Magnum 5.9, 30 over, compression 10 .5, EQ 318b heads with bowl work and 2.02 ,1.60 valves, six pack, TTI 1 5/8 TO 1 3/4 step headers, cam will be hyd roller of roughly 232 x240 @ .050, 108 cl, about .480+ lift using chev 1.6 rockers and olds studs. I am considering this as a possible combo for a 4 speed 1973 duster my son and i hope to purchase. It was a car i bought for my son in 1988, got sold, we are hoping to get it back and build this motor for it. Rear gears will be 3.55 or 3.73, tires 28 tall. I am hoping this combo will build very good torque from 3,000 up to about 6200 rpm and live well. Opinions? Similar success stories?
360 street build, please critiec
- Thread starter gregsdart
- Start date
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Do those heads have small size 318 ports? I'm not familiar with them.
abdywgn
dismantler
sounds good! I'll try it out and let you know 
No, they're magnum ports. Which are small just not 318 circa 1973 heads
The Magnum heads are all the same from the OEM or aftermarket except the Magnum R/T heads with 2.02/1.60 valves and better ports in and out and added strength if ribs like the W2 heads.
His heads may have better ports to start with and normally are reported to port out better than OEM casting.
IMHO, I’d use and do so currently use a cam one size smaller.
I happen to run an off the shelf Comp Hyd roller, cam card below.
I also use TF heads which increased the compression 1 point better than your build. A RPM & 750 top it off.
Power to 6K plus is not a problem and I’ll say it is due to the cylinder heads flowing so well which allow the cam a few mornRPM’s not normally available to a stock port head, which your are not as I read.
Lift is another thing I have a bunch of going to .573. Which works with the high flowing ports. IMO, that’s a key thing to the upper rpm power hanging on.
The car is a ‘67 Cúda with a custom stall converter in the 904 & out back are 3.55’s on 26” tires.
3.73’s would work a bit nicer on the street for you and I, IMO.
Or higher.
If I did a change to this Cúda here it would be 3.90’s and a maybe, maybe a taller tire. As it is now, I barley get out of 2nd gear at the track and I’m short shifting at 5K.
Enjoy brother!
mopowers
Well-Known Member
Do you have the cam card or #? Is this it: https://www.compcams.com/xtreme-energy-230-236-hydraulic-roller-cam-for-chrysler-273-360.html
Also, assuming you're using stock lifters, is there an issue with that amount of lobe lift with stock roller lifters? How close do the oil grooves get to the top or bottom of the lifter bores or the bottom of the flats hitting the stock dogbone?
4mulas
Fixem'up
Doesn’t matter too much but magnum r/t heads are 2.02/1.625 and came with stainless valves. Not sure why they increase the valve size by 25 thousandths.
For the OP, the build sounds fine but I don’t think it’ll get you to the 450 your looking for.
i think you'll be close but fall short on the hp number.
duration's fine if a little low, you could get saucy it's a stick car. or just stall it up if you wind up automatic. CL is tight, bonus.
i'd want more lift for sure though and you'd probably see that 450.
duration's fine if a little low, you could get saucy it's a stick car. or just stall it up if you wind up automatic. CL is tight, bonus.
i'd want more lift for sure though and you'd probably see that 450.
Here looks to be a similar build
https://www.hotrod.com/articles/build-455hp-pump-gas-magnum-v8-around-4000/
5.9L Magnum Small-Block
650 vs 750
| RPM: | TQ: | HP: | TQ: | HP: |
| 4,000 | 453.9 | 345.7 | 449.6 | 342.4 |
| 4,100 | 458.1 | 357.6 | 458.2 | 357.7 |
| 4,200 | 460.2 | 368 | 461.8 | 369.3 |
| 4,300 | 460.8 | 377.3 | 462.6 | 378.8 |
| 4,400 | 461.3 | 386.5 | 465.8 | 390.2 |
| 4,500 | 461.7 | 395.6 | 465.2 | 398.6 |
| 4,600 | 460.3 | 403.2 | 464 | 406.4 |
| 4,700 | 459.4 | 411.2 | 460.4 | 412 |
| 4,800 | 456.6 | 417.3 | 458 | 418.6 |
| 4,900 | 451.6 | 421.3 | 451.5 | 421.2 |
| 5,000 | 447.7 | 426.2 | 455 | 433.1 |
| 5,100 | 444.8 | 431.9 | 450.3 | 437.3 |
| 5,200 | 440.6 | 436.2 | 445.1 | 440.7 |
| 5,300 | 435.2 | 439.1 | 431.3 | 435.3 |
| 5,400 | 426.5 | 438.5 | 432.3 | 444.5 |
| 5,500 | 421.1 | 441 | 426.4 | 446.5 |
| 5,600 | 411.9 | 439.2 | 420.9 | 448.8 |
| 5,700 | 413.6 | 448.9 | 415.4 | 450.8 |
| 5,800 | 411.7 | 454.7 | 410.1 | 452.9 |
| 5,900 | 402.3 | 451.9 | 404.6 | 454.5 |
| 6,000 | 397.9 | 454.5 | 398.6 | 455.4 |
| Average: | 439.9 | 416.5 | 442.2 | 418.8 |
Reconsider the Chevy 1.6 ratio. Use 1.65 to achieve 1.6. The factory stamped steel are actually pretty close ratio wise. Magnum engines are 1.6 ratio. I have mocked up Chevy 1.6 on 318B heads. No matter the length of pushrod or how far up or down on the stud(rocker arm), the loss of lift was disappointing. Even considering the 59 degree lifter angle....
