273 solid Crower cam opinions

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CUDAGUY

aka Prince Valiant
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Putting together a 273 for mostly street use I picked this cam to take advantage of the solid valvetrain I have and with the thought of a smoother idle and good mid-range power. Anyone run this cam before?

http://www.crower.com/mopar-273-360-...m-278-fdp.html

Dur @ .050” Lift: 229°/229°
Adv Dur: 278 / 288
Gross Lift: .446”/.456”
LSA: 112°
RPM: 2200 to 6000
Redline: 6500


Rest of the motor

Standard bore block
Steel crank turned .010/.010
Stock early rods
Original set of commando 10.5:1 pop-ups
2658920 heads with some light bowl work and casting clean up
Marine 273/318 intake (very close to the commando intake)
575cfm Holley (440 truck with some mods)
Going back to stock exhaust manifolds but keeping the 2.25 duals
Cloyes double roller
 
If you call and talk to Dave Crower, he can custom grind any size cam that you wish. He made a nice one for my ex's 64 Dart slant 6 and she's happy with it....
 
Should be a good one. I used a Isky E-4 which is mild by comparison. (216@ .050, 260 advertised, .425 lift 108 degree.) I would like to hear that one run. It will like a converter for sure.
 
Smoother idle than what?
That's a pretty big cam for a 273.(59* overlap,67*ICA@108installed centerline) Lots of rumpity-rump.She'll burn some gas allright.
If you're gonna run logs, you might consider a split pattern cam with maybe 10 * more exhaust duration at 050, than what's on the intake.
And if you have a stick car, I would tighten up the LDA to 110/108
I would run as much lift as the heads will allow, and without getting into the pistons.
Ima thinking custom cam, as previously mentioned. If you go that route, be sure to know your exact combustion chamber volume.
 
Just an fyi someone just posted timing issues with their cloyes timing gears. Do a search on here and maybe give Cloyes a call. Just a heads up
 
I agree, pretty big for a 273, better have at least 3.55s and a loose converter. It'll lack low end torque. I went from a 224 @ 50 solid to a smaller cam. Gained a lot of low end, but lost a little on top. Gas mileage was terrible until about 70 mph. Then it got 20mpg.
 
Also, as for carbs, I've had at least 4 different ones on it. The best, by far, is a 570 street avenger I have on it now. Big increase in torque after rejetting the primaries.
 
I agree, pretty big for a 273, better have at least 3.55s and a loose converter. It'll lack low end torque. I went from a 224 @ 50 solid to a smaller cam. Gained a lot of low end, but lost a little on top. Gas mileage was terrible until about 70 mph. Then it got 20mpg.

Should be a good one. I used a Isky E-4 which is mild by comparison. (216@ .050, 260 advertised, .425 lift 108 degree.) I would like to hear that one run. It will like a little converter.

running 3.23's with a slant truck/van converter and a 26" tire
 
Just an fyi someone just posted timing issues with their cloyes timing gears. Do a search on here and maybe give Cloyes a call. Just a heads up

Id be pirating the set out of my 318 thats atleast 10-years old, however it only has MAYBE 5000-miles on it. Its their old top-O-the-line double roller.


Smoother idle than what?
That's a pretty big cam for a 273.(59* overlap,67*ICA@108installed centerline) Lots of rumpity-rump.She'll burn some gas allright.
If you're gonna run logs, you might consider a split pattern cam with maybe 10 * more exhaust duration at 050, than what's on the intake.
And if you have a stick car, I would tighten up the LDA to 110/108
I would run as much lift as the heads will allow, and without getting into the pistons.
Im thinking custom cam, as previously mentioned. If you go that route, be sure to know your exact combustion chamber volume.

Smoother idle than the mopar '759 in my 318 but not as pathetically small as the stock commando cam. This cam has more LSA than the '759 and should be a smoother idle than that option. What I've seen is the lift on the Crower is just shy of where the heads hit peak flow and on PAPER there won't be an issue with valve to piston clearance.

