273 cam

[toolmanmike]

Cam specs:
65 2 barrel 395/405 240/240
65 4 barrel 415/425 248/248
66 4 barrel 420/430 248/248

Isky E4 425/425 260/260
216/216 @ .050
Comp 270s 468/468 270/270
224/224 @ .050

And just to compare the Comp 270:

340 4 barrel 430/444 268/276
68 340 4 speed 444/453 276/284

That Comp 270 is pretty big for the 273. I'm surprised at how mild it idles.

 

[AJ/FormS]

There is an application for the thumpr, and I might someday even try one. If I live long enough.
Certainly 227/241@.050 can make good power, allbeit in a bigger engine. and
Certainly a cam with 73 degrees of overlap will have a thumping good idle.
And if you have enough cylinder pressure and/or cubes, It will be fun.

If you map out the events at .050, those numbers compare very favorably to my Hughes HE3038AL which in my combo is fabulous,lol.(third cam was the charm).
Lets compare the .050 durations;
........intake-comp-power-exhaust-overlap
Mine; 230....139.....127.5....237....13.5
Tmpr: 227...144.5...127.5....241....20
So it's a nice street cam, where it counts.Look the ICA is even 5.5* earlier

Now, I run aluminum heads and 10.9Scr and here is what Mr Wallace says about VP
using my 41*ICA@.050
Static compression ratio of 10.9:1.
Effective stroke is 3.25 inches.
Your dynamic compression ratio is 9.99:1 .
Your dynamic cranking pressure is 218.00 PSI.
V/P (Volume to Pressure Index) is 218 .

And the Thumpr in the same engine, with it's 35.5 ICA
Static compression ratio of 10.9:1.
Effective stroke is 3.34 inches.
Your dynamic compression ratio is 10.24:1 .
Your dynamic cranking pressure is 225.01 PSI.
V/P (Volume to Pressure Index) is 231
See, that's a 6% increase in VP from the earlier closing intake.

But now lets look at what the advertised is doing
First mine; 276/286/110+4
Static compression ratio of 10.9:1.
Effective stroke is 2.79 inches.
Your dynamic compression ratio is 8.72:1 .
Your dynamic cranking pressure is 182.97 PSI.
V/P (Volume to Pressure Index) is 157

Next the ThumpR at 279/296/107+5
Static compression ratio of 10.9:1.
Effective stroke is 2.85 inches.
Your dynamic compression ratio is 8.88:1 .
Your dynamic cranking pressure is 187.33 PSI.
V/P (Volume to Pressure Index) is 164

Well wouldjahlookitthat, an INCREASE IN vp of 4.5%!

So what they did was add about 10 to 13 degrees more exhaust duration, and then close up the LSA, and increase the Installed centerline a tad. What this did was steal a few degrees from the power stroke, and increase the overlap a bunch. The net of that is lumpy idle . And probably make it a bit of a gas-burner. ( mine sucks gas pretty bad around town)
The extra VP will increase my torque down low, which with a 4 speed is always welcome.
and the power peak will come down a few rpm and maybe make slightly less power than mine; but that extra overlap might just even it up.
The bottom line is that in MY combo, I could make it work.

But here's what it looks like in an 8/1, 273;
Static compression ratio of 8:1.
Effective stroke is 2.62 inches.
Your dynamic compression ratio is 6.53:1 .
Your dynamic cranking pressure is 125.01 PSI.
V/P (Volume to Pressure Index) is 81....................................... 81
A slanty is stronger than that.

Here it is with the pressure bumped up to close to the max for pumpgas
Static compression ratio of 9.7:1.
Effective stroke is 2.62 inches.
Your dynamic compression ratio is 7.88:1 .
Your dynamic cranking pressure is 160.34 PSI.
V/P (Volume to Pressure Index) is 104
Ok so 104 is STILL pretty doggone low,so this is why we need a hi-stall; to go find some power, and why we need some gears to make it driveable.
The problem remains that this is just a 227*@.050 so the power is gonna peak quite low for the combo, so you got no headroom, or not much, with the 3000/3500TC this is gonna take.
Say you put 3.91s in there.
You're gonna want to shift into second (904), at about 5800/44 mph. That's a really long pull for a 273.
Say 4.30s? Now you're down to 5800/40. Still a long pull.

