Looking for the right path!

-

Tmac85

Member
Joined
Jul 7, 2016
Messages
18
Reaction score
1
Location
Carrollton Va
I have a 73 Duster 340. Just pulled the motor/727 trans out Saturday. Budget plays a big part in any of this as most of you know. I "think" I want mid 400hp on 93 Octane in a streetable setup. I don't like throwing numbers out there because I don't have a lot of experience. Brand new to muscle cars and even newer to mopar. Basically I want to be pinned back to the seat but have great handling around turns. Just back roads, no auto x. Motor and trans both have 100k miles. What are my steps from here?? Thanks!

IMG_0766.JPG
 
Find a good machine shop, one with old motors piled up in or around the building and posters n **** hung up on the walls from the '70's-80's. ha ha
No seriously do some shopping around and locate one that have torque plates for a Mopar sb, knows something about setting proper valve stem height with a shaft mount rocker system and gives the pistons .003+ on the skirt clearance. But that's just where I would start.
 
recently paid $1800.00 to have my rotating assembly balanced and blueprinted.
new rings,bearings,etc
im running a stock AAR cuda cam
please don't let your friends talk you into a thumper cam and popups .
you don't need all the porting ,polishing,etc.
SHOP AROUND. good luck
 
I think, your goals are a little high considering the intended use. In terms of how I would do quick pricing: 400hp (1.17hp/inch) will run around $15/hp. 450hp (1.33hp/inch) will cost about $16.70 per horsepower. Something to remember is that these cars when new made an honest 270-290hp and were some of the most balanced street cars of their era. Simply by using modern performance components and modern high quality machining those numbers can easilly go up to 325-350hp with factory castings and manifolds. So as others have mentioned - shop around and don't get sucked into the "you need new heads", "need new rods", "need forged pistons" stuff. Those might help - but you don't "need" them to really make improvements and end up with a really great street package.
 
be sure to take a good close look at that transmission (or have someone do it)
that blue RTV worries me a bit

what you are looking for is found in the right combination of parts
and that is not limited to the rotating assembly only
once you know how you want to engine build (cam, pistons, C/R, intake and carb) figure out what size rear tires and which rear gears your running and then...get a torque converter that matches all of that


one a side note, we have a post on 9 second, 10 second, 11 second and 12 second small block combos (look for them in the racers section)
look through them and see what peaks your interest and fits your budget (this will also tell you where 400 HP gets you)
 
I thought 600 horsepower was the minimum number for " pinned backedness" .....
 
I thought 600 horsepower was the minimum number for " pinned backedness" .....
nah, the official number is 1200, and the calculation is (HP x gear ratio = accelerate)
so even if you only have 300 HP, but your running 4.11s you would be at 1233, which is still pinning
if you want to run highway gears, like the 2.73s and be pinned, you would need (1200/2.73=) 440 HP





(disclaimer, though there is some truth to it, the 1200 number is a complete fabrication I made up to explain a point)
 
I would back off of the mid 400 HP range as said for a budget. If you are new to muscle cars, you will have your hands full driving a true 325-350 HP anyway; it is not like a peaky 350 HP in rice burner; you will have gobs of torque in the low and mid range.

The idea of 'streetable' begs some more questions; a LOT of pretty wild engines are 'streetable'. Will you use this as a daily driver? Does fuel mileage matter? This all works into cam and piston selections.

Again, can you give any ideas on the budget limits?

IIRC, those 73 heads have 1.88 valves. If you can afford it, moving up to 2.02" valves would help the top end HP. That is the limit for reaching anywhere close to 400 HP BTW; the breathing is not there. If you have the money for some tools, a place to work, the patience and time, you could do some head porting yourself to save money. But it takes a lot of careful work and time, and some folks just should not do that.

The 73 is a lower compression ratio engine and if this is for roaring around the backroads, then it would be wise to get the CR back up to a true 9 to 9.5 range. This will help a lot with low RPM torque, which you will use coming hard off of corners as you romp around the back roads.

