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Re: 273 building and info needed PLEASE! [Re: dart4forte] #1661726
08/25/14 03:29 AM
08/25/14 03:29 AM
Joined: Dec 2010
Posts: 12,375
SoCal
MuuMuu101 Offline
I got lucky at Woodward!
MuuMuu101  Offline
I got lucky at Woodward!

Joined: Dec 2010
Posts: 12,375
SoCal
Quote:

I haven't denied mine but I'm thinking May 300 to the rear wheels. My 273 has a lot of trick thinks like low ring tension, offset balance, head porting and work on the runners. We were able to get 116% port velocity and about 168 in flow. That's with a 920 head, stainless 1.88 valves cut down to 1.84.




Geeze... That's like 350-375 hp at the crank? There is a guy on FABO who built a 273. Has a mild cam, 0.030" overbore with Egge pistons (10.5:1 cr), and a 4-barrel. He says he'd probably make around 275 hp and 300 ft-lbs of torque at the crank.

Re: 273 building and info needed PLEASE! [Re: MuuMuu101] #1661727
08/25/14 11:31 AM
08/25/14 11:31 AM
Joined: Feb 2003
Posts: 16,146
Mesa, Arizona
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dart4forte Offline
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Mesa, Arizona
Quote:

Quote:

I haven't denied mine but I'm thinking May 300 to the rear wheels. My 273 has a lot of trick thinks like low ring tension, offset balance, head porting and work on the runners. We were able to get 116% port velocity and about 168 in flow. That's with a 920 head, stainless 1.88 valves cut down to 1.84.




Geeze... That's like 350-375 hp at the crank? There is a guy on FABO who built a 273. Has a mild cam, 0.030" overbore with Egge pistons (10.5:1 cr), and a 4-barrel. He says he'd probably make around 275 hp and 300 ft-lbs of torque at the crank.




The Dyno doesn't lie

Re: 273 building and info needed PLEASE! [Re: ronhug] #1661728
08/25/14 03:30 PM
08/25/14 03:30 PM
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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HotRodDave Offline
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Joined: Jan 2005
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Kalispell Mt.
You can not use the 318 roller lifters, there is nothing in the block to hold them from twisting and destroying the cam.

You can not use a 2.02 valve, the notch required to get clearance much less unshrouding the valve will hit water.

You are not the first to try this, lots have tried it and an overwhelming number of them say it is very disapointing when done. The displacement is too small to make much TQ and the bore size is too small to make much HP.

The stock 273 heads are the best flowing stock head that will fit a 273 bore, use what you have if your budget is that tight. A little mild port work is fine, you can add 1.88 valves and a small notch at the top of the bore for the most flow. The 302 head flows less and will give you less compression and more crevice volume, all of those will result in less power. Mill the block to zero deck the pistons, run the .039 fel-pro head gasket. Get a comp 270S cam and run the factory adjustable valve train. This will be about as peppy as it will get without a bucks down build.

BTW
318 2bbl 230 HP 340 TQ
273 4bbl 235 hp 280 TQ
360 2bbl 255 hp 360 TQ.

Not trying to tell you not to build the 273 just letting you know what handicap you are working with.


I am not causing global warming, I am just trying to hold off a impending Ice Age!



Re: 273 building and info needed PLEASE! [Re: HotRodDave] #1661729
08/25/14 07:10 PM
08/25/14 07:10 PM
Joined: Dec 2010
Posts: 12,375
SoCal
MuuMuu101 Offline
I got lucky at Woodward!
MuuMuu101  Offline
I got lucky at Woodward!

Joined: Dec 2010
Posts: 12,375
SoCal
Quote:

You can not use the 318 roller lifters, there is nothing in the block to hold them from twisting and destroying the cam.

You can not use a 2.02 valve, the notch required to get clearance much less unshrouding the valve will hit water.

You are not the first to try this, lots have tried it and an overwhelming number of them say it is very disapointing when done. The displacement is too small to make much TQ and the bore size is too small to make much HP.

The stock 273 heads are the best flowing stock head that will fit a 273 bore, use what you have if your budget is that tight. A little mild port work is fine, you can add 1.88 valves and a small notch at the top of the bore for the most flow. The 302 head flows less and will give you less compression and more crevice volume, all of those will result in less power. Mill the block to zero deck the pistons, run the .039 fel-pro head gasket. Get a comp 270S cam and run the factory adjustable valve train. This will be about as peppy as it will get without a bucks down build.

BTW
318 2bbl 230 HP 340 TQ
273 4bbl 235 hp 280 TQ
360 2bbl 255 hp 360 TQ.

Not trying to tell you not to build the 273 just letting you know what handicap you are working with.




I think most people who are going to want to build a 273 are the ones who want their engine to match their car (like on an early-A) or those who want to be different (someone like me ).

Re: 273 building and info needed PLEASE! [Re: MuuMuu101] #1661730
08/25/14 07:33 PM
08/25/14 07:33 PM
Joined: Jan 2003
Posts: 104,346
Garden Grove, CA
OzHemi Offline
Penguin-hating Ginger
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Joined: Jan 2003
Posts: 104,346
Garden Grove, CA
My buddy in Oz built this 273 for his ute..


(mild solid cam and cleaned up heads..)

