need help with my 340

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mopow3r

mopow3r

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i recently just picked up a 69 340 and 727 from a friend. the motor has about 30k on the rebuild and trans is getting rebuilt next month. the motor has stock crank, 10.5 to 1 comp pistons, mopar 509 cam, 2.02/1.60 heads with 3 angle valve job, and an offy dual plane intake. im really looking to get more out of this motor without spending 5 grand, i dont really want to go the stroker route, and i want to run the cast heads for now, can anyone throw me some advice on more performance out of this old thing? open to any opinions, different cam, intake, anything?? whatever you think i should do please throw me ideas
 
I would ditch the cam and go with something around 230 @ .050 also the intake could be better, is it a port o sonic?
 
We'll your going to have to give a lot more info, what car is this going into, street or strip, highway??, what gears, do you plan on spending for a good converter, what rockers are on it now, you sure the pistons are 10.5 to 1 ?? Most times it's much less.
 
Generally the 509 cam is to large for a 340 unless it's way up on compression and big stall etc. that cam has about 248 @ .050 a good mild street cam for a 340'is between 220 to 230
@ .050 in my opinion.
 
A good cam is a cam that works with your converter, gear ratio, carb and intake to make a good overall combonation in the performance area your looking to drive or race in.

Tell us the following:

Year
Make
Model weight
gear ratio
tire size
trans type

And what you want to do with the car

Include as well what parts you have on the car. Saying you have an Offy intake boils it down to approx 5 or 6 possible intakes Offy has produced. Be specific as to what you have and what you want the car to do.

We are not mind readers. Your question would have had me thinking race, since you said more out of it. So getcha self some 4,56 gears and the comp 308 cam, a 5500+ converter and let er rip!

All joking aside... Whatcha got goin on over there?
 
Going in a 69 dart. Has a 3000 stall and 3.73 gears. I daily the car now and mileage doesn't matter. However dependability does lol. The motor and trans came out of a 65 barracuda with 3.55's and it was running 12.40's
 
Are you looking to go faster or have better street abilty
 
Both if possible! I'd like it to be a mid to high 11 second with daily possibilities. It only gets driven about 100 miles or less a week
 
Sooo, your comfortable with a operating rpm of 3000-6500 rpm and 4.30 gears, cruising at 3/3500 rpm?
 
mopow3r said:
Both if possible! I'd like it to be a mid to high 11 second with daily possibilities. It only gets driven about 100 miles or less a week
Click to expand...

A reliable, daily driven, 11 second, non-stroked budget build is really asking a lot.

To truly hit 11s on the street will take power, and chassis work that I just don't see happening for under $5,000.
 
Consider putting the motor in as-is,,, if you don't have good long tube headers, install them at same time as the engine,, - then when you can get it to hook-up,, - go for more power.. JMO
 
Thanks 340sfastback. That article was very helpful. It's funny what a lot of people don't realize is the 340 was made back when everyone was under rating their motors for insurance reasons, while the 340 was rated at 275hp dyno results later showed it actually made 330hp :) which is why the t/a and AAR were tearing up the competition back in the day
 
put an edelbrock rpm cam and a 150 shot of nitrous on it, should knock down close to 20mpg on the freeway and run mid-high 11s on the bottle
 
You want to "get more out of it". More than what? Have you even had it running yet?
 
probably try the motor as is, not sure the T/A and AAR were tearing up the competition in Trans AM. the actual 340 was a 303ci that had one carb no 6 pack and made around 460hp.
 
Port the heads, add 1-3/4 headers & 2-1-2 exhaust min.
Is look at a mechanical cam and roller rockers @ a 1.6 ratio.
A still smallish size Comp Cam 294s will do the trick.
 
Try what you have first.If you are willing to deal with rpm & gears,why change the cam.68/340 is dead on,about needing chassis work & gear.Rumble fish's post,if you don't hit the bogey.
 
to get 11's your gona need to look at the tyres, road tyres wont do, even if you do make 400 out the engine.
 
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