273 cam

[273 ball]

Hi will a tumper cam work on a 273 2 barrel motor

 

[rumblefish360]

Yup. But I have to ask, why a 2bbl. carb?

 

[mvh]

I think he means a standard compression 273, not the Commando. I assume he'd carb it up. I'm not sure a Thumper would be a good match for a small displacement, small port, low compression motor.

 

[Wyrmrider]

you could custom grind a shorter duration "Thumper" style cam
early intake close on a big fast lobe giving more overlap for that thumper sound- trying to make a low compression motor work (tight lobe centers like 107)
hyd or solid?
power brakes?
best to design all valve events and let lobe centers be a result not a design input
post up your cranking compression and all details like gears, trans, weight, goals, usage, headers or ???

 

[toolmanmike]

Isky E4

 

[Wyrmrider]

Oh Pleeze

 

[pishta]

The thumper cam was made for the 340/360. Those cams on smaller displacement engines tend to get very peaky in the power bands. The stock 340/360 4bbl cam is a good step up cam for a 273 if you have one laying around, as well as the ones ground for the 273/318.

 

[273]

Depends on the rest of the combo.
If your adding stall and gears can't why you couldn't go for one of the smaller thumpers.

 

[rumblefish360]

I don’t recommend it.....

 

[Wyrmrider]

you can make more power everywhere with a custom grind than a thumper but you give up overlap and rump d rump d rump with all the tuning work
non thumper will open the exhaust at the best time to capture the most power and cut down on overlap which puts exhaust gas in your intake charge like a big EGR
340 cam closes bot intake and exhaust really late- not what you want today in any motor and especially a smaller low compression motor
they like compression, gears, and rpm and yesterdays gas

 

[toolmanmike]

Interesting that the OP posted and we still don't know any more about his combination or needs than we did yesterday at 8:31 pm. Don't scoff at the E4. It's a great little off the shelf cam that is a nice bump or replacement for the HP273 cam. It would be interesting to see what the cam grinders would come up with and how theirs would compare.

 

[AJ/FormS]

Hi will a tumper cam work on a 273 2 barrel motor

Sure but
before you try it,
go find a mid-70s Dart with a 318. Take off two plug wires, get in and drive, keeping the rpms below 3000. Now imagine that 318 idles like a Super-Stocker.
Not fair! you say?
You're right.
Make it a slanty with a big cam, 4.30s and a hi-stall.
Not fair! you say?
You're right.
The point is, the Scr is gonna be so low, and the cylinder pressure so weak, that the combo is gonna need wicked gears and a high-stall TC to be able to get the car off the line at a rate of acceleration that is fair and reasonable. And then at lower rpms, that poor 273 is gonna be so inefficient, you will find it hard to justify driving it anytime except on Saturday night; which might actually be fun,lol. But don't even dream of taking it out on the highway, without a gas-card..
And don't forget the support works; headers are a must, as is a tuned intake, fancy valve gear will be in your best interest, a high-powered ignition, a DP carb, and a rock-solid cooling system. Oh and BTW,what heads will you run?
There is one good thing at least; you shouldn't need to run monster wide-tires back there, just tall will do; with a SureGrip.
And finally; resist the urge to install this in anything but the lightest of the lightweight-As.

 

[moper]

Comp XE256 works very well.

 

[cudajames]

Here is the Comp Cam 270s if you are staying mechanical on the 273.

 

[Wyrmrider]

In a chevy- you can do better
intake gets closed at 54 ABDC at .006 if I remember correctly
but not much lift for that intake close point
start with Voodoo 10200700
but there are still better choices
did we loose the OP?
no idea if this is a low or high compression build or not or what his details are but there is NO Thumper short enough for a 273

 

[273]

Too me everyone over worries cam size and small displacement. When its more to do with under gearing.

Take 340 vs 273 both have similar head flow to cid ratio which is why the both considered revvers over the more restricted ratios for 318/360.

