273 and 318 doner parts for 340 Build

[MObarracuda]

i'm building my first 340. I purchased just the block for 250 which cleaned up 40 over with one cylinder needed a sleeve

For the top end I have purchased eledelbrock RPM cylinder heads(63cc), air gap intake, valve covers and fitech mean street Carb replacement system.

For the bottom end I have a 1967 273 that came in my barracuda and 1968 318 for parts for the bottom end. Here is my plan for parts....am I making any mistakes for my 340-390hp build for my weekend driver.

Parts from the 273
Forged crank
Oil pump shaft and dist. Gear
Push rods
Adjustable cast rocker arms
Timing cover and water pump
273 stock oil pan

Parts from the 318
connecting rods (full floating pins)
Modern gear reducer starter

The machine shop doing the work is supplying the cam, lifters, flat top pistons and rebuild kit with oil pump and pickup. They agreed all the part selected will work under 7000 rpm.

Does every one agree? Would you substitute any part listed for the bottom end anything new? I'm a little worried about the oil pan capacity and connecting rods. I will be running the A904 and I will be surprised if the shift points will allow me to get above 5200rpm.

 

[perfacar]

i'm building my first 340. I purchased just the block for 250 which cleaned up 40 over with one cylinder needed a sleeve

For the top end I have purchased eledelbrock RPM cylinder heads(63cc), air gap intake, valve covers and fitech mean street Carb replacement system.

For the bottom end I have a 1967 273 that came in my barracuda and 1968 318 for parts for the bottom end. Here is my plan for parts....am I making any mistakes for my 340-390hp build for my weekend driver.

Parts from the 273
Forged crank
Oil pump shaft and dist. Gear
Push rods
Adjustable cast rocker arms
Timing cover and water pump
273 stock oil pan

Parts from the 318
connecting rods (full floating pins)
Modern gear reducer starter

The machine shop doing the work is supplying the cam, lifters, flat top pistons and rebuild kit with oil pump and pickup. They agreed all the part selected will work under 7000 rpm.

Does every one agree? Would you substitute any part listed for the bottom end anything new? I'm a little worried about the oil pan capacity and connecting rods. I will be running the A904 and I will be surprised if the shift points will allow me to get above 5200rpm.

the 273 rods will work. the pan is same as 340 for size. use a std volume pump.

 

[MOPAROFFICIAL]

The rods, both 273/318 '67-'68 are the same , smaller with a floating pin.
They would work but also be the first thing in my mind to break over 6,000 rpm....lighter pistons are an exception. imo

 

[MObarracuda]

The rods, both 273/318 '67-'68 are the same , smaller with a floating pin.
They would work but also be the first thing in my mind to break over 6,000 rpm....lighter pistons are an exception. imo

Do you think I should look at aftermarket connecting rods as insurance to prevent breakage?

 

[dadodgekid]

Break? I turn my factory 340 rods to 7800RPM alot, never had an issue. they have ARP rod bolts and were resized. Dont get crazy with aftermarket parts, factory stuff will do just fine for your build!

 

[stixx]

Do you think I should look at aftermarket connecting rods as insurance to prevent breakage?

I wouldn't be concerned too much about breakage... factory parts will hold up to quite some abuse when properly reconditioned and with decent bolts.
BUT, for the cost of having your 318 rods reconditioned you might be (almost) able to find a set of aftermarket rods... Scat comes to mind.

 

[MObarracuda]

the 273 rods will work. the pan is same as 340 for size. use a std volume pump.

I was under the impression the 318 rods were heavier than the 273. I must be confusing the event from the late '70s they made the press fit 360 rods common in the 318.

 

[nm9stheham]

I wouldn't be concerned too much about breakage... factory parts will hold up to quite some abuse when properly reconditioned and with decent bolts.
BUT, for the cost of having your 318 rods reconditioned you might be (almost) able to find a set of aftermarket rods... Scat comes to mind.

This is exactly where we ended up going with the rods for a similar 340 build: SCAT rods for lightness. Along with KB hyper pistons, it took 433 grams off the bobweight used to balance the 273 crank for 340 use. That is a lot of weight per crank throw to get rid of. The cost vs recon'd rods was not much different at all.

