1969 273 upgrade advice

i have a 69 Dart custom LA 273 engine 3 speed auto tranny collum shift. Appears to have stock everything, so it's running the 2bbl carb. It has stock exhaust manifolds but each side runs straight back through a muffler and out the rear, I can tell the exhaust pipe is a lil bigger than stock as whoever put it on hammered it in a bit than welded it onto the manifolds. Anyway to my point, I don't want a race car but I would like just a little more pep in her step any advice? I'm not mechanically stupid but I am
New at this so any advice is appreciated for parts or whatnot.

Before I suggest.... are you interested in changing out a torque converter for more stall and/or the rear gears for a numerically higher ratio?

Do you know your gear ratio now?

In general, a modest cam, 4bbl. carb on a dual plane intake with dual exhaust will go a long way.

OE style 340 cam, (or larger) 500 AVS, Performer intake, 2-1/4 (min) dual exhaust with a connecting H or X pipe.

Add a open air cleaner, upgraded ignition, excellent ad on's.

Rumble is working around the 273 to get you faster. You can easily drop a 360 short block in its place, literally a few washers on one side, and youll be 50% more HP and torque off the bat with full 273 dress (minus 360 balancer and torque convertor or B&M flexplate). But if you wanna stay with the 273, all the hop ups apply but your always going top be soft on torque without a tall rear gear crutch.

I do not know my gear ratio unfortunateli know I'm the third owner of the car since it came off the line so factory I'm pretty sure. One question I had if I upgrade the intake and put a 4bbl on it do I need to upgrade my distributer plugs and wires? Advance timing?

I have some dirty dreams of putting a fire breather in this car.... one day unfortunately my 25 year old self doesn't have the budget at the moment. My dream for it is to make it a 4 or 5 speed stick and yea a bigger motor, for now I'm gonna settle with just modest upgrades for what I have.

Does it still have the point style dist in it ? If so that would be the first step to help the 273 engine, so change that to electronic dist.. then I would change the intake to a 4 barrel dual plain intake and try a 600 cfm carb on it.
Do a good tune up and set the valves , check if any bearings are dragging the car down in the rear end (Keep it smooth) u-joints and check brakes.
All the members here are on the spot right on the upgrades, but what I just posted is what I did to a early engine and it woke mine up . The How To page has a bunch of good advice in it as well Articles | For A Bodies Only Mopar Forum

pishta said:

Rumble is working around the 273 to get you faster. You can easily drop a 360 short block in its place, literally a few washers on one side, and youll be 50% more HP and torque off the bat with full 273 dress (minus 360 balancer and torque convertor or B&M flexplate). But if you wanna stay with the 273, all the hop ups apply but your always going top be soft on torque without a tall rear gear crutch.

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I also agree but he can do what rumblefish360 said a first steps and later do 360 if wish and can swap the cam and intake from the 273 on to the 360.

If you think you might plan a 360 swap in the future I'd go with a 650 carb now instead of a 500. But not the 500 would be better.

The 273 tho small in displacement is a good engine,with a few mods, can and will run well.Lets make a list about what you have:
Condition of the engine now,start with a compression test.Does the engine huff any blue smoke on start up ? how about under full throttle ?
Check oil pressure with a mechanical gauge.Cold pressure at idle ? Hot pressure at idle ? Hot pressure at 2500 rpm ?
Pull and look at the spark plugs for condition.If they are clean and light brown/grey(for today's gasoline) and not soot black with lots of deposits.
At this point if all checks are showing good condition,THEN you can start to think about a cam,intake,carb,etc.
For now you can keep the Point distributor, But install fresh points,condenser,rotor and cap along with fresh wires and plugs.

Next you need to evaluate the rest of you drivetrain.
Condition of the transmission,fluid clean ? drives and shifts well ?
The rear most likely is a 7 1/4 with either a 2.76,2.93,or 3.23 ratio.My guess is the 2.76 as a standard ratio.

