340 Engine Shake

Rat Bastid

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You don't know my wife. She is very analytical and understands far more than most women when it comes to cars.


So what does she understand about engine science? I’m not degrading your wife. I’m saying (and this will piss some off but it’s a FACT) women and men do NOT think the same.

My wife has 2 college degrees and analyzes everything. She doesn’t understand mechanical things at all.
 

plumkrazee70

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So what does she understand about engine science? I’m not degrading your wife. I’m saying (and this will piss some off but it’s a FACT) women and men do NOT think the same.

My wife has 2 college degrees and analyzes everything. She doesn’t understand mechanical things at all.

All I was saying is she doesn't understand or see the reason to spend x dollars on sleeving it vs just starting over with a new block. Many people don't have sleeved blocks.
 

Rat Bastid

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All I was saying is she doesn't understand or see the reason to spend x dollars on sleeving it vs just starting over with a new block. Many people don't have sleeved blocks.


Ok, we are on the same page. What I’m telling you is a sleeved block (done correctly) will be BETTER a than a block that isn’t sleeved. Simple as that.

It may be counterintuitive, but it’s a fact. That’s why I said sleeve it and move on.

BTW, there isn’t an aluminum block out there that doesn’t have sleeves in it. All of them. The sleeve materiel is better than the original block is.
 

plumkrazee70

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Ok, we are on the same page. What I’m telling you is a sleeved block (done correctly) will be BETTER a than a block that isn’t sleeved. Simple as that.

It may be counterintuitive, but it’s a fact. That’s why I said sleeve it and move on.

BTW, there isn’t an aluminum block out there that doesn’t have sleeves in it. All of them. The sleeve materiel is better than the original block is.

Ok. now I understand.
 

plumkrazee70

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Also , your car will always have more value with a 340 vs 360

Eh. I think that is up to the buyer. Me,.I wouldn't and still don't have to have the 340. The only reason I do have it is because I found the entire motor for $300, back when I first got the car. I wasnt seeking one.

Truthfully, I'd rather sell it to someone who has to have a 340.
 

Rat Bastid

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Eh. I think that is up to the buyer. Me,.I wouldn't and still don't have to have the 340. The only reason I do have it is because I found the entire motor for $300, back when I first got the car. I wasnt seeking one.

Truthfully, I'd rather sell it to someone who has to have a 340.


If you can find a buyer that maybe the best option.
 

Phreakish

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Eh. I think that is up to the buyer. Me,.I wouldn't and still don't have to have the 340. The only reason I do have it is because I found the entire motor for $300, back when I first got the car. I wasnt seeking one.

Truthfully, I'd rather sell it to someone who has to have a 340.

Two things:
1) 340s are rare and come at a price premium. So it will always be worth more with a 340.

2) People with only a passing knowledge of Mopars will always think a 340 is better, or more special than a 360 in some mythical way that can't be replicated by anything but a 340.

I'm with you in that a 360 is no drawback, and can make "just as much" as a 340 with the proper build. Just pointing out that if value factors into your calculus, saving the 340 makes good sense. But if you're gonna ride or die with this car, do whatever makes the most sense for you.
 

GTX JOHN

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Ok, we are on the same page. What I’m telling you is a sleeved block (done correctly) will be BETTER a than a block that isn’t sleeved. Simple as that.

It may be counterintuitive, but it’s a fact. That’s why I said sleeve it and move on.

BTW, there isn’t an aluminum block out there that doesn’t have sleeves in it. All of them. The sleeve materiel is better than the original block is.

I agree with you = the only Caveat is it is easy to do one or two sleeves and keep alignment accurate.
I only know a couple in the western states I would trust to do 8 straight
and I would set me back $2,000 to $2,500. Perhaps $3,000.
A single thick sleeve cost me $400 to 500.
Maybe I am too fussy about who does this stuff for me.
It seems to have gone up 1/3 this year!
 

dano

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I'd sleeve it. Reason being, block are getting hard to find and even harder in usable shape. If you buy a used one you could still be putting the same money or more into the new one. Once this is all done you'll have a solid foundation and no worries if done correctly. Around here I've seen blocks be (when available) $800 to $1500 and none are stock bore.
 

JDMopar

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Interesting. I'll bring it up to him about the bearing spacers.


The 360 bore is 4.00, it would have to go .080 to use my 340 pistons.

