L.A 360..Magnum ?

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I think it depends on what the 360 currently has whether a 5.9 Magnum might be the way to go. If the 360 is bone-stock with some cylinder bore wear I'd pull it and have the bores sonic-checked. Supposedly the first few years of the 360 used the same casting cores as the 340 so with the bores being .040" smaller you get that much extra wall thickness to play with which makes them the best for a max-effort build. If the 360 LA checks out good with a compression test I'd just put in a cam, intake, headers etc. and have fun, 400 HP should be easy even with stock 8.5:1 (or less) compression.

Magnums are a great option, I have a 5.9L short block in my Duster with a custom-grind Racer Brown hyd roller cam and reused the stock roller lifters. Gotta make sure the top end setup works for it though, I put LA-based Edelbrocks on mine (long story) and had to devise an external oil supply to get oil to the rocker shafts (Magnums oil through the pushrods). If you find an earlier (pre-1997 or so) Magnum block they usually still have the oiling hole drilled in the block to oil LA shaft rockers so that becomes a non-issue, run whatever heads you want in that case! You can also run an LA flat-tappet cam and lifters in a Magnum block with no issues.
 
I bored my 1971 360 to 4.04
so I could call it a 340 stroker, to shut up the car-show-crowd, who almost every one of them will tell you;
"you shouldda built a 340"
I got so tired of hearing that.......
But after I started calling it a 367 stroker 340, not another peep did I hear.
 
AJ/FormS said:
I bored my 1971 360 to 4.04
so I could call it a 340 stroker, to shut up the car-show-crowd, who almost every one of them will tell you;
"you shouldda built a 340"
I got so tired of hearing that.......
But after I started calling it a 367 stroker 340, not another peep did I hear.
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Aand that's why I don't go to car shows anymore lol, unless I'm meeting friends there or it's a "Cars & Coffee" type thing. Really have no interest in strangers talk about my car unless they have useful advice on how to make it faster or better, which show people don't. They're just like teenagers trying to show off and get attention.

Sorry for the tangent LOL... anyway...
 
MopaR&D said:
I think it depends on what the 360 currently has whether a 5.9 Magnum might be the way to go. If the 360 is bone-stock with some cylinder bore wear I'd pull it and have the bores sonic-checked. Supposedly the first few years of the 360 used the same casting cores as the 340 so with the bores being .040" smaller you get that much extra wall thickness to play with which makes them the best for a max-effort build. If the 360 LA checks out good with a compression test I'd just put in a cam, intake, headers etc. and have fun, 400 HP should be easy even with stock 8.5:1 (or less) compression.

Magnums are a great option, I have a 5.9L short block in my Duster with a custom-grind Racer Brown hyd roller cam and reused the stock roller lifters. Gotta make sure the top end setup works for it though, I put LA-based Edelbrocks on mine (long story) and had to devise an external oil supply to get oil to the rocker shafts (Magnums oil through the pushrods). If you find an earlier (pre-1997 or so) Magnum block they usually still have the oiling hole drilled in the block to oil LA shaft rockers so that becomes a non-issue, run whatever heads you want in that case! You can also run an LA flat-tappet cam and lifters in a Magnum block with no issues.
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Yeah gonna pull the engine in the next week or so. Having a new garage door installed and it will be easier to move the car out of the way with the engine in lol. The bottom end sounds fine but it's got a lifter noise or bad cam lobe or something I think..sounds like dead smack in center of the engine. Would be nice if it is standard bore still. If all is well maybe get a good set of pistons with the thinner ring stacks..not the 5/64 . Kb 107 have thick rings right..may sell intake and go with a performer rpm air gap. Had one on a previous 340 worked really well
 
MoparLeo said:
Also pre 73 heads do not have hardened exhaust valve seats for unleaded fuels. More cost on te old heads. Tons of new replacement Magnum heads available cheap. Most have thicker decks to help eliminate cracking.
Magnumswap.com - Your source for Dodge Magnum and Mopar engine swap tech.
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He already has an LA 360 & heads Magnum heads as well also have induction hardened seats snd they suck and crack still... so either set of heads should get a set of hard seats if that's the idea. You arent saving... you re actually going out of your way to spend more to have a iron mag head pos 'that by the time you've swiped the credit card... you could bought aluminum heads and been ahead in weight and flow' .

