273 vs 318

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1964-1965 273 were theonl
cosgig said:
Since nobody has touched on what I consider the major difference between a 273 and a 318, I guess I will! The register on the rear of the crank of the 273 is a major limiting factor when it comes to finding compatible equipment, and thus will be overlooked by the knowing Mopar public! Unfortunately, not everybody knows of this and will just throw in a 318 in place of a 273 and go racing!! That is until the front pump wallers out after just a couple miles and renders the trans useless!! Now, try coupling that 273 with a 68 and later trans!!!....not gonna happen!!
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yones that had a (small) diffrent crank register. The rest were the sameas 318.
 
Hipo65 said:
1964-1965 273 were theonl

yones that had a (small) diffrent crank register. The rest were the sameas 318.
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Hmm, so this 67 Commando motor on the stand with the small register is a one off?? How about all of the 66 Commando motors I have here?? Yep, all small register!!!
 
the wall said:
basically agreed here but with one exception, the 360 head (non magnum)head flow is a very small number off on stock 340 head. the main diff in these heads is the intake valve, 202 for 340 till 72 were it was changed to 188, 360 heads were 188. 1970 340 head actually have 360 cast on them on the intake runner were 68-69 had 340. the casting number were the same. not sure but i believe T/A heads have the same casting number but a diff part number. the flow numbers between 202 and 188 heads are a diff of 5-10 cfm difference give or take. the good news for the later smog 360 heads is that the exhaust has a slightly raised floor because of air injection and these port flow higher then 340 heads
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From what I've read the 2.02 X/J flow about 20 cfm more than 1.88 heads. And a 360 has 20 cid more to feed which needs about another 15 cfm more than 340's 2.02 heads to put it in the same cfm:cid ratio as 273/340. Just to put in perspective a 408 and 440 to be in the same ratio would need 260 cfm and 280 respectively or basically eddy heads.
 
cosgig said:
Hmm, so this 67 Commando motor on the stand with the small register is a one off?? How about all of the 66 Commando motors I have here?? Yep, all small register!!!
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64 - 66 are like that 67 was the change and the first year of the 318 and from 67 - 69 the two are identical except bore size the was no more commandos steel cranks and solid cams. yes if you swap a 318 into an 64-66 you need a later trans also if you swap in a early 273 onto a later trans you need custom converter or later crank. Or go standard.
 
273 said:
From what I've read the 2.02 X/J flow about 20 cfm more than 1.88 heads. And a 360 has 20 cid more to feed which needs about another 15 cfm more than 340's 2.02 heads to put it in the same cfm:cid ratio as 273/340. Just to put in perspective a 408 and 440 to be in the same ratio would need 260 cfm and 280 respectively or basically eddy heads.
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i get it what your saying now. your talking head diff and cube diff is off by 30 40. i was thinking your were saying the head was off that far. my testing on 1.88 2.02 averages 10- 15 but the numbers do very from head to head quit a bit so even at twenty your close
 
cosgig yep yer right I biffeded! on the crank reg thought 65 was the last year of small reg. one of those days......
 
Once driving a hi-po with a 4 speed, in my former 67 notch back, these motors rev fast and high. Like previously discussed, this is not a standard motor. Aluminum pistons, high lift cam, dual point ignition. Very unique sound with the dual point distributor. However, the heads are it's limitation, so 650 cfm is the max carb to use. There are (2) 318 heads with hardened seats that will work on these with bigger valves. Do not remember which ones. Need to be careful of the valve to head face interference. With the smaller bore, the head needs to have the valves inside the combustion chamber.
 
yellow rose said:
For a second I thought he was talking Canadian but he's from here. I'll keep that word for my next scrabble game.

If it's on FABO it must be a word.
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True that!! Now to start using it in context....that'll be the trick!!! Not even a day old and it's already a complex part of my vocabulary!! No wonder I'm the most interesting man in Pinckney!!! Look out world!!!! :)
 
Whatca talken a boot ? LOL! Cudaguy6, yeah 650 is pushing it for a mild combo. Id be perfect for steep gears & healthy camshaft. I just (today) got my quick fuel HR 450 cfm mech secondary carb dialed in & the throttle response is sweet! & pulls harder rite into the rev limiter a whole lot better/smoother that the old 500 edelbrock ever did even dialed in! Easy to over carb thease little guys.
 
Cudaguy6 said:
Once driving a hi-po with a 4 speed, in my former 67 notch back, these motors rev fast and high. Like previously discussed, this is not a standard motor. Aluminum pistons, high lift cam, dual point ignition. Very unique sound with the dual point distributor. However, the heads are it's limitation, so 650 cfm is the max carb to use. There are (2) 318 heads with hardened seats that will work on these with bigger valves. Do not remember which ones. Need to be careful of the valve to head face interference. With the smaller bore, the head needs to have the valves inside the combustion chamber.
Click to expand...
#302 heads.
 
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