Need Help on Magnum 360/380 hp Crate Motor Tech Info

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fatazzchuck

fatazzchuck

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Hey guy's,

I have a tech question about the p5249499 Magnum 360/380 hp crate motor with this roller cam .501/.513 lift with .230/.236 duration @.050 with a 108 lobe ..
Are the heads on this motor plain stock heads? If not what's been done to them?
I'm thinking of buying the heads/cam and installing into a Magnum 5.2 with Holley 750.. 904, Hooker super comp fenderwell headers in a 65 Dart 2 dr sedan weekend driver...with power brake and vacuum assist
What size stall converter and gear ratio would be needed?

Thanks
 
Besides cam the long block is stock.

I got one in my 68 Valiant, the person I bought it off installed a 2800 stall converter but really under geared it 2.96:1. In town I got to drive in 2nd it's liveable but neuters the power substantially. I haven't decided which gear in gonna up grade to but 3.55 would be minimum. But im thinking more like 4.10. Since your doing a 5.2 your power band will move up 300 rpm or so. Mine starts coming in around 2000 rpm so you'd be 2300-2500.
 
Also if you don't have intake yet I'd go rpm airgap. I plan on switching sometime down the road. Theres a shoot out between the airgap and the M1 single plain. Both make similar top end but airgap makes 40 lbs-ft at one point and 20 lbs-ft average down low.
Especially will come in handy were your going 5.2.

Also if you decide to go EQ or edlebrock heads you'll just pick up 30-50 more hp plus opens cam choice since you can go more lift.
 
The engine is a stock engine minus the cam, valve springs and intake. I don't remember pistons being special.

Being the cams intake duration is [email protected], that points to a approximate starting rpm of 2000. You should be looking at a stall converter of approximately 300-500rpm more as a min. You may want the move that up to 3000 because it is in a 318, 42 cubes down from where it came from.

A min. gear recommendation is 3.91's. 26 inch tire to go with it. As a min.

Your P/B are on the border line.
 
Bought a 300hp 360 crate engine last January...Used with 15k miles on it. Been sitting in guy garage for years. He had partially disassemble the engine. He had changed out the stock pistons for KB362 pistons and Eagle SIR rods. He rebalanced the crank but nicked a rod journal putting the engine back together...So it sat....

I had the crank turned...had the block hot tanked and new cam bearing and honed the cylinder....Short block has been reassembled with new rings and bearing...I have the 380 hydraulic roller and a comp roller that is one size smaller...224/230..110 with same lift as mp cam.

Have not had a chance to check out the heads yet...look like standard magnum heads with upgraded valve springs.....Been thinking about getting EQ heads....but no decision yet until i look at the stock heads.
 
273 said:
Also if you don't have intake yet I'd go rpm airgap. I plan on switching sometime down the road. Theres a shoot out between the airgap and the M1 single plain. Both make similar top end but airgap makes 40 lbs-ft at one point and 20 lbs-ft average down low.
Especially will come in handy were your going 5.2.

Also if you decide to go EQ or edlebrock heads you'll just pick up 30-50 more hp plus opens cam choice since you can go more lift.
Click to expand...

I already bought from Ebay the knock off Assault dualplane air gap intake...
No A/C, No P/S so it should work
It's a bone stock 5.2, I'm thinking the stock springs will run the cam, I know it's best to replace but funds are limited like a fat lady squeezing a poot on a church bench, I expect the bashers to chime in but it's not their wallet..
273, Any chance you have a video of your car running? What exhaust are you running?
Always wanted a Thumping Mopar "sounds so good"

If the heads are stock no reason to by them, Just cam and converter for the Mag...

Keep in mind this is a V8 swap from 170 Slant six, so either way I go the car will be faster. ATM it sit's waiting on an eng. I'm already $$$$ way over then planned
I have an extra set Hooker fenderwell headers for sale already posted..

My original plan was 1979 318LA, flat tops, "1990 714 hogged out heads needs 3 angel valve job", "0.28 head gaskets also fits Mag" with 256/268 .447/.455 flat tappet cam, Offy Port O Sonic intake, 500 cfm Holley 2 bbl.. and still may use for mockup

The Magnum 5.2 is in my first gen Dakota parts truck

arc_pc5025_1.jpg


17632335_1620698364637512_4823132020448233695_o.jpg
 
Not replacing the valve springs is foolish.
Say what you want, think what you want.
 