As for suspension: (Yeah, I know... this is the engine section!) With the roads in your neck of the woods, they are not all that curvy (I live out in the Blue Ridge region of VA) but they can be bumpy and rough in spots. So don't go with the stiffest springs and front torsion bars; those are suitable for flat roads and auto-x, but not for keeping as much suspension travel as you can. You REALLY need to save your pennies for a set of Bilsteins; the result will be nothing short of spectacular on those roads. And be looking at anti-sway bars of course. Poly bushing will tend to beat up the suspension parts on rough roads, so I would stick with rubber when renewing the suspension parts.
 
I'd go for a feeling rather than a number, and here's the way I'd go to get your goal:

While engine is out of the car, check bore wear. If acceptable, reassemble with new bearings, timing chain, and camshaft of your choice - something mild in the 1500 ~ 5500rpm range or thereabouts.

If the bores are worn, add new pistons and rings to the above, as well bore machining to suit. Hypereutectic pistons are great for performance street use as they are strong, not temperamental when cold and not too expensive either; a great middleground between regular ol' cast units and top-o-tha-line forged ones.

Slap on a carby around 600 ~ 650cfm and call it a day!

- boingk
 
...take the time to read Rusty Rat Rod's guide to hot rod bliss
it'll keep you from wasting a lot of money on aftermarket bling and help
you with what you need economically and with good common sense.
 
Thanks for all your advice. There is no set budget just like there is no set time limit. Should I take the machine shop a bare block and tell them to go over it or??? Can head work be done to open the valves to 2.02, without buying new heads or is the cost about the same? Not concerned about fuel economy, however I want to be rolling at 70mph and not 7k rpms. So I'm guessing highway gear ratio? I have 275s on the back now which fit nice. I more or less want a cruiser with some *** behind it.
 
Thanks for all your advice. There is no set budget just like there is no set time limit. Should I take the machine shop a bare block and tell them to go over it or??? Can head work be done to open the valves to 2.02, without buying new heads or is the cost about the same? Not concerned about fuel economy, however I want to be rolling at 70mph and not 7k rpms. So I'm guessing highway gear ratio? I have 275s on the back now which fit nice. I more or less want a cruiser with some *** behind it.

Yes you can take them the block and have them clean and mag it , to start with.
To really get the ball rolling though...you need to figure out the rpm range and hp goal realistically attainable in that range with the gears you are chaining yourself to. kiddin.
 
My opinion is build your short block with high quality components and spot on machine work. With a good strong bottom end you can always add power later. I would use a quality forged piston around 10 to 1 for a street motor. Heads, intakes, cams etc can always be changed later as your thirst for power increases.

I like forged pistons because if I ever decided to run nitrous for a quick 150 horsepower jump, the motor will survive. On a budget I would most likely run a hydraulic flat tappet cam. Changing to roller is nice but you have the expense of different pushrods, adjustable rocker arms, distributer drive gear, sometimes oil system modifications.

Of course if you want to build a full roller motor with aluminum heads and other exotic components then it will cost you.
 
I'm still learning the proper lingo in all of this but when I take my stock heads to the machine shop, what exactly am I wanting done in order to "open valves to 2.02" and "bowl work"?
 
I'm still learning the proper lingo in all of this but when I take my stock heads to the machine shop, what exactly am I wanting done in order to "open valves to 2.02" and "bowl work"?

Ask them to rebuild the heads and use 2.02/1.60 11/32 stem +.100 stainless Chevy valves. On the heads...you want clean and mag, new guides, hardened exhaust seats, multi angle valve job, surface cut, guides cut for dbl springs. Ask to have them cc'd and equalized head to head if needed.
Bowl work , porting to blend the larger valve seat to the rest of the port, in lamens, it increases the air flow=make more power.
 
Just talked to local machine shop, rough estimate is 1500 in labor including head work. Assuming everything checks out.
 
-
Back
Top