in the charger and waiting around a while, I got to work. I dont know about you guys but when I put an engine together I dont like any distractions anyway. Nothing special about this part anyway, its just like any other motor. Oil everything, torque everthing, keep it clean. Fast forward. Camera battery is all charged up now I always thought the rockers on the nailhead looked funny. They look like there on backwards. Story I heard is buick came up with this design to keep the engine narrow so it would fit in the early 50's engine bays. Its one thing that makes this such a popular motor with the hot rodders, it fits where most big cube motors wont.
finally time to start making it look pretty. I rounded up a 66 Q-jet intake the other day. Man those things are pretty scarce. I have a NOS Edelbrock Q-jet that I picked up at a swap meet a while back. I always had good luck with these carbs and this is the first Edelbrock I've laid my hands on. The heat riser passages on this intake are wider than the carb base and sitting down on the intake the linkage below the right side base surface of the carb hits the manifold not letting the*****erflies open all the way. Buddy gave me a piece of 3/4 x 6 aluminum bar stock so I used it to make a spacer to mate the two together. Step one, cut out the rough shape and drill the mounting holes I cut the trottle bore holes with my drill press and a couple of Starrett hole saws. (used lots of oil and patience) Machined some clearance for the linkage with the old trusty die grinder. I got a q-jet sandwich. throttle blades open all the way, gaskets will seal top and bottom, and linkage clears now. I had picked a pair of Fenton repop valve covers and valley cover a few months ago at the DFW Swap Meet. Looks like O'brien Truckers stuff. Dresses up the nailhead pretty well if I say so myself.
I also have one of those rare Q-Jet intakes on my nailhead. Snagged it on egay for a buy it now price real cheap. I heard say they produce better power than a factory 2x4 set up. Although I would love to have something that had a little more cool factor involved.
Nice valve covers and valley cover. Need some pics of the finished product for my web site Thanks, Dennis
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