Fuel octane on hp 273charger engine 10.5:1 compression .

[stroker402]

I have complete bone stock internallly >>> 273 dartcharger with all the good stuff.. has the 10.5:1 compression ..
I checked the cylinder pressure with a compression tester .. engine hot with carb fully open . and numbers are between 180 -182 lbs/in. is that normal for this engine ? seems pretty high for a 10.5: engine doesn't it.
appears I would for sure need to run Premium 93 octane fuel. engine runs great !

 

[Demon416]

If it doesn't have hardened valve seats you will need a lead additive or race (leaded) fuel. If the valve seats are hardened then run 91-93 octane.

 

[OldmanRick]

Pretty good numbers on a stock block. May have to take into account a little carbon build up on piston tops. I'd run 93 and keep a eye on your timing as to not get into pinging. Should run pretty strong.

 

[jerry6]

I have complete bone stock internallly >>> 273 dartcharger with all the good stuff.. has the 10.5:1 compression ..
I checked the cylinder pressure with a compression tester .. engine hot with carb fully open . and numbers are between 180 -182 lbs/in. is that normal for this engine ? seems pretty high for a 10.5: engine doesn't it.
appears I would for sure need to run Premium 93 octane fuel. engine runs great !

Sounds about right , my 340 has 10.5 and cyl pressure was 190 , it was a fresh build when I last tested it .I run 94 octane gas all the time , shop that built it recommended I use 94 . So far over 10,000 miles and no problems .
Stick with 93 , with that compression you need it , back in the day that car was using sunoco 104 or 106 , if you could find some fill her up , bump up the timing and see what the car can do .

 

[toolmanmike]

The compression numbers are good. Sounds like a healthy mill. Like the others said, use 93 octane, don't crowd the timing, and watch for ping. Demon416 suggested lead additive which is a good idea too. When I rebuilt my Charger 273
the Egge HP pistons were a little over 9:1. I milled the heads a bit and got to 9.6 with a thin head gasket.. 93 octane and no ping with around 15* initial timing. I had a talk with the shop that did my heads and they don't like hardened seats in old heads. I only put a couple thousand miles a year on my car so the standard valves and seats should last for many years without lead additive. tmm

 

[stroker402]

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This 273 is all original internally . has 82K on the clock,

I Installed the intake, headers and exhaust system. nothing has been altered inside the engine.. it uses a little oil But runs as strong as a 340.
I've been running 93 octane . runs great on that !!
glad to here that is what is expected for the compression .

little video of engine after intake, headers and 2.5" exhaust with xpipe with dynomax mufflers installed .:burnout:

 

[stroker402]

Thanks for the info guys !
john

 

[Abodybomber]

Sweet engine! If I am not mistaken,a better exhaust could help lower octane requirements.Gets the spent A/F mixture out faster.On overlap(and inertia at work) bring in a fresh cooler intake charge quicker.Food for thought.

 

[stroker402]

Sweet engine! If I am not mistaken,a better exhaust could help lower octane requirements.Gets the spent A/F mixture out faster.On overlap(and inertia at work) bring in a fresh cooler intake charge quicker.Food for thought.

abodybomber ........ I think you may have something there... I just recurved my distributor and installed a pertronix III and flamethrower coil . I got this distributor really dialed in now. I wanted to try 89 octane in the 273hp to see how it liked it and it does not ping at all .. performance is still there overall.
It Rocks !
I do have the best intake out there for the small port 273 heads, the dougs headers , 2.5" pipes and x-pipe with dynomax ultraflows .. Sweet !!!
It all works to it's finest potential ..

:burnout:

 

[stroker402]

Pretty good numbers on a stock block. May have to take into account a little carbon build up on piston tops. I'd run 93 and keep a eye on your timing as to not get into pinging. Should run pretty strong.

oldmanRick ....This 273hp Runs very STRONG !:burnout::burnout::burnout::burnout:

 

[OldmanRick]

I haven't driven a hotrod with a stick in about 25yrs. Have fun, i know i would

 

[jerry6]

oldmanRick ....This 273hp Runs very STRONG !:burnout::burnout::burnout::burnout:

yeah the 273 goes well , my mother had a 68 GT convertable with the 273 4 bbl , I used to get her pissed off so she would floor the car , did superb burn outs !. It was much stronger than the 1970 318 she replaced it with , a much snappier engine , sounded better as well .
And really like your car dash looks great . So many cars , never enouh time or money !

