340 Build

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jthomas38

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I just picked up a complete 340 and some other after market parts. At the moment I know little about building horsepower, so my question is, will these parts work together and how well. The block is a 340 for a 70 car. I pulled the heads, they are 1.88 intake valves but I have a set of 2 inch j heads that I am going to have reworked to replace them. The pistons are L2316 +.030. I have a lunati voodoo cam kit, part number 60401 lk, a new Weiand intake part number 8007. The existing carb is an Edelbrock 1405, 600 CFM. I read some where that the valve springs depend on the cam used, is that true? any other issues that I should be concerned with? Thanks in advance...
 
Howdy and welcome. The first and most important question is: What are you going to do with this engine and car? Pure drag race? Long range interstate cruising? Local cruising and hot rodding? All of these factors will enter into what is the best combination of parts.

And what part of NC are you in? The flat part or the mountains?
 
You should get, beg or borrow an engine book. It would explain the theory and practicalities of all the things you will need to know about building the engine you want. Then you will know why you should choose or do everything that you will need.
 
Yes on the valve springs. Go back to Lunatipower.com and find your can and seek out the stings that match which you can purchase directly from Lunati. The springs your looking for are the 73195-16 or the upgraded spring 74895-16. A catolog is available from Lunati.

All your parts will work together. Though I don't know what a L2316 piston would spec out to be. I would myself use a larger carb but the 600 will get you going.

The MoPar book mentioned above can be purchased at a few places on line like Mancini racing .com.
 
L2316 should be a TRW factory replacement piston in a forged casting, 184 compression height. Old school and heavy, should come out of the deck a little. That being said I have a set in my 340. Your combo should be decent, if it were me, I would like more cam but we don't know your intended use, headers or manifolds, etc
 
gtsdude said:
L2316 should be a TRW factory replacement piston in a forged casting, 184 compression height. Old school and heavy, should come out of the deck a little. That being said I have a set in my 340. Your combo should be decent, if it were me, I would like more cam but we don't know your intended use, headers or manifolds, etc
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This is correct. In most cases if you actually want to be 10.5:1 compression you need to be at a minimum of .040 out of the deck. A POSITIVE deck height of .040.

You need to actually measure your volumes to get the compression ratio correct.
 
L2316..about 9.4:1 with stock 71 - 72cc heads.
..same as stock early 68 - 70 340
 
Can you post a pic of the top of the piston? I have a set of TRW's in mine but forgot to write the # down and check how far they were in the bore before I built it.
 

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The one in the pick looks like a stock early cast 340 piston IIRC, has the notches in it like a stocker, compression height should be the same as the TRW L2316
 
The rebuilder said they were nice old forged TRW's When I handed them to him.
 
The purpose of the car is local cruising and hot rodding. I'm a shade tree mechanic at best and know little about building an engine or horsepower. I have books on the way from Amazon, but I thought that information sharing was one purpose for these forums. The engine was recently rebuilt so I really don't want to go piston deep into it but I would like to get as much horsepower as I can, budget permitting. I'm in Fayetteville, spent 12 yrs on Bragg, retired in 2005.
 
The original standard out-of-the-block height was around .018". So presumably the TRW's are there too. With the heads off of the engine, that deck height will be easy to check and is the basis for seeing what CR you will have with the J heads.

The reason to ask the use of the engine is to focus the build and mods to the purpose. For your use, I'd be looking at keeping the SCR up to the mid 9 range to help low end torque, which is desirable for a perky response on the street. A bit of head shaving may help, but first, I'd check the piston deck height and then the SCR target can be computed. Many people here can help you with that, with the data, or can show you the computer tools to do that; it is not rocket science..... anymore at least.

I like the cam for street torque; with the compression data, then the dynamic CR can be computed to make sure you are not straying too close from the safe zone to avoid detonation. It is easy to keep in that safe zone with what you have. And since you are in the flat lands, you won't normally be pulling a lot of low or mid RPM's climbing up the mountains, and that helps stay away from common detonation conditions. Taking the effort to properly time the cam is a very good investment of your time while you have the timing cover removed for the cam change.

And the carb will work for street use just fine as said; a tad larger would work well too. I am not personally familiar with the intake.

Yes on the springs. I am sure that you can get a matching set from Lunati or many folks here can make a good recommendation.
 
Sedanman said:
The rebuilder said they were nice old forged TRW's When I handed them to him.
Click to expand...

Top pic is my old 340 that had the early stock cast pistons, second pic is the TRW2316, either way you have some decent compression pistons. The piston in the top pic was in a 73 340 that I expected to have the lower compression pistons in it when I pulled the heads off, it was a nice surprise and saved me some $
 

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Thanks for the clairification. Any clue what the CR ratio or specs is on them?
 
I picked up my complete 340 carb/pan with those cast pistons for $350 so I can't really complain. I had the bottom end balanced and put new valves and springs in. What I saved in parts cost me in machine work.
 
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