I have just done what you are thinking about with my 68 Valiant 273.After a complete evaluation,came the engine upgrades.Yesterday was it's Virgin Run putting about 100 or so miles on it.I was very happy with the results.This was done on a strict budget Used intake and 600 AFB carb. The cam is a Jegs #200161 .441 lift intake and exhaust, and a split advertised duration of intake 276 exhaust 286.This is a hydraulic flat tappet. 1968 and up the 273's got hydraulic cams and non adjustable rockers.
You got me beat as I am still running a single exhaust,2 1/2'' and a Jegs turbo muffler for now.As soon as funds allow a dual exhaust will be next.
Have fun with your project !!!

Above posts are great advice Dad and I did the exact same to a 67 273 2bl and although it looks and sounds great, it lacks the power I thought we would have.
We started out with stock 2bl 273. Here is what we did.
Comp cams cam/lifters/springs/dbl roller timing chain gears. Solid mechanicals. 270S is the cam I believe. it is specd slightly above stock commando cam.
Stock Cast iron 4bl intake.
Eddy 1405
MP elec ign.
I ended up swapping intake last year to an LD4B and I pulled stock heads (2bl and 4bl are the same) amd did a home port job on them.
Not sure of what stall the torque converter is.
Rear end is factory 8 3/4 with 323 gears.
Im not happy with it.
I believe there are a few mistakes I made in my.setup that hurts it.
Unknown stall
323 gears
Cam 2 big.
Stock 2bl pistons (low compression)
For me the next step would be commando pistons (very pricey) and if I went that route its a full teardown. (Bearings etc right?)
How much hp would I gain?
Stock factory commando 273 was 235 hp. Diddly squat really.
So I have started a thread looking for a "drop in" small block.
Good luck.

Jake lagrange said:

I do not know my gear ratio unfortunateli ....

One question I had if I upgrade the intake and put a 4bbl on it do I need to upgrade my distributer plugs and wires? Advance timing?

Click to expand...

Do you know what size rear end you have? The gear ratio is stamped on the ring gear. IF you so decided to service the rear and change the gear oil, rotate the wheel(s) and look on the ring gears side for the ratio stamped on it.

You do not "need" to upgrade but it would be a worthy upgrade. A TSP distributor from "Pace Performance" would be an excellent upgrade.
This is what I am now running on the wife's '67. This replaced the points.
TSP-JM7713R Mopar SB Pro Series Ready to Run Electronic Distributor. Red Cap
Purchase there coil with it.

New wires are always a plus, new spark plugs are always a good idea but nether need to be "trick" or expensive parts. Just a good quality part. Plugs would be the stock heat range in what ever manufacturer you like. Plug preferences vary widely. I stay with Champions myself. I custom fit my wires. But a pre-cut set out of the box would be fine.

Advancing the timing helps. It is not hard to do. You just need a basic timing light with a dial to twist. These can be inexpensive.
Advancing the timing adds ease of starting and allows the max potential of power.

Your 2bbl. linkage for the carb will not work. I suggest a Lokar or equal type of set up.

1. Find a set of 920 heads. Run stainless valves. You'll have to cut a set of 1.88s down to 1.84. The exhaust should be find. No need for hardened seats. The 272 2bl advertised at 8.8 to 1 CR. If the block hasn't been decked youmay be able to bump the CR up a bit by shaving a bit on the heads and running a thinner head gasket. You'll have to do the math.

2. The 340 grind works real well. Another grind is the Isky E3. As far as I know it's not being offered anymore however the specs of the cam are. The E3 was a solid cam so if you don't want the maintenance issue of adjusting valves go with a good hydraulic cam.

3. In my opinion the Edelbrock LD4B by far is the best intake for the 273. It's based on the Edelbrock LD340 only with smaller runners and ports. The LD4B was. Stock replacement intake offered by Edelbrock. It was also offered as an over the counter speed part with a MOPAR part number. As far as a Carb, either Holley 1850 or a Carter AVS. Real good carb which works well is the Carter Competition Series 9636. Not made anymore but plenty of them out there. Rated at 625cfm it works real well with a 273. Carters are real easy to tune.

4. Small displacement like the 273 requires some gear. A good compromise are either 3.23s or 3.55s. I wouldn't go more than 3.55s unless you are spending a lot of time at the track.


5. Of course a rear end change is probably in order. I had a 67 Dart GT with a 273 that had these Mods and with 3.23s I could get 18MPG with freeway driving.