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AMC Jeep V8 engine build; which sealants, RTV, etc to use and where?

JeepScrambler

CJ-oholic
Lifetime Member
City
Claflin
State
KS
I'm finally getting around to assembling my AMC 401 to swap into my 360 equipped '85 CJ8. Been a while since I've built a complete engine so I want to double check on a few things. The '76 FSM for the 401 calls for Permatex no. 2 on the chamfered edge of the rear main bearing cap and along the top and bottom of the lower rear main seal end tabs.

Is Permatex no. 2 the product of choice to use on these specific places on the rear main, or is there a better product out there now to use? I've seen others use black RTV, or some sort of anaerobic sealants like Loctite 518. I know products like this have advanced from what the factory originally had available so I want to make sure I'm using the best stuff possible.

In the past, I've used Permatex no.2 or Aviation form-a-gasket no. 3 as gasket dressing on the timing cover, water pump cover, valve covers, and oil pan, etc. when a cork gasket is used (had an old school high school auto mechanics teacher who did this as well). When a rubber gasket is used, I never apply anything else, only to make sure the surfaces are extremely clean.

Head gaskets I use the supplied gaskets only.

Intake manifold, RTV around the water ports only (at least I believe this is how I built my last AMC V8, been over 10 years).

What is everyone's recommendations for the rear main seal, as well as other areas that do, or do not require any additional sealants other than the standard gasket? Some of you much more frequent engine builders, what are your recommendations?


Sent via smoke signal
 

jammer1

Scrambler Junkie
Lifetime Member
City
Maple Hts.
State
Oh
Here is a excellent site on the amc engine. These guys will answer any questions you have. Kinda like this site is cj8, these guys are as very knowledgeable on the amc engines.
 

JeepScrambler

CJ-oholic
Lifetime Member
City
Claflin
State
KS
Here is a excellent site on the amc engine. These guys will answer any questions you have. Kinda like this site is cj8, these guys are as very knowledgeable on the amc engines.


Didn't get the link in your post!
 

JeepScrambler

CJ-oholic
Lifetime Member
City
Claflin
State
KS
Got it, thanks! I'm actually already signed up on that forum. Just never really post there. Will post my question over there and let everyone know what I find out. Thanks!


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AK-RWC

Legacy Registered User
Gold Member
SOA Member
City
south central
State
AK
I've always used the UltraBlue on the RMS corners and never had any issues on all the AMC engines I've done, except for my own 401 which I've essentially given up on it being sealed.

For rubber gaskets, I'll usually put RTV on one side just to glue it in place and prevent it from squishing out when I tighten it down. I now avoid cork like the plague, but will use RTV on both sides. Even when using paper gaskets (timing chain cover, water pump, thermostat housing), I'll usually do a light layer of RTV to help seal against pitted surfaces, as well as to help hold the gasket in place during assembly. The key with RTV is that less is more. I saw a show once where a Permatex rep gave a demonstration on how to actually use RTV, and he pointed out the instructions: put a light layer on both sides and let it get tacky (10-15 minutes), THEN mate the surfaces.

I've also run a number of different cams (a Crower, both Summits, and a Comp Cams in my 401; and a Lunati in my 360, plus the factory 304 cam in a 304 and the factory 360 cam in a 360), and recently had my 401 tuned on a dyno. I hung out a lot on the AMC Forum when I was first putting the engine together.
 
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cw05

Scrambler Junkie
Lifetime Member
City
Augusta
State
GA
I've always used the UltraBlue on the RMS corners and never had any issues on all the AMC engines I've done, except for my own 401 which I've essentially given up on it being sealed.

For rubber gaskets, I'll usually put RTV on one side just to glue it in place and prevent it from squishing out when I tighten it down. I now avoid cork like the plague, but will use RTV on both sides. Even when using paper gaskets (timing chain cover, water pump, thermostat housing), I'll usually do a light layer of RTV to help seal against pitted surfaces, as well as to help hold the gasket in place during assembly. The key with RTV is that less is more. I saw a show once where a Permatex rep gave a demonstration on how to actually use RTV, and he pointed out the instructions: put a light layer on both sides and let it get tacky (10-15 minutes), THEN mate the surfaces.

I've also run a number of different cams (a Crower, both Summits, and a Comp Cams in my 401; and a Lunati in my 360, plus the factory 304 cam in a 304 and the factory 360 cam in a 360), and recently had my 401 tuned on a dyno. I hung out a lot on the AMC Forum when I was first putting the engine together.

What was in your opinion, the best 'all-around' cam for the 401 for a mix of 90% street/10% light duty offroad.
 
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