273-2 performance (or lack there of) question

-
67CudaBob

67CudaBob

Well-Known Member
Joined
Jul 11, 2011
Messages
331
Reaction score
42
Location
Hugo, MN
Yesterday, I flew out to Denver to drive and secure the light blue Dart you see in my avatar. It was unbelievably slow. Like, wow, this thing tops out at 70 mph slow, and takes its time getting there.

It is a recently rebuilt 273 with a recently rebuilt 2 barrel carb with a 904 tranny and 2.94 one-wheel 7-1/4 rear.

The gas pedal was hard to depress, and I noticed what looked like new linkage and springs from pedal to carb, so I suspect there is something in the linkage or return spring strength that is holding this car back. It runs wonderful, but just is very slow to get going and tops out at too low a mph. The car runs too well, and everything else about it what was I wanted, so I bought it knowing I can always add performance :)

The car will be delivered to me in a week or so, and I can dig into it more then - but I wanted to lay this out to the knowledgable and see if there would be anything else I should be looking for, or maybe what type of "performance" I should expect from a 273-2.

Thank you in advance for your thoughts
 
I think it should be peppy as hell, at least up to about 4500 RPM. Might have some linkage slack issues or retarded timing holding it back. 70 MPH tops?......that's hilarious!
 
Just typical causes... wrong throttle cable and/or it not adjusted correctly would prevent full open throttle. This happens often when changing from 2 brl to 4 brl. Owners post they get full throttle by hand but not with the pedal.

If it was tuned to factory specs, there is part of the problem. Todays puppy pee they call fuel requires about 18 degrees initial or base timing. You can get a better throttle response off the light by disconnecting the vacuum spark advance but fuel mileage will decrease.
Any electronic ignition system will perform better than OEM mechanical points.
 
Thanks to both of you - I was starting to panic a little thinking I blew it buying this car without diving in deeper while I was there. When I wanted the car, I could convince myself it was something simple - and then when I bought it, I started thinking, "what if it is something serious..." Damn mind games.......

Side note, in the folder full of receipts they gave me, I found the invoice when they bought the car in 1977 for $650!! They had it 36 years - you don't see that too much anymore.
 
These guys are right. The 273-2 should be peppy and shouldn't labor to hit 70. It will be a little pokey with the 2:94 but. It just needs some love to make it happy. tmm
 
Back in the 80s I used to drive a 273-2 67 Dart with 300K miles, and it was fast enough to smoke skinny 13" tires, get speeding tickets, etc. So definitely something wrong with that "new" motor setup. I'm guessing it's the throttle linkage, as already mentioned. Probably only opening up halfway.
 
Either that or the tranny is stuck in 2nd -- that might top out around 70.
 
Could be simple like not getting full throttle or a few little things.
I'm wondering about solid lifters, the lash and cam timing.
 
How about altitude? On top of what's been mentioned, it's gonna feel like a dog at 5000' compared to near sea level. Just something else to think about.
 
71beater said:
How about altitude? On top of what's been mentioned, it's gonna feel like a dog at 5000' compared to near sea level. Just something else to think about.
Click to expand...

interesting point - I have never acquired anything from any sort of elevation before, but I have heard that it can have a major effect on performance.

I can't wait to get this thing back to MN and check all of your suggestions and then share with everyone what I find. Most of all I am super relieved that most options are easy fixes. I could tell myself that, but to hear it from the many is very easing. Thank you all.
 
I didn't notice the Denver thing. If the car has spent any time at altitude it will have been re-jetted lean to compensate for the thin air. When you get it back to Minnesota you might have to take the carb apart and re-jet it richer so that it doesn't ping. tmm
 
I drove my 1948 Plymouth from Omaha to the Bonneville Salt Flats going about 80mph on I-80 the whole way. Pulled (most) of the hills just fine and had enough power. My plymouth at that time had a 273 with 2-barrel and a 904 trans with a 8-3/4 rear with 2.94 gears. I would guess my Plymouth would be heavier than your car. The car also took 7 gallons of oil on the trip so I've since swapped to another 273 and put a 4 barrel carb on it in the process.
 
