401 engine, builder and advice wanted.

10a Rubicon

Hi, My name is Danny and I'm from Australia. I have a 74 CJ6 that I'll be starting a ground up build on soon. The plans are for a rig that will see plenty of highway, sand dunes and some rock crawling. I have a pair of J20 diffs and T18. It currently has a 67 high compression 4 barrel 290 in it. I would like some engine advice, I really want a 401, problem is there's none in this country. How hard is it to come by a 401 over there? What would I expect to pay for one? It may be a better to get it built over there, I havent found any AMC guru's over here yet... I would like the motor to make power to 6000rpms, the biggest cam I can get away with but still be able to idle ok, it will have some very low gearing so should be able to get a decent sized cam? Any advice or opinions are much appreciated so tell me what you think!!! Cheers Danny

jeepsr4ever

$1000 for a good core is almost the average here. Crating and shipping ...maybe another $5-800. Some decent pistons and a breathing intake and carb is all it would take to make some decent streetable power.

tufcj

The last 401 that AMC made was in 1978, so there haven't been any made in nearly 30 years. A lot of blocks that would have been scrapped years ago are now being repaired. Like MC said, good core long blocks are in the $1000 range. Running engines are more, you might find a short block for less. Look for Jeep Wagoneers, lots had 360s, some had 401s. The 360 can make respectable torque and HP, and are more plentiful, since they were made thru 1991 or 1992.

You might try www.theamcforum.com or www.amccars.net Both have an Aussie AMC section, someone might have a 401 stashed down there somewhere.

Bob
tufcj

10a Rubicon

There are 360's around here in FSJ's, not alot to choose from but they are here. I was wanting a 401 for something a little different and rarer than the rest and who wouldn't want another 41 cubes!!! Is there anything wrong with sleeving a block if I get one that can't be bored any more??? I wouldn't like to get one landed here only to find out it's an expensive boat anchor!!! Is there any other problems I should look for when searching for an engine??? Cheers Danny

tufcj

The factory recommended no more than a .040 overbore on a 401. I've seen bigger, but not without a sonic check. If you get a 401 that's already bored .030 and been used, it may not clean up at .040, so a sonic check is recommended. Cranks and rods are forged on a 401, bearings are listed to .040, but .040s are hard if not impossible to find, so if a crank is .020 or .030 and used, bearings may be hard to find. Nothing wrong with sleeves. If done correctly they're as good or better than the original cylinder. Around here it's $80-100 per cylinder to have a sleeve installed, so it's not cheap, but can save a slightly damaged block. Bob tufcj

10a Rubicon

Thank you for that, Here are my thoughts for an engine build, hopefully achieving 400hp with plenty of torque. Budget isn't to much of a factor, I just want to do it once and do it right! 9 to 9.5:1 compression ratio, forged pistons, Crower cam (45241,45246 or 45916???), bulltear timing cover, oil mods (cam bearings, bulltear oil pump kit?), 4 barrel (air gap?), quadrajet or Holley TA, bulltear HEI with matched gear set and headers. So what factory heads do you recommend for the above goals? I know a 3 or 5 angle valve job is a must but what sort of porting work is required? Keep in mind I'll be using an engine builder that's only experienced in fords and chevs. Or do I just bite the bullet and run a pair of edlebrocks? Cheers Danny

tufcj

400hp should be easy with what you're thinking about, even with iron heads. If you go aluminum heads, I'd bump the compression to around 10. AMCs like to breathe. For iron heads, I'd go with the 71-73 individual rocker style (casting ending in 090 or 993). Have the heads ported, polished and gasket matched, minimum 3 angle valve job. You can get nearly the same flow from iron heads as Edelbrocks, you just sacrifice a little weight. Get the matching valve springs and retainers from Crower. Pay attention of the match of the header to the exhaust port, a little work on the header port can gain a lot. I'm a big fan of Crower cams. I run the 45247 in my Rogue, and the 45243 in my AMX. My AMX ran a personal best of 13.57@103 a couple of weeks ago on street tires and full exhaust. The 916 cam may be a little small for a 401, the 246 may not give you enough low end, the 241 looks good for an off-roader. Sounds like you're on the right track with your build if you can find the 401. Good luck. Bob tufcj