Heres the '759 cam for reference

Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 1,200-5,200
Intake Duration at 050 inch Lift: 221
Exhaust Duration at 050 inch Lift: 228
Duration at 050 inch Lift: 221 int./228 exh.
Advertised Intake Duration: 260
Advertised Exhaust Duration: 268
Advertised Duration: 260 int./268 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.430 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.450 in.
Valve Lift with Factory Rocker Arm Ratio: 0.430 int./0.450 exh.
Lobe Separation (degrees): 110
 
Hey, check out that '759
Notice that it goes from advertised to .050 PDQ. From 260 to 221.That's just 39 degrees, and about the fastest hydraulic I've seen. That would be pretty good if it had more lift. With 1.6 arms that would be .459/.480; not too bad.This cam comes in at 44* overlap and a ICA of 56*@106installed. This would be a lot smaller (about 3 sizes-advertised/1.5 sizes-net) than the earlier one mentioned; with 59* overlap and a 67*ICA@108.This smaller cam will build significantly more cylinder pressure and thus significantly more low-end torque. This smaller cam has about 12% more degrees of power extraction too, making it much more economy oriented. It won't compete on the big-end tho.
Notice that the Crower goes from an advertised 278 to 229@.050. That's 49* on the lash-ramps. This is more typical.The .446/.456 lift compares well to the '759 with 1.6 arms. There is no smooth in that Crower.
The bigger Crower cam will idle pretty lumpy tho, as compared to the '759 which should have been real "smooth",.....so, I'm confused how you are using the word "smoother".
Let's stack them up;
Crower;..278/288 (net 229/229)/112LDA/.446/.456 (1.5 arms)/67*ICA/44*o/lap
'759.......260/268 (net 221/228)/110LDA/.459/.480 (1.6 arms)/56*ICA/59*o/lap

IMHO the '759 would be better suited to the 273, IF, the compression ratios favor it.It will idle way smoother, make more cylinder pressure, and more torque off the line, do really good in the midrange, and if delayed a few degrees, might surprise you on the top, with good valvesprings, all-the-while getting better fuel economy. The 1.6 arms will boost the durations a bit too, bringing it closer to the Crower specs, without the lumpy idle. The nets might be closer to 1 cam-size different.
Don't let the smooth idle fool you.

FWIW
I ran a 223/230 net cam in my 360 for about 2 or 3 years. That was a fabulous cam. So smooth it didn't scare anybody. Until the hammer fell! Went 12.6/106 with a 750DP, and got up to 32mpgUS with a 600VS and overdrive. Fabulous I tell you.
 
The rule of thumb every 25 cid smaller your engine is a cam will act 5 degrees larger so most cam are based on 340/360 size so the 278 cam would be more like 292 cam
 
It will work great but your idle will not be "smooth".
 
The thought was more LSA would build dynamic compression and for it to not have a super choppy idle. I never really payed any attention to the actual overlap. It was $40 BNIB at a swap meet so i scooped it up with that thought.
 
Ok. I replied before and even though I read and SAW that this was a solid cam, it still did not stick when I replied. Gettin old, I guess.

While I think it will not idle like a stocker, it will not be too bad. Remember, when comparing a solid to a hyrdaulic, you need to knock about 10* off the .050" duration of the solid, so it will "act" and "sound" like it has 219* @ .050". It will probably be ok.

I would run it either way and hope it had some chop. I mean damn, if you don't want it to sound cool, buy a honda.
 
Nice lope. How does it run? What are you idling it at?
 
Nice lope. How does it run? What are you idling it at?

idle is 900rpm in neutral, same longblock ran 14.6@97 in my 66 'S' never had it running right in the Valiant during race season and never had the chance to get a clean pass out of it. 318 with .060 off the deck, hogged out #302's, and a cast smog intake with a 600 Holley. Now it has an oil pressure and rear main issue. I have headers, performer RPM and a 750 Holley on it now and honestly pulls like a high 13's car if I could get it to hook up. Traction is an issue in second gear on the street with 245's.

Watched the vid
Your idle is too slow. heehee
Sounds great!

I had a 65 wagon like that with a 340 bottom, and a teener top end. Man that car went!

Ok. I replied before and even though I read and SAW that this was a solid cam, it still did not stick when I replied. Gettin old, I guess.

While I think it will not idle like a stocker, it will not be too bad. Remember, when comparing a solid to a hyrdaulic, you need to knock about 10* off the .050" duration of the solid, so it will "act" and "sound" like it has 219* @ .050". It will probably be ok.

I would run it either way and hope it had some chop. I mean damn, if you don't want it to sound cool, buy a honda.

