273 or NOT 273?

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67_Slimer said:
Thought about it but seeing my car is a 67 , it would seem fitting that I build a 273 lol. I guess I'm really the only one who understands but I think it's more the fact that my friend had a 289 mustang, 4 speed car with 12.5/1 revving screamer. The fact that the first number was a 2 and not a 3 was so impressive to me , even though it's basically the same engine. Nor sure if it makes sense lol.
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you can easily do what you want with a 273.
 
67_Slimer said:
Thought about it but seeing my car is a 67 , it would seem fitting that I build a 273 lol. I guess I'm really the only one who understands but I think it's more the fact that my friend had a 289 mustang, 4 speed car with 12.5/1 revving screamer. The fact that the first number was a 2 and not a 3 was so impressive to me , even though it's basically the same engine. Nor sure if it makes sense lol.
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I get it my name is 273 because when I joined up my goal was to build a 7000-7500 rpm 273 Time Attack 65 Cuda, but I realized Time Attack was above my pay graded :) sold that and bought a running, driving 68 Valiant Signet with 380hp crate 5.9l but I still thinking of finding a 273 to play around with, was thinking of running the magnum crate top end on a 273 short block and see what she would do in the 1/4 mile :)
 
273 said:
I get it my name is 273 because when I joined up my goal was to build a 7000-7500 rpm 273 Time Attack 65 Cuda, but I realized Time Attack was above my pay graded :) sold that and bought a running, driving 68 Valiant Signet with 380hp crate 5.9l but I still thinking of finding a 273 to play around with, was thinking of running the magnum crate top end on a 273 short block and see what she would do in the 1/4 mile :)
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That would be awesome. I'm wondering if I could use my 915 340 heads on the 273? (1.88 valves)
 
67_Slimer said:
That would be awesome. I'm wondering if I could use my 915 340 heads on the 273? (1.88 valves)
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@66fs runs 360 heads with 1.88 valves in his 273, he didn't notch the block, so yes you should be able to, he'd be the one to ask for exact details. I know he's a big 273 fan with 360 heads and 340 cam.

Stock 360 heads should be able to get 350 hp no problem, to get closer to 400 hp probably need to do some mild porting.
 
67_Slimer said:
That would be awesome. I'm wondering if I could use my 915 340 heads on the 273? (1.88 valves)
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Yes it is doable. With a good set of 1.88 intake J heads Just clean up the bowls, port match the intake and heads, milled .040 and .038 on the intake side. Double check everything. You can run a smaller cam and still make that 67 fly. I ran a used 340 cam, 71 intake a TQ. My favorite engine of all time. Now, I'd run a custom solid cam, probably Racer Brown. But that was when you could buy good high octane gas for 10.5:1 compression. Not sure what tire would hold it with 4.56 gears... You should also run the Commando single exhaust, that would really blow their minds.
 
66fs said:
Yes it is doable. With a good set of 1.88 intake J heads Just clean up the bowls, port match the intake and heads, milled .040 and .038 on the intake side. Double check everything. You can run a smaller cam and still make that 67 fly. I ran a used 340 cam, 71 intake a TQ. My favorite engine of all time. Now, I'd run a custom solid cam, probably Racer Brown. But that was when you could buy good high octane gas for 10.5:1 compression. Not sure what tire would hold it with 4.56 gears... You should also run the Commando single exhaust, that would really blow their minds.
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So i love high revving motors , would a victor style single plane intake with a 750 be overkill? Id have my same 1 5/8 headers and drivetrain. I'd want 11.5/1 Compression. Do they have aftermarket pistons for 273s?
 
67_Slimer said:
So i love high revving motors , would a victor style single plane intake with a 750 be overkill? Id have my same 1 5/8 headers and drivetrain.
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I wouldn't go single plane, it will give up too much bottom end power and a 273 gonna have a problem with that anyways with being so small, cam gonna be a tricky choice too, want something that will make great top end power 6000-7000 rpm but sacrifice as little as possible down low power. Need to make the power more from the heads than cam, like 4.8l LS engines do they make good 2500-6500+ power with small ish roller cams 215-225 because of the LS head. Carb wise if making 350-400 hp don't see no reason you can't run it.
 
This the type of power curve you want to try to replicate.
Not saying you can exactly get a curve like this LS 4.8l but be something to shoot for.

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273 said:
I wouldn't go single plane, it will give up too much bottom end power and a 273 gonna have a problem with that anyways with being so small, cam gonna be a tricky choice too, want something that will make great top end power 6000-7000 rpm but sacrifice as little as possible down low power. Need to make the power more from the heads than cam, like 4.8l LS engines do they make good 2500-6500+ power with small ish roller cams 215-225 because of the LS head. Carb wise if making 350-400 hp don't see no reason you can't run it.
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Even with a stick and 4.56s? As it is now , my 340 makes no power until around 3000.
 
