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Re: 273 + MP Commando Alum. heads [Re: B1Fish540] #868963
12/02/10 03:03 PM
12/02/10 03:03 PM
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick Offline
I Live Here
patrick  Offline
I Live Here

Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
Quote:

"what are the plans for the car? how much power do you want to make? what kind of mileage are you hoping for?"

since I want it for highway use, I'd like a motor that has the power down lower..so prob a stroked 318 or 360 would be best(?). I'd like milege to be reasonable, at least 15 mpg.
Thanks for the info on the magnum roller motor I hadnt considered the newer small blocks...but that makes sense.




again, how much power do you want to make? a well thought out, mildish, stock strole 318 should have no problem making 350-380 lb-ft, and 330-350 hp, and a similarly built 360 make 350-370hp and 400-430 lb ft....


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)
Re: 273 + MP Commando Alum. heads [Re: patrick] #868964
12/02/10 06:09 PM
12/02/10 06:09 PM
Joined: Sep 2008
Posts: 2,840
Flint, Michigan
B1Fish540 Offline OP
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B1Fish540  Offline OP
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Posts: 2,840
Flint, Michigan
Quote:

Quote:

"what are the plans for the car? how much power do you want to make? what kind of mileage are you hoping for?"

since I want it for highway use, I'd like a motor that has the power down lower..so prob a stroked 318 or 360 would be best(?). I'd like milege to be reasonable, at least 15 mpg.
Thanks for the info on the magnum roller motor I hadnt considered the newer small blocks...but that makes sense.




again, how much power do you want to make? a well thought out, mildish, stock strole 318 should have no problem making 350-380 lb-ft, and 330-350 hp, and a similarly built 360 make 350-370hp and 400-430 lb ft....




Patrick, not wanting to be vague on the horsepower..just want as much HP as possible and keep it dependable and highway friendly. The 430 lbs of torque sounds good...so maybe I dont even need a stroker(?). I think 370 HP sounds good too, but would'nt a 408 make more TQ and at a lower RPM? Being able to cruise is important, I figure a stock ratio rear end of 3.23 or so, so that limits my cam. The car will probably see the drag strip on occasion, too, but uinless I put an OD trans in it, the rear ratio will have to stay stock. An OD would be nice tho, then I would run like a 3.90 ratio.

Re: 273 + MP Commando Alum. heads [Re: B1Fish540] #868965
12/02/10 07:44 PM
12/02/10 07:44 PM
Joined: Feb 2010
Posts: 155
Tulsa oklahoma USA
2
2734bbl Offline
member
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Joined: Feb 2010
Posts: 155
Tulsa oklahoma USA
I did a 273 in my 67 Barracuda fastback back in 91 or 92.030 over TRW pistons with 318 High swirl heads(#516 I think and came out about 10:1) 1.88/1.60 valves,510/286 Erson solid,reused the stock adjustable rockers with new Prods,Holley single plane, 625 AVS and cheap headrs.

I reused the finned VCs with wrinkle paint and the original air cleaner that I modded and painted the motor Chrysler red.

904 trans w/stock histall and 3.91 gears

The car made really good power to 7K.I never dynoed or made a pass with it but it was a lot of fun and revved really fast.

Pistons might be hard to find now though

Re: 273 + MP Commando Alum. heads [Re: 2734bbl] #868966
12/03/10 07:12 AM
12/03/10 07:12 AM
Joined: Sep 2008
Posts: 2,840
Flint, Michigan
B1Fish540 Offline OP
master
B1Fish540  Offline OP
master

Joined: Sep 2008
Posts: 2,840
Flint, Michigan
Quote:

I did a 273 in my 67 Barracuda fastback back in 91 or 92.030 over TRW pistons with 318 High swirl heads(#516 I think and came out about 10:1) 1.88/1.60 valves,510/286 Erson solid,reused the stock adjustable rockers with new Prods,Holley single plane, 625 AVS and cheap headrs.

I reused the finned VCs with wrinkle paint and the original air cleaner that I modded and painted the motor Chrysler red.

904 trans w/stock histall and 3.91 gears

The car made really good power to 7K.I never dynoed or made a pass with it but it was a lot of fun and revved really fast.

Pistons might be hard to find now though




273four, thanks for the reply! sounds like your 273 was pretty strong! I'm unable to drive a 4 speed(bad feet) but if I could i always thought a motor like the one you built along with a 4 gear would be great fun to drive! But since this car has a TF, I wanna make alotta TQ down low and only spin it to 6k or so. max if thats doable and still get the HP(380/400) I want.

Re: 273 + MP Commando Alum. heads [Re: B1Fish540] #868967
12/03/10 07:29 AM
12/03/10 07:29 AM
Joined: Aug 2004
Posts: 2,128
sweden
S
sshemi Offline
top fuel
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Joined: Aug 2004
Posts: 2,128
sweden
Quote:

Quote:

I did a 273 in my 67 Barracuda fastback back in 91 or 92.030 over TRW pistons with 318 High swirl heads(#516 I think and came out about 10:1) 1.88/1.60 valves,510/286 Erson solid,reused the stock adjustable rockers with new Prods,Holley single plane, 625 AVS and cheap headrs.

I reused the finned VCs with wrinkle paint and the original air cleaner that I modded and painted the motor Chrysler red.

904 trans w/stock histall and 3.91 gears

The car made really good power to 7K.I never dynoed or made a pass with it but it was a lot of fun and revved really fast.

Pistons might be hard to find now though




273four, thanks for the reply! sounds like your 273 was pretty strong! I'm unable to drive a 4 speed(bad feet) but if I could i always thought a motor like the one you built along with a 4 gear would be great fun to drive! But since this car has a TF, I wanna make alotta TQ down low and only spin it to 6k or so. max if thats doable and still get the HP(380/400) I want.




you will NOT get any torque in low rpm with a 273. Even my bone stock barracuda with 273 2 barrel 904 and 3.23 gears should have had higher stallspeed.

Re: 273 + MP Commando Alum. heads [Re: sshemi] #868968
12/03/10 10:54 AM
12/03/10 10:54 AM
Joined: Nov 2009
Posts: 3,082
St. Paul , Mn.
tubtar Offline
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Posts: 3,082
St. Paul , Mn.
There is no substitute for what ?
Class.......... ?
Class..............?
Anyone................?

Re: 273 + MP Commando Alum. heads [Re: tubtar] #868969
12/03/10 11:53 AM
12/03/10 11:53 AM
Joined: Feb 2010
Posts: 155
Tulsa oklahoma USA
2
2734bbl Offline
member
2734bbl  Offline
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2

Joined: Feb 2010
Posts: 155
Tulsa oklahoma USA
I agree. The car was kinda lazy in low until about 3000 rpms and then pull pretty good.

A better vert (2800 or so)or a 4 speed woulda been nice but the 3.91 gears did help alot.

Last edited by 2734bbl; 12/03/10 12:06 PM.
Re: 273 + MP Commando Alum. heads [Re: B1Fish540] #868970
12/03/10 02:17 PM
12/03/10 02:17 PM
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick Offline
I Live Here
patrick  Offline
I Live Here

Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
Quote:

Quote:

I did a 273 in my 67 Barracuda fastback back in 91 or 92.030 over TRW pistons with 318 High swirl heads(#516 I think and came out about 10:1) 1.88/1.60 valves,510/286 Erson solid,reused the stock adjustable rockers with new Prods,Holley single plane, 625 AVS and cheap headrs.

I reused the finned VCs with wrinkle paint and the original air cleaner that I modded and painted the motor Chrysler red.

904 trans w/stock histall and 3.91 gears

The car made really good power to 7K.I never dynoed or made a pass with it but it was a lot of fun and revved really fast.

Pistons might be hard to find now though




273four, thanks for the reply! sounds like your 273 was pretty strong! I'm unable to drive a 4 speed(bad feet) but if I could i always thought a motor like the one you built along with a 4 gear would be great fun to drive! But since this car has a TF, I wanna make alotta TQ down low and only spin it to 6k or so. max if thats doable and still get the HP(380/400) I want.




here's what I'd do...get a 360 magnum shortblock. reuse the crank and rods. buy either RHS magnum (iron) or Edelbrock magnum heads. run kb107's at 0 deck and a .039" head gasket. if the roller lifters are in good shape, reuse them. for a cam, I'd probably look at having bullet grind you a cam. I'd see if they can regrind the stock cam using their HR272/340 lobe for both intake and exhaust, which will yield ~.544" lift with magnum 1.6 ratio rockers. if not, I'd have them grind on a new core, using a 112 LSA (factory magnum is 114). I'd install the cam at 106-108 ICL. rockers, the RHS's you could use stockers, the eddies take small block chev rockers. either way, I think I'd use Scorpion Performance rockers for small block chev in 1.6 ratio. intake, I'd use an RPM air gap. carb, I'd use an 800 eddie thunder series AVS.

a little cheaper, if you can find a whole magnum longblock that doesn't have cracked heads, just use OEM magnum heads, but do a little work to the heads--the valve job is undersized, have it redone, opening up the seats to 1.9 and 1.6", with a nivce 5 angle valve job and a 75-80 degree throat cut to open up the bowls, do some bowl blending, and open up the pushrod pinch.

converter, I'd use a tight ~2500-2800 RPM stall converter-- something that will flash up when you stomp on it, but not have a lot of slip at cruise. a lot of people seem to have good luck with dynamic 9.5" converters in that regard...

I'd swagger this combo should run on 89-91 octane, probably idle in gear at ~750 RPM with ~12-13" vacuum, probably make conservatively 350-360HP/410-420tq, and probably net you 17-20mpg highway with 2.94 or 3.23 gears.


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)
Re: 273 + MP Commando Alum. heads [Re: patrick] #868971
12/03/10 06:17 PM
12/03/10 06:17 PM
Joined: Sep 2008
Posts: 2,840
Flint, Michigan
B1Fish540 Offline OP
master
B1Fish540  Offline OP
master

Joined: Sep 2008
Posts: 2,840
Flint, Michigan
Quote:

Quote:

Quote:

I did a 273 in my 67 Barracuda fastback back in 91 or 92.030 over TRW pistons with 318 High swirl heads(#516 I think and came out about 10:1) 1.88/1.60 valves,510/286 Erson solid,reused the stock adjustable rockers with new Prods,Holley single plane, 625 AVS and cheap headrs.

