273 with 360 heads/valves

[MuuMuu101]

I'm not going to lie, but when everyone keeps mentioning that my 273 will have low 8's when it comes to compression, I keep on thinking, "BOOST!" Lol.

with 318 blocks on every corner of the world, and sometimes for FREE, a 273 makes ZERO sense to build. The 318 gives you affordable pistons where the 273 requires expensive pistons. There is no advantage to a small bore and a expensive piston. Now if you have one orig to your car, then that would make sense.

I mean, but a similar argument could be made against the 318. 360's are everywhere and not much more expensive so why not just build that instead? It's a never ending cylce. Maybe the cost doesn't matter too much to me, right now...

 

[273]

Cool story bro......273s had all the "good parts" ? you mean the early ones that had adjustable rockers we all rob off of them, right? The heads were terrible, rods were tiny, bore was small, that engine requires a DOME piston to even get to 10.5 to 1 compression ....crank was ok....what were the "good" parts? crank and rocker arms? I have a customer with a 96 ram van, 318 magnum with 365K miles on it also.........just sayin

For a 273 they are good parts, the heads are to small for any other small block but head flow per cubic inch the 273 is the highest of them all. Which makes them good little revvers and it's a lot easier to get 1.5 hp per inch out
of a 273 than a 408 or even 340/360.

It all depends what your after, to me it more interesting trying to squeeze 400 hp out of a 273 than a 360
Especially if your willing to live with race car idle, high stall and deep gears.

 

[69 Cuda 440]

Cool story bro......273s had all the "good parts" ? you mean the early ones that had adjustable rockers we all rob off of them, right? The heads were terrible, rods were tiny, bore was small, that engine requires a DOME piston to even get to 10.5 to 1 compression ....crank was ok....what were the "good" parts? crank and rocker arms? I have a customer with a 96 ram van, 318 magnum with 365K miles on it also.........just sayin

* Crankshaft
* Rocker Arms
* Dual-Point Distributor
* Intake
* Carter AFB

The Lightweight "thin' Full-Floating Connecting Rods were actually not bad for screaming.

 

[toolmanmike]

* Crankshaft
* Rocker Arms
* Dual-Point Distributor
* Intake
* Carter AFB

The Lightweight "thin' Full-Floating Connecting Rods were actually not bad for screaming.

Let's not forget the closed chamber heads. The chambers were shaped like the #302 casting heads released years after.

 

[replicaracer43]

I'm not going to lie, but when everyone keeps mentioning that my 273 will have low 8's when it comes to compression, I keep on thinking, "BOOST!" Lol.



I mean, but a similar argument could be made against the 318. 360's are everywhere and not much more expensive so why not just build that instead? It's a never ending cylce. Maybe the cost doesn't matter too much to me, right now...

That is true, I personally feel the 360 is the best bang for your buck smallblock. Assuming your starting with nothing.

 

[replicaracer43]

* Crankshaft
* Rocker Arms
* Dual-Point Distributor
* Intake
* Carter AFB

The Lightweight "thin' Full-Floating Connecting Rods were actually not bad for screaming.

I agree on the rods, we used to use the small rods in our oval track motors with light pistons, but that was before the cheap I beam rods came on the market.

 

[66fs]

Cool story bro......273s had all the "good parts" ? you mean the early ones that had adjustable rockers we all rob off of them, right? The heads were terrible, rods were tiny, bore was small, that engine requires a DOME piston to even get to 10.5 to 1 compression ....crank was ok....what were the "good" parts? crank and rocker arms? I have a customer with a 96 ram van, 318 magnum with 365K miles on it also.........just sayin

The good parts are pretty much everything, on any 1964-1967 273. Good compression ratio + piston .020 down from deck, closed chambered heads that flow very well for cubic inch, Mechanical valve train, forged crank, forged light weight rods, 4 barrel intake and AFB with velocity valve, dual point distributor, internal balanced. The only parts I used from a 360 were the heads and rods, unless it was a 4 barrel engine then I would take the intake and carb. Isn't it funny how we are all different? What mpg do you get cruising at 70 mph?

 

[replicaracer43]

I have no idea what kind of MPG I get cruising at 70, all my stuff is hot rodded, if I cared about gas milage I would buy a 4 cylinder. The good thing is that yes, we are all different, or else we would all like the same exact thing, and that would be boring!

 

[66fs]

I've rarely had a stock car till I was much older. It was nice to have a Hot Rod, and the mpg almost made me feel guilty.

 

[nm9stheham]

I'm not going to lie, but when everyone keeps mentioning that my 273 will have low 8's when it comes to compression, I keep on thinking, "BOOST!" Lol.

Actually, that is a cool idea.....! In some ways, it is the perfect engine for that. Small ports and valves pretty much disappear from the equation, and you get the good MPG of the small displacement. Just wish it was easy to find some medium priced forged pistons for such a combo. Even just 8 to 10 lbs boost would get you a lot of power increase. And the cam appropriate for a turbo will give a good DCR, and the low 8's SCR will not be an issue, so you will have reasonably good low end torque as the turbo is spooling.

Now I know what to do with that 273 block!

 

[chrissock]

I am not at all as smart as all you engine guys. But I got a FREE running 273. Its not home yet. My plan is to make sure it has the right crank and rods in it and put a supercharger to it. low boost 5psi with a cam, intake, and headers. I already took heads off and had them worked out so they are fresh with good springs. Also worked a deal for a Fast Fuel injection set up. So I figure if it makes anywhere in the 300 range thats cool. Plus I like being different. cant wait to see peoples faces when I tell them its a blown 273.
Im with the OPer. If you have the stuff go for it. Also if I blow it up or get tired of it I can swap in ANY mopar small block and this set up will go right back on. So no harm no fowl.

 

[nm9stheham]

Hope that all works out. Study up on cams for turbo'd or supercharged engines.... very different cams are used versus NA.

 

[chrissock]

Hope that all works out. Study up on cams for turbo'd or supercharged engines.... very different cams are used versus NA.

I have been messing with This stuff for a bit. This is another project of mine. I like the challenge of little motors.

 

[moper]

I like the idea of a good 273. I'm going to be using a 273 crank and rods in my 340. But again it comes to value. Value meaning cost vs. reward. To get a 273 done well, will cost more money. Custom pistons, and custom head gaskets, plsu a couple extra blueprinting steps like centering the chambers over the bores and notching the bores themselves. I think the larger LA head ports will be a bit much for the 273, but an early A is light, and with the right gears I don;t feel most drivers would notice any loss of response. To each their own. I have choices for my '65 from a slant 225 up to a 360 and I'm still not sure which will get the knod...lol.

 

[273]

I like the idea of a good 273. I'm going to be using a 273 crank and rods in my 340. But again it comes to value. Value meaning cost vs. reward. To get a 273 done well, will cost more money. Custom pistons, and custom head gaskets, plsu a couple extra blueprinting steps like centering the chambers over the bores and notching the bores themselves. I think the larger LA head ports will be a bit much for the 273, but an early A is light, and with the right gears I don;t feel most drivers would notice any loss of response. To each their own. I have choices for my '65 from a slant 225 up to a 360 and I'm still not sure which will get the knod...lol.

I agree especially the part about the right rear gears, you need to trading in the extra rpm available to these smaller engine to have the same power to the ground (torque) to make a 273 equal to a 3.55 geared 360 you would need to run 4.56-4.88. To have a more apple to apple comparison.

 

[MuuMuu101]

I just got the heads and some other parts today, so maybe sometime this week I'll play legos with them and my spare block. I also purchased an Edelbrock LD4B that should be coming the mail sometime soon, hopefully.

 

[MuuMuu101]

So, I just got my heads this weeks. I think they have 2.02" valves in them based off of my tape measuring skills. I couldn't find my digital calipers to verify.

 

[Abodybomber]

Stock 5.9 Magnum, not a stock 360 4-bbl LA... big difference

Agreed,with Khalid. Until you bring the LA production low compression up,lights out with the Magnum. Built both with stock short blocks,Magnum all the way.

 

[Abodybomber]

I like the idea of a good 273. I'm going to be using a 273 crank and rods in my 340. But again it comes to value. Value meaning cost vs. reward. To get a 273 done well, will cost more money. Custom pistons, and custom head gaskets, plsu a couple extra blueprinting steps like centering the chambers over the bores and notching the bores themselves. I think the larger LA head ports will be a bit much for the 273, but an early A is light, and with the right gears I don;t feel most drivers would notice any loss of response. To each their own. I have choices for my '65 from a slant 225 up to a 360 and I'm still not sure which will get the knod...lol.

Excellent statement... Cost vs. reward,is a big thing. Was going to do a 273 hot rod,for my 67 Formula S . The used 360 was cheaper & faster.

 

[krazykuda]

So, I just got my heads this weeks. I think they have 2.02" valves in them based off of my tape measuring skills. I couldn't find my digital calipers to verify.

That's cool!

But it's hard to tell the difference between 1.88 & 2.02 valves with tape measure... If you could find the calipers, then you could get a more accurate measurement...


If they are 2.02" valves, then you may have to notch the block for clearance and to minimize the shrouding effect from the small bore and large valve.

Tha ld4b is the best intake for your application, it should run great. We ran one on a stock 318 with a 4 bbl and dual exhaust and it pulled strong off the line with no bogs/stumbles... It's a great intake for those smaller SB's... We pulled off a Edelbrock performer intake to install the LD$B and it ran MUCH, MUCH better with the new intake and carb. We just popped a new Edelbrock carb on it and ran it with minimal tuning. It wouldn't spin the tires, but it also didn't bog or stumble off the line, pulled nice and strong... Nice throttle response also...

 

[66fs]

Since you have 360 heads I'd run a 360/340 large port intake like a LD 340 or Air Gap. But since you have a LD4B that will probably work, but was designed for the small 273/318 intake ports.

 

[MuuMuu101]

I'm going to try to find my calipers to make sure what I really have. Either way, I think I'm going to go with a stroker for my 360 so the Paxton may be left over for the 273 build. If I can save the original pistons, I may just run 4-5 lbs of boost (the pulleys I have now). I'm definitely going to save this setup for a wagon or convertible.

 

[MuuMuu101]

I found my digital calipers today. The intake is 1.88" and the exhaust is 1.60" or so. My intake should come tomorrow so maybe I'll play test fitting over the weekend.

 

[mech1nxh]

Legend has it that you can't get away with a 1.88" valve in the 273

--- LEGEND--- well legend is one thing , reality is another... .035 average between the cyl
wall & intake skirt x 8 cyls ...cold. of course this measurement was done with a 'snap on' 10 inch feeler gauge... I could be mistaken--- "the *****" did not blow up due to 'valve anomaly'
Rather lack of block prep, contrary to popular belief, You do not build a project around a cam, --- such bullshit--- Block prep is the absolute.

Apologies for the Rant Honored Posters.

 

[Abodybomber]

--- LEGEND--- well legend is one thing , reality is another... .035 average between the cyl
wall & intake skirt x 8 cyls ...cold. of course this measurement was done with a 'snap on' 10 inch feeler gauge... I could be mistaken--- "the *****" did not blow up due to 'valve anomaly'
Rather lack of block prep, contrary to popular belief, You do not build a project around a cam, --- such bullshit--- Block prep is the absolute.

Apologies for the Rant Honored Posters, I'm out.

Absolutely correct,Normster... Rat mill,060 over 402 .. 2.19 intake valve cleared , by a mile. (990 castings, bought with Hogan's early head work ..1700 to tune them up, steal of the century..