Google "Steve Dulcich" Magnum 360-380 dyno tests.. The factory cam, gets about 6"-8" inches at idle, in drive.... I went, with a slightly smaller Howards Cams: 282/286 advertised, 110 lobe centers,229/233 at.050"... It gets 11 " of vacuum, with a 2800 stall..(Ma Mopar, recommended a 4779 750 double pumper, & 1 .75 primary headers.. I went with the E.Q. heads, (bare castings, 1.92,1.62 stainless steel valves... .. This is where, the real h.p. comes from, on a Magum build..Used Hughes 1110 springs, matching retainers.. & a custom length pushrod( valve train geometry, is big here.. Other wise, you lose valve train parts, very possibly... You need to check out "www.Magnumswap.com).., or check out.."LXguy " members posts... Walker434 , is sharp here.. Rumblefish posts, are words of wisdom , here....
 
If your on a budget, stick with stock cam for now. Cam stall and gears all need to work together. Should be pretty fast as is.
If you can't do all 3 at once do gears 1st then stall then cam. Plus it gives you something to look forward to performance wise after each mod.
 
273 said:
If your on a budget, stick with stock cam for now. Cam stall and gears all need to work together. Should be pretty fast as is.
If you can't do all 3 at once do gears 1st then stall then cam. Plus it gives you something to look forward to performance wise after each mod.
Click to expand...
Might mention" actually checking the sgock cam lobes" ..They DO go flat, due to lack of recommended zinc oils, and weak factory valve spring pressures.. Seen it, on replacement ,Magnum heads....
 
273 said:
If your on a budget, stick with stock cam for now. Cam stall and gears all need to work together. Should be pretty fast as is.
If you can't do all 3 at once do gears 1st then stall then cam. Plus it gives you something to look forward to performance wise after each mod.
Click to expand...

The reason I asked was because I'm currently talking to a guy with heads, cam, and 3000 stall from his build they wasn't fast enough for him and at a great price fer me.
Thanks


Abodybomber said:
Might mention" actually checking the sgock cam lobes" ..They DO go flat, due to lack of recommended zinc oils, and weak factory valve spring pressures.. Seen it, on replacement ,Magnum heads....
Click to expand...

I thought that was a flat tappet cam issue not a roller cam issue???
 
The roller wheel eleminates most of the issues. But there are other parts that wear and hurt the rollers lifters.

The factory FInis an excellent unit that keeps the inside of the engine in great shape. Many here have reported near perfect cylinders with cross hatch marks still seen on the cylinders after many miles. I myself reported this on a 80K 5.9. Others have reported this on higher mileage engines.

Use of a carb doesn't have the FI quality and contaminated oil results due to fuel, carbon deposits getting past the rings will sooner or later get into all the small places of the engine.
 
fatazzchuck said:
The reason I asked was because I'm currently talking to a guy with heads, cam, and 3000 stall from his build they wasn't fast enough for him and at a great price fer me.
Thanks




I thought that was a flat tappet cam issue not a roller cam issue???
Click to expand...
They can be... I "inherited" a freebie 360 Mag, it had three flat cam lobes, It was using Delo 15-40 , with an oil additive... It does happen....
 
ISO: Magnum cam no larger then .550 lift @ 1.6 rockers
Running stock 5.2 Magnum with ported bowl heads, 3 angle valve job, .550 springs, Retainers, locks, stainless steel valves, hooker super comp fenderwell headers, dual stage airgap intake, 904 tranny, 3000 stall, 276 suregrip, P205/65R15, Power disc brake on front

I have a new in box Voodoo Hydraulic Flat Tappet Cam - Chrysler 273-360 268/276 - Lunati Power
I have 318LA I could run this cam in with Magnum heads

Update, the guy I was talking to about the cam sold it locally however I got the 3000 stall from him..
 
Badidea!
Very bad!
A 230 cam is about 276 advertised. In a 5.2 at barely 9/1 compression,these conspire to make a Dcr of about 7.3@142psi. Soggy soggy bottom end. You will for sure need that 3000TC. And don't try this with a 2.73 rear gears.
The power peak will be up around 5400, so forget the stock springs.The shift rpm with a regular ratio 904 will be about 6400.the stock springs will give up around IDK, guessing 4800.
The torque peak will be up around 4000, so yeah gears are a must. Ima thinking 3.91s or better.
With 2.73s the torque peak will not occur until 45mph, and the power peak not until after 60 and the shift speed is about 72mph; this all in first gear.Bad idea.
3.91s would reduce these numbers to 31/42/50
You want performance? Just go straight to 3.91s on the current engine and a 2800TC.Put some springs on the teener so it will pull 5000 and call it done! Those 3.91s will get you about 65 at 5000......at the top of second. Just about perfect for a weekend bomber.The 4bbl and headers will bring the current power level up by some 35 hp, but the torque peak will remain very little changed, so hang on!
If you are on a budget,this is the cheapest, easiest,quickest, way to lay rubber. If you are on a super tight budget, I would try it with the factory TC.
That 230 cam is gonna need gears and springs and a TC anyway, so you might as well start with those, Then,later, If the factory cam is no longer doing it for you, well then you will be ready for a cam, just not a 230*.That 230 wants 10 or 10.5 compression ratio to get rid of the soggy bottom end.
Shoot even the stock cam could use 9.4/9.5 Scr.
Oh yeah, the 750 will be too big in any case. With the 3.91s I would choose a 650DP type carb.
Ok so that's my opinion;"bad idea"

I must say tho with a 65 being some 350/400 pounds lighter than the later A's, it might not be quite as bad as I make it out to be; so if you're not looking for tire-shredding blast-off power, and if you're not against ripping it back out if it really is too soggy, and it's really cheap, well then; Go for it! But get the right springs to hit at least 6400rpm.BTW, the 230 will have great passing power with say those 3.91s,lol; 55 will be about 4300 in second gear.That's a rocket right there......and that gear is good to maybe 75 mph.......
As for me, I'm just getting lazy, and am no longer into doing things twice, or thrice or more ......like I used to be,lol.
 
Last edited:
Uuuuummmm?

AJ/FormS said:
Badidea!
Very bad!
A 230 cam is about 276 advertised. In a 5.2 at barely 9/1 compression,these conspire to make a Dcr of about 7.3@142psi. Soggy soggy bottom end. You will for sure need that 3000TC. And don't try this with a 2.73 rear gears.
The power peak will be up around 5400, so forget the stock springs.The shift rpm with a regular ratio 904 will be about 6400.the stock springs will give up around IDK, guessing 4800.
The torque peak will be up around 4000, so yeah gears are a must. Ima thinking 3.91s or better.
With 2.73s the torque peak will not occur until 45mph, and the power peak not until after 60 and the shift speed is about 72mph; this all in first gear.Bad idea.
3.91s would reduce these numbers to 31/42/50
You want performance? Just go straight to 3.91s on the current engine and a 2800TC.Put some springs on the teener so it will pull 5000 and call it done! Those 3.91s will get you about 65 at 5000......at the top of second. Just about perfect for a weekend bomber.The 4bbl and headers will bring the current power level up by some 35 hp, but the torque peak will remain very little changed, so hang on!
If you are on a budget,this is the cheapest, easiest,quickest, way to lay rubber. If you are on a super tight budget, I would try it with the factory TC.
That 230 cam is gonna need gears and springs and a TC anyway, so you might as well start with those, Then,later, If the factory cam is no longer doing it for you, well then you will be ready for a cam, just not a 230*.That 230 wants 10 or 10.5 compression ratio to get rid of the soggy bottom end.
Shoot even the stock cam could use 9.4/9.5 Scr.
Oh yeah, the 750 will be too big in any case. With the 3.91s I would choose a 650DP type carb.
Ok so that's my opinion;"bad idea"

I must say tho with a 65 being some 350/400 pounds lighter than the later A's, it might not be quite as bad as I make it out to be; so if you're not looking for tire-shredding blast-off power, and if you're not against ripping it back out if it really is too soggy, and it's really cheap, well then; Go for it! But get the right springs to hit at least 6400rpm.BTW, the 230 will have great passing power with say those 3.91s,lol; 55 will be about 4300 in second gear.That's a rocket right there......and that gear is good to maybe 75 mph.......
As for me, I'm just getting lazy, and am no longer into doing things twice, or thrice or more ......like I used to be,lol.
Click to expand...

Did you see this post?
fatazzchuck said:
ISO: Magnum cam no larger then .550 lift @ 1.6 rockers
Running stock 5.2 Magnum with ported bowl heads, 3 angle valve job, .550 springs, Retainers, locks, stainless steel valves, hooker super comp fenderwell headers, dual stage airgap intake, 904 tranny, 3000 stall, 276 suregrip, P205/65R15, Power disc brake on front

I have a new in box Voodoo Hydraulic Flat Tappet Cam - Chrysler 273-360 268/276 - Lunati Power
I have 318LA I could run this cam in with Magnum heads

Update, the guy I was talking to about the cam sold it locally however I got the 3000 stall from him..
Click to expand...

I'd like to find a Hydraulic Roller with .550 lift or less for my 5.2 Magnum and if not..
I have a 79 318LA that has this kit in it now https://www.summitracing.com/parts/cca-k20-221-3/overview/make/dodge
and I bought this Voodoo Hydraulic Flat Tappet Cam - Chrysler 273-360 268/276 - Lunati Power to put in it and run 93 Magnum heads with 3 angle valve job and bowl porting with these springs Valve Spring Kit - 550 and these valves
Valve Kit - Premium Polished Stainless Steel
and use Assault polished aluminum arg gap dual plane intake with a Holley 600 vac 2nd quick fuel carb with hooker super comp fenderwell headers with 10 blade Mopar racing water pump and Holley fuel pump.... Got to start somewhere and the 7.25 suregripe will be swapped out later as soon as I can find what I need

How does that sound?
 