I reused the finned VCs with wrinkle paint and the original air cleaner that I modded and painted the motor Chrysler red.

904 trans w/stock histall and 3.91 gears

The car made really good power to 7K.I never dynoed or made a pass with it but it was a lot of fun and revved really fast.

Pistons might be hard to find now though




273four, thanks for the reply! sounds like your 273 was pretty strong! I'm unable to drive a 4 speed(bad feet) but if I could i always thought a motor like the one you built along with a 4 gear would be great fun to drive! But since this car has a TF, I wanna make alotta TQ down low and only spin it to 6k or so. max if thats doable and still get the HP(380/400) I want.




here's what I'd do...get a 360 magnum shortblock. reuse the crank and rods. buy either RHS magnum (iron) or Edelbrock magnum heads. run kb107's at 0 deck and a .039" head gasket. if the roller lifters are in good shape, reuse them. for a cam, I'd probably look at having bullet grind you a cam. I'd see if they can regrind the stock cam using their HR272/340 lobe for both intake and exhaust, which will yield ~.544" lift with magnum 1.6 ratio rockers. if not, I'd have them grind on a new core, using a 112 LSA (factory magnum is 114). I'd install the cam at 106-108 ICL. rockers, the RHS's you could use stockers, the eddies take small block chev rockers. either way, I think I'd use Scorpion Performance rockers for small block chev in 1.6 ratio. intake, I'd use an RPM air gap. carb, I'd use an 800 eddie thunder series AVS.

a little cheaper, if you can find a whole magnum longblock that doesn't have cracked heads, just use OEM magnum heads, but do a little work to the heads--the valve job is undersized, have it redone, opening up the seats to 1.9 and 1.6", with a nivce 5 angle valve job and a 75-80 degree throat cut to open up the bowls, do some bowl blending, and open up the pushrod pinch.

converter, I'd use a tight ~2500-2800 RPM stall converter-- something that will flash up when you stomp on it, but not have a lot of slip at cruise. a lot of people seem to have good luck with dynamic 9.5" converters in that regard...

I'd swagger this combo should run on 89-91 octane, probably idle in gear at ~750 RPM with ~12-13" vacuum, probably make conservatively 350-360HP/410-420tq, and probably net you 17-20mpg highway with 2.94 or 3.23 gears.




Thanks again, Patrick for all the info..just one question.Which combo would make the 360 HP? And get the 17-20 mpg? The first combo you mentioned with the RHS heads seems like it would make alot more than 360 hp.

Re: 273 + MP Commando Alum. heads [Re: B1Fish540] #868972
12/04/10 12:02 AM
12/04/10 12:02 AM
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick Offline
I Live Here
patrick  Offline
I Live Here

Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
I'm being conservative in my estimation....

given the published flow data I've seen on RHS's and eddies, I'd think they'd be pretty close power wise, maybe 10hp more with the RHS's...but they'd also be 50+ lbs heavier.


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)
Re: 273 + MP Commando Alum. heads [Re: patrick] #868973
12/04/10 01:17 AM
12/04/10 01:17 AM
Joined: Sep 2008
Posts: 2,840
Flint, Michigan
B1Fish540 Offline OP
master
B1Fish540  Offline OP
master

Joined: Sep 2008
Posts: 2,840
Flint, Michigan
Quote:

I'm being conservative in my estimation....

given the published flow data I've seen on RHS's and eddies, I'd think they'd be pretty close power wise, maybe 10hp more with the RHS's...but they'd also be 50+ lbs heavier.




So with a .557 cam do you still think I will get 17+ mpg? that'd be great! I like th idea of a tight convertor, too. I like those RHS heads but like you said..an added 50lbs...so I would want the eddies for sure. Anyhow, I will looking for the magnum motors now. Hopfully i can find one in a junk yard around here with low miles.

Re: 273 + MP Commando Alum. heads [Re: B1Fish540] #868974
12/06/10 01:26 PM
12/06/10 01:26 PM
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick Offline
I Live Here
patrick  Offline
I Live Here

Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
Quote:

Quote:

I'm being conservative in my estimation....

given the published flow data I've seen on RHS's and eddies, I'd think they'd be pretty close power wise, maybe 10hp more with the RHS's...but they'd also be 50+ lbs heavier.




So with a .557 cam do you still think I will get 17+ mpg? that'd be great! I like th idea of a tight convertor, too. I like those RHS heads but like you said..an added 50lbs...so I would want the eddies for sure. Anyhow, I will looking for the magnum motors now. Hopfully i can find one in a junk yard around here with low miles.




what .557" lift cam? lift is meaningless in powerband discussion. duration is the important figure, especially advertised and .050 duration, and possibly something like .2" duration.

a .557" MP solid probably not, since it's a big cam duration wise. a .557" hydaulic roller with ~218 degrees of .050 dur, probably.


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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