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401 to HEI

Printed From: TheAMCForum.com
Category: The Garage
Forum Name: AMC V8 Engine Repair and Modifications
Forum Description: AMC-made V8 engine mechanical, ignition and fuel from basic repair to high-perf modifications
URL: https://theamcforum.com/forum/forum_posts.asp?TID=50307
Printed Date: Mar/28/2024 at 6:39am
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Topic: 401 to HEI
Posted By: motiv8ya
Subject: 401 to HEI
Date Posted: May/19/2013 at 12:44pm
I am putting an HEI Distributor in my AMC 401 Jeep build. The engine is rebuilt with a Melling MTA-1 RV Cam and has not been fired up for break-in yet. With all of the stories of "HEI's eating up cam gears" I am contemplating swapping the new HEI gear with an old AMC factory distributor gear from an old points distributor that came on one of my donor 401's. The speed shop guy says I won't need to swap the gear because the cam is new (gear not matched to a different distributor gear) but I'm not a gambling man. Anyone have any experience with this?.  

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1979 CJ7 - AMC 401 (.040), Melling MTA-1 RV Cam, Edelbrock Performer Intake and #1406 Carb, AMC TH400
1977 CJ7 - AMC 401 (.040 over) Melling MTA-1 RV Cam, Edelbrock Airgap Intake, HEI, Howell TBI



Replies:
Posted By: whizkidder
Date Posted: May/19/2013 at 1:28pm
The speed shop guys are thinking Chebby - where the cam gear is part of the cam. Ours is bolted on, so important to use an OEM set, or a matched set for Bulltear.

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Ron Frost
marne1ancient @ gmail.com
910 nine two two 0563

"There is no limit to what a man can do, so long as he does not care a straw who gets credit for it. Charles Montague


Posted By: 390spirit
Date Posted: May/19/2013 at 1:33pm
the cam gear bolts on, its not part of the cam like SBC's. so where did they get the cam gear?

if you got a set of gears that came from the same engine that is your best bet. or you can get a matched set from bulltear

not a good idea to use a dist. gear from one engine and a cam gear from another, most likely will be a disaster

i got a set from Bulltear for mine, did not want to take any chances.


Posted By: 390spirit
Date Posted: May/19/2013 at 1:34pm
lol Ron beat me to it


Posted By: motiv8ya
Date Posted: May/19/2013 at 3:00pm
Thanks guys, I built both of my 401's and completely forgot about that fact. Now that I'm thinking correctly, I remember reusing my Mallory Unilite Distributor and gear from my 304 on my first 401 build, (hope that one holds up now too). I definitely don't trust the chinese hardened gear that came on the HEI.

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1979 CJ7 - AMC 401 (.040), Melling MTA-1 RV Cam, Edelbrock Performer Intake and #1406 Carb, AMC TH400
1977 CJ7 - AMC 401 (.040 over) Melling MTA-1 RV Cam, Edelbrock Airgap Intake, HEI, Howell TBI


Posted By: motiv8ya
Date Posted: May/19/2013 at 7:55pm
Here's the two side by side. I tried swapping the gears but the factory AMC gear doesn't fit on the HEI. The roll-pin holes are at different heights so it pulls the top of the gear into the shaft causing it to lockup and not rotate. Looks like I'll be rolling the dice with the gear that came with it.

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1979 CJ7 - AMC 401 (.040), Melling MTA-1 RV Cam, Edelbrock Performer Intake and #1406 Carb, AMC TH400
1977 CJ7 - AMC 401 (.040 over) Melling MTA-1 RV Cam, Edelbrock Airgap Intake, HEI, Howell TBI


Posted By: whizkidder
Date Posted: May/19/2013 at 8:09pm
You can drill the HEI shaft using the OEM gear as a guide.

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Ron Frost
marne1ancient @ gmail.com
910 nine two two 0563

"There is no limit to what a man can do, so long as he does not care a straw who gets credit for it. Charles Montague


Posted By: motiv8ya
Date Posted: May/19/2013 at 10:11pm
The holes will intersect and I think it'll weaken the shaft. The roll pin holes are just slightly off, like the thickness of the washer between it and the housing.

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1979 CJ7 - AMC 401 (.040), Melling MTA-1 RV Cam, Edelbrock Performer Intake and #1406 Carb, AMC TH400
1977 CJ7 - AMC 401 (.040 over) Melling MTA-1 RV Cam, Edelbrock Airgap Intake, HEI, Howell TBI


Posted By: Charles Smiley
Date Posted: May/19/2013 at 10:24pm
Why not drill the new hole in the gear to match the shaft so the shaft weakening isn't an issue? Did I miss something?


