junkyard 360 magnum? big block?

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Idaho

Idaho

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I have a '73 340 needing rebuild for my Demon clone project but am considering all options. It's intended for weekend street fun, maybe occaisonal 1/4 mile runs.

I ran across this article:

http://www.hotrod.com/techarticles/engine/hrdp_0804_small_block_mopar_engine/viewall.html

Here's a quote:

It isn't a problem to find a decent used 5.9 Magnum engine from late-model used-parts sources, ripe for whatever performance plans you might have. In fact, Magnum mills seem to have survived the rigors of service much better than the earlier engines, owing to improvements like a better ring pack with thinner moly rings and effective MPI fuel injection with modern engine management, all leading to a reduction in bore wear. It's not uncommon to pop the lids on a 100,000-plus-mile Magnum and discover negligible bore wear, while the older carbureted small-blocks would have been spent. Good bores and a sound engine are essential to the foundation of a low-buck performance engine.
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Given the above, and the fact you get a hydraulic roller cam, I'm thinking of finding a relatively low mileage junkyard engine, and doing what's in the article. Here's a summary:

swap to LA timing case cover (free)

use distributor/ignition I have (free)

use the TQ carb I have (cost of carb kit)

purchase intake (they use Mopar M1 single plane) ($)

purchase cam (their choice if suitable for 4 speed) ($)

Edelbrock Magnum heads ($$$)

suitable roller rockers, pushrods (they use Comp 1.6:1-ratio aluminum roller rockers, Comp Magnum pushrods. ($)

headers (thinking Hedman) ($)

They get 448 hp/445 ft lb with this package. Seems to me I'd spend less with this build than rebuilding my 340.

I'd be taking a chance on the unknowns of the used engine, but getting a roller and the rest of the noted durability advantage of the "better ring pack".

I have thought about going big block. I'm thinking this option would give me more power than a similar build using the 340, cost a lot less than going big block, less work to achieve and easier to maintain.

Something that surprised me:
With the Magnum's stock, dished pistons, the compression ratio was 9.0:1
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I guess I thought all these 360s were low compression. Seems awesome to me that you don't need to get into the bottom end.

Something that bugs me:

The base engine outperforms the modded engine at lower RPM, all the way to 4000 rpm! I suppose I'm revealing my ignorance here but this kinda shocked me. It seems the base engine would break the tires loose better.

Makes me wonder if the street performance (which to me includes being able to roast tires) is all that great.

I have a hemi in my '06 Ram pickup. It's power is really only impressive at around 4000 rpm and up. It does not break the tires loose at will with the automatic tranny. Of course its a heavy 3/4 ton 4x4.

The only really high performance engine I've driven was a built Ford 460 in a similar pickup and the power was jaw-dropping.

So do all high performance smallblocks really suck at low rpm?

Maybe a heavy duty clutch and making good use of it will do the job? :burnout:

The junkyard 360 magnum seems like it might be the best bang for the buck but maybe I need to think more seriously about a big block. Or maybe I'm just confusing myself with numbers. Wish I knew someone with a built smallblock in an A-body.
 
Idaho, Go find a 360 magnum, what they say is true, They are true performers, You don't need eddy heads, just get a set of RHS heads, even in stock form they work very well, good to 500+ HP, I dropped a 95 360 in a 71 swinger, stock bottom end, RHS heads, re-ground factory cam from bullet, .477/.477 lift, .218/.218 dur. @50 on a 112, summit headers, RPM airgap knock-off intake, 650dp, MSD dist & Mallory 6AL, PTC 11" 2800 stall, 3.73 gears, drove several times 100 miles round trip to the track, car ran consistant 8.0s @ 84, 12.5s @ 104-105 shifting at (get this) 5100 RPMs on 1.80/1.81 60fts. 27" MT DRs, installed a sniper N2o kit & pilled it for 125 shot, ran a best of 12.48 @ 95 & that still wasn't a crisp run, all the others times it just blew the tires off.

As for low end torque, theres plenty, I layed down a solid 180 ft. marks on the DRs even shifted into 2nd. I say go for it!!

