73' 340 Shopping List

[6dart9]

So I am finally going to pick up the 340 I was asking about on a previous thread this Friday. A couple of questions I have to some of the 340 experts out there.

1.Being a 73 it obviously wont have the same compression with stock replacement parts so what are some good not to expensive ways to build up the compression?

2. Also I was using the Comp Camquest thing and I was getting numbers like 350 hp 380 tq however i wonder what it isn't taking into consideration.

3. I will not be racing this or at least not planning on it and would like to get 300hp and 350 tq out of the build so any set ups you all might have would be helpful.

It is going into a 69 Dodge Dart with a 904 I plan to upgrade the torque converter (any suggestions) I will also be adding a 8 3/4 rear with gears im still unsure of (any suggestions) I have elec ignition and a edl 600cfm carb i would like to keep since they are both brand new.

I know this question has probably been asked 1000 times but any way you guys can point me in the best direction so i can start buying parts for this thing would be great.

Thanks Everyone

Justin

 

[AdamR]

Even the low compression motors run pretty good. I would run a little smaller cam in it then I would a high compression motor, Like an XE262, Use an edelbrock RPM or LD340 on it if your not using the stock intake and thermoquad

 

[demon sizzler]

I agree with Adam's idea on the cam specs with stock pistons(compression).

On my low compression '72 340(now in my '71 Demon), I had the block bored .030" and knew I would want at least 10:1 compression over the stock 8.5:1 rating. My cranking compression is actually 10.4:1 due to the use of Keith Black #243 pistons, 68 cc 915 heads and the thin .028" MP head gaskets. I have a cam with 74 degrees of overlap so some of the compression is blead off and I can run 93 octane pump gas. I run a LD340 intake with a well-prepped ThermoQuad.

The engine makes plenty of low end power/torque so traction is a really big problem. But the limited traction is with street tires. Just be sure to 'match' engine components correctly for best performance.

If you have to bore the motor, use a light piston and the balance job is easier and less costly since weight is remover from the crank, David.

 

[65 Dartman]

It is going into a 69 Dodge Dart with a 904 I plan to upgrade the torque converter (any suggestions)
Justin

I talked extensively with Sean at Racer Brown concerning cam and torque converter selection for a 340 going in my 65 Dart wagon. He asked Lots of questions - weight of the car, intended usage, rear end gears, intake/exhaust, carburetion, transmission, who would be driving the car, and many more that I can't remember now. Based upon all the info, they custom built me a 9.5 inch converter, a cam and a much beefed-up 904. Whoever you get to do a converter, make sure they get as much info from you as possible.

 

[AdamR]

You mean Sean at Dynamic Transmissions ? They build a good converter but everything they sell now is a 9.5" unit and I dont believe they are right for every application.

There are some good off the shelf 10" and 11" converters for those who dont need a custom $600 converter.

I used a 10" Dynamic behind a big block and it worked great but I really like the Turbo Action converters.

 

[6dart9]

Ok cool thanks for the insight It will be bored .30 over so if there are anymore ideas you can give me that would be much appreciated

thanks!

 

[AdamR]

well if you have to bore it your going to end up with higher compression anyways. I dont think anyone sells low compression 340 pistons anymore. If you run a set of KBs you will end up around 10:1, Then I would run a comp cams XE268 and a 750 Holley vacuum secondary.

 

[6dart9]

Ah ha I thought that would be the case...Thanks Adam

Justin

 

[perfacar]

hi, sealed power has 72-73 340 pistons. the 72-73 340 with deck hgt set at .054 down, and 65.4 cc heads and .028 mopar gasket will give you 9.52 cr. more than enough for todays gas. the cam should be a short duration and ground on tighter lobe centers, like 106-108 LCA. this will build cylinder pressure and a broader torque curve. long duration cams kill low comp motors.
having a quicker advance curve in dist will also help. 1.88 sst valves will flow more than enough air for the motor. use a 587 head, with a mild bowl blending. this is basic stuff that works!!!

 

[65 Dartman]

You mean Sean at Dynamic Transmissions ? They build a good converter but everything they sell now is a 9.5" unit and I dont believe they are right for every application.

Yep I stand corrected. Must be getting old as I remembered Dynamic & Racer were one and the same - NOT. Sean is definitely at Dynamic. I too had my doubts about using the 9.5 converter, but after talking with him (and discussing with a well respected engine/trans guy over at 62-65 Mopars), went ahead with it. Said my wife wouldn't even have any problems with it. Sean said the car will act like a regular car (how regular can one be with a 340) until you got on it. We shall see. Did get my cam from Racer Brown and he also asked lots of questions. My point is whoever you get to build this stuff needs as much info about the car as possible.