Input needed on engine mods

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purplebeast

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I'm starting to plan the mods I want to make to my Dart, and would appreciate some input. It's a 273/904 combo, with a recent stock rebuild, .020 overbore. According to stock specs, the motor should be 9.0:1 comp. I don't want to pull the engine, so I'm looking mostly at cam/intake/carb suggestions, possible a head swap.This is to be a street cruiser, so nothing too radical. The car has A/C, manual brakes. I want to keep things looking original under the hood. I've picked up a 8 3/4 rear w/ 3.23 sure grip. I've got a set of early 340 exhaust manifolds to use, as well as a Edelbrock 600 cfm carb. I also have an original '68 340 4 speed cam. As far as heads go, I've got a set of 340/360 1.88 heads, but I think the cc volume would be too big for the 273, as well as the ports.

I'll probably have a shift kit installed , and possibly a better convertor down the road.

Let the suggestions fly!! :mrgreen:
 
Id go real mild on it. Small cam like a cmp cams XE252, Dual plane intake like a performer and a 500 cfm Carb. Alittle gear like some 3.55 and it should be pretty peppy.
 
Small cam like a cmp cams XE252,
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Would this cam give it a "muscular" idle? I don't mind a little lope, but I want to maintain low-end torque. Ideally, I'd like to get as close to stock 340 performance as possible, without actually dropping in a 340- possible?
Thanks.
 
IN A 273 YES IT WILL....BE CARFUL WITH USING 340 MANIFOLDS ON A 318/273 HEAD SINCE THE PORTS ARE LARGER ON THE MANIFOLD, SOMETIMES THE MANIFOLD WILL "HANG OVER" THE HEAP PORT MOUNTING SURFACE
 
It wont sound stock but it wont sound like a prostock.
The 273 used such a small cam from the factory that anything is a step up.

Also you probably have a solid cam now so you will need new pushrods.
 
If you can find a ld340 dual plane intake grab it. Almost looks stock, but an awesome intake for the street. I think it is better than the performer, but harder to find one.
 
I would give Racer Brown a call for the cam. They give you a custom ground cam taking into consideration your intake, heads, combustion chamber size, valve sizes, altitude were you are at, convertor stall, and gear ratio. I got mine from them and a set of MP hydrolic flat tappet lifters for around $125 with shipping. Dollar for dollar it would be your best performance cam. Go with the RPM Air-Gap intake and Edelbrock performer carb. Good luck :thumrigh: .
 
yup good intake. Its the same as the LD340 but with 273/318 port size
 
My first choice would be the later 318 casting "302" heads..They are closed chamber, have much better ports, and will accept all your rocker gear. Then I'd swap in the small Comp XE256H, and an edelbrock performer 318/360 non-egr. Paint up the intkae engine color, and run a small (500-600 cfm) carb. The heads will add a little in compression over what you have, and that will also help. You should not need pushrods. Later 273s were not solid cam. What year is your 273?
 
moper said:
My first choice would be the later 318 casting "302" heads..They are closed chamber, have much better ports, and will accept all your rocker gear.
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I had been thinking about these heads. Would there be any valve-to-block clearance issues? It's a numbers-matching 1969 block, so hydraulic lifters. I have access to an Edelbrock SP2P, in keeping with the vintage of the car- would the Performer 318 be a significant improvement?

Thanks for all the input!
 
I've heard that the later 86-92? 308 swirl port heads work well..
 
The chambers on thsoe will drop compression to much. The 302 or Magnum heads would be a better choice.
 
I have an Eddy SP2P manifold and Carter 500cfm carb on my 318. It has very crisp throttle responce and is very drivable with the stock low compression and stock cam. But I do have full length headers and 2-1/2" dual exhaust. The ports in the SP2P intake are quite narrow... smaller that the stock 318 heads. A little bigger cam and more compression would only improve things.
 
6T9 GTS said:
I would give Racer Brown a call for the cam. They give you a custom ground cam taking into consideration your intake, heads, combustion chamber size, valve sizes, altitude were you are at, convertor stall, and gear ratio. I got mine from them and a set of MP hydrolic flat tappet lifters for around $125 with shipping. Dollar for dollar it would be your best performance cam. Go with the RPM Air-Gap intake and Edelbrock performer carb. Good luck :thumrigh: .
Click to expand...

Yes 6T9 GTS is right! Go with Racer Brown!!! :thumleft: 1-410-866-7660 I think is the number to call. Racer Brown cams make more power!!! You will also get better customer service then with other companies.
8)
 
You should not have any interferance issues, although I'll have to double check the bore clearance in regard to the valve size. As long as you stay with the 318 size valves, you're fine. As far as intakes, the performer has very slightly larger runners than a factory intake, but comes with the 318 size ports..If you use the Magnums, you will have to notch the bores to fit the 1.94 intake valves they use. The "302"s use a standard 1.88 intake, and should clear fine. The eddy performer 318 can usually be found for $50-75 at swaps too...so it's easy to get.
 
50* today!Just got back from the junkyard with a set of 302's to put on the 273. I got there kind of late, so I didn't get much of a chance to look around, but I did see a couple trucks & vans with 360's- possibly 308 heads? So, now I'm thinking 3-angle valve grind, any port work? I still have some springs W/damper from my 340 heads, plus the heavier rocker assemblies- should I use these? Does anybody know what the cc volume is on the 302's, and how close it is to the stock 273 head? Thanks.
 
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