8251503-Picture010.jpg (123 downloads)
Re: 273 building and info needed PLEASE! [Re: OzHemi] #1661731
08/25/14 10:37 PM
08/25/14 10:37 PM
Joined: Dec 2003
Posts: 22,696
Bitopia
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jcc Offline
If you can't dazzle em with diamonds..
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Posts: 22,696
Bitopia
He should have used a TR to be different.


Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
Re: 273 building and info needed PLEASE! [Re: jcc] #1661732
08/25/14 10:45 PM
08/25/14 10:45 PM
Joined: Jan 2003
Posts: 104,346
Garden Grove, CA
OzHemi Offline
Penguin-hating Ginger
OzHemi  Offline
Penguin-hating Ginger

Joined: Jan 2003
Posts: 104,346
Garden Grove, CA
He has 3 or 4 dual quad intakes...had to use them up I suppose.

Re: 273 building and info needed PLEASE! [Re: OzHemi] #1661733
08/25/14 11:25 PM
08/25/14 11:25 PM
Joined: Feb 2003
Posts: 16,146
Mesa, Arizona
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dart4forte Offline
I Live Here
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Posts: 16,146
Mesa, Arizona
A lot of auto enthusiast don't know that Shelby at one time considered using the 273 in the Cobra. They didn't go with it because of the location of the distributor.

Re: 273 building and info needed PLEASE! [Re: dart4forte] #1661734
08/25/14 11:49 PM
08/25/14 11:49 PM
Joined: Jan 2003
Posts: 4,323
NY NY
3
340duster340 Offline
master
340duster340  Offline
master
3

Joined: Jan 2003
Posts: 4,323
NY NY
273 vs. 318/40/60, debate comes up every now and then.

if you insists on building the 273, i am sure you can look up the specs on the d-dart motors from 66. they were probably the pinnacle of 273's. in certain applications they are fine, but the small bore size, small intake ports, funky intake manifold bolt pattern (depending on year) really put them at a disadvantage to the other motors in the LA series. think about it; they were discontinued for a reason.

Re: 273 building and info needed PLEASE! [Re: ronhug] #1661735
08/26/14 01:57 AM
08/26/14 01:57 AM
Joined: Dec 2010
Posts: 32
Nebraska
R
ronhug Offline OP
member
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Posts: 32
Nebraska
A mopar brother has offered a motor for the cause, it is a 318 with 273 heads, this threw me... so why would one put 273 heads on a 318 ?

Re: 273 building and info needed PLEASE! [Re: jcc] #1661736
08/26/14 04:10 AM
08/26/14 04:10 AM
Joined: Dec 2010
Posts: 12,375
SoCal
MuuMuu101 Offline
I got lucky at Woodward!
MuuMuu101  Offline
I got lucky at Woodward!

Joined: Dec 2010
Posts: 12,375
SoCal
Quote:

He should have used a TR to be different.




If I found a cheap one, I was actually thinking about running one on my 273.

Re: 273 building and info needed PLEASE! [Re: ronhug] #1661737
08/26/14 04:55 AM
08/26/14 04:55 AM
Joined: Jan 2007
Posts: 1,668
Mi,U.S.A.
M
mike s Offline
top fuel
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top fuel
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Joined: Jan 2007
Posts: 1,668
Mi,U.S.A.
IIRC 66 and older.


Leave the gun.......take the Cannoli's....Mike
Re: 273 building and info needed PLEASE! [Re: mike s] #1661738
08/26/14 11:03 AM
08/26/14 11:03 AM
Joined: Aug 2003
Posts: 1,978
Moncton, New Brunswick
hemidart1 Offline
top fuel
hemidart1  Offline
top fuel

Joined: Aug 2003
Posts: 1,978
Moncton, New Brunswick
I was in the same boat-wanting to build a hot 273.
The easiest solution ---stick the valve covers and breather on a 360 and paint it red


1967 Hemi GTX
1969 Chrysler 300
Re: 273 building and info needed PLEASE! [Re: ronhug] #1661739
08/26/14 02:17 PM
08/26/14 02:17 PM
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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HotRodDave Offline
I Live Here
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I Live Here
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
Quote:

A mopar brother has offered a motor for the cause, it is a 318 with 273 heads, this threw me... so why would one put 273 heads on a 318 ?




We have been trying to explain that to you all along. 273 heads flow better and will give you a higher compression ratio. The 318 short block will give you more TQ and HP because of the bigger displacement and bigger bore opening the area around the valve to flow better.


I am not causing global warming, I am just trying to hold off a impending Ice Age!



Re: 273 building and info needed PLEASE! [Re: HotRodDave] #1661740
08/26/14 04:25 PM
08/26/14 04:25 PM
Joined: Dec 2010
Posts: 32
Nebraska
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ronhug Offline OP
member
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Nebraska
any ball park idea on what the HP range may be ?

Re: 273 building and info needed PLEASE! [Re: hemidart1] #1661741
08/26/14 04:29 PM
08/26/14 04:29 PM
Joined: Dec 2010
Posts: 32
Nebraska
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ronhug Offline OP
member
ronhug  Offline OP
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Joined: Dec 2010
Posts: 32
Nebraska
360?? Magnum? or older 360? whats the best choice? how workable is a carbureted intake on a magnum?

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