Troubles taking a 360 .060?

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I think everyone is missing the elephant in the room.
siuauto said:
I have some 4.060 pistons and rods that I want to use on a engine and debating on a 340 or 360. I would prefer to use the 340 but it seems to be difficult to find a 340 in either a standard bore or a ready to go .020 340 (4.060 bore). I could use a 360 but curious if anyone has issues with their blocks that prevented them to bore that much. I know I will need to get it sonic tested but if everyone is having issues going that big, there is no reason for me to explore that route.

Thanks in advance.
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siuauto said:
my buddy gave me a great deal on a set of Molner rods and it has a set of 4.060 ractec forged pistons on them that are set up for a 3.79" stroke and I thought if I could use them it would make a killer small block.

I know, I am kind of working backwards... story of my life
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He has slugs for a 3.79 stroke crank....

main size... main size....

The 340 has the smaller mains than the larger 360...

The crank won’t work unless he spends more money on crank spacers. Then line hone....
 
siuauto said:
my buddy gave me a great deal on a set of Molner rods and it has a set of 4.060 ractec forged pistons on them that are set up for a 3.79" stroke and I thought if I could use them it would make a killer small block.

I know, I am kind of working backwards... story of my life
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Bummer. I have 2 blocks I could use for those pistons if they have a dome.
 
rumblefish360 said:
I think everyone is missing the elephant in the room.




He has slugs for a 3.79 stroke crank....

main size... main size....

The 340 has the smaller mains than the larger 360...

The crank won’t work unless he spends more money on crank spacers. Then line hone....
Click to expand...


To clarify, I don't have a crank, I just have the rods and pistons. My next step is to get a block so I can order the right crank.
 
famous bob said:
Out of curiosity , generally speaking , how far can a 340 and 360 "usually" be bored safely ??
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I used to take 340’s out .060 and then we bought a sonic tester. Damn few blocks around I would take more than .030 because they are thin.

The longer the stroke, the lower the lower the rod to stroke ratio, the harder it is on those thin cylinders.

I haven’t sonic tested nearly as many 360’s, but most of what I tested would go .040 over.
 
I am with Rusty here, I have a 1975 360 block out to .070 and the thinnest cylinder wall will take a .100 over bore and still have enough meat left in the bore. The machinist who checked my block said he has seen 340 and 360 blocks at .030 over that were at there max bore. But he did say at the time he did a early 340 block out to a 4.125 bore that could have gone bigger. Sonic test it's the only way to know.
 
siuauto said:
To clarify, I don't have a crank, I just have the rods and pistons. My next step is to get a block so I can order the right crank.
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OK, then the crank your looking for is a small journal unit. I am unaware of a 360 main crank with that stroke.
Keep us updated!
 
When I'm taking any block over.040, I always have then sonic tested for peace of mind. I really don't want to build an engine & have it self destruct the first time it's put under a big load. But then again, most of what I build are race engines for myself and a few select friends.
 
I believe 71 -73 were the old 340 block with 4.00 bore. Everything I,ve read says you can go .060,but as others have stated sonic check is highly recommended.

Tim
 
19DART66 said:
Molnar makes a 3.79 crank for the 360 mains, but it only comes with Chevy 2.100 rod journals.
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Ahhhh man! Thanks. That’s awesome. I wasn’t sure at all anymore of what’s out there. The thing I like (might be a wee lacking in knowledge here...) is the easily available multi length con rod with the Chevy journal. I’m not sure anymore on what is out there or what can be a cost effective ordering of a custom rod length for a MoPar. Much less on a stock rod journal size. If I ever get there, in building a heck of a power plant that I could custom build/tweak, I would like to opt in on a longer rod rather than deck a block down to the zero deck or domed slug to meet the zero deck of the flat top or achieve a superior quench, flat top or dome piston.

On e you mill the deck, way often the intake gets killed to suite. This is an Annoyance for me. But if it has to be done, but it has to be done. It is what it is.
 
Tim, FWIW;
The 340’s OE bore size stock is 4.04.
The 360’s OE bore size stock is 4.00.
Race blocks vary. Often delivered @ 3.90 rough bore for final sizing to 3.91 or to overbore to the desired size.
 
rumblefish360 said:
On e you mill the deck, way often the intake gets killed to suite. This is an Annoyance for me. But if it has to be done, but it has to be done. It is what it is.
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Annoyance is right! I’m going through this on my 360 build. now when you say ‘killed’, what do you mean by this?
@yellow rose on a milled intake, would I use thicker gaskets to make it work on another engine?
 
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mopardude318 said:
Annoyance is right! I’m going through this on my 360 build. now when you say ‘killed’, what do you mean by this?
@yellow rose on a milled intake, would I use thinker gaskets to make it work on another engine?
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Auto correct/lack of proof reading, instead of “Killed” it should read “Milled.”

Your question to YR is yes, depending, there are factors of how much the intake has been milled and how much the deck was milled and how much the cylinder head has been milled. It is possible that a thicker gasket will not have to be used. The aluminum also bends a lot, so a most minor gap can be OK. Ideally, you want the intake to sit, without help, you n the cylinder head perfectly aligned ready to be bolted down, ports aligned.
 
siuauto said:
I could but I enjoy problem solving these types of things. Also, after doing some research it seems the 3.79" is a better combo due to it's ideal rod ratio.
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A lot of people agree with you on this. The problems arise when people want a specific part or cubic inch displacement. The rate is saying, “I have a 4.0 crank” or a 408/416...

For very high performance and race builds, I would rather a sub 4.00 crank throw on a 4.10 bore (or bigger) type of combo.

This is just me. Others here have done VERY well with the 4.0 arm crank.
 
rumblefish360 said:
A lot of people agree with you on this. The problems arise when people want a specific part or cubic inch displacement. The rate is saying, “I have a 4.0 crank” or a 408/416...

For very high performance and race builds, I would rather a sub 4.00 crank throw on a 4.10 bore (or bigger) type of combo.

This is just me. Others here have done VERY well with the 4.0 arm crank.
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I tend to just say its a "little old small block"

My buddy that's making over 1500hp out of his 3.79" would agree with you.
 
First SB Mopar bracket car I seen run in the 9's back in the late 80's ran that combo you are talking about rumblefish a W2 400 inches(4.100 bore 3.79 stroke). They were the Crane Brothers, can't remember if they were from Mass. or Conn. 71 back halfed Challenger, beautiful and meticulously put together car. I haven't see the brothers or the car since the mid 90's
 
The Ford 351 Cleveland is the same way. Some are done at .030 and some can go .100. There's no way to tell the difference except by sonic testing. I got lucky with the one I have. It's .040 but has enough to go .100 more. It's the first production year, a 1970, but I'm unsure that has anything to do with it.
 
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