 

[Abodybomber]

My engine builders first mopar was a 67 F/B Cuda.Bought it used in 68.273/833/8.34.Had less than 10k miles on it.Got it home,promply stuffed 4.88s in the rear end.Ordered the biggest cam NAPA had listed(definetly a Mellings).Yanked the heads,ported them with a sand drum,and a power drill.Best pass was 13.88@104 at Santa Maria dragstrip.That car still wears 95% of its original paint,the odometer stills says less than 80k.A sweet machine.Turbine bronze,black inside.

 

[stroker402]

yeah the 273 goes well , my mother had a 68 GT convertable with the 273 4 bbl , I used to get her pissed off so she would floor the car , did superb burn outs !. It was much stronger than the 1970 318 she replaced it with , a much snappier engine , sounded better as well .
And really like your car dash looks great . So many cars , never enouh time or money !

Thanks jerry6 !:burnout::burnout:

 

[stroker402]

My engine builders first mopar was a 67 F/B Cuda.Bought it used in 68.273/833/8.34.Had less than 10k miles on it.Got it home,promply stuffed 4.88s in the rear end.Ordered the biggest cam NAPA had listed(definetly a Mellings).Yanked the heads,ported them with a sand drum,and a power drill.Best pass was 13.88@104 at Santa Maria dragstrip.That car still wears 95% of its original paint,the odometer stills says less than 80k.A sweet machine.Turbine bronze,black inside.

Abodybomber......that little 273 engine moves out !

 

[jerry6]

There is a convertable 1963 Dart down the street for sale , I am getting the itch after reading this thread and seeing the pics . HMM a convertible Dart with a screaming 273 , you got a sound bite ?
What are the problem areas to look at on this model ? List all the trouble spots , I'll go inspect he car tomorrow . Are the 60's lighter than the 70's Darts
My wife is going to kill me , but damn . I want screaming 273

 

[stroker402]

Jerry6 ... yes the earlier darts are lighter.
I've had several newer style darts67 and up >> I think the earlier darts ride nicer .
My stroker 65 dart rag rides real nice .. it has a mopar sm 402 crate magnum engine .. runs low 11's 1/4 mile.

It a hand full !!!
stays straight as an arrow when I get on her .

I don't see any down faults on this early dart..
you can even get a larger tire up in that rear wheel house.. with out altering .

 

[jerry6]

Jerry6 ... yes the earlier darts are lighter.
I've had several newer style darts67 and up >> I think the earlier darts ride nicer .
My stroker 65 dart rag rides real nice .. it has a mopar sm 402 crate magnum engine .. runs low 11's 1/4 mile.

It a hand full !!!
stays straight as an arrow when I get on her .

I don't see any down faults on this early dart..
you can even get a larger tire up in that rear wheel house.. with out altering .

Thanks , what I mean is , what spots to look for rust on the 60'S Darts convertible . I don't know the history of the car so I want to know where to look . Are there parts of the frame to check for stress cracks , things like that .What about electrics ,any dash probs to look for ? The more I see of these cars the more I want one .
Yeah I can see where an 11 sec car is a hand full , means 9 sec and you're at go directly to jail speeds !
Thanks

 

[stroker402]

Thanks , what I mean is , what spots to look for rust on the 60'S Darts convertible . I don't know the history of the car so I want to know where to look . Are there parts of the frame to check for stress cracks , things like that .What about electrics ,any dash probs to look for ? The more I see of these cars the more I want one .
Yeah I can see where an 11 sec car is a hand full , means 9 sec and you're at go directly to jail speeds !
Thanks

hahaha ..
rust... soft areas on torsion bar areas rear spring perches ,floor boards and trunk floor.
electrics are usually Good all over.