Opinions on a 340

[Coyote Jack]

You are getting a lot of conflicting information. Some good, some bad. Rusty and moper are both giving you good info. Just different ways to get there.

I am looking at a couple of your posts and the one thing I see is that you want to keep the costs down. If it was me, I would spend a few dollars and get a set of hyper pistons to get me in the 9.0 to 1 range, they are relatively cheap and then slide a Comp 268XE (or similar) cam into it. Then put your J heads and a vac secondary 750 Holley on it with a decent ignition. All that keeps the cost down and will put a smile on your face.

Jack

 

[BlueDream]

Alright, I went and picked up the 340 yesterday! I think it'll be a solid engine when it's all said and done. I got the block thats fresh from the machine shop. Crankshaft casting # 3462387. Sealed Power 428P pistons. And I got a windage tray and an oil pan with it too. I also think I'm also going to go with later 318/360 rods. Since the pistons are supposed to be 10:1 I won't be milling the heads or doing anything to raise compression at all since I'll be using my 915 heads. With the big chambers and a thick head gasket I think I'll still be able to run on pump gas.

One thing I'm confused about is the balancing of the engine. Some sources say internal, some say external. Some say its dependent on a forged or cast crank, some say it doesn't matter. This is my first time building an engine from the ground up like this, with my 318 I reused the stock rotating assembly. I'd like to get this right the first time! My wallet can't build two 340's. So, is this thing internally or externally balanced? And how important is it to balance the rotating assembly? My shop quoted me $175 to do it and the guy I spoke to said I might not have to. If I can save the $175 and use it elsewhere, great! If my engine will explode if it's not balanced then I'll go ahead and spend the money. What do you all think?

I also want to reuse my harmonic balancer and timing cover from my 318. Will I run into any problems doing this? Or do I have to use a different balancer thats specific to the 340?

 

[RustyRatRod]

If it has a steel crank, it's balanced internally. Cast crank 340 were externally balanced. You can remove the pan to tell for sure.

 

[BlueDream]

Pictures! We all like pictures right?

 

[BlueDream]

If it has a steel crank, it's balanced internally. Cast crank 340 were externally balanced. You can remove the pan to tell for sure.

My 340 crank is definitely cast. It doesn't ring for an eternity when I hit it with a ball peen hammer and it has the narrow casting line. Will this be a problem with my neutral balance flywheel?

 

[RustyRatRod]

My 340 crank is definitely cast. It doesn't ring for an eternity when I hit it with a ball peen hammer and it has the narrow casting line. Will this be a problem with my neutral balance flywheel?

Yeah. You need a counter balanced flywheel. No big deal. Those pistons are perfect. They are the late 340 replacements. You can get 8.5 easy. Perfect for a street motor.

 

[BlueDream]

Yeah. You need a counter balanced flywheel. No big deal. Those pistons are perfect. They are the late 340 replacements. You can get 8.5 easy. Perfect for a street motor.

I'm glad the pistons are what I need. One less thing I have to buy! :cheers:

Would this flywheel be a good choice? http://store.440source.com/1045-Billet-Steel-Flywheel-New/productinfo/113-1014/

And since it's externally balanced would I need to balance the rotating assembly? Or just get the counterweighted flywheel and that's it?

 

[RustyRatRod]

"I" would probably have it balanced. If the parts were not running together in the engine I think that's the best idea.

I am not familiar with the 440Source flywheel. But I don't think they sell crap so it's probably good.

 

[BlueDream]

"I" would probably have it balanced. If the parts were not running together in the engine I think that's the best idea.

I am not familiar with the 440Source flywheel. But I don't think they sell crap so it's probably good.

I'll put that flywheel on the shopping list then. Would I be able to run the 318's balancer and timing cover? I'm making a list and this stuff is starting to add up fast. I'm almost $2,000 in already. :banghead:

 

[BlueDream]

Heres what I've got worked up so far.... It adds up to a little over $2,000 including the purchase of the 340 block and the things that came with it.