Posted By: whizkidder
Date Posted: May/20/2013 at 7:47am
Originally posted by motiv8ya motiv8ya wrote:

The holes will intersect and I think it'll weaken the shaft. The roll pin holes are just slightly off, like the thickness of the washer between it and the housing.


In that case, I'd measure the distance from the flange that locates the housing in the front cover to the top of the gear, and either trim the housing or gear to make it the same dimension as the OEM distributor, and use the existing hole. (if a thinner washer wouldn't make it fit as is...)

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Ron Frost
marne1ancient @ gmail.com
910 nine two two 0563

"There is no limit to what a man can do, so long as he does not care a straw who gets credit for it. Charles Montague


Posted By: jgarverick
Date Posted: May/20/2013 at 11:28am
Not sure if this will help or not but I'm running a Mallory HEI in my car. The distributor didn't come with a gear or a hole in the shaft. The install instructions stated to use the old gear and drill a hole through the shaft using the old gear as a guide and that's what I did. It may have come with some sort of drill jig, I can't remember as it's been a while.


Posted By: motiv8ya
Date Posted: May/20/2013 at 4:11pm
Originally posted by Charles Smiley Charles Smiley wrote:

Why not drill the new hole in the gear to match the shaft so the shaft weakening isn't an issue? Did I miss something?

Good call! Thanks


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1979 CJ7 - AMC 401 (.040), Melling MTA-1 RV Cam, Edelbrock Performer Intake and #1406 Carb, AMC TH400
1977 CJ7 - AMC 401 (.040 over) Melling MTA-1 RV Cam, Edelbrock Airgap Intake, HEI, Howell TBI


Posted By: motiv8ya
Date Posted: May/20/2013 at 4:38pm
Originally posted by whizkidder whizkidder wrote:

Originally posted by motiv8ya motiv8ya wrote:

The holes will intersect and I think it'll weaken the shaft. The roll pin holes are just slightly off, like the thickness of the washer between it and the housing.


In that case, I'd measure the distance from the flange that locates the housing in the front cover to the top of the gear, and either trim the housing or gear to make it the same dimension as the OEM distributor, and use the existing hole. (if a thinner washer wouldn't make it fit as is...)

That sounds like another great option. I wasn't sure if I could shave some material off the top of the gear without ruining it. The factory gear made contact with the HEI housing without the washer (thrust washer?) installed and locked it up. The roll pin holes are about 1/32" off

I think I'll try to redrill the gear first. If that doesn't work then I'll shave the top of the gear and look for a really thin washer.   


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1979 CJ7 - AMC 401 (.040), Melling MTA-1 RV Cam, Edelbrock Performer Intake and #1406 Carb, AMC TH400
1977 CJ7 - AMC 401 (.040 over) Melling MTA-1 RV Cam, Edelbrock Airgap Intake, HEI, Howell TBI


Posted By: scott
Date Posted: May/20/2013 at 4:50pm
I'd throw the HEI in the trash & run the OEM distributor.


Posted By: White70JavelinSST
Date Posted: May/20/2013 at 4:57pm
I don't know wether to think I got lucky or what.
In the middle 70's I swapped in a new Mallory dual point distributor. I didn't swap the cam gear out then. The car was driven about 40 to 50 thousand miles after that. No trouble.
When the Mallory was obsolete, (Mallory didn't support it with replacement parts) I swapped the dual point for an MSD billet distributor. Again I didn't tear off the water pump, front case, and replace the gear on the cam.  I pulled the distributor out after about 2 to 3 thousand miles and saw no excessive wear or damage. Now nearly four years later and probably 6000 miles additional on the car, I haven't seen problems.
I guess I was just lucky.
 
BTW both of the replacement distributors had iron gears.
 
 
Just my personal experience
Armand


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70 Javelin SST, second owner, purchased 1972


Posted By: motiv8ya
Date Posted: May/20/2013 at 5:36pm
Well that was quick and painless, hope it actually works. I drilled another 3/16" hole through the gear about 1/32" higher and reused one of the factory washers after I filed the inner lip off of it. Worked like a charm!

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1979 CJ7 - AMC 401 (.040), Melling MTA-1 RV Cam, Edelbrock Performer Intake and #1406 Carb, AMC TH400
1977 CJ7 - AMC 401 (.040 over) Melling MTA-1 RV Cam, Edelbrock Airgap Intake, HEI, Howell TBI


Posted By: Charles Smiley
Date Posted: May/20/2013 at 6:07pm
 
Ditch the GM HEI. Putting electronics inside that hot cap filled with Ozone and sparks flying around is something only GM would dream up.
 
These photos are my J10 401.
 
I run the 1980 Motorcraft?AMC dizzy (curve it) and run the Motorcraft/AMC "blue-ribbon" box or the repalcement MSD box in the photo.
 
The MSD version has a dashmount advance control.
Get the cap adapter, cap and rotor for the 8mm snap in wires it all comes from circa 1980 mustang 5.0 V8.
 
I put the Motorcraft system in dozens of cars. The only hard part is learnig how to recurve them but you can find plenty of Ford guys with a Sun machine tha tknow how.
 
I ran this combo on road race tracks for almost 10 years. That car saw 7000+ rpms for sustained periods of time and never missed  beat.


Posted By: Charles Smiley
Date Posted: May/20/2013 at 6:08pm
I hate how this website distorts photos and can't maintain the original rectangular aspect ratio!!!
 
Here's the advance control where the Jeep ashtray used to go.
 


Posted By: Ron R
Date Posted: Jun/10/2013 at 9:46pm
I just installed an e bay HEI and ended up using the old stock gear and shaving it down on top to fit.
No problems yet, have about 3000 miles on it so far.


Posted By: motiv8ya
Date Posted: Jun/11/2013 at 5:28pm
Originally posted by Ron R Ron R wrote:

I just installed an e bay HEI and ended up using the old stock gear and shaving it down on top to fit.
No problems yet, have about 3000 miles on it so far.

How do you like the HEI? I'm hoping to be problem free also.

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1979 CJ7 - AMC 401 (.040), Melling MTA-1 RV Cam, Edelbrock Performer Intake and #1406 Carb, AMC TH400
1977 CJ7 - AMC 401 (.040 over) Melling MTA-1 RV Cam, Edelbrock Airgap Intake, HEI, Howell TBI


Posted By: WesternRed
Date Posted: Jun/11/2013 at 5:53pm
I have the Mallory HEI, worked all right for a while, but now I seem to be having issues with the advance not returning all of the time, MSD next time I reckon.


Posted By: Ron R
Date Posted: Jun/11/2013 at 10:44pm
I love it, more power, smoothed out the idle, crisper throdel, can't complane for 200.00 with wires.


Posted By: motiv8ya
Date Posted: Mar/08/2014 at 10:15pm
http://s487.photobucket.com/user/motiv8ya/media/IMG_5770.mp4.html" rel="nofollow - http://s487.photobucket.com/user/motiv8ya/media/IMG_5770.mp4.html

Here's a link to my 401/HEI/TBI, it's been a while since I started the project but I finally got it running and broke the engine in. 


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1979 CJ7 - AMC 401 (.040), Melling MTA-1 RV Cam, Edelbrock Performer Intake and #1406 Carb, AMC TH400
1977 CJ7 - AMC 401 (.040 over) Melling MTA-1 RV Cam, Edelbrock Airgap Intake, HEI, Howell TBI


Posted By: 70AMX401
Date Posted: Mar/08/2014 at 10:25pm
Bothered by the fact that everyone thinks they need an Hei. Run a 78 and later factory distributor or a pertronix ignitor.   You are just upgrading from points to electronic.   It is just a switch. You aren't talking a big HP increase.

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70 AMX 401/727

66 Rambler Classic 770


Posted By: motiv8ya
Date Posted: Mar/09/2014 at 10:40am
Originally posted by 70AMX401 70AMX401 wrote:

Bothered by the fact that everyone thinks they need an Hei. Run a 78 and later factory distributor or a pertronix ignitor.   You are just upgrading from points to electronic.   It is just a switch. You aren't talking a big HP increase.


The other 401 I built and put in my 79' Jeep has an Edelbrock carb, Performer intake, Mallory Unilite Distributor and an MSD Box. I built this engine for my 77' with the same internals and wanted to try something different for myself so I went with the Airgap/HEI/TBI combo. My next 401 build will have a torker manifold and some other ignition setup. I like to mix things up, no sense in having three of the same.

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1979 CJ7 - AMC 401 (.040), Melling MTA-1 RV Cam, Edelbrock Performer Intake and #1406 Carb, AMC TH400
1977 CJ7 - AMC 401 (.040 over) Melling MTA-1 RV Cam, Edelbrock Airgap Intake, HEI, Howell TBI



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