Mild 401 Build

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   Hi All, I'm building a 401 for a friend, it's from his dad's 74 Javelin (original owner) and only had around 28,000miles on it when it was parked and everything looks great with minimal wear.  It's been over 10 years since I've done an AMC so have a few questions:
What are you doing for pistons, Wiseco seem like a good option though with the bore being so true we aren't too keen on boring it 30 thou.  Don't need anything radical, 9.5:1 is fine.
How about timing chains, I seem to recall some having oiling issues for the distributor gear?  Is Romac still decent?
Bearings...what's a good brand?
Gaskets...Fel Pro still any good, especially the head gaskets?
Thanks in advance!

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AMX401 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Mar/16/2009 Location: Edmonton, AB Status: Offline Points: 599	Post Options Post Reply Quote AMX401 Report Post Thanks(0) Quote Reply Topic: Mild 401 Build Posted: May/02/2021 at 9:37pm
	Hi All, I'm building a 401 for a friend, it's from his dad's 74 Javelin (original owner) and only had around 28,000miles on it when it was parked and everything looks great with minimal wear. It's been over 10 years since I've done an AMC so have a few questions: What are you doing for pistons, Wiseco seem like a good option though with the bore being so true we aren't too keen on boring it 30 thou. Don't need anything radical, 9.5:1 is fine. How about timing chains, I seem to recall some having oiling issues for the distributor gear? Is Romac still decent? Bearings...what's a good brand? Gaskets...Fel Pro still any good, especially the head gaskets? Thanks in advance!
	Regards, Jeff...

Trader Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6881	Post Options Post Reply Quote Trader Report Post Thanks(0) Quote Reply Posted: May/03/2021 at 9:39am
	DDS and Racetec sell STD bore 401 forged pistons at approx. 9.5:1. Both are good quality and you need a little more clearance for a forged piston anyhow so honing will get you there. The 3/4" and 7/8" silent timing chains with steel sprockets are fine for a street build. ALL chains sets have to be checked for proper oil passage alignment. Many posts with pictures and drawings on that subject. King make the better bearings in my opinion now. If the crankshaft polishing is just under size for the rods I'll use the Pontiac 400 rod bearings as they offer .001" undersize. You have to grind off the locating tabs but that's fine as bearing crush holds the bearings. Bearing crush has to be measured, as this will tell you if the rods need resizing. I have had no issues reusing the factory forged rods for street motors. New rod bolts are a good investment. As a kit, Felpro are a good gasket set. Watch out for bargain sellers on-line as some I've come across seem to be knock offs or maybe sets the don't pass inspection but are being picked up for cheap profit.

AMX401 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Mar/16/2009 Location: Edmonton, AB Status: Offline Points: 599	Post Options Post Reply Quote AMX401 Report Post Thanks(0) Quote Reply Posted: May/04/2021 at 11:08am
	Thanks, great info and nice to see more manufacturers of AMC pistons!
	Regards, Jeff...

PHAT69AMX Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/07/2007 Location: West Virginia Status: Offline Points: 5919	Post Options Post Reply Quote PHAT69AMX Report Post Thanks(0) Quote Reply Posted: May/04/2021 at 12:43pm
	Sadly today's aftermarket parts all, every one of them regardless of brand, are questionable, unreliable. It just ain't what it used to be even only ten years ago. One must disassemble and inspect to the finest detail every single piece part imho to be safe. Even cam lifters must be disassembled & internally inspected, as flaws, defects, even metal chips have been reported found, as an example. Yes, for some odd reason for like the past 20 years or so cams & cam sprockets just fail one way or the other about 95% of the time to line up the distributor oil passage. New out-of-the box cam snout distributor drive gears with the oil holes drilled in the wrong plain which would NOT oil have also been posted. Brand new Rear Main Seals that crumble in your hand... Mechanical Fuel pumps that fail in hours, ripped out diaphragm rod slots, dropping out rod seals... It goes on... It's a minefield... tread lightly, cautiously, slowly, deliberately, and inspect every piece part, aspect & detail. Just one old dude who's spent to much time on AMC social media for a couple decades plus opinion, worth what it costs ya. Peace Edited by PHAT69AMX - May/04/2021 at 3:49pm
	Link to a Short YouTube Burnout Video

Heavy 488 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Apr/27/2019 Location: In the Status: Offline Points: 3553	Post Options Post Reply Quote Heavy 488 Report Post Thanks(0) Quote Reply Posted: May/04/2021 at 12:52pm
	The price you pay for trying to keep an artifact on the road.

AMX401 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Mar/16/2009 Location: Edmonton, AB Status: Offline Points: 599	Post Options Post Reply Quote AMX401 Report Post Thanks(0) Quote Reply Posted: May/05/2021 at 9:33pm
	Unfortunately, due to covid spiking like mad in Alberta I will have time to take my time. Sadly, I find issues with pretty much everything you buy nowadays so I'm used to it...I guess we've taken our "throwaway" society to a whole new level.
	Regards, Jeff...

javsst70 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Jun/15/2008 Location: Peoria, IL Status: Offline Points: 114	Post Options Post Reply Quote javsst70 Report Post Thanks(0) Quote Reply Posted: May/06/2021 at 8:27am
	If you use one of the std bore forged pistons with 291-C heads would you need to do anything else to prevent detonation at 10.5:1? I want to use the heads from my current 360 on a similar build.

Trader Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6881	Post Options Post Reply Quote Trader Report Post Thanks(0) Quote Reply Posted: May/06/2021 at 3:42pm
	This depends on your fuel availability. Here, even premium is 10% ethanol and going to 15%. Ethanol is an octane booster but has much less BTU's. The combination leaves you hard pressed to get an iron head engine to run well on 10% ethanol 91 without major detuning above 9.7:1 SCR.

BassBoat Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Aug/29/2008 Status: Offline Points: 1719	Post Options Post Reply Quote BassBoat Report Post Thanks(0) Quote Reply Posted: May/06/2021 at 4:23pm
	Compression ratio is not the only thing that determines suitability for driving on pump gas. A camshaft with 230 degrees of intake duration at 050 and a lobe separation angle of 112-114 degrees will work differently than a camshaft with 208 degrees of duration and 108 lobe separation. You can use the effective compression ratio calculator on the KB-Silvolite website to get an effective compression number based on your engine specs and the intake closing of your cam. This number is just a number, but it will show you how things trade with cam and compression ratio. I can tell you that with an effective compression ratio of 8.5-8.75 you can pretty much run on 93 octane even without good quench. Not everyone can get 93, and a 360 or 401 typically has good quench as long as the pistons don't have soup bowl dish. Pick the rpm range you want, pick the cam that will operate at that range, and then match the compression to the cam using the effective compression tool.

AMX401 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Mar/16/2009 Location: Edmonton, AB Status: Offline Points: 599	Post Options Post Reply Quote AMX401 Report Post Thanks(0) Quote Reply Posted: Jun/01/2021 at 12:47pm
	I saw a note on the forum that the clevite rod bearings have no tangs and rely on bearing crush...being both old and old school I’m slightly paranoid of this...has anyone had any issues or is there a brand that makes rod bearings that have the tangs on them, I need 10 under.
	Regards, Jeff...