More small block help
#492478
10/09/09 02:18 PM
10/09/09 02:18 PM
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Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
1swingin
OP
mopar
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OP
mopar
Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
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I didnt get to much feedback on the pros and cons of the magnum heads so i thought i would ask you small block guys this. What should I do to get the most performance out of my current 360 short block? Its a fresh mid 70s block with just a basic rebuild. I want to run 93 octane,hydrolic cam,and i dont wanna rev it over 6000 rpm. Cam size?,intake?,heads?etc. Its going in a 70 cuda and i would like to see mid 12s through the mufflers. I know my compression ratio stinks but i dont wanna dump a ton of money in it. I plan on a hemi swap in a couple of years. Let me know if you have any suggestions. Thanks for you time.
"I aint here on buisness baby,Iam only here for fun"
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Re: More small block help
[Re: 1swingin]
#492479
10/09/09 02:51 PM
10/09/09 02:51 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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assuming rebuilder 360 flat tops, those typically are ~ .080 in the hole, and have an 8cc dish.
assuming 72cc stock heads, and the MP/Mr Gasket .028" thick head gaskets, you're looking at a CR of 8.25:1
step up to magnum heads, assume 64cc, now you're looking at 8:9:1 ompression
mill those down to 60cc, you're looking at ~9.2:1 compression.
I'd say your stock short block, OEM, enginequest, or RHS magnum heads that you open up the pushrod pinch, open up the valve job to 1.90/1.60 (OEM mag valve jobs are typically undersized) with a good valve job, and some bowl and short side blending, probably hughes 1110 springs and their retainers (or 2.2L chrysler retainers), and a comp 270H or 280H, an RPM air gap, decent carb & headers will net you in the 380+ HP range, which should get you in the 12's depending on converter and rear gear.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: More small block help
[Re: viperblue72]
#492481
10/09/09 05:28 PM
10/09/09 05:28 PM
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Joined: Apr 2007
Posts: 375
NE Oklahoma
71valiant
enthusiast
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enthusiast
Joined: Apr 2007
Posts: 375
NE Oklahoma
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I have a similar motor in my valiant. I got a good deal on a stock late 70's rebuilt short block. I put some late 70's heads that I cleaned up alittle bit. I put a
480/480 lift 292/292 duration 230@ .050 cam
headers
edelbrock rpm airgap intake and 625 carter afb
4:30 gears and 2500 stall converter
It runs excellent and is very streetable. I've run a best of 13.20 with slicks and a 750 holley DP I slapped on there. The bigger carb made a big difference even without being properly tuned. I'm sure it could be fater with a better driver and a proper tune.
Its a fun simple motor.
Last edited by 71valiant; 10/09/09 05:33 PM.
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Re: More small block help
[Re: 71valiant]
#492482
10/09/09 05:44 PM
10/09/09 05:44 PM
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Joined: Aug 2007
Posts: 498
El Dorado Ca
65signet
mopar
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mopar
Joined: Aug 2007
Posts: 498
El Dorado Ca
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You can deck the block make sure it's square and pick up a little more comp.
1965 Plymouth Barracuda 273 M/SA
1970 Plymouth Duster 360/904 10.60s with J heads
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Re: More small block help
[Re: patrick]
#492485
10/11/09 06:25 PM
10/11/09 06:25 PM
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Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
1swingin
OP
mopar
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OP
mopar
Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
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I have a guy thats willing to trade me a set of magnum heads,mp 1.6 roller rockers,280 dur. 480 lift cam,pushrods,guideplates,headbolts,and a 2500 ati convereter. With the air gap intake,750 carb,3.91 gears and open headers would that be enough to get me close to the 12s?
"I aint here on buisness baby,Iam only here for fun"
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Post deleted by moparts
[Re: 1swingin]
#492486
10/11/09 07:35 PM
10/11/09 07:35 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Re: More small block help
#492487
10/12/09 04:02 PM
10/12/09 04:02 PM
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Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
1swingin
OP
mopar
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OP
mopar
Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
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I dont wanna go to crazy on the converter. This is pretty much gonna be a cruzer but i want it to at least hit a 12. Thanks alot for all your help.
"I aint here on buisness baby,Iam only here for fun"
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Re: More small block help
[Re: 1swingin]
#492488
10/12/09 09:38 PM
10/12/09 09:38 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
I have a guy thats willing to trade me a set of magnum heads,mp 1.6 roller rockers,280 dur. 480 lift cam,pushrods,guideplates,headbolts,and a 2500 ati convereter. With the air gap intake,750 carb,3.91 gears and open headers would that be enough to get me close to the 12s?
is the 280 dur/480 lift cam 480 lift w/1.5 ratio rockers (sounds like a comp magnum 280?) if so, it'll be .512" lift with the 1.6 rockers.
if it's a comp magnum 280, I'd say you're pretty darn close to what a 380 HP crate motor puts out...
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: More small block help
[Re: 1swingin]
#492489
10/12/09 10:11 PM
10/12/09 10:11 PM
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Joined: Feb 2007
Posts: 1,025
Las Vegas, NV
dodgeboy11
super stock
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super stock
Joined: Feb 2007
Posts: 1,025
Las Vegas, NV
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Quote:
I have a guy thats willing to trade me a set of magnum heads,mp 1.6 roller rockers,280 dur. 480 lift cam,pushrods,guideplates,headbolts,and a 2500 ati convereter. With the air gap intake,750 carb,3.91 gears and open headers would that be enough to get me close to the 12s?
Not enough compression, too big of a cam and too tight of a converter. On top of that the stock magnum heads don't flow for squat and, as I previously mentioned, they are probably cracked between the intake and exhaust seats. I'd at least get your current block apart and put some flat top pistons in it WITH a good valve relief so you have some piston to valve clearance. I also like the looks of those new Indy cast iron magnum heads.
But if you must use those stock heads at least stipulate to the guy you're buying them from that you can return them for a full refund if they're cracked, and make sure to have a machine shop check them out thoroughly. Often you can see the cracks between the valves without even magging them.
Have a ball.
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