Your donations help keep this valuable resource free and growing. Thank you.
|
Help with 401 heads |
Post Reply | Page 12> |
Author | |
markbritt
AMC Fan Joined: Mar/20/2017 Location: Merriville Status: Offline Points: 5 |
Post Options
Thanks(0)
Posted: Mar/20/2017 at 7:55am |
I just completed a rebuild and paint of a 1973 401 engine and installed it in my Jeep CJ7. After running the engine for a short time, I am noticing that there is a small amount of both oil and antifreeze weeping out of a factory accessory hole in the right front head. This hole is what I use for alternator mount!!!! It is not much - about a thimble amount of antifreeze/oil mix puddled on the timing chain housing.
I suspect that the head must be cracked on the inside causing both water from the water jacket and oil from the oil drain hole to sump. While finding another 401 head may be impossible, can I consider using a head from an AMC 360 as a core for replacement? I have searched on this topic, but cannot find anything. Any help would be appreciated. I spent a year (on and off) assembling and painting this engine to it looks show and now I may have to remove the darn head. Note: I took an old 304 head and sliced about 1/2 of the edge off to see how deep the bolt hole goes as well as the surrounding oil gallery and water jacket. The blue dot is where the bolt hole is. Edited by markbritt - Mar/20/2017 at 7:03pm |
|
304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
Post Options
Thanks(0)
|
A 360 head for that year has bridged rockers. 73 401 was the last year for studded rocker arms. It would be easier to find 74 on up heads, but there are a few late 71 to late 72 heads out there. Just make sure the valves are the same size. I have latr 70 heads which are high compression 291 versions, which wont match due to compression differences. Though they had two different sized valves done for the heads. Some ended up on 4bbl 360 engines while mostly were installed on 401 engines. So I would assume a 4bbl 360 engine would have the large valves, but would need someone who knows heads of all years to chime in on verification.
I would pull the head and have a pro mag it and see if that area can be fixed. Much easier and less costly to redo another head. |
|
71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
|
akimmet
AMC Nut Joined: Aug/02/2012 Location: Republic OH Status: Offline Points: 428 |
Post Options
Thanks(0)
|
Heads off a 360 will work just fine.
If I remember correctly, the 360 and 401 engines used the exact same heads for a given year. Only the 304 had different heads with smaller valves. |
|
tsanchez
AMC Addicted Joined: Jul/09/2007 Location: Arizona Status: Offline Points: 4303 |
Post Options
Thanks(0)
|
If its not leaking internally just stick a 3/8 set screw with sealer in the hole.
|
|
Moffman
AMC Nut Joined: Sep/28/2011 Location: New Jersey Status: Offline Points: 287 |
Post Options
Thanks(0)
|
Got a pic of it? That's an interesting place for a leak
|
|
tsanchez
AMC Addicted Joined: Jul/09/2007 Location: Arizona Status: Offline Points: 4303 |
Post Options
Thanks(0)
|
MOst likely someone put too long a bolt and cracked the inside of bolt boss, just plug it
|
|
304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
Post Options
Thanks(0)
|
I bet at one time either the hole was chased too far with a standard thread chase and cracked when bottomed, or undo pressure was exerted with a bolt still attached, possibly dropped or hit face down to the ground when pulled out of an engine bay. That area is thin and would not be the spot I would yank an engine with. Diagonal from front driver to rear passenger. Not diagonal front passenger to rear driver side, even though you can bolt up the heads to mount a chain with for pulling. |
|
71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
|
markbritt
AMC Fan Joined: Mar/20/2017 Location: Merriville Status: Offline Points: 5 |
Post Options
Thanks(0)
|
Picture - yes I have several and will post tonight. I have one of those diag cameras on the long want, so I was able to get right up to the hole.
My main concern here is plugging the hole Yes, that will resolve the drips, but can this crack be large enough that anti will still flow into the oil behind the plug? |
|
Moffman
AMC Nut Joined: Sep/28/2011 Location: New Jersey Status: Offline Points: 287 |
Post Options
Thanks(0)
|
If you're lucky, you should be able to get away with plugging it with an insert and some sealer. To me the most concerning part is not only coolant but oil as well. How does your oil and coolant look, any cross contamination inside? |
|
ghinmi
AMC Addicted Joined: Apr/04/2010 Location: Grand Rapids MI Status: Offline Points: 978 |
Post Options
Thanks(0)
|
If you end up needing a head, let me know. I sold a large lot of parts to a buddy in Indianapolis including a bare 1973 401 head. The other was damaged so only the one is usable.
|
|
1975 Cherokee S - Turbo Hemi stick shift autocross/drag race/street 9.97 @ 140.4
|
|
Post Reply | Page 12> |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |