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JeepScrambler
02-05-2009, 11:25 AM
Welp, I finally found a 401 V8 to take the place of my 360 V8 I have in my '85 CJ8 Jeep Scrambler. The 360 only has a couple thousand miles on it since I rebuilt it but I have been wanting to put a 401 in the Scrambler for some time. The 360 has a 670 cfm Holley Truck Avenger, performer intake, Harland Sharp 1.6:1 roller rockers, hedman headers, and a crane cam but I cannot remember the specs on it. This engine is then going to go in my '84 CJ7. Here are the current drivetrain specs on my Scrambler:

-NV4500 5 spd
-Atlas II 4.3:1 Transfercase
-Dana 60 front axle, 5.13 gears, Detroit locker
-Dana 70 rear, 5.13's, Detroit Locker, narrowed to front width
-40"x13.5"-R17 Goodyear MT/Rs

Since I already have my '84 CJ7 built for the trails and rocks, I mainly use the CJ8 during the summer for trips to and from the lake although it is built (yeah, it gets babied)! It is about a 30 mile trip to the lake and another 30 back and I also do some interstate and other longer highway trips. Since I do run it on the highway the majority of the time with sustained higher RPM's (2200-2600) would I need to address any of the oiling issues? I am not sure of the timing cover condition on the current engine so should I just go ahead and pick up a new timing cover to prevent any future headaches? Any other oiling upgrades/parts y'all would recommend (oil filter adaptor, pushrods to increase crank oil, different cam bearings, different oil pump, Crank scrapers, etc)? Since I am going to to a complete rebuild on the engine would I be better off buying a complete rebuild kit or should I buy the parts I need separate? If I buy a complete kit, who has the best prices and quality? If I buy the parts separately, what pistons (I am wanting to stay on pump gas so nothing over 10 to 1), cam (I have read many prefer the summit part # K8600), and other parts with their part numbers do y'all recommend? Could I actually come out with significantly more power for only slightly more money if I buy the parts separately? I will be running a Holley Truck Avenger carb, performer intake, and a set of shorty headers (anyone have suggestions on a set I should run?) Would I benefit much from running roller rockers on this engine as well? If any body has any more info to throw at me let me know! I am wanting to build this motor right(avoiding current and future oiling issues to extend engine life) with a significant HP increase while still keeping it somewhat streetable(at least as streetable as a Scrambler on 40's can be!!!) Sorry for the long post!!!

JERSEYJOE
02-05-2009, 12:35 PM
Welcome to the forum. You have come to the right place to find a talented pool of AMC motor heads to help. I also have a CJ 7 wit ha 401 as well as a J-20 that I just completed a 401 for. You can't go wrong with a stock type rebuild. Keep the cpmpression at 9.5 to 1 or lower to be able to use regular. You can still make 400 hp and lots of torque. I am running an Engle cam in mine with the Harland Sharp rollers. The performer is good as is the Holley 670. Oiling mods can be limited to the reduced ID cam bearings, a mid plate, new cover or as wild as you want including dry sump ect. Really not needed for what we do. Wait for some of the senior guys like MUDRAT, FUZZ 401 and TUFCJ to respond with detaled recommendations.

MC our host can supply everything you need.....

Dusty
02-06-2009, 02:10 PM
Keep in mind if you ever plan to go to Throttle body injection. like the howell system that certain cams and intakes will give you headaches.
but then again in the fuel injection arena i am not the one to ask i have screwed my last two builds listening to the wrong advice and wrong info ...... ishould have stuck to carb'd motors. they always ran well but the ability of going from sea level to 10000 ft without any need for carb adjustments has been nice. no more on trail adjustments :!:

JeepScrambler
02-06-2009, 02:38 PM
Jersey Joe,
are you running 9.5 to one compression pistons in your 401? Are you running 91 octane without any problems? If so, where did you purchase them from and do you have a part number? I am leaning more towards buying the parts individually so I can get different came bearings and such I need through this site.

Dusty,
I have thought about a TBI system but have heard several people complain they are not getting the maximum HP with a built 401 and a TBI system. Have you had any trouble with yours? Also, which cam would you recommend that would work well with both a carb or TBI? I still love the simplicity of a carburetor is another reason I keep steering away from a TBI system; well that and the initial cost of one!

Thanks for the info so far! :lo1l:

JERSEYJOE
02-06-2009, 03:26 PM
THEY ARE KEITH BLACK PISTONS. IF YOU WANT TO RUN 8.5 TO ONE THE STOCK TYPE CAST ONES ARE FINE FOR A MILD MOTOR. SEE THE KB WEBSITE. MAKE SURE YOU TELL THEM WHICH CC HEADS YOU ARE USING. THE EARLY ONES WITH THE 58 CC CHAMBERS AND NON-BRIDGED ROCKERS DO NOT HAVE HARDENED EXHAUST SEATS AND FOR EXTENDED STREET MILES YOU NEED TO HAVE THE SEATS REPLACED. I AM ALSO RUNNING AN ANCIENT EDELBROCK WATER INJECTION SET UP AS EXTRA INSURANCE. I LIKE TO RUN 91 OCTANE BUT IT WILL WORK WIT 89. I HAVE RUN THIS EXACT SETUP PREVIOUSLY AND MY CURRENT J-20 PROJECT IS STILL IN THE BUILD STAGE.

Dusty
02-08-2009, 12:00 AM
Jersey Joe,
are you running 9.5 to one compression pistons in your 401? Are you running 91 octane without any problems? If so, where did you purchase them from and do you have a part number? I am leaning more towards buying the parts individually so I can get different came bearings and such I need through this site.

Dusty,
I have thought about a TBI system but have heard several people complain they are not getting the maximum HP with a built 401 and a TBI system. Have you had any trouble with yours? Also, which cam would you recommend that would work well with both a carb or TBI? I still love the simplicity of a carburetor is another reason I keep steering away from a TBI system; well that and the initial cost of one!

Thanks for the info so far! :lo1l:

I wish i could tell you the cam to run but i am at a loss, i ran a howards 479 lift 222 dur @ .050 292 adv dur on a 114 lobe sep and it was great with a torquer and 600 holler double pumper, took the carb off ditched the headers, went to manifolds single 2.5" exhaust and the TBI and this motor became full blown turd. i am currently emailing back and forth with mc on this one. i totally botched my last two efi motors. i seriously wonder if i am loosing velocity with the TBI kit over my old holley double pumper. i really like the TBI at times because it will never die but the lack of bottom end power and mid range sucks. WOT is what my old mid throttle used to be. i imagine its a combination of issues i screwed with exhaust, headers and then added TBI all in one weekend, i dont normally do that all at once but i scored the tbi for 800 and i had header issues and i wanted to quiet the rig down from the dual 3" pipes and i had a jeep trip actually my bachelor party in 6 days to go on so it was done.

i'll get back to you when i find a winning combo till then i can only offer my wild ass guess. which is i think i need to find a cam that maintains higher vacuum especially with the big 670 tbi unit that they send you to maintain bottom end snap. i suspect a cam like the lunati cam i cam looking at with the sharp ramps. high lift and cam even timing like it is will lend itself to dynamic compression, and will keep up vacuum and combined with the performer intake over my torquer i hope to increase velocity to a point where the bottom end power will return to my rig. Right now my 304 2bbl powered cj 7 walks all over my 401 powered cj7 in ever aspect but idling ability. the 401 with the TBi will idle over anything but the rest sucks.

i'll keep you posted.


heres what i am thinking this go around
Advertised Duration (Int/Exh): 256/262
Duration @ .050 (Int/Exh): 213/220
Gross Valve Lift (Int/Exh): .484/.507
LSA/ICL: 112/108

8.5 pistons
58 cc heads
stock manifolds ported out
dual 2.5 exhaust
performer intake

I am still concerned that i am cutting my motor off at its knees with too small a cam but we'll see. what sucks is the fresh short block i have is a .030 over motor with the forged speed pro 9.8:1 pistons on 58 cc bridged heads. I really think that i may source some lower compression pistons but then that means i have to tear down a perfect good already setup short block..................... SO you can see my dilema

otherwise my current motor is a std bore stock compression motor with the howards cam, 58cc early heads, manifolds, torquer intake..... that needs machine work. the other motor is a cheaper option but how i setup it up is yet to be decided. i like the idea of lower compression in a trail rig. but i may have to take what i already have and make it work



one of the more balanced motors that a buddy and i built was a 9.8:1 with comp cam 270H an airgap intake and a 770 holley though he later changed to the 670 and a performer for better results towing with a th400 but with the t18 in his cj the 770 and air gap had no problems. but overall a great engine holds 20-21 inches vacum with that 670 performer held 18 in with the 770 and the air gap. but weight was an issue the cj 5 was light and had small tires the cherokee chief he put that motor into had a th400 33's and weighed alot more so it needed the changes. remember you are building a jeep. keep it simple with cj's and lighter rigs we've always been able to get away with a little more cam and drive around it but big tires heavy rig i error on the safe side.


shorty headers the only ones i know out there are edelbrock's otherwise i just run manifolds anymore. i've grown tired of header headaches and the heat they create. i used to try and squeeze every last pony out of the motors. now i just do a mild port match on the manifolds and the heads, clean up the exhaust ports. a good valve job witha performer intake and i live with a motor that idles at 500 rpm and that will spin down the road

JERSEYJOE
02-08-2009, 08:39 AM
Call me old fashion but I like to run combinations that are tried and true. Stock heads with minor throat and bowl cleanup, Performer rather than a Torker. The cam I like to run in 401 Jeep motors than need low end torque but also some HP for towing is the ENGLE 5054 which is .501 lift int and ex and 214@.050 with 112 lobe centers. Perhaps the split pattern one that Dusty mentions is a bit more aggressive and would also work fine. I always resist the temptation to over cam any Jeep that needs road manners. AMX's and Spirits are another story.

Dusty
02-13-2009, 02:08 PM
i am hoping with my build up that with the 9.8:1 pistons the longer exhaust duration might help some otherwise i have always really like the engle grind that jersey joe pointed out. i would be inclined to run that if i was going with stock compression. probably could have gotten away with it on my higher compression but i was a little detonation shy

JeepScrambler
03-10-2009, 04:07 PM
Hey thanks for the info guys! I appreciate it. I, finally got my 401 here a couple of weeks ago. I'm going to have the machining work done to the block, crank, and heads sometime later next week or the following week. So far here are the following oiling upgrades I plan on doing(I plan to get the parts through bulltear):

-pushrods with .015 smaller feedholes
-cam bearings (increased pressure setup)
-midplate

A couple of other questions:
-which oil pump would y'all recommend, the AMC "HRC" oil pump gears, or the (HP) Oil pump kit through bulltear?
-are the pushrods with the smaller feedholes compatible with guideplates?
-would 9.8:1 compression pistons be to much to run on pump gas or should I stick with something under 9.5:1?
-I think I have my cam choices narrowed down, either the ENGLE 5054, comp cam 270H, or the summit K8600. Just have to decide which will work best for my setup?

Again, thanks for all the help and info so far!
Here's a picture of the 401 and the Jeep CJ8 it will be going in:
http://i6.photobucket.com/albums/y202/JeepScrambler/401_0011.jpg
Sorry, pictures of the '8 are over a year old, they don't show the warn 9.5ti winch mounted, the rear end (dana 70) narrowed slightly to match the front dana 60 width, and decals on the windshield removed! I need to get some updated photos:
http://i6.photobucket.com/albums/y202/JeepScrambler/1985%20CJ8%20Scrambler/PC180008.jpg

http://i6.photobucket.com/albums/y202/JeepScrambler/1985%20CJ8%20Scrambler/PC180001.jpg

jeepsr4ever
03-10-2009, 04:09 PM
Look at the body on that one! :shock:

ironman_gq
03-10-2009, 05:54 PM
not sure but are BOTH the small hole pushrods and bearings neaded? I was under the impression that it was either one or the other. Hopefully MC will chime in

JeepScrambler
03-24-2009, 04:21 PM
If they are both not needed which would y'all recommend, the smaller hole push rods or the bearings?

Also, I was thinking with my Jeep, since it is geared so low and the Jeep the Jeep is usually running at rpm's above idle, would I benefit from running an edelbrock air gap intake over the performer intake? Or should I just stick with the performer? Would there be much of a notable difference?

One another side note, I got the engine to the machine shop to begin some of the machining work. The cylinder walls do not have any ridge on them at all so I'm hoping they will just need hone the walls so I can still be at standard bore to allow plenty of room for a future rebuild.

Jeepsr4ever, yep the body is and has always been completely rust free! My family has owned the Jeep since 1990 when we bought it with 33K miles where it was used primarily to drive around our trails on our ground in the sandhills, haul firewood, etc., it rarely left 4-Low and was garaged every night. I did the frame off build about 7 years ago when the CJ8 had 44K miles. And now it has just over 48K. It spends it winters in a heated warehouse and comes out only during nice weather! But when it is nice I drive it as often as I can! Lots of sentimental value with this Jeep since we have had it since I was four years old.

ironman_gq
03-24-2009, 08:02 PM
If you can I would go with the bearings cause it opens up the options for different pushrods if you ever decide to do anything with the heads or mill anything.

JeepScrambler
03-25-2009, 11:04 AM
Ironman, thanks for the reply. I will be going with the cam bearings. I have a question about the rocker arm studs. I am having the heads machined for the 7/16-14" base and milled down 0.375". Is there any benefit to running rocker arm studs with the upper portion 7/16" or should I run the 3/8". I have searched on summit racing for rocker arm studs and there are many different choices (brand, length, etc.) Which ones do you guys prefer? I plan to run Harland Sharp roller rockers with the 1.6:1 ratio. For my build would the 1.7:1 rockers benefit me at all? Thanks for the help. :t:

ironman_gq
03-25-2009, 02:53 PM
If you use 1.7's you need to make sure you wont have any coil bind in the valvesprings and make sure you have clearance for the valves so they wont hit a piston

JeepScrambler
03-25-2009, 07:07 PM
I believe I will just be sticking with the 1.6:1 roller rockers. Would I be better off running rocker arm studs with 7/16" or 3/8" upper portions. Will the 7/16" studs be notably stonger? I am having the heads drilled to accept the 7/16-20" studs and machined down .375". What is the effective stud length you have all gone with to allow proper set up and adjustment of the rocker arms with the .375" machining? One more quick question: are the non -small holed push rods listed on the bulltear site hardened for use with guide plates?

AMX69PHATTY
03-26-2009, 12:29 AM
On the '70 heads with no guideplates and Harland Sharp 1.6 ratio 7/16 stud rockers I used ARP #100-7101 for sbf. If buying new Roller Rockers and Rocker Studs, and have not bought them yet, why not go ahead and get the bigger 7/16 studs and matching rockers ? As "insurance" ? Wouldn't think the cost difference between 3/8 studs & rockers and 7/16 studs & rockers would be that much. If cost difference is a lot, then it would be a tougher decision. Larger studs just provide higher valve train stability when using beefier springs and more radical cams and higher rpm's. Since I was buying both new anyways, I went ahead and bought the 7/16, but they were used in original screw in stud type heads, so I'm not sure what specs are needed for modified bridged rocker heads, overall length, bottom thread length, length above hex, and top end threaded portion length. Studs do gotta be right so the lifters can be properly preloaded without running out of thread and the poly-lok bottoming out and running out of adjustment (studs too long), or not enough thread engagement of poly-lok on stud (studs too short). Stud length also effects where the socket head jam screw ends up sitting in the top of the poly-lok.

fifesjeep
03-27-2009, 12:57 AM
I used the 7/16" 1.7 Harland Roller Rockers on my heads... The machine shop figured it all for me... They insured proper geometry etc. I didn't have the studs for the 1.7 Rollers but the shop had the ones I needed... I get back to land today... I can look at my reciepts for some part numbers etc etc. With my set-up there is no binding etc... After the shop milled the bosses (roughly the thickness of the stud nut & guide plate added together)... they drilled and tapped the bosses and when they did they went into the water jacket... Not an issue (IMO) as everything was sealed and I have been running it like that for over 2 years, no leaks etc.

JeepScrambler
03-27-2009, 10:13 AM
Hey, yeah if you could get me some part numbers and possibly some of the specs that would be great!!!

JeepScrambler
08-06-2009, 04:48 PM
Its been a while but I'm finally getting back to working on the 401. I'm getting ready to select the pistons to use in the engine. I am wanting to keep the compression ratio around 9.5:1. The block will be bored .030 over. Does anyone have any piston recommendations that will keep me at that compression ratio? I was looking at the KB354-030 but I have heard these require a bushing in th wrist pin. Would I be better off with forged pistons or Hypereutectic aluminum? Also, what rings should I choose, cast iron or moly? And where is a good source to buy these rings from? Thanks for all the help! :t:

jeepsr4ever
08-06-2009, 05:59 PM
We can accomodate pistons for you with rings. We are setting up for H13 tool steel pins and have forgings available for virtually any compresison. Give a shout when your ready to pull the trigger on pistons.

fifesjeep
08-06-2009, 07:34 PM
IMO... go with the forged pistons... and make sure the garage doing the work zero decks it or slightly has the pistons in the hole .005" to .007"... for quenching reasons... Definitely check out the Bulltear stuff... as well as everybody elses... compare and then look for the best deal(s) etc.

Mudrat
08-08-2009, 07:21 AM
JeepScrambler that is a seiously fine looking CJ-8!! And I can see why your are looking for an ideal build.

Taking into account what you plan to do with it - which sounds like mostly road work, you can build a 401 on the mild side and still have enough ass to do what you need to without the super expensive high-tech parts. Little touches like bushed pistons, the cam oil mod, and I agree with Ironman on the push rods and with AMX69 on the 7/16 studs with 1:6 rollers if you think you need them - a wee bit less friction, but like he said make sure your shop understands about angles and binding. The little things to reduce friction, add to HP and economy.

Pistons are personal :-| If your wanting to stay with 87 octane and a 8.5-9.5:1 CR, cast will probably serve you well. Look at the hundreds of thousands of miles on stock motors as evidence they work. If your pushing the envelope with routine hi-RPM passes, race fuel or Nitrus then super-whamadyne high tech is the only way. I think any of the cams mentioned would work well with a Performer - not sure about any future EFI set up, I'm still mulling that over myself. You won't find a cheap R4B anywhere (cheap is a relative term to some folks though #-o ). The major thing to keep in mind, and that was mentioned, is vacuum. If your going to tow ANYTHING you'll need the brakes to stop you and the load, and if you don't have them already put in a vacuum assist brake system (dual diaphragm 7' or 8') will do you nicely. So the cam and intake need to provide at least ( and BARE MINIMUM is) 16 in, better is 18-20 inches. The Torker intake is a misnomer in my opinion - had one on a 304 and hated it. Even tried one on a 327, 4-bolt SBC and it sucked!! Stay to the high side on the carb 650-700 CFM. It's easier to restrict air flow than it is to open.
The HD oil pump from MC gets me 60psi cold, 30-35 warm without a mid-plate on my 360 (bored, balanced, yada, yada, yada), but I'm looking to do that later as insurance against wear.
Engine work should include trueing both block and heads, line bore mains and cam. If your doing the work balance the rotating assembly best you can (or pay the shop to do it ). And if your reusing your con-rods, gett'm refurb'd! In the oil valley, clean up the flash around the oil drain holes and any casting flash that will keep oil from flowing back down. I try and chamfer the holes a little to help the flow. Not a big deal, but one of those 'little things' to get the oil back to the pump as fast as it will go. I've seen guys paint the inside of the oil valley to help as well - but I've not tried it.
Heads - THE most critical part of your build. It allows the air/fuel mixture into the cylinder and holds it all together while it explodes several thousand times per minute, then lets the gases out. Where ever you can improve flow, do it. Port match to the intake , smooth but don't polish the intake path (you still need some swirl to mix the air and fuel) and polish the exhaust to reduce carbon build up. You need some back pressure on the exhaust so you don't suck burnt gases back in when the piston starts to move downward. This is the balancing act on the guzz-out side and takes some research to get right. While it's combusting you need to have good valve seats to hold it all together. You've heard of 3 and 5 angle valve jobs to provide good valve seating and a 3 angle would suffice. And make sure all your valve springs are matched (and not binding). This will apply an even load on the cam and make your motor much happier :t: Valve diameter is also something to consider. Stock 401's have a 2.025 intake and 1.68 exhaust diameters, this should be enough, but you can always open them up if you have the $$$.
If your not going to go too extreme in running this rig off road or trying for a 10 sec pass in a straight line, you shouldn't need a crank scraper or stud girdle. A good oil pump, properly spaced pick-up tube and windage tray will get you through.
The exhaust needs to handle all the air flow leaving the engine of course, and the design is all theoretical. Long tube headers get low end, short tube headers get better high end, just as small primary tube with 1 5/8" diam to a 2 1/2 collector will do better for low-medium end grunt than a 2 1/4 to 3" collector - unless your running flat out down the strip. So you'll have a trade off of hi/low power based on road/off-road manners and the desire for where you want your torque band. What that trade of is depends on you. I would go with the 1 5/8 to the 2.5 collector with a cross over pipe (improves cylinder scavenging in a dual exhaust set up) before it gets to the muffler - after that a 3" pipe will do ya :t:

Good luck on the build and we DO expect pictures and progress reports :t: :!:

JeepScrambler
08-13-2009, 09:47 AM
Mudrat, thanks for all the info and advise!

Got my pistons on order from Jeepsr4ever last weekend, they should be here in two weeks or so. The pistons are forged, are set up for a 4.195 bore and chevy piston rings (1/16, 1/16, 3/16) and a CR of 9.5:1. Anyone have any recommendations on what type of piston rings I should order (cast, chrome, moly, plasma-moly)? I have been looking at these sets from summit:
http://www.summitracing.com/parts/TSR-CR2455-30/
http://www.summitracing.com/parts/TSR-CR2455-35/
http://www.summitracing.com/parts/TSR-CM2455-35/

fifesjeep
08-13-2009, 10:09 AM
I used chromoly rings in my 360... I didn't have any issues with the rings seating...
Another thing you can do is go with Chevy valves... they're a lot lighter but, machine work will be needed... (this is probably overkill for what you plan on using the motor for but, it's another Idea)...

JeepScrambler
08-24-2009, 08:02 AM
Still collecting parts for the build, but I do have one more question about the piston rings. One set I have looked at are file fit http://www.summitracing.com/parts/TSR-CR2455-35/ and have a slightly larger bore of 106.680mm. The other set are not file fit http://www.summitracing.com/parts/TSR-CR2455-30/ and have a bore of 106.553mm. The are both the same price but I was needing to know which would benefit my build. Are the file fit rings much more work than the non fileable ones? Or should I just go with the non-fileable ones and be done with it? Thanks again for all the help. :t:

Mudrat
08-26-2009, 05:50 PM
All rings are fileable for fit, except the spiral type and they are self-adjusting :?

JeepScrambler
12-15-2009, 10:53 PM
Progress has been slow on the 401 build since I am currently living and working in Houston, TX and all of my Jeeps and the 401 are back in Kansas. But I have been able to get most of the parts ordered that I am needing to complete the build, including some forged 9.5:1 pistons from bulltear along with the oiling pump kit with some of the upgrades.

I do have one more question regarding rocker arm studs. I am having the head machined for 7/16"-14" base and milled down 0.375" for the guide plates and ARP studs to run Harland Sharp 1.6:1 roller rockers. I know this is a pretty common procedure for those wanting to run roller rockers on the later model AMC's so does anyone have the ARP part number for the rocker arm studs I will be needing?

I have searched and all I have come up with is that I should use SBC or BBC studs, but there are several different options for that as well. Can someone give me a part number so I can get these ordered!

I was able to go back home to Kansas for two days around Thanksgiving so I figured I'd better get the Scrambler out and snap some current photos! :t:

http://i6.photobucket.com/albums/y202/JeepScrambler/1985%20CJ8%20Scrambler/7.jpg

http://i6.photobucket.com/albums/y202/JeepScrambler/1985%20CJ8%20Scrambler/3.jpg

JeepScrambler
12-18-2009, 07:37 PM
Got my Harland Sharp 1.6 ratio roller rockers orders as well as the ARP rocker arm studs. The studs I am going with have an effective length of 1.75" with the threads being 7/16-20" and the base studs threads being 7/16-14". They are ARP part number 135-7101 . That's all the progress I have for now!

I still haven't decided on what cam and an intake I will be running. I'm leaning towards an Offenhauser intake http://www.summitracing.com/parts/OFY-5917/ since I already am running the Edelbrock performer on my 360, and I have an old school set of offy valve covers I will be using. And for the cam, possibly an Engle, part number 5052H or the 5054H, or a custom grind; still not sure yet.

I'm definitely open to suggestions since I won't be ordering these parts for a month or so.

AMX69PHATTY
12-24-2009, 03:23 AM
ARP 135-7101 are the studs I used with HS #S4004-7 Rockers in 1970 AMC heads.
The ARP #134-7103 studs were too short, not enough thread ingagement.
Sounds like you've got the right studs for the 7/16 HS rockers.
Might want to remove the locking set screws from all the Poly Locks and run them all the way down onto the studs to make sure they're all smooth with no burrs in the threads.
Would suggest using a pair of adjustable length pushrods and a pair of solid lifters temporarily to determine correct pushrod length once a cam is chosen. Keep an eye on bottom of rocker arm to rocker stud hex clearance where they screw into the heads, as well as rocker geometry throughout the entire valve travel range.

A little pricey, but like the Lunati part #31702 grind #SPT1-285-300.
It's a dual pattern cam, allows about 10:1 or a little more CR, and still should work with pump gas since the Intake Valve closing angle bleeds off some CR.

Need to pick a cam and slide it in the completed short block and use a pair of solid lifters and adjustable length pushrods to determine correct pushrod length before ordering the puchrods, and check piston to valve clearance. Have the new hydraulic lifters on-hand so any pushrod pocket depth differences between the solid and hydrauilc lifters can be compensated for when determing and calculating correct pushrod length. Each cam can be different, they may have a different base circle radius dimension which will affect correct pushrod length. I used Comp Magnum Pushrods. They're available in a lot of off-the-shelf stock lengths. If a stock length can be used it might save some money on pushrod cost over a purely custom length pushrod.

Cam I guess depends on desired RPM range and the Lunati is listed as good from 2500 to 5600, and the rpm range will help determine what Intake Manifold for the same range. I'm a believer in the Torker Intake on an AMC as long as the gearing and such lets the engine get up to about 2500 before loading it up, so depends on rear end gears, tire size, and converter stall speed if an auto.

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