Does the connecting rod length change on a stroker

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Dan s

Dan s

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Can u just change the crank in an engine or do you have to have new connecting rods. Sorry for the dumb question
 
Short answers-
Does it have to change? No.
Can it change? Yes, for a variety of reasons- ie trying to adhere to an "ideal" rod/stroke ratio, going with Chevy rods for lighter wrist pins/smaller journal size, and a myriad of other reasons. You could write a book on the subject, and some have.
For basic street duty, most kits are designed to use standard factory spec pieces unless otherwise specified.
But you can't "just change the crank", at a minimum you need pistons to suit your new stroke.
 
Dan s said:
Can u just change the crank in an engine or do you have to have new connecting rods. Sorry for the dumb question
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When you change the stroke length it pushes the rod further up into the bore. You have to either use shorter rods with pistons that have a stock pin height or use stock length rods with the piston pin moved higher towards the top of the piston...or both depending on what rod length/stroke you use.
 
If you get a stroker crank (4.00" for example), you just have to get the correct "stroker pistons" to go with it. The piston needs to be a little shorter so that they don't exit the top of the block and knock the heads off. The simplest way to go about this is order a stroker kit from Scat (or another reputable company). This will come with the correct crank/piston combo, along with rods, rings, etc.
 
flyfish said:
If you get a stroker crank (4.00" for example), you just have to get the correct "stroker pistons" to go with it. The piston needs to be a little shorter so that they don't exit the top of the block and knock the heads off. The simplest way to go about this is order a stroker kit from Scat (or another reputable company). This will come with the correct crank/piston combo, along with rods, rings, etc.
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Yep. They have done thousands of them and they know what works.
 
Depends on the kit, pin height, stroke.

But most use a std rod length.

What does change ...is the rod stroke ratio.
 
At some point,when the stroke increase gets too large, the rods MUST be changed to a longer rod, to keep the pistons from hitting the crank counterweight. Ask me how i know.
 
Thanks for all the replies. After reading all these 318 stroker threads i feel the need to build one. I have 3 really good running 318’s. I won’t never do it but it does sound like fun.
 
MOPAROFFICIAL said:
Depends on the kit, pin height, stroke.

But most use a std rod length.

What does change ...is the rod stroke ratio.
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Good mention of rod ratio. You can get a longer or shorter rod to meet the need or target rod ratio. This can get expensive.
AJ/FormS said:
A lotta lotta problems could be solved with adjustable-length rods.
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Now that would be nice if it could be done and yet still handle 750hp NA.
 
AJ/FormS said:
A lotta lotta problems could be solved with adjustable-length rods.
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May be a good idea in theory.

Adjustable-Rod-Back-low-res-300x129.jpg
 
Yeaaaaaaa, LMAO, a set up I wouldn’t trust to hold my pizza! A handy tool for a thing or two, oh yea!
 
toolmanmike said:
May be a good idea in theory.

View attachment 1715627586
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Lol.

Someone was doing some piston swap experimenting there.
Physically adjusting the rod for a desired comp height with x or y piston perhaps.
Figure or find a length close or have them made. Pistons can be 750-1200 bucks to custom make. Rod the same or less when you can a lot of times just machine them to desired spec.
 
toolmanmike said:
May be a good idea in theory.

View attachment 1715627586
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I'd like to have a hydraulic vari length rod, self learning computer controlled and tied to a knock sensor. This way I could run a ton of compression and race gas, or change the program and run 87 pump gas. Couple this with a vari lift lifter and have a docile cruiser and a race engine all in one.

I know, I know, put down the crack pipe and slowly back away. LOL
 
justinp61 said:
I'd like to have a hydraulic vari length rod, self learning computer controlled and tied to a knock sensor. This way I could run a ton of compression and race gas, or change the program and run 87 pump gas. Couple this with a vari lift lifter and have a docile cruiser and a race engine all in one.

I know, I know, put down the crack pipe and slowly back away. LOL
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You can increase compression to a point by keeping the valves closed longer. I saw a engine or two in the last coupe days that have computer controlled valves. That would do it.
 
Dan s said:
Thanks for all the replies. After reading all these 318 stroker threads i feel the need to build one. I have 3 really good running 318’s. I won’t never do it but it does sound like fun.
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Dan, if you're going to spend the money on a stroker kit, don't use a 318 as a base. Sell the 318 and stroke a 360. You'll get even more cubes and better breathing heads (some heads can't be effectively used on a 318 bore).
 
toolmanmike said:
You can increase compression to a point by keeping the valves closed longer. I saw a engine or two in the last coupe days that have computer controlled valves. That would do it.
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I seem to recall reading several years ago that F1 (I think) was using either a pneumatic or hydraulic operated valve with no cam. For the most part infinite lift and valve timing profiles would be achievable.

I could be wrong though as it's been several years.
 
It's pretty interesting to think about. You could possibly have the valves open and close much quicker than a cam lobe and have it vary with load, rpm and who knows what else. That engine could purr like a kitten at idle and drive so nice, then when you wanted to crack the taps the possibilities are numerous. Although, when it tears up that's a different story.
 
dart_68 said:
(some heads can't be effectively used on a 318 bore).
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Really! Do tell me what cylinder head can not be used.
IF you lean back on the word “Effectively” I can make a case on that alone for most any head on a stroker.

Considering the bore on the 318 is down .091 to start with, boring the 318 out (with a sonic check) .091 to match the 4.00 of a standard 360 erases any Deficiencies that it may be born with. Even if you could only go 60,000 over the original bore size, you would still be an excellent shape.

I believe the Edelbrock Victor head has tremendous fouls that may be an issue. But I do not know about this for sure. If I remember correctly, the intake valve size is 2.15? Basically what you need to do is the math on the valve size and the space left in between them and on the ends versus your cylinder bore size and the room left over from the valve sizes and space between them.

Valve shrouding is something to avoid. But I wouldn’t worry about it. Many many engines from home built to factory produced can be found with this issue but still yet maker some killer power.

The word effective here is truly subjective and limited to what the engine is being called on to do.
 
toolmanmike said:
You can increase compression to a point by keeping the valves closed longer. I saw a engine or two in the last coupe days that have computer controlled valves. That would do it.
Click to expand...

I e seen this guy and his videos before and it is simply amazing what comes out of there shop.
Mind blowing and the out of the box thinking is outrageous.
 
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