Watch the video in my sig. thats the car running against a 69 Yenko 427 Camaro, He beat me running a 12.4 too my 12.5, I was on motor NA.
 
If you do this, save all the EFI stuff and tell me what you want for it.
 
Look up LXguy. Has a nice running JY sourced 360 engine.
 
JoeDust451 said:
Idaho, Go find a 360 magnum, what they say is true, They are true performers, You don't need eddy heads, just get a set of RHS heads, even in stock form they work very well, good to 500+ HP, I dropped a 95 360 in a 71 swinger, stock bottom end, RHS heads, re-ground factory cam from bullet, .477/.477 lift, .218/.218 dur. @50 on a 112, summit headers, RPM airgap knock-off intake, 650dp, MSD dist & Mallory 6AL, PTC 11" 2800 stall, 3.73 gears, drove several times 100 miles round trip to the track, car ran consistant 8.0s @ 84, 12.5s @ 104-105 shifting at (get this) 5100 RPMs on 1.80/1.81 60fts. 27" MT DRs, installed a sniper N2o kit & pilled it for 125 shot, ran a best of 12.48 @ 95 & that still wasn't a crisp run, all the others times it just blew the tires off.

As for low end torque, theres plenty, I layed down a solid 180 ft. marks on the DRs even shifted into 2nd. I say go for it!!

Watch the video in my sig. thats the car running against a 69 Yenko 427 Camaro, He beat me running a 12.4 too my 12.5, I was on motor NA.
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You went from 12.5@ 105 N/A to 12.48@ 95 on a 125 shot? You're right, I'd say that wasn't a crisp run!
 
Idaho,x2 on the Magnum.I swapped one in myself.Good bottom end,bolt heads and a foller cam,call it good.Boils down towhat you want,and what you have to spend.
 
Grab the MAgnum, ditch the Eddy head idea, Buy some EngineQuest Magnums (they make more power than RHS ootb and are cheaper). Keep the camshaft tight. Install Eddy RPM Air-Gap--Burn rubber. Any 360 I've built with the EQ heads has never made less than 470hp and 480 ft/lbs on the dyno. FWIW. J.Rob
 
If you cam wait,and on a budget.You can get your cam core ground for less than half of a new cam.Thw stock cam is so small is why it makes more down low. The magnum 380 crate is the same long block with a bigger cam,and single plane intake.
 
I can not see a Magnum engine being a suckie bottom end performer. A lot has to do with gearing and stall converter. Also, when you swap a cam out for a larger duration one, the RPM band goes up. If the converter and rear gear do not match, crappy performance follows. As with any engine.
 
I sure appreciate the replies. Of course I have more questions now! I'll be happy with whatever tidbits you can add. Just so you know, I'm serious about doing this. It's been a long time coming. My budget is flexible, but this is a toy, so I want to be very cost effective. I don't want it to delay paying down my mortgage so much that I have to work a lot longer!

I've not been real active on the forum but lurking around long enough to know that the advice is generally very good. Anything really out of wack gets challenged. So I plan do a 360 magnum.

This from LXguy helped to convince me (thanks crackedback). Hope he doesn't mind me using it:

http://www.forabodiesonly.com/mopar/showthread.php?t=156081

OK, its a 5.9 magnum shortblock straight out of the junkyard. Custom comp grind cam, Iron Ram 1.9 valve heads, Eddy Air Gap, Quickfuel 750, Hooker Comps, TTI X, Dynomax Ulraflow mufflers dumped at axle, built 904, Ultimate Converter, 4.11 gear, cal-tracs and mono leafs, 8" hoosier slicks, Car is all steel with full factory bench seat interior.
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I'm throwing this in just as a reminder:

If I had it to do over again, I'd go with less lift on the cam. Its got (EDIT .544, and that's just too much. It causes valvetrain issues, puts a hurting on the springs, and I cant get the cool Hughes shaft rockers because they're 1.65 ratio. I bet if I had .525 lift the power would be exactly the same.

