Posted By: gogo318
360 rods in 318 block - 02/19/12 07:58 AM
what if i put 360 rods in a 318 could it even be done? would it make a 340 lol just curious 
360 rods in 318 block
Posted By: 340SHORTY
Re: 360 rods in 318 block - 02/19/12 09:04 AM
NO
Posted By: BulletBob
Re: 360 rods in 318 block - 02/19/12 10:15 AM
Those rods are 6.123 long & are the same as your 318 so making a 340 is out of the question
Posted By: 70Cuda383
Re: 360 rods in 318 block - 02/19/12 02:15 PM
Quote:
what if i put 360 rods in a 318 could it even be done? would it make a 340 lol just curious
the size of the engine is calculated by using the size of the bore, and the length of the stroke--how much the piston moves up and down, which is determined by the crankshaft only.
what pistons, rods, heads, etc. you use, will not have any effect on what size the engine is.
Posted By: TheBlueBeast
Re: 360 rods in 318 block - 02/19/12 02:52 PM
no.
the 340 is the same stroke as the 318 but has a bore of just over 4 inches. You can not bore the 318 enough before you clear the cylinder wall.
the 360 also has a larger journal on the rod than the 318 has on the crankshaft. IIRC And there is no way to make the rod fit properly onto the smaller diameter crankshaft.
And no you can not destroke a 360 back down to a 340 with a 318 crankshaft. unless you want to spent lots and lots of money in research and development and machine work.
the 340 is the same stroke as the 318 but has a bore of just over 4 inches. You can not bore the 318 enough before you clear the cylinder wall.
the 360 also has a larger journal on the rod than the 318 has on the crankshaft. IIRC And there is no way to make the rod fit properly onto the smaller diameter crankshaft.
And no you can not destroke a 360 back down to a 340 with a 318 crankshaft. unless you want to spent lots and lots of money in research and development and machine work.
Posted By: RapidRobert
Re: 360 rods in 318 block - 02/19/12 02:59 PM
I think the later 318's got the "645" 360 rods
Posted By: scratchnfotraction
Re: 360 rods in 318 block - 02/19/12 03:41 PM
Quote:
no.
the 340 is the same stroke as the 318 but has a bore of just over 4 inches. You can not bore the 318 enough before you clear the cylinder wall.
the 360 also has a larger journal on the rod than the 318 has on the crankshaft. IIRC And there is no way to make the rod fit properly onto the smaller diameter crankshaft.
And no you can not destroke a 360 back down to a 340 with a 318 crankshaft. unless you want to spent lots and lots of money in research and development and machine work.
IIRC..the main bearings are larger on the 360 crank,they both use the same rods.
they did make main bearing spacers that would allow you to run a small main bearing 318 crank in the 360 block to destroke it.
putting a 360 crank with the mains cut down to 318 size with a stock 318 bore will make a 346 cubic inch and with a .030 over bore and stroker pistons you get a 349 cubic inch.
use of a 4" stroke crank in a 318/340 will get you 390/416 cubic inch stroker
use of a 4" stroke crank in a 360 will get you 408 cubic inch stroker
just boreing a 318 out .030 will get you a 323 cubic inch
I am doing up a 349 roller cam stroker engine myself
Posted By: Supercuda
Re: 360 rods in 318 block - 02/19/12 03:42 PM
Quote:
no.
the 340 is the same stroke as the 318 but has a bore of just over 4 inches. You can not bore the 318 enough before you clear the cylinder wall.
the 360 also has a larger journal on the rod than the 318 has on the crankshaft. IIRC And there is no way to make the rod fit properly onto the smaller diameter crankshaft.
And no you can not destroke a 360 back down to a 340 with a 318 crankshaft. unless you want to spent lots and lots of money in research and development and machine work.
BZZZT!
Rod journals are the same, later 318s ran the same rods as the 360. Main journals are where the difference lies.
If you 318 already runs the 360 rods you can swap no sweat. If it has the early light 273/328 rods you may have to rebalance. Other than the, no problem swapping.
Posted By: TheBlueBeast
Re: 360 rods in 318 block - 02/19/12 03:49 PM
OK. I stand corrected.
But to the original poster's question we still did not make a 318 into a 340.
Bigger? Yes
Smaller? Yes.
BTW I was unaware that there was a change in the 318/360 to make parts interchangable. Did this happen in the mid eighties or on the magnum motors?
But to the original poster's question we still did not make a 318 into a 340.
Bigger? Yes
Smaller? Yes.
BTW I was unaware that there was a change in the 318/360 to make parts interchangable. Did this happen in the mid eighties or on the magnum motors?
Posted By: scratchnfotraction
Re: 360 rods in 318 block - 02/19/12 04:14 PM
Quote:
OK. I stand corrected.
But to the original poster's question we still did not make a 318 into a 340.
Bigger? Yes
Smaller? Yes.
BTW I was unaware that there was a change in the 318/360 to make parts interchangable. Did this happen in the mid eighties or on the magnum motors?
mag rods are thinner on the small end.
IIRC the change over when they droped the 273 with floating pins,not sure,never had any of the early rods myself.
Posted By: vdriver
Re: 360 rods in 318 block - 02/19/12 04:38 PM
I've torn down 4 318's in the last 2 years, the oldest a late '72 casting from a '73 Valiant; the newest an '86 roller. They all had the heavier '645 (340/360) rods with pressed pins. The '72 bearing shells were dated late '72 so I'm sure it was a virgin motor.
Posted By: TheBlueBeast
Re: 360 rods in 318 block - 02/19/12 04:47 PM
from the chilton's repair manual for 1975, page C336, chart Crankshaft and connecting rod specifications.
The Journal Diameters for the connecting rods from 1968 through 1975 for all listed small blocks (273-360) is actually the exact same 2.124-2.125 inches.
I am very impressed with your knowledge. I was misinformed.
The Journal Diameters for the connecting rods from 1968 through 1975 for all listed small blocks (273-360) is actually the exact same 2.124-2.125 inches.
I am very impressed with your knowledge. I was misinformed.
Posted By: HotRodDave
Re: 360 rods in 318 block - 02/19/12 05:40 PM
Basically 4 different SB rods used through the entire production run includeing the poly 318.
1. The 273 and 318 through 71 used the lightest version with bushed small ends.
2. The 340 came out with a slightly beefier rod (all other rods were variations of this one)with a bushing and floating pins.
3. Some time in 71 they came out with an unbushed 340 rod for use in the 360 and 318 until 92 for the 318 and 93 for the 360.
4. When they went to magnum engine desighn in 92 and 93 they used the same basic rod still but they narroed the top end.
All rods are the same length and journal diameters. You can use the magnum style rod in ANY older SB (balance should be checked). The pressed fit 318 360 LA rod can be used in any other SB (they need narrowed small end to fit in a magnum). The early bushed rods can be used in any engine with floating style pistons, some 340 guys will run the lighter 273 318 floating rod to lighen it up, I have seen some of the heavier 273 318 rods that weighed as much as the lighter of the 340 rods, the weights are all over teh place.
1. The 273 and 318 through 71 used the lightest version with bushed small ends.
2. The 340 came out with a slightly beefier rod (all other rods were variations of this one)with a bushing and floating pins.
3. Some time in 71 they came out with an unbushed 340 rod for use in the 360 and 318 until 92 for the 318 and 93 for the 360.
4. When they went to magnum engine desighn in 92 and 93 they used the same basic rod still but they narroed the top end.
All rods are the same length and journal diameters. You can use the magnum style rod in ANY older SB (balance should be checked). The pressed fit 318 360 LA rod can be used in any other SB (they need narrowed small end to fit in a magnum). The early bushed rods can be used in any engine with floating style pistons, some 340 guys will run the lighter 273 318 floating rod to lighen it up, I have seen some of the heavier 273 318 rods that weighed as much as the lighter of the 340 rods, the weights are all over teh place.
Posted By: gogo318
Re: 360 rods in 318 block - 02/20/12 02:54 AM
great info guys sorry it didnt dawn on me that the crank is what modifies the stroke not the rods (laughs at self) but now im really curious what about the pistons from a 360 could i get them on a 318 rod and bore out my holes to take them just asking cause im about to rebuild the virgin 318 that gose in my belvedere and i got some 360 guts that im likely to never use unless some find there way into this engine ps im not actually tring to build a 340 it was more of a joke 
Posted By: scratchnfotraction
Re: 360 rods in 318 block - 02/20/12 03:20 AM
no,cant bore the 318 block that much,would need a sonic check and be real thin if it did get bored to that piston specs.
cut the 360 crank mains down,get the .030 over 349 stroker pistons,bore your 318 block.
they say you can use some early 318 pistons that are way down in the hole on the 360 crank/318 block,just need to clearance the piston pin boss and skirt to clear the crank weights.
that will make the 346 cubic inch stroker on the cheap.
i just opted for the 349 pistons with the roller cam 318 block..
member "performance only" can cut the 360 crank and take care of the raer oil seal cut with a more than fair price.
cut the 360 crank mains down,get the .030 over 349 stroker pistons,bore your 318 block.
they say you can use some early 318 pistons that are way down in the hole on the 360 crank/318 block,just need to clearance the piston pin boss and skirt to clear the crank weights.
that will make the 346 cubic inch stroker on the cheap.
i just opted for the 349 pistons with the roller cam 318 block..
member "performance only" can cut the 360 crank and take care of the raer oil seal cut with a more than fair price.
Posted By: dogdays
Re: 360 rods in 318 block - 02/20/12 05:44 AM
Unless machine work is really cheap where you are, a 4" crank and pistons would get you more cubes for the buck.
If you wanted to go the 360 crank stroker route I'd use 360 "645" rods and LC371P sealed power pistons, with 360 heads. There are three 318 pistons for ultra low compression that have a 1.658" compression height which is almost exactly what a 360 piston is. I remember that one.
R.
If you wanted to go the 360 crank stroker route I'd use 360 "645" rods and LC371P sealed power pistons, with 360 heads. There are three 318 pistons for ultra low compression that have a 1.658" compression height which is almost exactly what a 360 piston is. I remember that one.
R.
Posted By: 70AARcuda
Re: 360 rods in 318 block - 02/20/12 06:51 AM
just make sure the "318 pistons" skirts clear the counterbalances on the cut down 360 crank...
scat make a 3.58 stroke crank with 318 bearing size...
scat make a 3.58 stroke crank with 318 bearing size...
Posted By: Dusted_Ya
Re: 360 rods in 318 block - 02/20/12 07:40 AM
ALL small block rods are interchangable for the most part with minor variations.
273-318 rods were the same for cars up until 1970 (light duty)
70-2 car and 68-73 truck 318's shared the same floating pin rod as the 340.
All 360's used the same rod as the previously mentioned floating 318-340 rod only with a pressed pin up until 1994 when the 318-360 went to magnum design which is essentially still the same rod only with a narrower width (on the machined side) as Scratch mentioned.
If putting 360 rods in a 318 made a 340 I'd put cummins rods in a 440 to make a 572 monster! But unfortunately it doesn't work that way.
273-318 rods were the same for cars up until 1970 (light duty)
70-2 car and 68-73 truck 318's shared the same floating pin rod as the 340.
All 360's used the same rod as the previously mentioned floating 318-340 rod only with a pressed pin up until 1994 when the 318-360 went to magnum design which is essentially still the same rod only with a narrower width (on the machined side) as Scratch mentioned.
If putting 360 rods in a 318 made a 340 I'd put cummins rods in a 440 to make a 572 monster! But unfortunately it doesn't work that way.
Posted By: dogdays
Re: 360 rods in 318 block - 02/20/12 05:22 PM
It's not the skirtsthat are the major issue.
You may have to grind a little off the piston pin bosses for clearance but that will help balance as 360 pistons are about 20 grams lighter than 318s, so you're getting the 318 piston to be closer to the 360 piston weight.
It's been done before. Speedomotive used to sell a cheap 349 kit that could only have used the LC cast pistons and I believe they did the cleanup on the pistons for clearance.
R.
You may have to grind a little off the piston pin bosses for clearance but that will help balance as 360 pistons are about 20 grams lighter than 318s, so you're getting the 318 piston to be closer to the 360 piston weight.
It's been done before. Speedomotive used to sell a cheap 349 kit that could only have used the LC cast pistons and I believe they did the cleanup on the pistons for clearance.
R.