273 commando Build

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from erson catalog ::
Excellent choice for slightly modified, daily drivers, i.e.: Dodge Darts or Plymouth Challengers with 8.75-9.5:1 compression in 318-340 CID engines. Should have aftermarket aluminum, dual plane style intake with up to 650 cfm 4-barrel carburetion and gasket-matched cylinder heads for best results. Largest camshaft with stock converter and mid-3 series gearing... basic rpm range 2,000 - 5000- E420721 284° IN 220° IN .472" IN 108° 0° .000" IN .... Hi Flow AH 284° EX 220° EX .472" EX .000" EX.
 
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from erson catalog ::
Excellent choice for slightly modified, daily drivers, i.e.: Dodge Darts or Plymouth Challengers with 8.75-9.5:1 compression in 318-340 CID engines. Should have aftermarket aluminum, dual plane style intake with up to 650 cfm 4-barrel carburetion and gasket-matched cylinder heads for best results. Largest camshaft with stock converter and mid-3 series gearing... basic rpm range 2,000 - 5000- E420721 284° IN 220° IN .472" IN 108° 0° .000" IN .... Hi Flow AH 284° EX 220° EX .472" EX .000" EX.
just read those 2 specs and.......... the catalog says its a hydraulic flat tappet cam .. the other info site says its a solid flat tappet cam.
now who's correct ? I ran it with solid lifters previously
 
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When I mention a powerpeak, that is exactly what it says , the rpm at which the power on a dynograph has reached it's highest number.
This has nothing to with the engine's redline
nor to it's shift point.
It's just a powerpeak.
The peak can be long/relatively flat, or it can be short/narrow/ and pronounced.
In a given longblock, in most instances this includes with headers, this peak cannot be moved around much. Yes you can increase/decrease the horsepower number, a little bit, at the peak, with intake carbs spacers and so on, but fundamentally, the rpm of the peak doesn't change much. That will take a different cam, or at least a different LSA..

Your shift point, for a fast trap speed is related to the powerband requirement of the transmission. With a 4 speed this is easy cuz each gear is nearly the same shift split of about 72%. So then whatever rpm you shift at, in the next gear, the rpm will drop to about 72%. and you want the incoming power to be at or near the same as the outgoing power. With a 4-speed, this is gonna be about 400rpm past the peak power, depending on a host of engine parameters. So if your power peaks at 5000, then you might outshift at 5400, and you're looking for the same incoming power at 5400x .72=3900; thus your powerband is from 3900 to 5400. From there you gotta go out and test it. But thru the traps you wanna be very close to, if a lil past, peak power.
If you shift too early, your rpm will fall further down the powercurve, making your engine struggle to get back up on the cam.
If you shift late, you should come in at a higher power, but leave at a lower power. I like this a lil better, cuz this gives the car a lil kick-in-the-azz; but your engine has to survive the extra top-end rpm.
Now, if you have an automatic, that's a whole nuther thing.
So
If your engine is pulling past 5100, with a 222/108 cam, that only means one of maybe three things;
1) the cam you installed does not match the camcard you posted, or
2) the cam has flat-lined early, due to environmental complications, or
3) you haven't actually driven it fast enough to feel it nose-over, cuz until you do, there is not enough time to actually feel it.

The camcard you posted says 44* of overlap. With headers, that should put a nice lil power bulge on the power curve. With headers but a less than stellar exhaust system, or without headers at all; that would mean a long flat power curve/without a powerbulge, like a 340... So yeah, I get it, that you might think it's still pulling at 5800.

I assure you, that I have had bigger cams in much more potent SBM engines than your 273. I even had a cam similar to the one that you posted the camcard for, and while it was a nice hi-torque cam(223/230/110/51overlap), it peaked at around 5000.
Oh sure that lil cam pulled to 7200 as well, but it was way past pulling hard. I just went there cuz she sounded awesome, screaming thru dual 3" cannons, and she was happy about it. The thing is, until it hit mid-Third gear, there was no way to feel the nose-over, cuz at WOT, the tires were still spinning.

I'm glad you like your 222/222/108 cam but 050-wise, let's face it; it's just not that big.
Get yourself a windshield-mounted accelerometer and it will reveal the truth to you.
What an absolute load of crap.
 
if that cam was suppose to be all done under 4800 why would it still feel strong and still pull to 5800
Because he's wrong, that's why. Do you think for one minute he knows more than the engineers at Isky? The first cam you had is pretty close to the factory 340 cam and they routinely pulled to beyond 6500, plus yours was a solid. I like the new cam though. It's kinda rowdy. Sounds good. My end opinion is, if you're happy with how it runs, don't worry about all the supposed forum gurus.
 
