Clearance for a 340 Stroker Conversion

[340inabbody]

Merry Christmas everyone!

Can you guys explain what might need to get clearanced in a 340 stroker conversion? Lets assume flat pistons at zero deck.

Let it rip…

 

[toolmanmike]

Crank and rod clearance at the bottom of the bores is related to the stroker kit. Piston to valve clearance should always be checked and has a lot to do with your cam specs and cam timing.

 

[j par]

Using Scat I- beam NO clearance needed..
H-beam needed...

 

[toolmanmike]

Merry Christmas everyone!

Can you guys explain what might need to get clearanced in a 340 stroker conversion? Lets assume flat pistons at zero deck.

Let it rip…

Here is an example. Note the material removed at the bottom of the bore for rod nut clearance. Your engine may not need any or a lot. It depends on what rod you are running.

 

[340inabbody]

Here is an example.

View attachment 1715840655

Thanks I love pictures. Where exactly is the possible interference at between the crank and rod? What gets ground down ? The rod I assume? Does that get done before balancing?

 

[340inabbody]

Using Scat I- beam NO clearance needed..
H-beam needed...

Why?

 

[toolmanmike]

Thanks I love pictures. Where exactly is the possible interference at between the crank and rod? What gets ground down ? The rod I assume? Does that get done before balancing?

Crank and rod is no issue. The rods and block or may be the crank and block may have issues. The stroker kits have been out there for long enough there are usually no issues but it should always be checked during pre-assembly.

 

[j par]

Why?

H-beam big hit block..
I-beam not big, no hit block...

 

[toolmanmike]

Here's a comparison photo.

 

[340inabbody]

Here's a comparison photo.

View attachment 1715840660

Yeah the width of the armature is significantly wider thanks for the picture! But is the possible issue the armature or at the bolts at the big end?

 

[toolmanmike]

Yeah the width of the armature is significantly wider thanks for the picture! But is the possible issue the armature or at the bolts at the big end?

The nuts usually hit but the balance pad can as well. .

 

[340inabbody]

The nuts usually hit but the balance pad can as well. .

View attachment 1715840662

I see said the blind man….but isn’t that part “in-line” of the rotating assembly? As opposed to offset meaning how would that touch the crank??

 

[Professor Fate]

I see said the blind man….but isn’t that part “in-line” of the rotating assembly? As opposed to offset meaning how would that touch the crank??

As said, it's not touching the crank. It hits (possibly, depending on parts used) the block, usually at the bottom of the cylinders.

Arrows are the points of interference, circle is the clearancing needed.
Other points that may need attention:
Piston skirts (to clear the crank throws)
Oil pump housing
Windage tray
Any other points of conflict found during trial assembly.

 

[pishta]

I had to just nick the bottom of the cylinder bore with a grinder for rod bolt clearance on stock rods and ARP bolts. Turn the assembly and you'll see the "barely there" interference on a 4.00 stroke crank in a 83 360 block. I only had to clearance 2, not all 8 iirc. Been a while....your only taking about 3mm off.

 

[toolmanmike]

[QUOTE
Any other points of conflict found during trial assembly.[/QUOTE]

THis ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


(Note "TRIAL ASSEMBLY")

 

[Professor Fate]

And just to be clear, OP did not mention what type of "stroker conversion" he's considering- the bigger the stroke increase, the more likely it is some mods will be needed and the more aggressive the mods will need to be.
Different manufacturers will vary in the sizes and shapes of their parts, so things like cranks, rods and pistons will need varying degrees of modification, or none at all. Individual blocks vary, too.
This is why trial assembly is essential, as no two builds will have the same needs to address.

 

[pittsburghracer]

Im going to edit this to add this is a 360 block. A few pictures from my 408 build with K1 rods and 4” K1
crank

 

[340inabbody]

Great inputs thanks for the schooling. Looks like every stroked set up needs to assume NOTHING clearance wise and that hand rotation and inspection is a must to make sure everything clears properly.

 

[CRUZE 418]

And do not grind on the rods!

 

[pittsburghracer]

And do not grind on the rods!

Stock rods and the like have pads on the upper and lower end to grind as needed for balancing. But after market rods do not. Most of these new rods are pretty close right out of the box.