Excellent IMO

Don't mind AJ. He tends to ramble on and on and on while sometimes not realizing he didn't read the post right. He will continue on and on with technical ramblings until you eyes bleed and leave you dazed & confused.

But he means well for sure.

He will be along shortly to complain I'm picking on him being a bully and an assh#%^ and that I'm a bad person.
 
Per post #1
fatazzchuck said:
Hey guy's,

I have a tech question about the p5249499 Magnum 360/380 hp crate motor with this roller cam .501/.513 lift with .230/.236 duration @.050 with a 108 lobe ..
Are the heads on this motor plain stock heads? If not what's been done to them?
I'm thinking of buying the heads/cam and installing into a Magnum 5.2 with Holley 750.. 904, Hooker super comp fenderwell headers in a 65 Dart 2 dr sedan weekend driver...with power brake and vacuum assist
What size stall converter and gear ratio would be needed?

Thanks
Click to expand...
This cam,(288/292) ,in a 9:1-5.9, in at 104 makes a Dcr of 7.0@135psi. In a360. Check out the torque graph;about 360# at 3000. it makes 410# but not until 4500. The bottom end is somewhat (being kind) weak. I ran the 292* cam in my 360 @11.3Scr and the bottom end was so weak I had to install 4.30s and a 3.09 low gear set to get off the line,( that's a starter of 13.29), and I had a Clutch!
Now put same heads and cam into/onto 9.0 -5.2,with a 2.76 gear; I dare you. A Dcr of 6.96@133psi and 2.76s and no valve springs, no matter how you look at it "is a very bad idea".
That 904 will want a 1-2 shift rpm of well over 6500, probably about 6800 to come in at 4000. If you shift it at 5400say, the Rs will drop to 3200, and there just ain't no power down there. Well there is but it's feeble. The 5.9 has about 210 there, compared to 380@5400, and maybe 340@6800
You will want to gear that combo to hit 65 at about 6000 in second gear, to be fun on the street from zero to 60. This would take 5.13s and at least a 3000TC, to be close to optimum. Sure you can run less. But then the soggy bottom end shows up, and the OH-CHIT moment.And to blast off from 32mpg downshifted into first, you'd want 4.30s or a bit more.

But if you've moved on while I was typing, then I'll try to catch up.

In the mean time ponder this; How many times a month do we see a fella come on here needing help cuz his stock lo-compression 318-LA and 268* is gutless off the line, even with 17% more gear and 48% more TC,than what chuck is contemplating.
So let's see the new combo then, so I can get back to harrying Rumble,lol.
 
Last edited:
I just scanned for my name.
I can't read all of that dribble in one shot. My eyes can't take it.
 
fatazzchuck said:
Hey guy's,

I have a tech question about the p5249499 Magnum 360/380 hp crate motor with this roller cam .501/.513 lift with .230/.236 duration @.050 with a 108 lobe ..
Are the heads on this motor plain stock heads? If not what's been done to them?
I'm thinking of buying the heads/cam and installing into a Magnum 5.2 with Holley 750.. 904, Hooker super comp fenderwell headers in a 65 Dart 2 dr sedan weekend driver...with power brake and vacuum assist
What size stall converter and gear ratio would be needed?

Thanks
Click to expand...
Steve Dulcich of Engine Masters has dynoed this cam in a 5.9 Magnum (the 380 horse 360 grind) in several 360 Magnums.( it usually gets7"-8, inches of vacuum , at a 1000 rpm idle, in a 360....) I would call Oregon Cams, ask for something in the 200-210 @ .050 zone, with a 110-112 lobe center, around .460"-.480 lift. (remember it is on a 1.6 rocker ratio, upgrade those silly stock valve springs with Hughes 1110 , or equivalent) Best of luck
 
AJ you're looking at old post and I already posted the guy sold the cam before you go carried away yesterday ...

Can you focus on
I'd like to find a Hydraulic Roller with .550 lift or less for my 5.2 Magnum and if not..
I have a 79 318LA that has this kit in it now https://www.summitracing.com/parts/cca-k20-221-3/overview/make/dodge
and I bought this Voodoo Hydraulic Flat Tappet Cam - Chrysler 273-360 268/276 - Lunati Power to put in it and run 93 Magnum heads with 3 angle valve job and bowl porting with these springs Valve Spring Kit - 550 and these valves
Valve Kit - Premium Polished Stainless Steel
and use Assault polished aluminum arg gap dual plane intake with a Holley 600 vac 2nd quick fuel carb with hooker super comp fenderwell headers with 10 blade Mopar racing water pump and Holley fuel pump.... Got to start somewhere and the 7.25 suregripe will be swapped out later as soon as I can find what I need

How does that sound?

Thanks
 
Oh whatch out! AJ may now regulate you to a mean person for correcting and embarrassing him.
 
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