If you use the 273 66 and later heads the LD4b is a great choice. If you use the 360J heads like 66Fs you probably wouldn't want to use this intake. I had a 67 Barracuda which was actually my first car that had the 273 with 360 J heads with a thermoquad intake on it. The previous owner was a machinist and used to run it at US 41. He was actually running a Rochester carb on it. He had a Dana 60 slightly narrowed with 411 gears and a mopar 4 gear. He had an old set of chrome reverse baby moon mag wheels on the Dana about 10 inches wide with much narrower front wheels that were matching chrome reverse. Big bolt in rear 5x4 on the front. Being a machinist the internals were beefed and a robust port and polish. He sold me the car as he was retiring from racing for $450.00 in 1980. I truly loved that car!
 
jeff alder said:
If you use the 273 66 and later heads the LD4b is a great choice. If you use the 360J heads like 66Fs you probably wouldn't want to use this intake. I had a 67 Barracuda which was actually my first car that had the 273 with 360 J heads with a thermoquad intake on it. The previous owner was a machinist and used to run it at US 41. He was actually running a Rochester carb on it. He had a Dana 60 slightly narrowed with 411 gears and a mopar 4 gear. He had an old set of chrome reverse baby moon mag wheels on the Dana about 10 inches wide with much narrower front wheels that were matching chrome reverse. Big bolt in rear 5x4 on the front. Being a machinist the internals were beefed and a robust port and polish. He sold me the car as he was retiring from racing for $450.00 in 1980. I truly loved that car!
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The big reason I'm contemplating this build is because I found out I can use 1.88 J heads (which I have on my shelf) That is a big game changer , now the motor can both spin and breathe. Not sure if I would need to do any bore work to make that happen? .030 over? Any reliefs? Also , what rods and pistons are recommended? Remember , I want strong and lightweight.
 
67_Slimer said:
The big reason I'm contemplating this build is because I found out I can use 1.88 J heads (which I have on my shelf) That is a big game changer , now the motor can both spin and breathe. Not sure if I would need to do any bore work to make that happen? .030 over? Any reliefs? Also , what rods and pistons are recommended? Remember , I want strong and lightweight.
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Ask @66fs, I know he didn't notch, not sure about over bore etc..
 
67_Slimer said:
The big reason I'm contemplating this build is because I found out I can use 1.88 J heads (which I have on my shelf) That is a big game changer , now the motor can both spin and breathe. Not sure if I would need to do any bore work to make that happen? .030 over? Any reliefs? Also , what rods and pistons are recommended? Remember , I want strong and lightweight.
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Double check everything during assembly. There might be clearance but shrouding may occur and you should notch the bores. CC the heads because the chambers are huge compared to the small bore closed chamber 273 heads. Just guessing but you could start with 10.5/1 pistons and end up with compression in the lower 9's with a big open chamber. Measure and calculate it all carefully.
 
toolmanmike said:
Double check everything during assembly. There might be clearance but shrouding may occur and you should notch the bores. CC the heads because the chambers are huge compared to the small bore closed chamber 273 heads. Just guessing but you could start with 10.5/1 pistons and end up with compression in the lower 9's with a big open chamber. Measure and calculate it all carefully.
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Thats why you run the piston out of the deck.
 
67_Slimer said:
So i love high revving motors , would a victor style single plane intake with a 750 be overkill? Id have my same 1 5/8 headers and drivetrain. I'd want 11.5/1 Compression. Do they have aftermarket pistons for 273s?
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So do I, not sure about a 750 Holley, The TQ was very tunable with choke and all for the street. 273's are still being raced so custom pistons are available. 10.5 was stock. A .040 cut will yield 65cc chambers.
 
66fs said:
So do I, not sure about a 750 Holley, The TQ was very tunable with choke and all for the street. 273's are still being raced so custom pistons are available. 10.5 was stock. A .040 cut will yield 65cc chambers.
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What's the chamber diameter on a 340 head? Same as the bore size? .040+ is a long ways from 340 bore size.
 
66fs said:
So do I, not sure about a 750 Holley, The TQ was very tunable with choke and all for the street. 273's are still being raced so custom pistons are available. 10.5 was stock. A .040 cut will yield 65cc chambers.
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Do you have to bore or any modifications to put 1.88 valve heads on?
 
273 said:
This the type of power curve you want to try to replicate.
Not saying you can exactly get a curve like this LS 4.8l but be something to shoot for.
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you'd have to pour so, so much money into a LA head to get even close to a LS head. that's really an apples and oranges comp.
 
toolmanmike said:
Pocket change is all you needed. I think they got close to 30 mpg. You could buy one for $2000.

There is a stock 302 Comet sitting in a driveway not far from me. I am almost tempted to stop by and ask about it. Naw, I don't need another car.
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Is it in good shape?
 
junkyardhero said:
you'd have to pour so, so much money into a LA head to get even close to a LS head. that's really an apples and oranges comp.
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Never said to make the LA into LS head, but the hp building process can be inspired by the basic premises of the LS, Hemi even Magnum, 340, 302 Boss etc.. Over larger cams and weak heads like 302,327,350 Chevy's , hp by higher % from cylinder head over cam.
 
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66fs said:
Yes it is doable. With a good set of 1.88 intake J heads Just clean up the bowls, port match the intake and heads, milled .040 and .038 on the intake side. Double check everything. You can run a smaller cam and still make that 67 fly. I ran a used 340 cam, 71 intake a TQ. My favorite engine of all time. Now, I'd run a custom solid cam, probably Racer Brown. But that was when you could buy good high octane gas for 10.5:1 compression. Not sure what tire would hold it with 4.56 gears... You should also run the Commando single exhaust, that would really blow their minds.
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Which head gasket did you use?
 
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