This combo wants a 5 speed stick, like the Dakota trans. Ratios of 3.49-2.16-1.40-1.00-.73
Yeah, now you have an overdrive so now, 3.91s are looking good with that 3.49 low, and 5800 will get you 32mph, BadaBOOM!! And 65 will be 2450, about perfect for that cam.
Recap
So there you go OP, you can have the combo I have been dreaming about; namely; a 9.7Scr 273, with a wicked sounding idle, and the punch to back it up, in a lightweight-A, and still hit the hiways for extended trips.
Well actually, in my dream, it's a 5.2,lol, which is born closer to 9.5.And has Magnum heads.But if the engine needs pistons anyway..........................it don't much matter, lol.

 

[Bighead440]

Cam specs:
65 2 barrel 395/405 240/240
65 4 barrel 415/425 248/248
66 4 barrel 420/430 248/248

Isky E4 425/425 260/260
216/216 @ .050
Comp 270s 468/468 270/270
224/224 @ .050

And just to compare the Comp 270:

340 4 barrel 430/444 268/276
68 340 4 speed 444/453 276/284

That Comp 270 is pretty big for the 273. I'm surprised at how mild it idles.

TM Mike: I am like you, I don't usually recommend things unless I have personally used them or been involved with someone else's successful usage. The 270S can be run as loose as .030" lash hot, which takes some "lump" out and helps the bottom end, or be run as tight as .015" for a touch more top-end and a lil more lope. The 110*LSA makes it punchy (and the 108*LSA of the E-4, as well) compared to the wider lobe spread of the factory HP hydraulic cams, plus the lash really shortens the effective duration to about 260* (minus 10* adv. duration for lash).

 

[nm9stheham]

Cam specs:
65 2 barrel 395/405 240/240
65 4 barrel 415/425 248/248
66 4 barrel 420/430 248/248

Isky E4 425/425 260/260
216/216 @ .050
Comp 270s 468/468 270/270
224/224 @ .050

And just to compare the Comp 270:

340 4 barrel 430/444 268/276
68 340 4 speed 444/453 276/284

That Comp 270 is pretty big for the 273. I'm surprised at how mild it idles.

That 270solid is really more like a 260 hydraulic once you take the lash into account, as my best guess. So you gotta be careful when comparing solids to hydraulics.

And, IIRC, wyrmrider has pointed out that the Mopar 'advertised', or seat, duration specs were taken at a different valve lift than is standard now; IIRC he said it was taken at .008" lift, which means their advertised duration would be 10 +/- degrees longer if measured at .006" lift. So all of those specs are not really apples-to-apples, and that 270 solid's duration is probably only + or - a few degrees different from a stock 'advertised' duration once you account for everything. Just more lift.

 

[toolmanmike]

That 270solid is really more like a 260 hydraulic once you take the lash into account, as my best guess. So you gotta be careful when comparing solids to hydraulics.

And, IIRC, wyrmrider has pointed out that the Mopar 'advertised', or seat, duration specs were taken at a different valve lift than is standard now; IIRC he said it was taken at .008" lift, which means their advertised duration would be 10 +/- degrees longer if measured at .006" lift. So all of those specs are not really apples-to-apples, and that 270 solid's duration is probably only + or - a few degrees different from a stock 'advertised' duration once you account for everything. Just more lift.

Yep, I knew someone would mention that. Unless we have all the specs of all the cams they can't really be compared accurately. You guys are all technical and I use common sense. Small engine with low compression and a 2 barrel can't handle much more than a stock spec cam. Let's do the op a favor and don't over cam his little engine. We're not going for maximum power here just something a little more fun than what he has. (common sense approach speaking here.) We have had many discussions about 318 cams as well. They too are easy to overcam without adding a couple thousand dollars of parts to make them work. I'm done here. tmm

 

[273]

That Comp 270 is pretty big for the 273. I'm surprised at how mild it idles.

Sure displacement has an effect on how a cam will act. But your leaving out heads (including full intake and exhaust tracts). Impact on the powerband.

Take 273 340 and 440 the intake exhaust tracts are proportional the displacement.
Even the cam is very similar between the 340 and 440.

 

[4spdragtop]

So Tyler what's your expectations/plans? All these members respond and nothing but crickets at your end.
@273 ball

 

[toolmanmike]

So Tyler what's your expectations/plans? All these members respond and nothing but crickets at your end.
@273 ball

I pm'd him and no answer. I think we scared him off!

