Stock 340 Upgrade Questions

[Glow Worm]

My 73 Cuda, as far as I know, has the original, unmolested 340 engine in it. The car has approximately 58, 500 miles on it. I would like to try to get a few more horsepower out of it.
A very good friend of mine told me that putting different heads, intake and cam will help, but unless I am willing to change the pistons, and do some other upgrades I will be throwing money down the toilet. He says the engine has low compression because "the pistons are buried in the cylinders." I'm not a mechanic, but I do understand that.
My initial thoughts were to buy an Edelbrock top end kit and just go with what I got, but after talking about it, I'm thinking I should go with the entire rebuild.

What could I expect if I just went with the top end kit? I need to have the engine bay painted and I want to do the transmission too while everything is out of the car.

Any thoughts? Suggestions?

 

[IQ52]

Of course it will help to increase the compression ratio, but "down the toilet" may not apply here to your considered changes. Here are some results on a low compression 400 B engine, just doing what may be considered a "top end kit".

http://www.forbbodiesonly.com/moparforum/showthread.php?80843-The-slug-400-on-the-dyno&highlight=400+2bbl

If you can afford to go with an entire, proper rebuild, you would of course get even more gain.

 

[Adam]

Good info here: http://www.allpar.com/mopar/mopar340.html

If you have an unmolested 1973 340 I would recommend a total rebuild. Have the 2.02 valves put in the heads and have the cc,s measured. Then you can pick a piston which will give you the compression ratio you want (around 10 to 1) you will need premium gas. A 340 has a short stroke and is a good reving engine; most of the power is up in the rpm band so go with a cam that has around 230 =/- 5 degrees of duration, @ .050 (for the street, my opinion).

Even though the car only has 58K miles the seals and gaskets are over 40 years old and need replacing. New bearings wouldn't hurt as long as you are taking it apart. If the bore is good you may be able to use a standard size piston and not over bore it.
Modern pistons tend to be lighter than the originals, this helps in quick reving, but will require balancing; this includes the dampner and flywheel or converter. If you have an auto trans go with a bit looser converter like 2500 for the street, it will flash higher when you get on it. Also a new valve body like a Cheetah Turbo Action manual will allow you to shift it manually when you want or just stick it in drive...

Edelbrock heads are nice but they are obvious, you can kick ass with an original Mopar engine and tell people its stock. Also Aluminum heads effectively reduce compression because they dissipate heat so well. They do take 40 lbs or so off the front of the car so its give and take.

If your original heads are cracked another option may be Indy LAX heads, take a close look at the 300-H1-LAX, http://www.aeroheadracing.com/chrysler.html such a small chamber will really up your compression ratio with a bolt on, and same price as the Eddys. I have a set of these and they are very nice. More info:http://www.hughesengines.com/TechArticles/8laxandmaxironsmallblockheads.php

 

[moparleo]

Without getting into the tech stuff like CR, valve sizes, duration and lift numbers, What are you really trying to do ? Is the rest of the car original and if so what are your future plans with the car. If it is not modified do you want to keep it that way ? What is your budget ? 2k, 5k, 10k ? If you are not very experienced in engine building, you are going to get a million different opinions on what to do. If future value is important, pull the engine and out and set it aside. Do some research. Check with the major engine builders. Tell them what performance you are looking for and what your budget is. They can normally answer your questions with out making you feel like you have to be a scientist to understand what they are talking about.
By the way, I notice that you are new to the site. A BIG WELCOME, Go to the welcome wagon and intro yourself to the rest of the group.

 

[KATSAAR]

with out breaking the bank.
start with a mild cam, alum intake and a good carb.
see how you like it .
OMG what ever you do ,don't put the biggest cam your friends can find for you.

 

[challenger6pak]

with out breaking the bank.
start with a mild cam, alum intake and a good carb.
see how you like it .
OMG what ever you do ,don't put the biggest cam your friends can find for you.

I agree. Save EVERYTHING you take off the motor. You never know if you will want it to be original again.

 

[moper]

If you want to paint and detail, it's coming out anyway. IMO, the best way is to address the power issue without too much bling. You will still incur cost, but you're not "overpersonalizing" or potentially turning off resto freaks that way. Of course if you want to it's your car.. This is what I'd do given the limited input you supplied:
Rebuild the engine. Re-use your basic parts, but install KB hyper pistons that will restore a bit of the static ratio. Have it internally balanced. Have the heads treated to a modern performance valve job and upgrade the valves to 2.02/1.65. If you retain the stock look and manifolding/carb, install a milder camshaft - in the 210-220° at .050 range. If you want more power, replace the intake with an RPM Air gap, the carb with something more modern, and a set of headers and run a cam in the 225° @ .050 area.
Without changing the cam the top end change is not enough return on investment. By replacing the pistons, doing a good valve job, and solid rebuilding you will get 50% of the power the heads would give you alone in a package that will last for thousands more miles and look great doing it. By adding the bolt ons with the rebuild, you can eclipse what the head package would give you.