I would also have the heads machined for better springs than the ones Hughes provides (though to be fair I didn't realize they had to be machined for that when I bought them).
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This just confirmed the deal. He runs high 11s in a 3200 lb car.

I've got about $2800 in my engine carb-to-pan (including gaskets, bolts and oil-LOL), and I think that's pretty good for an 11 second Mopar combo considering I started from zero.
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67Dart273: I'll be snooping around, could be a while as I'm doing bodywork first. We have a big wrecker not far away in Spokane. I think they test a lot of the engines they sell.

Head choice will be an issue, nice to have choices! JoeDust says RHS. LXguy has Iron Rams, RAMM says EngineQuest (found some good info on these 1/2 way through this article).

http://www.popularhotrodding.com/tech/0810phr_chrysler_318_engine/viewall.html


Engine Quest has a viable alternative to the OEM Magnum castings with their iron Lightning cylinder heads. Essentially an OEM replacement casting, the Engine Quest heads feature refined ports and higher flow than the stock pieces, and just as importantly, these are all-new castings without the fatal Magnum head cracks. One of the traditional drawbacks of the original Magnum design was the revision with this cylinder head series to a vertical intake bolt pattern, precluding the use of readily available aftermarket manifolds designed for the earlier LA-series engines. Engine Quest addressed this compatibility issue by offering their Magnum-style replacement heads for either the Magnum-style intake (PN CH318A), or for a conventional non-Magnum-style intake (PN CH318B).
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I'll likely take the custom cam advice from Abodybomber. Seems like a no-brainer as long as their reputation is solid. Hopefully I can avoid the bent pushrod issue LXguy had. Never found his solution - I'll ask.

I'll be doing a 4 speed (I have one from a truck with OD) so no converter issues but I'll have to research on a clutch.

Sure is good to access the knowledge base here.
 
Both joedust and LXguy have had good running inexpensive 360 builds.

Speak with someone about a cam. I get my cams from Brian at IMM and he does a really good job at specing stuff. Just have to be honest about what you are using. He did a hyd roller cam for Mshred and it worked very well.

The stock stick doesn't have enough meat on them for decent lift.

Nice thing about the stock hyd rollers, they will go to 7K if the rest of the valvetrain is right. I've seen short duration hyd rollers turn 6800 with no float.

There are a bunch of different flavors of heads to choose from. If going with 1.92, any of them are fine. if going to a 2.02, I'd lean towards the RHS. As with everything, compare everything you are buying, valves, springs retainers, as not all are outfitted the same. Some have stuff on them that makes rocker arm selection much easier.
 
My car is light (~2900 lbs), but I was pleasantly surprised by the performance of my budget Magnum engine. It's nothing fancy at all, just a stock long block, small cam (218/224, .506/.506), air-gap, block huggers, and a 650 dp. It ran pretty strong with a best time of 7.89 @ 90 mph, and that's with a stock lockup 904, including converter. The only modification to the trans was a TF-2 shift kit. You'll be happy with your choice to go Magnum.





...............and I just realized that everything in this post is listed in my signature. Oh well.
 
...............and I just realized that everything in this post is listed in my signature. Oh well
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LOL - cool and amazing it fits in that little beast.

Found this link for Old Geezer's swap.
http://www.forabodiesonly.com/mopar/showthread.php?t=41302

Good stuff. He kept EFI and went with auto trans so I'm looking for info on how mating up an A-833 will go. I have a unit from a truck, have info on how to deal with longer tailshaft...

( http://www.slantsix.org/articles/4-speeds/ODA833fourspeed1.htm)

but... not sure about the flywheel to clutch issue, and whether I need an engine from a stick vehicle, or if an auto crank will work with a flywheel.

From what I see 5.9 magnums were built 89-02 and came in pickups, dakotas, vans, grand cherokee limited, and durango. Should be lots out there.

Gotta find the right engine, then focus on the details of the build. There's a big rebuilder in Spokane, a freshened shortblock could be an option if I don't find a low mileage one.
 
magnum's use a bearing in the register that the torque converter fits in instead of a bushing for manual trans applications
problem is the crank may not be drilled deep enough for the input shaft of an A-833, so you will need to check that, you can however use the late style bearing with the A-833 trans
you will also need a flywheel balanced for a MAGNUM 5.9 / 360, a regular 360 flywheel will not work,

http://www.mopartsracing.com/parts/trans.html
 
Idaho said:
LOL - cool and amazing it fits in that little beast.
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LOL, there's more room than you would think. It's usually one of the first comments I get.


One thing about finding a good engine. With advances in materials, machining, EFI, and others, the Magnum shows little wear even with lots of miles on them. My engine was just under 100k miles and looked great. What I'm trying to say is don't be afraid of mileage on a possible engine.
 
you will also need a flywheel balanced for a MAGNUM 5.9 / 360, a regular 360 flywheel will not work,
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Thanks. Do you know if the magnum flywheel will work with an 833? If so I'll save almost $300 getting one from a stick vehicle.

UOP - good to hear. Quite a project you did! Didn't like your Wankel?
 
Seems I will want an engine with a flywheel to avoid purchasing the mopartsracing unit (thanks caferacerx). This issue is a little tricky. I read a bunch of stuff. Here's what I understand.

Due to external balancing I must use a magnum flywheel.
The magnum uses a bearing not a pilot bushing.
I may have to trim some off the 833 input shaft.
Those keeping EFI have to notch their LA bell to allow for the crank sensor. I should not as I can remove the sensor.

Here's what I'm not sure of.

Does the magnum bearing fit the 833 shaft or do I need to change over to a bushing as suggested in the post below?

Is there an issue with the type or size of clutch mating the magnum flywheel and LA bell?

I found this way back in archives. I did not find newer posts with clear answers but I may not be using the right terms.

http://www.forabodiesonly.com/mopar/archive/index.php/t-9356.html

Mark Nixon05-25-2006, 08:55 AM
I am having trouble getting my 4 speed tranny to bolt to my new magnum 360 crate motor. I seem to remember reading that you may need to cut the input shaft shorter on the tranny to fit magnum motors because the depth is shallower on magnum then on LA engines. Has anyone out there done this combo or can confirm my problem?

I have done this swap.
All you need is the crank bushing from an '89 Dakota, with a V-6 5 speed (generic application) and it'll bolt up fine, NO CUTTING OF THE INPUT SHOULD BE NECESSARY, but your situation may be different, as you're dealing with Mopar "Performance".
I installed a '73 833 behind a PRODUCTION '93 360 Magnum last year, using a '90 D-150 V-6 bellhousing, and it all basically bolted right together.
Of course, I had to find the right bearing retainer to mate the 2, but it wasn't so bad.

Mark.
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Other tidbits:

Apparently one reason to not keep the serpentine system is the magnum's power steering pressure is wrong for an A body gear.

The magnum block uses different mounts but retains castings for the old mounts as well. This impressed me. Someone was thinking about retrofits. (see pic)

Quick online searching found only engines with 100k plus miles. I'm hoping for much lower and local.
 

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Idaho said:
UOP - good to hear. Quite a project you did! Didn't like your Wankel?
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I like rotaries just fine, they're just not for me. I've always liked the lines of the car but never wanted to deal with the rotary. A friend of a friend had this one for sale, and I had a complete 360 sitting in my garage, seemed like a good idea.
 
One thing to check for.Mock up the headers on the engine stand.Some headers have clearance issue with the truck mount bosses on the sides.I had to grind mine down for hooker super compa.
 
Abodybomber said:
One thing to check for.Mock up the headers on the engine stand.Some headers have clearance issue with the truck mount bosses on the sides.I had to grind mine down for hooker super compa.
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Good point. Also, some people have had issues with the older style starter having clearance issues with the block, myself included. Get a later style Dakota starter (factory mini starter) to avoid this problem. You'll also appreciate the extra room you gain with it.
 
Disregard above. I was very tempted, but I've decided to stick to the magnum plan. I'll likely spend more but learn something in the process and know exactly what I've got.
Unless I go for a big block - not too likely.
Thanks for all the input.
 
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