Bobzilla
Well-Known Member
Which version of those heads do you have? The older, better Australia or New Zealand castings or the current China castings?
Here another EQ headed 5.9l this one not ported, basically 380hp crate with EQ heads.
https://www.hotrod.com/articles/59l-magnum-engine-make-mine-a-5-9/
https://www.hotrod.com/articles/59l-magnum-engine-make-mine-a-5-9/
| On The Dyno5.9LMagnum | ||
| RPM: | TQ: | HP: |
| 3,000 | 407 | 233 |
| 3,100 | 406 | 240 |
| 3,200 | 406 | 248 |
| 3,300 | 409 | 257 |
| 3,400 | 411 | 266 |
| 3,500 | 413 | 275 |
| 3,600 | 414 | 284 |
| 3,700 | 415 | 293 |
| 3,800 | 416 | 301 |
| 3,900 | 416 | 309 |
| 4,000 | 417 | 318 |
| 4,100 | 419 | 327 |
| 4,200 | 420 | 336 |
| 4,300 | 419 | 343 |
| 4,400 | 419 | 351 |
| 4,500 | 419 | 359 |
| 4,600 | 418 | 366 |
| 4,700 | 416 | 373 |
| 4,800 | 413 | 378 |
| 4,900 | 409 | 382 |
| 5,000 | 405 | 386 |
| 5,100 | 401 | 390 |
| 5,200 | 397 | 393 |
| 5,300 | 392 | 396 |
| 5,400 | 387 | 398 |
| 5,500 | 381 | 399 |
| 5,600 | 375 | 400 |
| 5,700 | 367 | 399 |
| 5,800 | 361 | 399 |
| 5,900 | 354 | 397 |
| 6,000 | 347 | 396 |
We don't currently have a set, but after the success of my 408 build, felt they were the way to go. A little bowl work, chev 8mm valves, and the Aussie versions shined. How different are the newer castings?
ValiantS
Well-Known Member
Sounds like a decently matched set of parts. Some of those iron aftermarket heads are interesting and have shown good results thru the years. Anymore if I didn't have EVERYTHING, I'd use a gen3 and leave everything else behind.
Sorry, I was distracted. Thanks for the post letting me know I screwed up.
The cam below is used with 1.6 rockers in the TF heads.
I tend to like these small duration camshafts for a everyday usage hot rod since very little to no extra stall is required for use though the benefit of extra stall is obvious.
The car is an absolute driver. While the 3.55 gets on 26 inch tires isn’t very quick at the track or a major monster on the street, it does have what seems to be a very long power band. When you’re used to 4.10’s and up, it feels like the car has a super high jump to the next time it is ready for a gear change.
If I was looking for a max return on the camshaft in the 1/4 mile, I would need a pretty big jump up from 3.55’s! That’s not such a happy thing on the street.
Being your heads are well done considering the flow/lift specs you have given, I don’t think power will be the issue. I think you’ll get it.
I have faith in the 6 pack set up. As well as better drivability over the single 4bbl because of the carbs size. Much of this of course is also gear and converter related and will relief the engines/carb low speed complications that can occur. The other issue is tuning not just the mix but timing when the outboards come in.
In various tests throughout the years from various sources, the Chrysler 6 pack has seemed to perform super well against the ROM & single 4bbl set up. The design in the runners are a bit tricky and convoluted to be top end superior in all cases but has non the less darn near identical dyno numbers.
A RPM and a single 4bbl is the best, easiest, less complex and of course, IF you don’t have he 6 pack already, cheapest way to do it. Basically you do a 6 pack because you want to.
For better results on the 6 pack, look into not just port matching & as deep as you can go but, with special attention to the very low runners (like number 3) but also under the carb. The entrance way is normally not all that great and rough to which it can be opened up to at least the butterfly size though larger may show no real win.
Overall, your first post combo is pretty good IMO and should be just fine overall. 6 pack or 4bbl.
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mopowers
Well-Known Member
With that much lobe lift, how close do the oil grooves get to the top or bottom of the lifter bores or the bottom of the flats hitting the stock dogbone?
I've read .350" -ish lobe lift is about max with stock roller lifters. I haven't checked though.
4mulas
Fixem'up
These hotrod magazine Westech dyno pulls always seem a little ‘happy’ to me. If these numbers come out of that motor it (and 400hp out of the junkyard 360 on the other example) makes me wonder if Mopar underrated their crate motors?.
I wonder what the the Mopar crate 402 435 hp motor would show on a westech dyno? The did a junkyard 360 with smaller less efficient heads, stock bottom end, and the same cam as in the 402 and it made 400hp? The 402 has superior r/t heads, hyper u pistons, h-beam rods, larger valves, same cam, m1 intake, and 42 cubic inches more and only makes 35 horsepower more than the junkyard 360 as according to Mopar’s rating anyway?
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