Horsepower guess?

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74desertduster

74desertduster

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I have settled on this setup and am wondering about how much Horsepower it will make....any guesses are welcome. Also...compression with this setup?

360 block bored .030 over
Stock pistons and crank
Magnum heads
Summit K6901 cam...with magnum rockers lift should be about .470
Edelbrock Air Gap magnum intake
Carter AFB 625cfm
Stock exhaust manifolds until I can get headers
Dual exhaust with glass packs

Thanks!
 
I would guess somewhere around 280 hp. Please loose the glass packs.
 
Ya....I keep hearing that. Want to do the whole exhaust and open it up...but one thing at a time.
 
Since that cam is pretty darn close to a stock 340 grind I'd say 275 at the flywheel. Besides the low compression, your limiting factor will be the exhaust and carb (I understand you are using what you have and building in stages). You'll certainly notice a difference with dual exhaust and a 750 CFM carb (the heads and manifold will certainly support it). But the low compression will hurt you.

I would think long and hard about KB107 pistons and a Comp XE274 cam, and a Thunder AVS carb.
 
I'll go with 304hp and 360 ft lbs. at the crank.

If you would step up to a bigger cam, and a larger carb...I would say you could scratch 350chp pretty easily.
 
Yeah....bigger than .470 lift.

You would need 274* plus duration, and around .520" lift, but with the cam and a 750 carb...I know of more than a few 360's with similar mods that make at least 350 at the crank.

Matter of fact...350 is easy to get to with a 318...so I would sure hope so.
 
I haven't got the cam or carb yet so I have options...but I don't want crazy either...needs to be a driver with some umph to it....
 
If he goes with more cam should he not at least mill the heads a little to bump the compression, he may hurt the low end some?
 
converter will be in order with any more cam. i ran little tires for years so i didnt load the motor before it was making power. 60. foots werent good but i blew by a lot of people on top end. all tire spin is not totally detrimental.it depends on how youre set up.
 
I thought the magnum heads did bump the compression a bit?

I am a bit concerned about going bigger on the cam because of using a stock converter.

I bought a rebuilt 360 block ready to go with stock pistons so would like to use it as it is instead of changing pistons.
 
The stock pistons will be waaay down the hole. Even with magnum heads you will be lucky to get 8.5 to 1 compression. For a cam I would thick long and hard about the XE262 Comp Cams. Lots of low end, decent lift with the 1.6 rockers and vacuum to run power brakes. It will definitely work with a stock converter.
I run a cam similar to the XE268 with more compression and the stock converter and power brakes worked fine......
 
CamQuest shows about 293hp/393 torque for a similar setup, using the 262/264*-.450/.480 Comp Cam.
 
I was gonna guess 300 HP and about 390 lbs. of torque. The heads flow a little better in there stock form than the older heads and the 1.6 ratio will help top end HP a tad.
 
The Magnum doesnt use the AIR injection holes. I agree with the 300-325hp. A good solid street engine. The stock magnum type valvetrain does not work well with valve lifts over about .490 with 1.6s. I think you'll be happy with it, but like the others said... by using the KB flat tops for another hundred bucks over stock, you will get a better output all the way around and I'd estimate a pretty easy additional 25hp over the stock ones. Stock pistons yeild about 7.8:1 when it gets figured with the factory heads. Add Magnums and it will go up to about 8.3:1.
 
For a cam I would thick long and hard about the XE262 Comp Cams.

Wouldn't this be too much cam for the stock piston compression ratio?
 
Ahhh...then I am thinking about it.

I have this complete rebuilt short block with stock pistons already in it. I would love the kb107's but hate to rip it apart...plus the money too....because

I am going to be spending more than I thought on upgrading the Magnum heads to different springs. When I bought them I was thinking I could use the stock Magnum springs. My fault for not doing enough research before I spent the money.

If I could get away with the Magnum stock springs I could use that money on the pistons.......hmmm...this is sounding kinda whiney....

Not whining, just talking.
 
I don't know if this will help, but I can tell you what worked for me. 1973 360 block, .060 over, speed pro h405cp60 pistons, speed pro camshaft #cl1143r, 587 heads milled .020 and gasket matched, rpm airgap intake, 750 eddie carb, with stock converter and 3.23's. Nasty idle, awesome mid range, driven every single day with 12-13 inches of vacuum and power brakes, never had brake fade at all, could leave 25 yards of rubber from a dead stop with no brakes and got 14 mpg. Good enough for me!!! This cam has alot of overlap, hence the nasty idle, but on the recommendation of some guys here I swapped it in.I was running a 272 energizer before and the car, my dart, sounded and pulled like a truck, which is not bad, but I wanted more, I wanted a fast reliable driver, and I got it! You might consider this cam. If you are anything like me, the 262 will leave you wanting more...
 
I have almost exactly the setup you're suggesting...mine is:

77 360 +.040
8:1 Federal Mogul pistons
Magnum Heads-R/T Springs and Retainers
Summit K6901 camshaft
Eddy Air Gap intake for Magnum Heads
600 Holley Vacuum Secondary
Spitfire 1 5/8" Shorty headers-2" head pipes-2.5" dynomax mufflers (don't ask why it has 2" head pipes)
Modified electronic distributor to give 14 degrees BTDC inital advance, 34 degrees total advance (I still need to quicken the rate a little)

This engine pulls 14-15 inches of vacuum as of right now with an 800rpm idle.

I put this combo into desktop dyno (not sure how good it is) but it came out with 373hp@5500rpm and 396 lb-ft @4000rpm. I had put in commonly accepted magnum head flow numbers out of Mopar Action magazine.

with a 4-speed, 3:23's, and 225/60R15 goodyears, the car does not get traction at under 20mph at WOT in 1st. You can burn them no problem. Still working on the "economy" setup on the carb, but I'm getting about 12.5 MPG.

Its not a bad combo at all. Once i get the main bearings replaced (this was a used short block), i can run a thinner than 15w-40 oil and probably pick up a little power.
 
Wow...I just need to decide and be done with it...

The pistons in the engine have a deck height of .127

I found some Speed Pro's for $130 that would be at .050

And then there are the KB107's at .012 for $200

All up to me......it's really not the money either, I dread the tear down and reassemble...

You guys are all great!
 
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