I am not sure about the OP's ratonale about the shift points limiting the RPM; once in 3rd gear, shift points do not matter.

 

[TrailBeast]

This is exactly where we ended up going with the rods for a similar 340 build: SCAT rods for lightness. Along with KB hyper pistons, it took 433 grams off the bobweight used to balance the 273 crank for 340 use. That is a lot of weight per crank throw to get rid of. The cost vs recon'd rods was not much different at all.

I am not sure about the OP's ratonale about the shift points limiting the RPM; once in 3rd gear, shift points do not matter.

The shift points can be easily changed with a governor kit from A&A transmissions online anyway.

 

[Plymouth 65]

i'm building my first 340. I purchased just the block for 250 which cleaned up 40 over with one cylinder needed a sleeve

For the top end I have purchased eledelbrock RPM cylinder heads(63cc), air gap intake, valve covers and fitech mean street Carb replacement system.

For the bottom end I have a 1967 273 that came in my barracuda and 1968 318 for parts for the bottom end. Here is my plan for parts....am I making any mistakes for my 340-390hp build for my weekend driver.

Parts from the 273
Forged crank
Oil pump shaft and dist. Gear
Push rods
Adjustable cast rocker arms
Timing cover and water pump
273 stock oil pan

Parts from the 318
connecting rods (full floating pins)
Modern gear reducer starter

The machine shop doing the work is supplying the cam, lifters, flat top pistons and rebuild kit with oil pump and pickup. They agreed all the part selected will work under 7000 rpm.

Does every one agree? Would you substitute any part listed for the bottom end anything new? I'm a little worried about the oil pan capacity and connecting rods. I will be running the A904 and I will be surprised if the shift points will allow me to get above 5200rpm.

Make sure the 273 crankshaft end pilot (register) is correct for the transmission converter you intend to use. Also, buy a good quality hardened oil pump drive.

 

[krazykuda]

I wouldn't be concerned too much about breakage... factory parts will hold up to quite some abuse when properly reconditioned and with decent bolts.
BUT, for the cost of having your 318 rods reconditioned you might be (almost) able to find a set of aftermarket rods... Scat comes to mind.

But the aftermarket rods do not have oil squirt holes, where the factory rods do... I prefer to spend the extra $40 and get new bolts installed and recondition the factory rods....

I like the oil squirt holes to help keep the bores oiled...

 

[krazykuda]

i'm building my first 340. I purchased just the block for 250 which cleaned up 40 over with one cylinder needed a sleeve

For the top end I have purchased eledelbrock RPM cylinder heads(63cc), air gap intake, valve covers and fitech mean street Carb replacement system.

For the bottom end I have a 1967 273 that came in my barracuda and 1968 318 for parts for the bottom end. Here is my plan for parts....am I making any mistakes for my 340-390hp build for my weekend driver.

Parts from the 273
Forged crank
Oil pump shaft and dist. Gear
Push rods
Adjustable cast rocker arms
Timing cover and water pump
273 stock oil pan

Parts from the 318
connecting rods (full floating pins)
Modern gear reducer starter

The machine shop doing the work is supplying the cam, lifters, flat top pistons and rebuild kit with oil pump and pickup. They agreed all the part selected will work under 7000 rpm.

Does every one agree? Would you substitute any part listed for the bottom end anything new? I'm a little worried about the oil pan capacity and connecting rods. I will be running the A904 and I will be surprised if the shift points will allow me to get above 5200rpm.

First, the 273/318 had light duty rods, where the 340/360 came with heavy duty rods... Light duty will help save some weight, but you may have to get the crank rebalanced...

Also if you go with Keith Black pistons, they usually run lighter than factory pistons, but the skirts are thinner. I had one that broke on me so I'm cautious of them..,.

Speed Pro/ Sealed Power pistons have thicker skirts and weigh close to stock...

******************************************************

You may want to look at some of Mancini Racing's rebuild kits, it may save you some $$$$...


