So I scored this AMC 401 and spent a good couple hours attempting to get more info from the block and head casting #s. This is what I know so far. This specific mill came from a early 70's wagoneer Block# 3198951 Heads# 18202 Tag on valve cover# 906Z30 All these tell me is the block is a 71-77 year. The letter "Z" on the valve cover tag is supposed to tell me if the cam bearings are under sized or if it was a factory over-bore, or something to that effect, but all I found for that letter is conformation of year and engine size. I will post some pics of the #s I found. My other question is about the trans. The pic shows the pan being stamped a GMC product, And I do believe it is a GM turbo400 but with the AMC bell housing bolt pattern. If I'm correct, is there a specific tail shaft I need since this was behind a transfer case? And do I need a short shaft or a long shaft? Let's load up some pics (sorry for the bad pics, my pain meds were kickin' in) P.S. I learned a bunch of interesting info about these engines (forged crank and rods, poor oiling system, blah blah) but if there is anything else you could add to aid in my quest for knowledge, I'm all ears. Thanks guys!
congrats on scoring a 401.....yes that is a turbo 400. You can use any short shaft th400 with the housing. The trick is the speedo cable...Does yours have a freez plug where the speedo is supposed to be? If not, you will have to bore a hole because the speedo goes to the transfer case on the jeep...Don't be alarmed when you put it in something, the trans is slightly tilted for floor clearance for the transfer case. It will work fine in your car. As far as the "z" code, that just means it is a 401. No idea where you found the info about the cam bearings...Hope this helps.
Thank you Mr. Moyer for your info. I didn't check to see about the speedo cable, I had to climb over a bunch of stuff and couldn't move the trans to get better pics. About the "Z" code. I had stumbled across a AMC website that listed several letters that indicated any internal mods from the factory, but they were all for years 58 to 70. When it showed the listing for the letters for 71 on up they didn't tell me anything other than it was a 401. I believe these are the "dog leg" heads, but would they have 2.02 intake/1.60 ex valves? Thus the 18202 stamp? I also read that you can use mopar 360 roller rockers in these heads and BB chevy ARP main cap bolts also. learning as I go...
If you know where to look, there are more speed parts than you might think for these. I built a 401 and put EFI on it for my Jeep. Torquey beasts with high nickel content blocks. As you'd expect, AMC guys are freaks about this stuff. I used to know a guy that had a glass bodied door slammer with a built AMC 390 in it. Check these guys out for more info. and a forum http://www.bulltear.com/
pull the valve covers off and there are more numbers in there...most heads have the year cast on them also...Probably you do have the 2.02 heads....the later the year of manufacture, the lower the compression (bigger combustion chamber) Also, ALL 401 motors have forged rods and cranks.....there are tons of go fast parts available for these motors...Bulltear is a great guy....got one of his new covers on my engine. Don't know about the man cap bolts. The heads you can use BBc studs and rockers, sbc push rods, and I have heard small block mopar lifters, but summit caries most everything you need....Ebay has several new venders selling stuff like H beam rods and 4 bolt main caps etc....Indy and Edelbrock have new aluminum heads. Milodine has modified oil sump and pan set ups. Also look into running a line in the vally to help get oil to the rear main, an amc weekness under extreme conditions. If you really want to go fast, look into Herman Lewis.....
The bulltear web site has a forum where there is a thread that shows the tech info for all AMC engines. Also alot of info for imroving oiling. Bulltear offers cam bearings that restrict oil to the heads, which is a big problem as the pan can run low enuf to suck air causing catastrophic disassembly. If you don't plan on racing, or high rpm opperation, oiling will be fine. The dogleg ports where used on all v8s after '69. The early d/l heads have individual rockers, no problem converting to full adjutable, the late heads have bridged rockers, which need machining to fit individual stud rockers. Harlan Sharp does make an adj. kit for the bridged heads that take little or no machining.Planethoustonamx.com (Eddie Stakes) has a lot of AMC info also.
Mr Moyer- Thanks again, I will look under the valve covers next time I get a chance, and check for the speedo freeze plug hole in the trans also. Comet- Thanks much for the link! It had all the info I wanted to know. I see these guys putting 2.08 intake/1.688 exhaust valves in these heads. these engines can be lethal if set up correctly. Now I don't have 5k to dump into this engine before I put it in my truck, but I still want to take a peek inside for good measure. Mr Kramer-Thank you much for the valve train and related info! Great info about the oiling issue too. I was reading about someone drilling some drain holes in the lifter valley to get the oil back to the pan a little faster. They also state that once you reach the 500hp mark, the main caps start to walk. I think anything over 400hp would keep a smile on my face. I can't see that being to far out of reach without breaking the bank.
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