Never get caught up in head preference.
Weigh the return vs cost and know your power goals.Going out of your way to spend just to run some mediocre production..all cuz you love it so much. Lol expect disappointment.
 
Unless someone is trying to run a certain class or build a stock appearing street car or show car I don’t know why anyone would want to spend money on old cast iron junk.
 
pittsburghracer said:
Unless someone is trying to run a certain class or build a stock appearing street car or show car I don’t know why anyone would want to spend money on old cast iron junk.
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I actually found a remanufactured magnum has 33k miles ..The heads still look like clean castings no rust..500 bucks be hard to beat. I'd like to just pull pan check a few bearings put a car pan on it and a .500 lift cam , headers, 750 carb , rpm intake, correct stall and 3.55 gears should be a fun car and I'd like to hit under 8.0 in the 1/8. Should be able to with that combo I'd think
 
Sounds like someone just doesn't like the Magnum engine. With the exception of the cracking problem, which has been addressed years ago...The heads have a much better combustion chamber shape and better flowing ports without doing anything to them. For a 400 hp motor individual rocker stands have been used by GM for many decades and they didn't all fail.
You can nitpick the shortfalls but there were a lot of upsides to the engine which is a roller cam 360 truck engine. Just like the Gen III 5.7 was the replacement truck motor for the 5.9.
Just a cam and spring change really wake the truck engine up. It was not originally a car engine so the cam was spec'd was for truck gearing and low rpm use.
All Mopar engines are good, you just pick the one you like best and go for it. There is aftermarket support for all of them.
 
My buddy a local Mopar engine builder has finally been visiting this site after my prodding. He built a 360 magnum engine for his son with magnum heads that easily runs 10’s at keystone. I never had an opportunity to port a set of magnum heads as I run all LA style engines. I got to run my fingers through a set of magnum heads at his shop and was rather surprised how nice the short turn was in these heads. But and I said BUTT if you are going to put time in doing a nice set of magnum heads it would kinda suck if they cracked right away for you. That’s that reason went I ported my W2 Econ’s heads I quit when they hit 300 cfm because my part number were prone to cracking, and did so.
 
I like them all for where they work best.
I'm hopping up my magnum with new "junk iron" heads that flow better than aluminum eddy head and with smaller 1.94 chevy size int valves... and have to move nothing nor modify to put them on dressed in full accessories. But I have a flow bench and did the work.
Hey... I just read the opener ..and i thought OP already has a 360..so of you're going to buy heads, by La heads and move on already . You don't need to buy a whole new motor...just rebuild the one you have so it's like new and you don't have to worry about what the $500 motor may or may not have wrong with it. I really don't understand these sensitive magnum people. It really irritates the ever living **** out a me reading the biased attitude. If he had a magnum 360..i would be talking magnum all the way.
Believe that.
But consider this... if this were a thread arguing a solid flat tappet against a roller ..everybody would be talking about how ..."it's not life-or-death"..or .. "the roller ain't **** if you can get the same rate with a flat tap". ...but once it comes to a Magnum..oh "the roller is god"...Same for open chamber verses closed.. vise versa ..because its holding hands with quench, and do you desire it or is not worth it... so on and so forth onnonnonnon. So one day quenches not worth it... the next day using the quench feature as a part of the selling point.
Whats real ..and whats preference motivated advice. Know the diff or you'll be up someone else **** creek.

So let's throw in help either way, because I dont give a flying fart where it ends up 'la or mag' It's his choice.
So if you do Magnum retain the factory rollers and use those they're good to about 600 lift.
Heads...well...you're buying heads because apparently the stock ones no one here likes and it's your money they're spending lol so f it.. what is there for a magnum head? The eddy? Not impressive 'flow wise' and ah yes..more iron 'boarderline' Stk replace stuff that needs 500 in extras to make it right. La heads would work w/modified push rod holes.. now where are those 1.7 shaft rockers though..pricey.. so an accurate 1.6 rocker is out there all day for 450-1,000.00.