340 bore is 4.04 and .040 makes it 4.080. he has a crank for the 360.
When you use the main bearing spacers, you use the 340 crank to make it a 3.31 stroke. Sell the 360 crank, and sell your .040 pistons for the 340. Bore the 360 to 4.040, stock bore for a 340 and buy the pistons in the link below to use in the freshly bored 360 block. The biggest expense would be the bearing spacers.
[FOR SALE] - Used std bore pistons - 340 | For A Bodies Only Mopar Forum

The other most frugal option would be to sell the 340 rotating assembly and buy a set of KB-107's or similar pistons for the 360 and roll with that. I have had dozens of 340's over the years, but I have a mildly built, well-mannered 360 in my 71 Challenger conv. It's a ride around and enjoy it type of car that is plenty fast enough for what it is. My conv has 340 Four Barrel badges on the hood and 99% of the people can't tell the difference by just looking at it. Good luck to you. You've been put in a tough spot with the motor, but just make the best of it for you.
:thumbsup:
 

plumkrazee70

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When you use the main bearing spacers, you use the 340 crank to make it a 3.31 stroke. Sell the 360 crank, and sell your .040 pistons for the 340. Bore the 360 to 4.040, stock bore for a 340 and buy the pistons in the link below to use in the freshly bored 360 block. The biggest expense would be the bearing spacers.
[FOR SALE] - Used std bore pistons - 340 | For A Bodies Only Mopar Forum

The other most frugal option would be to sell the 340 rotating assembly and buy a set of KB-107's or similar pistons for the 360 and roll with that. I have had dozens of 340's over the years, but I have a mildly built, well-mannered 360 in my 71 Challenger conv. It's a ride around and enjoy it type of car that is plenty fast enough for what it is. My conv has 340 Four Barrel badges on the hood and 99% of the people can't tell the difference by just looking at it. Good luck to you. You've been put in a tough spot with the motor, but just make the best of it for you.
:thumbsup:

This is what ai am leaning towards, mainly because the machinist has a 360 and crank ready to be prepped for $250.
 

512Stroker

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This is what ai am leaning towards, mainly because the machinist has a 360 and crank ready to be prepped for $250.
Can of worms
Dude unless you are going to have a QUALIFIED engine builder assemble this engine dont go there. Not saying it cant be done.
Plus the balancing issue
Man I would bite the bullet and sleeve the block or find another block.
 

GTX JOHN

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It would possible be easier to find a nice 340 Block.
They are still out there and not that expensive.
Not hard to find one that will go 040. Many when rebuilt
were generally 020 or 030.
 

plumkrazee70

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Well I found a 340 block local. Can't believe it actually.

It's a standard bore, it's a late 69 block. The main caps are missing though. Someone also painted the deck.

So I'm going to take it to the machine shop and have them look it over. See what they think.

I should be able to use my main caps, but I know there will be machine work to align hone. I'm concerned about taking too much off the deck to clean it up. I want to re use my rotating assembly and my pistons sat proud of the deck .018. I do have the Edelbrock open chamber cyl heads, so hopefully there will be enough clearance.

The best part is it was only $100 for the block. Here are some quick pics.

IMG_20220917_162236717.jpg


IMG_20220917_162240951.jpg


IMG_20220917_162301700.jpg
 

mgoblue9798

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Well I found a 340 block local. Can't believe it actually.

It's a standard bore, it's a late 69 block. The main caps are missing though. Someone also painted the deck.

So I'm going to take it to the machine shop and have them look it over. See what they think.

I should be able to use my main caps, but I know there will be machine work to align hone. I'm concerned about taking too much off the deck to clean it up. I want to re use my rotating assembly and my pistons sat proud of the deck .018. I do have the Edelbrock open chamber cyl heads, so hopefully there will be enough clearance.

The best part is it was only $100 for the block. Here are some quick pics.

View attachment 1715987186

View attachment 1715987187

View attachment 1715987188

That is a good score and worth taking a chance on for sure.

Switching main caps you likely will need an align bore though. More to it than just a hone. Talk to your machine shop.

As far as the deck goes I wouldn't worry much about it. You can always adjust with a thicker head gasket if needed.
 

GTX JOHN

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You will definitely need align bore.

You used to be able to buy shorter timing chains
to make up for crank being closer to cam?

IF the seller could find the Main Caps it would make
you build a lot easier.

I would even offer him another 50 or 100 if he could find them
 

plumkrazee70

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You will definitely need align bore.

You used to be able to buy shorter timing chains
to make up for crank being closer to cam?

IF the seller could find the Main Caps it would make
you build a lot easier.

I would even offer him another 50 or 100 if he could find them

They are long gone.. He got the block from a guy that was going to throw it away. I asked.
 

mgoblue9798

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You will definitely need align bore.

You used to be able to buy shorter timing chains
to make up for crank being closer to cam?

IF the seller could find the Main Caps it would make
you build a lot easier.

I would even offer him another 50 or 100 if he could find them

If the shorter chain isn't availabe (like most things now) check into a tensioner.
 

gzig5

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If the shorter chain isn't availabe (like most things now) check into a tensioner.
Or a Milodon gear drive....
More expensive but you won't have to worry about it stretching or being sloppy if the center line moves a lot.
 

gzig5

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I'm trying not to deviate too much from stock setup.
I picked up a standard bore 340 block cheap and later came to realize the caps that came with were not what it was born with. I found a new gear drive set for about half price and figured it would cure any ills from line boring. I'm going to get the caps fitted and either fit a 273 crank I have with some light weight pistons and rods, or go with a 4" stroker setup. I don't have a vehicle to put it in yet, but that should get taken care of once the path is decided.
Good luck.
 
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