Im not looking for a dead sounding idle but not something that cant pull 10" of vacuum either. Hoping to get an honest 260chp/300-320ftlbs out of this motor and still be dailyable if I had to (Honestly Id perfer it :glasses7:)
 
Are you saying that the idle speed of the wagon in the vid is 900, AND the cam is the '759 AND the specs are as listed; namely 260/268/110, and it is correctly installed ?
In my head, that does not compute!I have had, in my 360, the 292/508/108 installed from 104 to 112 and idled at 750. It did not have that lovely lope. And IIRC it pulled 11inches with 14*initial. So you can imagine how confused I am. I really wanted that lope.I spent a lotta hours trying to get it.
P4120233; 292/292/(nets 248/248)/108LDA/.543/.543(1.6 arms)/70*ICA/76*overlap
The only way for me to get the lope was to idle it way down and retard the timing. I bought a dash-mounted dial-back timing device. When I pulled up to a guy in the next lane I would retard the timing about 10*, and let 'er rumpity rump to intimidate, then when the light went green, I cranked the timing back in to normal (and lost most of the lope).
That's not all I used that device for tho...Once you figure out it's capabilities, your tune can get real sharp. I think everybody should have one...For a little while, anyways.
 
I'm pretty sure that cam is all wrong for what you want
Weak exhaust and intake, single plane, small displacement and low CR are all sensitive to large overlap. If the smaller cam in a 318 is too much I can't see a larger cam in a 273 being right. I agree the stock 273 cam is weak and can be improved on. Probably want a cam that has an LSA of 112 and 50 degrees or less of overlap and over .450 lift.
 
The thought was more LSA would build dynamic compression and for it to not have a super choppy idle. I never really payed any attention to the actual overlap. It was $40 BNIB at a swap meet so i scooped it up with that thought.

It's not the LSA per se that builds compression, it is in fact the ICA ;Intake Closing Angle.
Let's see if I can diagram this;
Suppose that you had 2 cams of the same exact advertised durations, ie both cams had identical lobes. Now let's make one of them with a 114*LDA, and the other on a 108LDA. This is about the range you find on street cams.Let's install them both at 4* advanced, which is also typical.And finally let's make them both 260intake/268 exhaust. Let's not talk about lift yet.
This is how they will fall in;intake open/intake closed/ex open, ex closed/o-lap
next I will list the number of degrees of compression and the the number of degrees of power extraction.

the 114; 20*B/60*A/72*B/36*A/36*o-lap.....120*compression/108*extraction
the 108; 26*B/54*A/66*B/22*A/48* o-lap....126*compression/114*extraction

Notice the bold numbers.The sooner you close the intake the sooner you begin to build compression, and the longer you build it.Also notice it comes on the 108cam, the one with a tighter LDA.
Now check out the degrees of compression; notice that the 108 has 6 extra degrees of compression
Now check out the extraction. the 108 has 6 extra degrees of extraction.
And finally check out the overlap. this is the penalty of the 108, lots of overlap.Now overlap is of no concern at the racetrack,cuz the engine spends almost 100% of its time at rpms well past those where overlap is a concern.
--But for streeters that do spend a lot of time at idle and rpms in reversion, this is what produces most of the rumpity-rump. By itself,it serves almost no useful purpose. It also doesn't matter if some is there,in fact some has to be there. This is the period where both valves are open to some extent. This allows exhaust to flow into the intake, and also allows fresh charge to flow straight out into the header. Headers can make use of this event. Logs not so much. In fact this phenomena can be considered a 5th event subsequent to the 4 of a 4-stroke engine. When it's right it can help an engine get closer to 100% volumetric efficiency.
But let's get back to the compression and extraction events.The extra compression is felt by the driver as more giddy-up off the line, and the extra power extraction means you get to drive a little further on your tank.
This becomes bit of a balancing act, cuz the 108 is wasting gas at idle, while it's saving gas at rpms above reversion due to overlap.
Hope thats not clear as mud.

I think 273 hit it pretty good, but I'd like to add that if you get the fastest lobes possible/available, and the highest lift the grinder will give you and or get some longer arms, then you will get the most bang for your buck. Also careful co-ordination of the Scr/Dcr/quench will get the most out of the little engine.Lobes like this may have special spring needs.
 
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