The rest you can come with.. like compression and the ring size
5/64 vs 3/16 or whatever, that's the equivalent power adder of a knat fart on the street but why the heck not ..if it happens to be the piston you need as well.


Either 360 will do what you want it to do.
 
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pittsburghracer said:
Unless someone is trying to run a certain class or build a stock appearing street car or show car I don’t know why anyone would want to spend money on old cast iron junk.
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I know if it were me I'd go to the next bore size on the early 360 and use 4" kit, promax heads, victor340 with 1/2 spacer, .engle .560 solid 108lsa, mancini billet time set ,10.2 comp and be done. That will do what he wants and then some.
 
MOPAROFFICIAL said:
I like them all for where they work best.
I'm hopping up my magnum with new "junk iron" heads that flow better than aluminum eddy head and with smaller 1.94 chevy size int valves... and have to move nothing nor modify to put them on dressed in full accessories. But I have a flow bench and did the work.
Hey... I just read the opener ..and i thought OP already has a 360..so of you're going to buy heads, by La heads and move on already . You don't need to buy a whole new motor...just rebuild the one you have so it's like new and you don't have to worry about what the $500 motor may or may not have wrong with it. I really ddon'tunderstand these sensitive magnum people. It really irritates the ever living **** out a me reading the biased attitude. If he had a magnum 360..i would be talking magnum all the way.
Believe that.
But consider this... if this were a thread arguing a solid flat tappet against a roller ..everybody would be talking about how ..."it's not life-or-death"..or .. "the roller ain't **** if you can get the same rate with a flat tap". ...but once it comes to a Magnum..oh "the roller is god"...Same for open chamber verses closed.. vise versa ..because its holding hands with quench, and do you desire it or is not worth it... so on and so forth onnonnonnon. So one day quenches not worth it... the next day using the quench feature as a part of the selling point.
Whats real ..and whats preference motivated advice. Know the diff or you'll be up someone else **** creek.

So let's throw in help either way, because I dont give a flying fart where it ends up 'la or mag' It's his choice.
So if you do Magnum retain the factory rollers and use those they're good to about 600 lift.
Heads...well...you're buying heads because apparently the stock ones no one here likes and it's your money they're spending lol so f it.. what is there for a magnum head? The eddy? Not impressive 'flow wise' and ah yes..more iron 'boarderline' Stk replace stuff that needs 500 in extras to make it right. La heads would work w/modified push rod holes.. now where are those 1.7 shaft rockers though..pricey.. so an accurate 1.6 rocker is out there all day for 450-1,000.00.

The rest you can come with, like ompression and the ring size
5/64 vs 3/16 or whatever, that's the equivalent power adder of a knat fart on the street but why the heck not ..if it happens to be the piston you need as well.


Either 360 will do what you want it to do.
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Thanks for the input I agree. I don't get to biased on either engine. I've never ran a magnum engine except in my old ram. Great engine no issues. Makes sense to use what I got unless I open it up to find major issues which I doubt because it's a good running engine just has what sounds like after tick. Thanks again L.A. it is just wonder if I should use the J heads on it and put bigger valves or just go with some new aftermarket heads. Around 400 hp is where I wanna be ..more importantly into 7 sec 1/8 mile which should be easy lol
 
MOPAROFFICIAL said:
I know if it were me I'd go to the next bore size on the early 360 and use 4" kit, promax heads, victor340 with 1/2 spacer, .engle .560 solid 108lsa, mancini billet time set ,10.2 comp and be done. That will do what he wants and then some.
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Sounds like a good combo for sure. Are the Promax heads decent and is it better to buy bare . I would assume to 4 inch scat kit with cast crank is fine
 
71scamp78 said:
Thanks for the input I agree. I don't get to biased on either engine. I've never ran a magnum engine except in my old ram. Great engine no issues. Makes sense to use what I got unless I open it up to find major issues which I doubt because it's a good running engine just has what sounds like after tick. Thanks again L.A. it is just wonder if I should use the J heads on it and put bigger valves or just go with some new aftermarket heads. Around 400 hp is where I wanna be ..more importantly into 7 sec 1/8 mile which should be easy lol
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Price out some heads. Look at promax.
Heads really make or break a motor.
The old j is good but it would really need work, that's not always or at all cheap.

