Re: 408 small block....which head?
[Re: marvo451]
#2800663
07/24/20 03:24 PM
07/24/20 03:24 PM
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Joined: Mar 2005
Posts: 403 Colorado front range
BcudaChris
mopar
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mopar
Joined: Mar 2005
Posts: 403
Colorado front range
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Good time to be doing a small block from a head perspective!
For max OGF, I'd recommend the EQ Iron Rams if your project is Magnum based or the Indy iron heads if your going LA. They will get you where you want to be out of the box if you're in the 9-9.5:1 CR range, and with a cam that will work will well with a stock converter. And you'll be able to really spend a lot of money on tires. You can easily get more with bigger valves and more cam. They have a closed chamber and there are lots of piston options to get you to where you want. Heavier but cheaper than AL.
I did a Magnum 408 with a 230/.55/110* class cam from Hughes, a 2500 stall converter in a 904 in an E body (750DP, RPM Airgap, 1 3/4 Super Comps, 2.5" exhaust). I got the EQ's with the LA intake bolt pattern.
No real metrics to give you, but it is somewhere in between scalded dog and sodomized primate on my butt dyno readout. I've spent a lot of time drivability tuning, but da Kovid botched the club days at the track where I was going to tune this spring.
In all honesty though, you could probably get there with a good valve job on a set of either 308 or Magnum castings given your goals. If Magnum though, it is probably easiest and less brain damage and not much more money to use new castings. In my searches in the yards, I found 1 head on 6 engines that didn't have cracks between the valves on at least one cylinder.
Have fun!
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Re: 408 small block....which head?
[Re: marvo451]
#2800689
07/24/20 05:02 PM
07/24/20 05:02 PM
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Joined: May 2019
Posts: 6,250 nowhere
Sniper
master
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master
Joined: May 2019
Posts: 6,250
nowhere
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As the title says, which head for a street car? It’s going in a Duster for some old guy fun. Hopefully 350- 400 horsepower. The old Magnum crate motors from MP, at that level, were essentially a stock long block with a single plane and a cam swap. As mentioned, a set of magnum heads on an LA block will do, but you will need to deal with compression ratio (lack of that is) using an LA shortblock. If a rebuild was already in the cards then it's not really an issue.
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Re: 408 small block....which head?
[Re: BcudaChris]
#2800732
07/24/20 07:25 PM
07/24/20 07:25 PM
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Joined: Jan 2003
Posts: 9,826 las vegas
70AARcuda
master
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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Good time to be doing a small block from a head perspective!
For max OGF, I'd recommend the EQ Iron Rams if your project is Magnum based or the Indy iron heads if your going LA. They will get you where you want to be out of the box if you're in the 9-9.5:1 CR range, and with a cam that will work will well with a stock converter. And you'll be able to really spend a lot of money on tires. You can easily get more with bigger valves and more cam. They have a closed chamber and there are lots of piston options to get you to where you want. Heavier but cheaper than AL.
I did a Magnum 408 with a 230/.55/110* class cam from Hughes, a 2500 stall converter in a 904 in an E body (750DP, RPM Airgap, 1 3/4 Super Comps, 2.5" exhaust). I got the EQ's with the LA intake bolt pattern.
No real metrics to give you, but it is somewhere in between scalded dog and sodomized primate on my butt dyno readout. I've spent a lot of time drivability tuning, but da Kovid botched the club days at the track where I was going to tune this spring.
In all honesty though, you could probably get there with a good valve job on a set of either 308 or Magnum castings given your goals. If Magnum though, it is probably easiest and less brain damage and not much more money to use new castings. In my searches in the yards, I found 1 head on 6 engines that didn't have cracks between the valves on at least one cylinder.
Have fun! You need to check on the availability of the EQ heads.....they are not making the LA intake head anymore and the standard EQ head is a different design ....in Fact it looks actually like a Speedmaster Magnum head....and the performance is not nearly as good..
Tony
70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: 408 small block....which head?
[Re: Sniper]
#2800739
07/24/20 07:53 PM
07/24/20 07:53 PM
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Joined: Jan 2011
Posts: 15,871 Central Florida
larrymopar360
Stud Muffin
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Stud Muffin
Joined: Jan 2011
Posts: 15,871
Central Florida
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As the title says, which head for a street car? It’s going in a Duster for some old guy fun. Hopefully 350- 400 horsepower. The old Magnum crate motors from MP, at that level, were essentially a stock long block with a single plane and a cam swap. As mentioned, a set of magnum heads on an LA block will do, but you will need to deal with compression ratio (lack of that is) using an LA shortblock. If a rebuild was already in the cards then it's not really an issue. As Sniper says ^ I had one of those crate engines rated at 300hp and 375tq and it was STRONG! Felt a lot more like over 400lb/ft torque! I would love to build one of those again. You can still find those specs if you search "Mopar Performance 360 crate engine" and look for the 300hp one. Smooth idle and very street pleasant, but would roast the tires if you wanted.
Facts are stubborn things.
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Re: 408 small block....which head?
[Re: topside]
#2800938
07/25/20 11:25 AM
07/25/20 11:25 AM
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Joined: Jan 2011
Posts: 15,871 Central Florida
larrymopar360
Stud Muffin
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Stud Muffin
Joined: Jan 2011
Posts: 15,871
Central Florida
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Iron heads at around 9.5:1 are pretty close to detonation on the street in my experience. (That's with a reasonable cam that isn't bleeding off CR (and low-end torque). If it doesn't have to look OEM, I'd run aluminum heads, which are better pretty much everywhere you compare. Paint them & the intake engine color and most folks won't catch it. It also never hurts to take some nose weight off a car. True. And that's what I'd do (paint them block color). But then you start spending. My MP crate 360/300hp was underrated IMO. So strong. Just not the best assembly probably. 9.0:1 compression, no problem on pump gas. Over 60k miles never an issue with the Magnum heads or anything else.
Facts are stubborn things.
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Re: 408 small block....which head?
[Re: larrymopar360]
#2801003
07/25/20 01:24 PM
07/25/20 01:24 PM
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Joined: Jan 2003
Posts: 14,498 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,498
So. Burlington, Vt.
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Ede RPM’s or one of the import equivalents.
I think you’d actually have to “try”....... to end up with less than 400hp.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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