Had my 273 2bbl to up to 105 mph and it was still climbing ^^^. That was in a 65 B-body. It had plenty of bottom end torque for stop lights, passing, and pulling hills. No, it wasn't a race car.... lol
 
Most likely the throttle isn't opening fully, or something restricting air flow like a rag in the inlet. If it wasn't getting appropriate fuel, it would mis-fire noticeably. If it was getting too much fuel, you would see thick black smoke behind. It could be greatly retarded timing, or the advance weights stuck. A timing light can determine that. Turn the engine over by hand and feel for 4 strong "air springs" per revolution to verify all cylinders seal well.

Two similar stories, both with my 1985 M-B diesel. Once coming home, the engine wouldn't go much faster than idle. I thought maybe I was running out of fuel (not knowing how a diesel behaves then), though it ran smooth. When I got home, I found a rubber isolator in the throttle link (rotating rod like our early-A's) had split, so pushing the pedal wasn't getting to the injection pump. Another time, after installing a used engine that had run great out of the car, it ran real slow around the block. I pulled the plastic intake tube and found paper towels I had stuffed to keep things out of the turbo and didn't notice when I re-installed the tube in the dark. Ran great without those.
 
The folks I am buying the car from have owned it for 36 years, and they tell me they have never had it over 65 MPH, and rarely, if ever, have it on the freeway. They do not feel there has been any change over time as to the performance of the car. They were told about 10,000 miles ago that they had a couple cylinders test low, and they had the motor completely rebuilt at that time - and bored .030 over. Since then the carb was then rebuilt and rejetted and most recently a stiffer return spring intalled. All of these things are pointers, but according to them the performance has not changed before or after all of this. Then again, this is a retiring couple who have never had performance on their agenda for this car - it was a light duty occassional cruiser.

My initial gut says throttle hinderance of some sort, as I never felt like I got any RPM's, and the pedal was so stiff to depress - but I will check out all of your suggestions until I figure it out.
 
Wrong carb? I can't remember the details but I had a bad combination of intake and carb on my 66 when I got it. The intake holes were smaller than the carb butterfly.
 
I cant add much, but if its a fresh rebuild ask for the reciepts to see what was done. If its bored 30 over I would be checking the cam and maybe swapping to a 4bbl for fun
 
4spdragtop said:
I cant add much, but if its a fresh rebuild ask for the reciepts to see what was done. If its bored 30 over I would be checking the cam and maybe swapping to a 4bbl for fun
Click to expand...

Of course, I left the folder of receipts at work today, but will post a copy of it tomorrow.

I like where your head is at though.....I will be looking for intake and carb recommendations soon.
 
Dad n I put an Eddy 1406 on his 273 and it works great!

Edit: And a cam n lifters timing chain gears from Comp. Very happy with it.
 
Ok - found the hand written receipt for the motor rebuild. Done only 10,000 miles ago, but done 20 years ago! Date on receipt is 2-4-1993 from a place called REV Motors in Englewood/Denver Colorado.

Parts are all new, and listed as follows:
.030 pistons, .030 rings, std rod brg, std main brg, cam brg, freeze plugs, cam, lifters, timing set, oil pump, gasket set, and 8 "A 1907" exhaust valves.

Labor is listed as: Rebuild 273 long block, tear down, hot tank clean & check, bore and hone, polish crank, rebuild heads, prep block, assemble and paint.

$899.30 (433.30 parts / 466.00 labor)
 
I hope they kept the original heads on it, not do the ol' "trade in" for some other later 318 heads when they did the rebuild.
 
4spdragtop said:
Dad n I put an Eddy 1406 on his 273 and it works great!

Edit: And a cam n lifters timing chain gears from Comp. Very happy with it.
Click to expand...

4spd - would you mind sharing if you went with an original 273 4-barrel manifold or if you went aftermarket?
 
Nice looking Dart. I had a 66 273 2 bbl 3-on-the-tree, 13-inch tires, that would fill the speedometer on flat ground with the same final gear you have. The rebuild info didn't mention overbore pistons. In addition to the throttle opening, check compression not only for variation but also for the absolute number. It should be around 150 psi.
 
If I was younger, had more money and ambition, I'd do a mild build on my original 273 "just for the fun." And there's always turbos..................
 
You must log in or register to reply here.
-

Back
Top