273 cam selection on Desktop Dyno

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toolmanmike

toolmanmike

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I have a Dyno 2000 program (not even Desktop Dyno) and was messing around today with solid lifter cam specs for my 273. I messed with the stock specs and tried the Isky E-4, and the Schneider #14202. I also tested a couple hydraulics but diddn't like the results.
I was looking for a cam to replace the stocker with maybe a little more kick
without getting too radical. There's only a couple choices of mild flat tappet
cams for small block Mopars with the E-4 being the closest to stock. As usual the stock cam has the most torque especially at 2000 rpm. And as expected the most radical of the three produced the most horsepower but at 6000 rpm.
I guess it depends what you want as to which one you choose. I changed lift,
duration and lobe centers till I found the best combination. I also kept the same specs but changed from solid to solid roller for more gains. I know the program isn't true but if used as a guide it gave me an idea what changes could do. I tried to duplicate the charts as attachments but can't get there. so here's a few specs;

Stock cam: 248/248 .415/.425 108 degree solid flat tappet
105 hp@2000 rpm 276 lb/ft @2000 rpm
288 hp@5500 rpm 323 lb/ft @3500 rpm

Stock cam 248/254 .415/.425 108 degree solid flat tappet
more ex. 104 hp@2000 rpm 274 lb/ft @2000 rpm
duration 298 hp@ 5500 rpm 324 lb/ft @4000 rpm

10 hp gain@5000rpm

change to 248/254 .415/.425 108 degree solid roller
roller 109 hp@2000 rpm 286 lb/ft @2000 rpm
320 hp@5500 rpm 342 lb/ft @ 4000 rpm
22 hp gain @ 5500 rpm
more torque at low and high rpm

It would be much cheaper to install the E-4 and call it good or spend hundreds of dollars for a roller set up to gain 22 hp and more torque.
This is all just for fun. What do you guys think? toolmanmike
 
I ran the Summit cam .441/.441 hydraulic for awhile in my 273 before I changed motors. What does it show in the Dyno 2000?

It had a Engles cam when I bought the car which was .420/.420 hydraulic.

The motor was like 8:7 compression, bored .060 over, Performer intake, 500 cfm carb, stock heads "302" 318 heads.
 
You need a can that is high lift short duration and low over lap.

I have built many a 273 and raced them in years past dataing back to early 70s.

The D dart and performance even 235 HP 273 used a cam metioned as above. In the D dart it was a racer brown cam that speced to over .515 lift and a advertised 260 duarion stick. The little motor needs all the low end it can get.

I played with the 340 cams, purple shafts 260, 270, 280, hemi grinds etc. All yeilded very poor low end below 4000 and peaky torque curves.

Isky used to make a stick better than the E4 it is no more, you could have a custom ground cam, I think I would look for that type of a solution rather than rollers, high ratio rockers etc.

I was able to put 275 HP to the tires in my 273 at 7500 crankshaft RPMS to the rear tires, and 245 HP to the tires at 6000 RPMS. HP & Torque was still decent at 3000, but the stock 1800-2200 rpm torque peak on the 2V motor will go by by. You also nede to get more compression, at least 10.5 with the bigger cams, and a lot of base timing too.

good luck!
 
D Dave, The ol' 273's do need more low rpm oomph. For a basic overhaul
and only street use I would be happy with the E-4. If I felt the need to
have a cam ground to my specs I would do the 248/254 stock spec cam.
The extra HP and torque gains of the roller are impressive but how much
should 32 HP cost? If I was class racing I would build for high performance.
toolman
 
Mike have you tried any of Comp's XE cams or Lunati's Voodoo series? They are ground at a fast rate of lift with more duration at .050 but keeping the total duration down. The 273 is such a small engine it's easy to loose all your bottom end but I'd think a fast rate cam would help keep the bottom end torque while providing more top end hp. I have desktop dyno and play with different combo's just to see the results and in smaller engines the fast rate cams seem to help allot.

BTW: Do you have your head flow #s? That makes all the difference in the world of how accurate it is and what cam works the best with your heads and engine size.
 
I don't have any port specs. I just chose pocket ported wedge heads with stock valve size from the dropdown box. I tried the Voodo 60400 and a Comp
number I didn't write down. I could get more HP and torque at a lower RPM
with a stock spec solid lifter cam than either of the hydraulics. Headers seem
to be the best improvement if I decide to install them and a stock spec roller cam is also a nice improvement but lots of $$$$/HP. toolman
 
toolmanmike said:
I don't have any port specs. I just chose pocket ported wedge heads with stock valve size from the dropdown box. I tried the Voodo 60400 and a Comp
number I didn't write down. I could get more HP and torque at a lower RPM
with a stock spec solid lifter cam than either of the hydraulics. Headers seem
to be the best improvement if I decide to install them and a stock spec roller cam is also a nice improvement but lots of $$$$/HP. toolman
Click to expand...

Ok. That's surprising. I don't know much about the stock solid cam but it sounds like it must be pretty decent if it's better than modern stuff. How much porting have you had done to the heads? Headers do make a big improvement if you don't mind putting them on.
 
I haven't started my rebuild yet. I've been gathering info and checking availability of parts, gettin' my ducks in a row so to speak. There is a
local shop that has a flow bench and specializes in Mopar head work.
Thay said they could port match and bowl blend to improve the flow.
They know I'm just doing a rebuild and not building an all out race motor.I think it's just fun to rebuild with basic stock stuff and get over 1 hp/cube.

toolmanmike
 
oldkimmer said:
..................Get yourself a set of the 85 up 302 heads, will do alot 4 that little 273..........kim.............
Click to expand...


That's very true. I bought a set of "302" heads milled down to 59cc combustion chambers. It was a different motor just with the head change.
 
From what I've read, the 302's are the only head, other than the stockers,
for the 273. I've got a pair of 302's in the garage. The chambers are about the same size and shape but the ports flow much better than the stockers.
Better leave for work. catch you guys on the flip side. toolman
 
While browsing the bone yards, what vehicles should I check to find a set of those 302 heads ?
 
toolmanmike said:
From what I've read, the 302's are the only head, other than the stockers,
for the 273. I've got a pair of 302's in the garage. The chambers are about the same size and shape but the ports flow much better than the stockers.
Better leave for work. catch you guys on the flip side. toolman
Click to expand...

The chambers are closed instead of open. "Heart shape".



RedFish said:
While browsing the bone yards, what vehicles should I check to find a set of those 302 heads ?
Click to expand...


The are called "318 Fast Burn" and came on 85-86 cars. Mine came off of a 85 Diplomat 318.

Heads 004.jpg
 
Fast burn the same as lean burn or found in those with the lean burn ignition ?
Where would I look for identifying marks on those heads ?
You said milled to 59 cc , so what was it before or about what in thousandths was remeoved ?
Will the stock 273 single plane 4v intake port to match to them fairly close ?
Too many questions ?
:)
 
RedFish said:
Fast burn the same as lean burn or found in those with the lean burn ignition ?
Where would I look for identifying marks on those heads ?
You said milled to 59 cc , so what was it before or about what in thousandths was remeoved ?
Will the stock 273 single plane 4v intake port to match to them fairly close ?
Too many questions ?
:)
Click to expand...

I'm pretty sure the lean burn computer engines went away before the fast burn heads came out. I know my buddies 78 Fury that had a 318 lean burn didn't have 302 heads cause I took them off to replace leaking head gaskets. They were just like all 70's open chamber 318 heads.

What year intake do you have? Remember the older 273's had a different bolt angle than newer LA's. Think it was 66 on back that had the odd angle.
 
Mine is a dated 67 commando. I want to keep the appearance as stock as possible, just a little more hidden performance.
I also have a 68 car here that doesn't have the original 318 in it. The 318 that came in it runs very stong but I really dont know anything about it. I may already have a pair of those heads LOL
 
RedFish said:
Fast burn the same as lean burn or found in those with the lean burn ignition ?
Where would I look for identifying marks on those heads ?
You said milled to 59 cc , so what was it before or about what in thousandths was remeoved ?
Will the stock 273 single plane 4v intake port to match to them fairly close ?
Too many questions ?
:)
Click to expand...

I don't no the cc before the mill or how much was removed. BJR Racing rebuilt these heads and milled them down. So you could PM him and find out the work done. He cc'd them after they was milled and it was 59cc. I also used the thin Mopar Performance gasket to kick up the compression some.

The intake deal is just as fishy mentioned.

My heads have a big "1" on one head and a "2" on the other around the exhast side area. But other than that you'd have to look under the valve covers for the casting numbers.
 
i used to run a comp cam 282 , .495" solid, with ported 273 heads,Ld4b intake , 600 holley,3000 converter,and 4.57 gears. car ran 13.8@110mph, street trim , drove anywhere.
 
I should apologise to ToolmanMike for the hyjack here. The commando has closed chamber heads and doom top pistons too. I know I need to lower the compression for todays pump gas so open chamber heads and increased flow makes sense. Already have the Magnum exhaust manifolds. Thanks guys :)
 
RedFish said:
I should apologise to ToolmanMike for the hyjack here. The commando has closed chamber heads and doom top pistons too. I know I need to lower the compression for todays pump gas so open chamber heads and increased flow makes sense. Already have the Magnum exhaust manifolds. Thanks guys :)
Click to expand...

I'm running 10:7 compression without any troubles. I run 93 octane.
 
No problem Redfish, I do the same. When you read a post and have a question you have to ask it. That's what FABO is all about. I have a set of 302's and a spare 273 head. I haven't looked at them close for a few months but I remember that the chambers looked about the same. A couple small block books I have list the 273 heads as having the smallest cc chambers of all small block heads( mostly because of the small bore). I don't know about the intake port matches because I've never tried any other intakes. I have heard a lot about the Edelbrock LD4B because it was designed for the smaller cube and port 273/318. When I was dinkin' around on the dyno program I
changed the intake from a open plenum to a dual plane and gained some
low end torque. If I was planning on modifying my motor very much I would try to find a LD4B. Driving your 273 on the street needs more low end. Every performance mod you do increases power but adds rpm to get there. I'd like to rebuild mine basically stock but with a modern cam and some minor head work to get at least 300 hp. I don't think that's out of line. There's lots of parts out there to build a max output screamer but I don't want to go that direction. toolman
 
Stick with the 920's. They out flow and have more port velocity stock than the Swirlport

And the e-4 is a really good cam for your combo. You need to put some gear in the butt of that car to realize the potential.

ISKY
Grind No./Type
E-4 SOLID Tremendous torque & good mid-range power. 9-10.5
1 compr. good idle stock converter. 3.23-3.70 axle ratio. Up to 625 CFM Carb. RPM-Range
2000-5500 Valve Lift - INT
.425 EXT
.425 Valve Lash Hot -
 
I've tried all sorts of combos but for this combo the stock heads seem to work the best. Radar (Roger Luctenburg) and Woody (Keith Briden) @ R&J Performance can work some magic on the stock heads. I don't want to build a 10,000rpm screamer just a healthy rebuild with a little more. Toolman
 
Great info here!

Toolman,

If I wanted a cam like the one you and BJR are talking about would I have to get it made? (assuming I would) Can you post the #s or pm me if you would.

I have a 273 4sp commando that I will doing similar and this cam has my attention along with the rest of this thread.

I think I will get a hold of BJR and see what he can do with these heads.

The rest will be like mentioned.

Bob
 
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