You can sell the j heads or stash them.
 
71scamp78 said:
Sounds like a good combo for sure. Are the Promax heads decent and is it better to buy bare . I would assume to 4 inch scat kit with cast crank is fine
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Bare? Only if you know setup, have the tools and have a cheaper part source and still be 'quality'. If not, buy complete.
Figure
Springs
$70-300 elgin/comp/pac/herbert/isky/
Valves
$98-400+elgin,ssi,ferrea,milodon,engine pro,etc
Locks
$19- 40 comp super
Retainers
$35-54 comp
Seals-
$12-20 good ones

So it depends on what you are doing..whether or not it's more economical bare or complete. As PBR said ..they do good work. Great product.
 
I think that you can NOT buy Promaxx heads bare. Building them is kind of what they are all about. They probably buy crates of bare
Speedmaster heads and build them to order. Mine should be here any day. :)
 
Bodyperson said:
I think that you can NOT buy Promaxx heads bare. Building them is kind of what they are all about. They probably buy crates of bare
Speedmaster heads and build them to order. Mine should be here any day. :)
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yep. When I called and talked to him he said they are shipped in as raw as they can get them. Then they go to town machining them.
 
MoparLeo said:
Also pre 73 heads do not have hardened exhaust valve seats for unleaded fuels. More cost on the old heads. Tons of new replacement Magnum heads available cheap. Most have thicker decks to help eliminate cracking.
Magnumswap.com - Your source for Dodge Magnum and Mopar engine swap tech.
Click to expand...

71scamp78 said:
Thanks for the input I agree. I don't get to biased on either engine. I've never ran a magnum engine except in my old ram. Great engine no issues. Makes sense to use what I got unless I open it up to find major issues which I doubt because it's a good running engine just has what sounds like after tick. Thanks again L.A. it is just wonder if I should use the J heads on it and put bigger valves or just go with some new aftermarket heads. Around 400 hp is where I wanna be ..more importantly into 7 sec 1/8 mile which should be easy lol
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I pulled the original J heads from my 1972 360 truck engine and the exhaust valve seats were gone; one was sunk about 1/8" so it does happen. I'd only run them if they're in good shape and require minimal machine work since the costs of that add up really fast. On that engine I just found a set of late-70s 360 heads already rebuilt with fresh valves, seats, springs, hardware from a FABO member since it's in a truck and I'm not going for HP (the ports and casting quality were visibly worse than the older '915' heads though). Otherwise if you can swing the cash aluminum heads are by far the way to go. I'm just hearing now about this Promax deal, sounds like a good option. Trick Flows are also a great option for an assembled bolt-on head but I don't know how the price/value compares. Things are changing rapidly in the SBM world it's only been in the past 5-10 years there are more viable affordable options for aluminum heads besides the typical Edelbrocks and such.
 
71scamp78 said:
Really damn. Most cars I've had big blocks in so I'm a little green on small blocks lol.
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It's not etched in stone. They all still need to be sonic tested. Some of the early blocks are thick and some are not.
 
Well I took intake and head off the 360. Looks super clean and it looks like it's never been bored but I don't have a tool to measure. There's not even a lip at top of cylinder bores. The pistons obviously are low compression stock one and they don't look to be bigger than stock. No oversize numbers on them. Here's a pic of the heads they look clean but have the small tulip valves so bone stock low compression engine. I think I'm gonna stick with this LA build. I guess I should just sell these heads not sure what they are worth now days. I'm sure someone could bolt them on and go. Like I said wanting a 400 hp engine or close to it. Should I keep the Performer intake or go with the RPM . It also has a nice new 750 demon carb and I think it would work well in a street strip car..pic attached.

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