Here's kit A & B for basic refresh with bearings and gaskets:

Kit A is basic:

Sealed Power Engine Kit - 340

Clevite 77 Engine Kit - 340

Kit B is the same but moly rings:

Sealed Power Engine Kit - 340

Clevite 77 Engine Kit - 340


Here's the kit C with bearings, oil pump, gaskets, cam bearings, freeze plugs, moly rings, and cast pistons. Make sure that they are the compression that you want, or call them for other options:

Sealed Power Engine Rebuild Kit - 340

Clevite 77 Engine Kit - 340


Main page for all small block rebuild kits:

Engine Rebuild Kits

******************************************************


Here's a good timing chain that's one step above the stock 340 double roller, a true roller double roller. I've used these for many years and they hold up well...

Edelbrock


******************************************************

I would recommend getting the heavy duty distributor drive gear from Mancini Racing as they are stronger than the stock ones:

Mopar Oil Pump Driveshaft & Distributor Gear

******************************************************

The 273 adjustable rocker arms are good, but you will not be able to run the stock 273 push rods as they are made for a solid lifter which is different height.... If you want to run the stock 273 rocker arms with a hydraulic cam and lifters, then refer to these threads for how to get the proper push rods:

273 stock push rod length?

Pushrod for hydraulic cam and 273 rocker arms


******************************************************


As far as timing cover and water pump, that should be determined by what year car you are going to put it in... If you are putting it in a 69 and earlier car, use the ones on either of the engines that you have... If you are putting it in a 70 and later, get the later timing cover and aluminum water pump so the radiator hoses match the ones in the car...

 

[MObarracuda]

First, the 273/318 had light duty rods, where the 340/360 came with heavy duty rods... Light duty will help save some weight, but you may have to get the crank rebalanced...

Also if you go with Keith Black pistons, they usually run lighter than factory pistons, but the skirts are thinner. I had one that broke on me so I'm cautious of them..,.

Speed Pro/ Sealed Power pistons have thicker skirts and weigh close to stock...

******************************************************

You may want to look at some of Mancini Racing's rebuild kits, it may save you some $$$$...


Here's kit A & B for basic refresh with bearings and gaskets:

Kit A is basic:

Sealed Power Engine Kit - 340

Clevite 77 Engine Kit - 340

Kit B is the same but moly rings:

Sealed Power Engine Kit - 340

Clevite 77 Engine Kit - 340


Here's the kit C with bearings, oil pump, gaskets, cam bearings, freeze plugs, moly rings, and cast pistons. Make sure that they are the compression that you want, or call them for other options:

Sealed Power Engine Rebuild Kit - 340

Clevite 77 Engine Kit - 340


Main page for all small block rebuild kits:

Engine Rebuild Kits

******************************************************


Here's a good timing chain that's one step above the stock 340 double roller, a true roller double roller. I've used these for many years and they hold up well...

Edelbrock


******************************************************

I would recommend getting the heavy duty distributor drive gear from Mancini Racing as they are stronger than the stock ones:

Mopar Oil Pump Driveshaft & Distributor Gear

******************************************************

The 273 adjustable rocker arms are good, but you will not be able to run the stock 273 push rods as they are made for a solid lifter which is different height.... If you want to run the stock 273 rocker arms with a hydraulic cam and lifters, then refer to these threads for how to get the proper push rods:

273 stock push rod length?

Pushrod for hydraulic cam and 273 rocker arms


******************************************************


As far as timing cover and water pump, that should be determined by what year car you are going to put it in... If you are putting it in a 69 and earlier car, use the ones on either of the engines that you have... If you are putting it in a 70 and later, get the later timing cover and aluminum water pump so the radiator hoses match the ones in the car...

I really appreciate you putting so much time and detail into your recommendations. I will it all over tonight.

 

[perfacar]

I really appreciate you putting so much time and detail into your recommendations. I will it all over tonight.

the 273/318 rods are very strong. we had them in a 235/273 stocker, turned it 7000 rpm and 7500 in traps. we didn't polish the beams, ran them stock!! same with the 496 340 rod, ran a set 1800 runs, 7200 traps with heavy trw pistons. mopar built good parts 11

 

[MObarracuda]

Make sure the 273 crankshaft end pilot (register) is correct for the transmission converter you intend to use. Also, buy a good quality hardened oil pump drive.

The 273 crank is from my 1967 and the end pilot is consistent with later year transmissions

 

[dadodgekid]

How much lighter is a 273 forged crank vs 340 forged crank?

 

[MObarracuda]

I don't know. I only have the 340 block and I'm reusing parts I have to build it. I will check the site to see if there are any other posts on this

 

[MOPAROFFICIAL]

Break? I turn my factory 340 rods to 7800RPM alot, never had an issue. they have ARP rod bolts and were resized. Dont get crazy with aftermarket parts, factory stuff will do just fine for your build!

He isn't talking about 340 rods, he's talkin about the skinny 318/273 rods.

 

[MObarracuda]

He isn't talking about 340 rods, he's talkin about the skinny 318/273 rods.

I saw a post where rustyratrod was courteous, at one time, to see a 340 built with 273 light weight components. He remembers that mopar performance once sold the light weight 273 rods as an upgrade. I think if your pistons were the same or no heavier that the 10:1 domed commando pistons it will be within exceptable limits up to 7000rpm.

 

[MObarracuda]

How much lighter is a 273 forged crank vs 340 forged crank?

Found this from brother rustyratrod
".....
Lots of mis info in this thread. I have had both the 273 forged crank and the 318 cast crank on the scales. The 273 forged crank is lighter. The one we had was about 3 pounds lighter. Also, the 273/early 318 rods are lighter by a long shot than the later 318/340/360 rods. Balanced my share of those too. Of course, all of this could require rebalancing, depending on which piston you use. Lastly, no need to worry about the lighter rod's strength. Mopar Performance offered a performance version of the 273 rods using the same forgings as factory, but with good rod bolts and balanced very closely. They are long discontinued, but they do pop up on Ebay from time to time and they sell for a high price, because people looking for them know what they are. I suspect you could make a 340 scream real good with the 273 crank, rods and some really light pistons. I wouldn't be skeered to run them at all."

 

[MOPAROFFICIAL]

I saw a post where rustyratrod was courteous, at one time, to see a 340 built with 273 light weight components. He remembers that mopar performance once sold the light weight 273 rods as an upgrade. I think if your pistons were the same or no heavier that the 10:1 domed commando pistons it will be within exceptable limits up to 7000rpm.

The rods were changed because the pistons got heavier, aka 340 came out. I wouldn't use 273 rods with stock weight 340 pistons...maybe with lighter forged though..

 

[MOPAROFFICIAL]

FWIW The 273 crank with 360 rods and stock weight 340 pistons, as example, would require heavy metal because the counter weights are cut for the lighter pistons and rods.

 

[pishta]

340 crank had the throws drilled to offset the 129g heavier pistons and 32g heavier rods of the 340. 273 rods will hold up. Cast cranks are usually heavier than forged. When you got a "340 forged" crank from PAW it was a forged 318 poly or 273 that had its throws drilled and register resized.

instead of adding heavy $$ metal to the throws, remove metal from the crankpin side.

 

[MOPAROFFICIAL]

340 crank had the throws drilled. When you got a "340 forged" crank from PAW it was a forged 318 poly or 273 that had its throws drilled and register resized.

instead of adding heavy $$ metal to the throws, remove metal from the crankpin side.

Forgot about that, That's 1.
I'd hope he uses a lighter piston, either way its gettin a balance job.

 

[j par]

I would say that you've already saved $500 on the Block. If it was me I'd sell all all that crap and spent $1,400 on a complete stroker kit bearings Rings light rods the whole nine yards and have gobs of power beyond your World Imagine Nation. By the time the Machine Shop gets done buying Pistons refurbishing rods and grinding your Crank and adding the cost of bearings, Ten Bucks says you have had enough money to buy a stroker kit...
But to answer your question I think all the stuff you using what you just fine.