Build a 340 and a 273 to have a powerband of say 2000 - 6000 rpms. They will both need similar cam degrees to fill the cylinders. But need vastly different gears to make it work. Since the 273 will make about 100 hp less and probably be 20 mph slower at the end of the quarter mile. But have the same peak rpm need.

So say 4.10 are the perfect gear for the 340 and 5.13 are for the 273. But instead you run the common 3.55 gear choice. The 340 is only about 0.5:1 off but the 273 is 1.5:1 off big difference.

 

[toolmanmike]

@273 ball , what say you. What's your plans, expectations and your current combination?

 

[AJ/FormS]

Too me everyone over worries cam size and small displacement. When its more to do with under gearing.

Take 340 vs 273 both have similar head flow to cid ratio which is why the both considered revvers over the more restricted ratios for 318/360.

Build a 340 and a 273 to have a powerband of say 2000 - 6000 rpms. They will both need similar cam degrees to fill the cylinders. But need vastly different gears to make it work. Since the 273 will make about 100 hp less and probably be 20 mph slower at the end of the quarter mile. But have the same peak rpm need.

So say 4.10 are the perfect gear for the 340 and 5.13 are for the 273. But instead you run the common 3.55 gear choice. The 340 is only about 0.5:1 off but the 273 is 1.5:1 off big difference.

Gearing and stall and above all; application, cuz;
How many guys will want to run 5.13s and a 3500, with that low-C 273?
When for the same machining costs, they could run that 340 with 3.55s (that they might already own),and a fast-rate 223* cam, for similar performance, but now includes hiway use.
I'm not arguing BTW, just expanding, cuz nobody puts a thumpr in to go racing. I mean why would you? I mean if you're gonna install a 279* cam I would want about 236/240@.050 performance as opposed to 227*.
But then I would want a 227* on a 266,more compression,and more cubes,lol............

 

[4spdragtop]

Exactly the same cam we put in our 67 273 barracuda. Love the sound, but we over cammed it in my opinion. 2bl slugs in it. 323 gears.

Here is the Comp Cam 270s if you are staying mechanical on the 273.

 

[toolmanmike]

Isky E4 You don't need much especially in a 2 barrel engine.

 

[Wyrmrider]

you can do a lot better than a 50 year old one size fit's all cam I haven't used one in 40 years

 

[toolmanmike]

you can do a lot better than a 50 year old one size fit's all cam I haven't used one in 40 years

Some of your statement is true. It is a 40 year old cam and a modern cam would do better I am sure. The op has a 273 2 barrel and apparently wants a Thumper which we both know is too much. I don't think he is interested in maximum performance from his 2 barrel engine. If he was to rebuild it to at least HP compression, 4 barrel and performance intake, Headers, converter, gears etc. then a custom grind cam would be a great idea. Why reinvent the wheel? The OP can do what ever he wishes. He asked for suggestions and I gave what worked good for me.

 

[Wyrmrider]

E-4 works just OK we sold a lot of them way back when
lots of other grinders stole Isky's grinds
Isky actually bought several other camgrinders to help them retire and to get their grinds

 

[toolmanmike]

E-4 works just OK we sold a lot of them way back when
lots of other grinders stole Isky's grinds
Isky actually bought several other camgrinders to help them retire and to get their grinds

There's not too many mild off the shelf cams left for the 273. Lots of solid small block cams but not ones the 273 can use unless you build it for max horsepower. That's why I chose it and recommend it. It would be interesting to buy a custom grind and dyno the 2. Percentage wise with all things being the same, there might be much difference. The 273 can only produce so much.

 

[Bighead440]

Believe it or not, for the mildest of 273/318 builds on a budget, the 360 2bbl camshaft is a nice upgrade if you have original (low) compression. The 273 would require conversion to 318 non-adjustable rockers and pushrods. If you are willing to change pistons or mill block/heads (increase compression) and get 9:1'ish compression, I'd say go with a Comp Cams 270S solid (and drop in #901 valve springs) and retain the adjustable rockers and ball/cup pushrods. The E-4 is tiny, IMO.