MACHINE SHOP

Crank: turn, polish, vat: $100
Rods: resize, ARP bolts, install new pistons: $175
Balance rotating assembly: $175
Heads reworked: $250



NEEDA BUY

Cam & Lifters - bout $200
Rings-$80
Bearings-$75
440Source Flywheel - $200
Gasket Kit: $60
Header Gaskets: $20
Fluids- $100
Big bag ‘o FLOOR DRY-


ALREADY BOUGHT

340 Block
Main caps and bolts
Oil pan
Windage tray
Rods
Pistons & wrist pins



SOURCE FROM 318

600CFM 1405 Eddy/ Performer intake
Rocker arms/Shafts
Pushrods
Timing set
Valve springs
Timing cover
Balancer
Distributor
Water pump
Front accessories
Oil pump & Pickup
Oil pump shaft
Various bolts & things
Valve covers
Mopar Performance air cleaner
Carb spacer
Other things I need but can’t remember but that I know swap over


FUTURE UPGRADES FOR WHEN I'M NOT BROKE

Edelbrock Air-Gap intake
MP electronic ignition or MSD
Holley 750 double pumper or Speed Demon 750 mechanical secondary

 

[RustyRatRod]

2K is nothing for a good engine. Consider yourself lucky. Most people spend 5K or more. Don't be cheap. It will be the worst mistake you can make.

 

[trapster]

I think you should spend more on head gaskets if you are planning on running any kind of compression. I think I spent $50 on mine 20 years ago.

 

[BlueDream]

2K is nothing for a good engine. Consider yourself lucky. Most people spend 5K or more. Don't be cheap. It will be the worst mistake you can make.

This engine has to last me until I'm at least out of college and can afford to stroke the 340. That's why I'm trying to plan it all out and build it right and use quality parts while still on a budget. I figure it's a lot easier to spend the extra money on machine work and good parts now than to throw a rod at 6,000 RPM and poke a hole in the block a couple months after I get it built and have to start all over again. I'm going to spend the extra money on things like Mahle rings, Clevite bearings and ARP bolts. I also considered new rods but went with 360 rods instead because I know they're proven to be tough and 6,000 rpm isn't going to break them if they're prepped right. I saw some Eagle rods for about $250 today but I wouldn't trust Eagle I beams in my engine nearly as much as I'd trust prepped Mopar rods. Anyways, thanks for all your help with this 340! And you're right, $2,000 is pretty damn good for a nice engine. :burnout:

 

[BlueDream]

I think you should spend more on head gaskets if you are planning on running any kind of compression. I think I spent $50 on mine 20 years ago.

I was planning on Fel-Pro head gaskets. I have a Fel-Pro gasket set on my 318 and it hasn't given me any problems at all.

 

[66fs]

My 340 crank is definitely cast. It doesn't ring for an eternity when I hit it with a ball peen hammer and it has the narrow casting line. Will this be a problem with my neutral balance flywheel?

If you are balancing your rotating assy, why not just use your flywheel from the 318. They can balance it out with that. I was told never to hit a crank with a steel hammer.

 

[BlueDream]

If you are balancing your rotating assy, why not just use your flywheel from the 318. They can balance it out with that. I was told never to hit a crank with a steel hammer.

I just tapped on it with a tiny hammer to see if it'd ring. I didn't want to break it so I was pretty conservative with how hard I tapped it. As for the flywheel... I'm not sure my current one can take the power. This is what I have: http://www.summitracing.com/parts/zzz-50-3409/overview/

Fine for my 318 but I don't know if I want to risk it blowing up and taking off a chunk of my foot or damaging the 340.

 

[RustyRatRod]

Then you better take good care of it and not abuse it, hadn't you?

This engine has to last me until I'm at least out of college and can afford to stroke the 340. That's why I'm trying to plan it all out and build it right and use quality parts while still on a budget. I figure it's a lot easier to spend the extra money on machine work and good parts now than to throw a rod at 6,000 RPM and poke a hole in the block a couple months after I get it built and have to start all over again. I'm going to spend the extra money on things like Mahle rings, Clevite bearings and ARP bolts. I also considered new rods but went with 360 rods instead because I know they're proven to be tough and 6,000 rpm isn't going to break them if they're prepped right. I saw some Eagle rods for about $250 today but I wouldn't trust Eagle I beams in my engine nearly as much as I'd trust prepped Mopar rods. Anyways, thanks for all your help with this 340! And you're right, $2,000 is pretty damn good for a nice engine. :burnout: