I doubt the accuracy of your assumptions
True its my guess on how it would play out.
I doubt the accuracy of your assumptions
Noise, Vibration, and Harshness
336 cubic inches. lol a tractor engine lolI suppose someone with some $$$$$ to experiment could always build a stroker 273 with a 4" crank. Wait....where'd I put that pot stirring smiley?
I agree the 273 is a good small engine, not what I would consider a powerhouse.
Can they built for moderate HP , yes, but then you have a grenade at the 400 HP level.
I have to disagree with the 360 under powering the 273.
Graphs and data from 1967 Dodge (USA) Dart 270-Custom Hardtop full range specs
Lots of comparisons and metric heavy graphs.
318-2 edges out 273-4 from raw data. 273-4 pulls ahead after 100MPH due to higher revving potential of 273-4 cam profile and solid lifters.
273 3sp manual
lView attachment 1715529631
273 4sp manual
View attachment 1715529632
273-4 4sp manual
View attachment 1715529633
318-2 4sp manual
View attachment 1715529636
Drag race distance in time
View attachment 1715529634
Fun fact, 273-4 had a higher top speed due to camshaft profile and higher solid lifter RPM potential. Simulation says 68 318-2 would beat 67 273-4 by 21 feet at 1/4 mile with a slower MPH but faster ET.
Looks like both 2bbls run out of cam at 4200
View attachment 1715529635
... There was also never a 67 318 4bbl..imagine where that power level would have been compared to a like cammed 273. <<<<
True! All subjective!What do you call powerhouse? 12 second quarters? 10 second quarters? 140 mph + in the top end? Ability to burn rubber through 1st and 2nd gear?
Any basic upgrades (without creating a wacko out of balance combo) are normally a fine addition that will make the engine and owner really happy. I love these kinds of basic upgrades and a simple street machine.He does not need anything but a cam and valve spring change, a 4 barrel and intake for what he wants.
No doubt!I know more than most of you what drag racing is. Once you start down that road, if you are really serious, it never ends.
You for surely picked up the right car.As for 273's and 360's I have driven both. There is no way a stock HP 360 would take my 273, which was not stock. I looked at buying a new car in the mid 70's with A HP 360. I ended up keeping the 64 Barracuda and 273 since it was faster.
Actually, it does, sort of... driver dependent is the first issue and then there is the possible issue of chassis or traction deficiencies. I say this often, “To bad I’m not a multi millionaire!” Just build stuff just to have fun and test and destroy and rebuild and test again with engine vs engine shoot outs. Like a combo of Richard Holdner, engine masters, road kill, top gear mixed with idiots delight. I guess I better start playing lotto for a change huh?!?! It would make for a awesome you tube channel.Too bad it does not work out that way in real life.
Well played. I didn't think of the marine apps. Stump pulling cam with a flat torque curve. Gobs more torque where its needed in a boat, down low.I have one in my 68 Correct Craft Barracuda. 318 Marine 4 barrel 225 hp.
Well played. I didn't think of the marine apps. Stump pulling cam with a flat torque curve. Gobs more torque where its needed in a boat, down low.
... Actually, it does, sort of... driver dependent is the first issue and then there is the possible issue of chassis or traction deficiencies. I say this often, “To bad I’m not a multi millionaire!” Just build stuff just to have fun and test and destroy and rebuild and test again with engine vs engine shoot outs. Like a combo of Richard Holdner, engine masters, road kill, top gear mixed with idiots delight. I guess I better start playing lotto for a change huh?!?! It would make for a awesome you tube channel.
LMAO!!!
The part that has the biggest effect on HP is the cylinder head and because of the small bore, big valve heads will not work. The intakes would contact the block unless you grind relief notches in the deck. Keep the 273 what it is. Any 4 bbl 318, 360, 5.9, or 5.7 will far out perform the 273 and have unlimited parts available.
Ugh! You just reminded me in the head flow numbers I forgot to post up on with the flow rates from two different bore sizes. Bore size has a direct impact on HP.True but we don't know how much actual effect the bore size will have on flow. Haven't seen anyone do flow numbers a 318 bore nevermind 273. Did see one article on 350 vs 305 bore sizes on some Chevy cylinder heads and there was like a 10 cfm difference. I know 305 has a bigger bore than 273.
To get 400hp out of 318/340/360 the formula seems to be 200-220 cfm heads 10:1 cr and a 285 ish cam. With a 273 probably got to add another 20 cfm. The main problem for some would be at 400 hp you would need to turn the 273 around 7000 rpm.
If I was gonna build a 273 between 250-400hp I'd go with mild ported stock valve size magnum heads on a notched block with some 4.??:1 gears out back.
I suppose someone with some $$$$$ to experiment could always build a stroker 273 with a 4" crank. Wait....where'd I put that pot stirring smiley?
I know (Chevy) guy that built a stroker 305 (400 crank, 3.75" stroke), I kid you not. I asked him why and he said "gas mileage." Had to buy crazy $$$ dished pistons to keep the compression pump gas with the tiny chamber 305 heads. If I'm not mistaken he used some hind of "305 Torquer" World Product heads from the '80s. A good deal on those heads probably was the catalyst for the whole build. I would have just built a 307 (3.25" stroke, basically Chevy's 318).
I know (Chevy) guy that built a stroker 305 (400 crank, 3.75" stroke), I kid you not. I asked him why and he said "gas mileage." Had to buy crazy $$$ dished pistons to keep the compression pump gas with the tiny chamber 305 heads. If I'm not mistaken he used some hind of "305 Torquer" World Product heads from the '80s. A good deal on those heads probably was the catalyst for the whole build. I would have just built a 307 (3.25" stroke, basically Chevy's 318).
The part that has the biggest effect on HP is the cylinder head and because of the small bore, big valve heads will not work. The intakes would contact the block unless you grind relief notches in the deck. Keep the 273 what it is. Any 4 bbl 318, 360, 5.9, or 5.7 will far out perform the 273 and have unlimited parts available.
What year was that Petty Enterprises motor list in ? 273-318-340 ? All the same year ?
Well, that was fun to read...now back to where this topic has morphed - building this 318.
I have a 318 with 675 casting heads. I tore it down and the block seems good, no bore taper, only one questionable area on cylinder 3. Mains are 10 over, but rods seem to all be stock size and measured consistently and not out of round.
I also have a running 273 that I pulled on Saturday. Ideally, I leave this thing complete and stash it away to remain untouched for the car in the future.
From these parts, what is my optimal build here?
Desires:
318 street build - fun driver
Plan:
Vat/clean block - remove ring ridge and hone cylinders
Disassemble/clean/inspect heads for damage
Port 675 heads at home
Valve job at home
Edelbrock 2176 dual plane
Hughes Whiplash Cam and supporting parts from Hughes
New bearings/gaskets
Unknowns/Still left to decide:
Compression ratio - which pistons to use? Which head gasket to use?
Carb - Thinking we gonna be around 650 cfm?
Exhaust - car currently has 2" true duals...going headers I would imagine, which ones for 67 Dart?
Thanks