Because he's wrong, that's why. Do you think for one minute he knows more than the engineers at Isky? The first cam you had is pretty close to the factory 340 cam and they routinely pulled to beyond 6500, plus yours was a solid. I like the new cam though. It's kinda rowdy. Sounds good. My end opinion is, if you're happy with how it runs, don't worry about all the supposed forum gurus.
Thanks RustyRatRod !
Yeah that bigger Rowdy erson cam does sound nice but the Isky (milder cam) would have walked all over that larger erson camshaft.I like the siky cam better and will probally stick it back in the new 273 build . thanks !
 
Thanks RustyRatRod !
Yeah that bigger Rowdy erson cam does sound nice but the Isky (milder cam) would have walked all over that larger erson camshaft.I like the siky cam better and will probally stick it back in the new 273 build . thanks !
I bet the milder cam might have done that on the bottom end and some of the mid range, but the bigger cam would kick its butt up high.
 
from the seat of the pants , I would put $$ on the isky smaller cam.. all around . by the time take erson cam winds up i'd be 3 cars out . there's no way in **** the erson cam would run the isky down. LOL. and at one point I installed 410 gears with the erson and it still was not fast at all.
 
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I know this isn’t what you want to hear, but why are you putting some much effort and $$$ into a 273 if what you want is “fast”? I’d be building a 360…same $$$, more cubes.

…and BTW, I’m a 273 lover!

JMHO.
 
I know this isn’t what you want to hear, but why are you putting some much effort and $$$ into a 273 if what you want is “fast”? I’d be building a 360…same $$$, more cubes.

…and BTW, I’m a 273 lover!

JMHO.
great to here 273 lover....I have been waiting for someone to ask that question .... the answer is because I like to be the underdog and I proved it with a few of my buddies built 340 360 and 380 horse magnum engines in dart duster and barracuda . you just have to spin the engine a little higher and they will rev LOL. they still think it's not a 273 engine. I love the small block engine !
This built 273 in my 65 barracuda is the fastest small block i ever owned and I had dozens of sb mopars and nothing compairs to this built 273 except for a magnum crate 402 stroker I had in that 65 dart rag. that car was a 11:50 car all day on motor.

402 stroker.jpg


rag by steps 50KB.JPG


RAGGY at GROVE.jpg
 
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video time check this out !!
this was my car also it's a rare 65 dart charger 273 commando with cam and d4b intake/ headers. don't know anything about the cam but that engine would rev to the moon.. previous owner use to race it. here is a video .. It's tired as you can see and real loose. those revs were over 6k one 6500 rpms. this video is right after I installed new valve seals.. did not help much..
 
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great to here 273 lover....I have been waiting for someone to ask that question .... the answer is because I like to be the underdog and I proved it with a few of my buddies built 340 360 and 380 horse magnum engines in dart duster and barracuda . you just have to spin the engine a little higher and they will rev LOL. they still think it's not a 273 engine. I love the small block engine !
This built 273 in my 65 barracuda is the fastest small block i ever owned and I had dozens of sb mopars and nothing compairs to this built 273 except for a magnum crate 402 stroker I had in that 65 dart rag. that car was a 11:50 car all day on motor.

View attachment 1716330692

View attachment 1716330693

View attachment 1716330694
I want to clone this car—I’ve seen your YouTube videos. Have one waiting in the wings.

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IMG_3350.jpeg


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when did compression checks it was always a tad over 150# with stock domed pistons and composite 318 head gaskets at3.90 bore fire ring. I believe compressed gasket was approx .039. I thought compression would be more that 8.8
I looked up an ESSO tune up guide for a "1967" 273 Commando and it lists compression check from 130-165 psi minimum variation of 25 psi. 1966 for the same engine is 150-180 psi and a 2 barrel 273 as 120-150 psi.
 
I looked up an ESSO tune up guide for a "1967" 273 Commando and it lists compression check from 130-165 psi minimum variation of 25 psi. 1966 for the same engine is 150-180 psi and a 2 barrel 273 as 120-150 psi.
Interesting. No difference between 66 and 67 that I know of.
 
here is a 273 on dyno >>>>>>>>>>>>>>>>there is a video of a 530 horse 273 on the dyno . awesome ! //www.facebook.com/jason.verke/videos/1903567253072861/
here is some info on the nhra 273 >>>>>Jason Verke .060 over 273 Mopar
Extensive porting to stock iron castings, super victor intake also ported. Custom Harland Sharp full roller shaft rockers. Custom cam [email protected] .800 lift. Spec. 730 Holley vac. secondary. 14.0:1 on VP C-12 gas.
 
light tan appearance . no signs of plug looking fat.

I need to correct myself here.

A light tan plug IS correct IF you are using points. You likely can't get it much leaner than a very light tan before you start getting a lean miss, even though its not actually lean.

So if you are running points then your tune up is pretty close.

I don't consider points by themselves a performance ignition. If you are triggering a box with points that's good too.
 
Running before the end of the weekend, right?
I don't think so... winter will be here tomorrow, in the 30* all week.. at least the major part is done, the rest is a piece of cake .
 
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