 

[nm9stheham]

LOL..... well I guess the direct answer is: "Yes, it will work. It will turn and will lift the valves in the proper sequence."

 

[toolmanmike]

LOL..... well I guess the direct answer is: "Yes, it will work. It will turn and will lift the valves in the proper sequence."

That's even more confusing. Will it work well? Let's put it this way, I wouldn't use it. It's better to undercam than over cam. There is no magic bullet.

 

[nm9stheham]

Yep, I knew someone would mention that. Unless we have all the specs of all the cams they can't really be compared accurately.

Just tryin' to 'splain why that 270s probably idles mildly....

 

[4spdragtop]

Lol, "we"?? Lol I had nuttin to do with scaring off.....unless Tyler's a girl, but I doubt it lol.
I scare girls easy....
Where's the Tom Cruise clip??? "HELP ME HELP YOU!!" lol
Lots of good advice here, and expensive mistakes can be made, so make sure to hit the "thanks" buttons.

I pm'd him and no answer. I think we scared him off!

 

[toolmanmike]

Lol, "we"?? Lol I had nuttin to do with scaring off.....unless Tyler's a girl, but I doubt it lol.
I scare girls easy....
Where's the Tom Cruise clip??? "HELP ME HELP YOU!!" lol
Lots of good advice here, and expensive mistakes can be made, so make sure to hit the "thanks" buttons.

First name basis. even more scary! LOL

 

[Del]

I have a 66 Barracuda factory 2 barrel. Now thumper cam , LD4B intake,600 Edelbrock,electronic ignition, 2200 stall converter, dual exhaust ( no headers ) 7:25 rearend with I think 276 gears. Car was built to be dependable sound good not a street racer done all my racing back in the 70's just wanting a nice driver that looks decent. It's definitely not fast from a dead stop but not bad above 30 mph. I know most people want a tire burner but that wasn't what I was shooting for. I'm a believer you build the it way that is for you.

 

[Wyrmrider]

I have sold Isky e-4's to 318 users- do not remember LA 318 but defiantly poly
my biggest concern this century is that it is a pricey cam unless you have a long deal
and it was designed for the obsolete valve springs of yesteryear only .425 lift 216 @.050 260 adv (means???)
Do not compare Mopar durations with anyone elses unless you use the SAE method
that said Comp recommends 3.55-3.91 and 9 to 9.5 for the 270S with a 340-360 so I agree with an earlier poster that in a 273 would be the High compression version and think of 3.91 gears
Comp has NO solid flat tappet grinds for mopar in their master list except some old top fuel profiles-270s is for a .842 lifter so it leaves torque on the table
and their XE series would seem to work better than the Magnum- but still one size fits all profiles
XE series
.015 .050 .200 lift
256, 218 129 479
262, 224 135 489
268 230 141 503
why support a grinder that does not support us?
Compare with Ultradyne Below
who does?
Could not find any at Howards or Lunati but both Bullet and Ultradyne do as does Mike Jones and Racer Brown

Bullet is here way to many to list
Bullet Cams Master List
a couple of Ultradyne- and we know who designed these
Ultradyne

NF .904 Flat Tappet Profiles VL = .016" w/1.5:1 Adv = .020"
.015 .050 .200 lobe 1.5 rocker
NF70 266 239 158 0.3576 0.536
NF62 270 243 162 0.3651 0.548

you did notice the 015 vs .020 duration difference
the 266 may be bigger than the 270
I'd contact Bullet/ Ultradyne for something "shorter"
a 260 @.020 .904 profile should rock
Jones and Racer Brown work with these three and see what they come up with

 

[273]

I have a 66 Barracuda factory 2 barrel. Now thumper cam , LD4B intake,600 Edelbrock,electronic ignition, 2200 stall converter, dual exhaust ( no headers ) 7:25 rearend with I think 276 gears. Car was built to be dependable sound good not a street racer done all my racing back in the 70's just wanting a nice driver that looks decent. It's definitely not fast from a dead stop but not bad above 30 mph. I know most people want a tire burner but that wasn't what I was shooting for. I'm a believer you build the it way that is for you.

This is why I don't like telling what to do and rather give info to help people come to there own conclusion. Every mod is basically a set of compromises, and everyone has the own limits of acceptability. Technically your combo is wrong but for you its perfect or at least acceptable. And is probably close to what the OP wants.

 

[AJ/FormS]

Well now I know why I didn't like the 292/508 in my combo even at 11.3 Scr with aluminum heads. I degreed that cam like 4 times, and the low-rpm still sucked. Yet when I punch the numbers in to the Wallace, It come up smelling like roses.
Well now I know why I loved the top-end rush of that 292/508, and why it liked 7200.
cuz it wasn't a 292 was it?,lol.
At least not at .006 like others measure theirs.
I suspected that after I yanked it. It did measure pretty much bang on to the .050 number, namely 248*. I did not measure the advertised.
Oh yeah there it is; I just punched in the numbers for a 300 duration cam in at 104 with an ICA of 74* and the dang Wallace spit out 166psi@129VP at 11.3Scr and my 900ft elevation. There is my problem in living black; VP of 129, lol.
The next cam I had,(270/276/110 Hughes HE2430AL) on the Wallace spec's 183psi@ 161VP, Heck yeah that's what I wanted! But in my engine it didn't measure 183psi, and I wondered about that. I come to find out some years later when Hughes disco'd that cam, that it was measured at .008. lol.No wonder it.....nevermind,lol.
I need to put the thinner headgasket back in ,lol

 

[moper]

I was mistaken on the cam I used. Thought it was the XE256, but in checking I used the XE262. It's got a nice sound in the car. Engine is a '65 273 2bbl with OEM pistons and bore. Cheap and effective, as they say.​

 

[toolmanmike]

I was mistaken on the cam I used. Thought it was the XE256, but in checking I used the XE262. It's got a nice sound in the car. Engine is a '65 273 2bbl with OEM pistons and bore. Cheap and effective, as they say.​

Nice, I like your test stand.

 

[Wyrmrider]

Aj that must have been an ENGLE they use .008 which is close to what MP would be if they measured duration by lifter rise- but they don't
they take it off the blueprint starting where there clearance ramp meets the acceleration ramp
The stock 440 magnum cam is like 310 SAE (004)
toolguy Comp Cams and Isky are not exactly cheap and certainly not a good value in a Mopar XE-HL exceptred to bad they do not make a complete line
and no one in their right mind would custom grind of the lobe list

 

[pishta]

I had this in a stock 318 with 273/4 intake and it worked well. Probably a little mild today.
CLE2N 205/215 DUR@.050, 425/445, 112LC, 1000-5000 Cam & Lifters 9669

 

[ir3333]

Just found this.Turn the volume up for the last 30 seconds when he scampers away.
This is a very nice car!

 

[Wyrmrider]

I crewed for Lefty in the early 60's RIP
Chet had some good MOPAR cams- most not in the catalog- most you had/have to ask for
Not a bad choice for 50 year old masters if you want a custom cam and are on a tight budget
Chet advertised is at .005 so a little shorter than a 260 comp, little longer than a 260 Crane- much shorter than an about .008 MP or Engle or ISKY
one was 260 210 454 lift Mopar cam
CLE2N 265/275 205/215 425/455 cam posted above
the chevy version was 270 215 450 (10 more degrees seat to get less lift)
chrysler version of 270 270 220 485 in the Catalog as 3A 270-285 220-230 486-494
Ford version 3-D .475-500 (note long exhaust- plenty of room to play with to get a little more lift
Not hard to see why the Nascar guys liked the Ford .875 lifter better than the tiny chevy .832 but Mopar is still much better
given the choice of Chevy, Ford, or Mopar versions which would perform better?

 

[moper]

Not just Nascar... My custom cams are usually fast rate for the .875 Ford lifter. Which is why I always call your Chevy lobe comments total bullshit...lol. No cam lobe knows what it was designed for. And for the vast majority of enthusiasts shelf grinds from then major manufacturers will provide the performance and value they require. There's always exceptions. But if everything is an exception, none of them are... you know?...lol

 

[moper]

Nice, I like your test stand.

Thanks Mike! Don't ever let it be said I'm a "no budget" kind of guy...lol.
I came from nothing. So my **** works, and does it for as little $$ as it takes to get the desired result. That stand cost me about 6 hours and $130. Most of it for the casters and wheels. But it sure saves a boatload of time, so when a customer gets an engine, it's all ready to go in and run. No leaks, no break in, no retorquing, no worries going into the chassis.