Rod Length On Stroker Engine

[mopar_vince]

  Have a question for the serious engine builders out there.Would there be any advantage in using a Chevy 6.250 Center rod in a street/strip style small block stroker engine?Not a full race tpye of an engine.Have acess to rods already.Thanks 

[bOb shingler]

shorter piston, less weight, better rod to stroke ratio=more power

[speedymopars]

I agree with bOb. When you start doing stroker combos, it is a matter of what you got vs what you want. Offset grind your crank so you can use the increase stroke with the smaller chevy bearing, figure out what compression height you need, and go for it. Nothing wrong with "chevy" rods, its is the quality of the rods and rod bolts not the manufacturer brand name on them that matters...

Generally, use the longest rod (which gives the shortest and lightest piston) you can when building a stroker. In the 440's, using the 7.1 inch Chevy rod is the way to go due to the deck height. In the 400's, use the 440 rods..etc etc etc...

[mopar_vince]

The reason why I'm leaning towards a stroker is that the harmonic balancer is walking back & forth about 1/16 of an inch.NOT COOL  !But since the crank will most likely need replacing I figured going w/a stroker.Possible 250 shot,too.Does anyone make an off the shelf piston for this rod length or would it be custom?Would it also move the pin up too close to the ring land & would there be room to move the ring land away from the deck some for No2?

[WarLocK451]

The reason why I'm leaning towards a stroker is that the harmonic balancer is walking back & forth about 1/16 of an inch.NOT COOL  !But since the crank will most likely need replacing I figured going w/a stroker.Possible 250 shot,too.Does anyone make an off the shelf piston for this rod length or would it be custom?Would it also move the pin up too close to the ring land & would there be room to move the ring land away from the deck some for No2?

The better rod stroke ratio will also result in less side load on the cylinder walls.

You better find out why there is a 1/16 of an inch play in that engine before you build the stroker engine and try driving it again. If you don't, you could run into the same problem all over again...as I have been there, done that.

Whats the engine and drivetrain right now? Auto or Manu? If auto, what converter?

Shawn

[ou812]

If you go with a 4" crank, the extra .125 of rod length will make your compression height awful tight.  Plus the only crank setup to run chevy rods is the callies crank.  Not cheap.  I just sold 2 of them at 960.00 a piece!
Good luck
Brian

[Midnight Special]

I agree with bOb. When you start doing stroker combos, it is a matter of what you got vs what you want. Offset grind your crank so you can use the increase stroke with the smaller chevy bearing, figure out what compression height you need, and go for it. Nothing wrong with "chevy" rods, its is the quality of the rods and rod bolts not the manufacturer brand name on them that matters...

Generally, use the longest rod (which gives the shortest and lightest piston) you can when building a stroker. In the 440's, using the 7.1 inch Chevy rod is the way to go due to the deck height. In the 400's, use the 440 rods..etc etc etc...

I'm using a 7.250 rod

[mopar_vince]

If you go with a 4" crank, the extra .125 of rod length will make your compression height awful tight.  Plus the only crank setup to run chevy rods is the callies crank.  Not cheap.  I just sold 2 of them at 960.00 a piece!
Good luck
Brian

Yeah main thing I'm worried about is the duability or blowing the ring lands out if I sniff it or something dumb.I HATE THIS  idea!Might drop it down to the 3.79 stroke if need be & just make it up w/    

[PureGTS]

Compare your big end widths beween the Chebby and the Mopar rods. The side clearance will have an effect on the oil control in the motor and oil pressure at idle. Too much side clearance and oil pressure drops at idle AND when running it will cause the cylinder walls to recieve too much oil and possibly cause oil fouling of the plugs. Not enough and...     well , you need to check these things. Also the added expense of special rod bearings for radiused cranks, as that too will have to be cut to take the Chebby rod big end diameter. The small end width isn't as critical but it does bear some scrutiny, especially under the piston head for clearance. The ratio change of 1.710 vs 1.745 (using a 3.58 stroke crank for reference) is somethine but is it worth all the extra problems it creates?

It's amazing how one change effects so many others, isn't it?

[mopar_vince]

Compare your big end widths beween the Chebby and the Mopar rods. The side clearance will have an effect on the oil control in the motor and oil pressure at idle. Too much side clearance and oil pressure drops at idle AND when running it will cause the cylinder walls to recieve too much oil and possibly cause oil fouling of the plugs. Not enough and...     well , you need to check these things. Also the added expense of special rod bearings for radiused cranks, as that too will have to be cut to take the Chebby rod big end diameter. The small end width isn't as critical but it does bear some scrutiny, especially under the piston head for clearance. The ratio change of 1.710 vs 1.745 (using a 3.58 stroke crank for reference) is somethine but is it worth all the extra problems it creates?

It's amazing how one change effects so many others, isn't it?

YUP!,that's why I figured on bouncing off of you guys.Never been steered wrong yet by any advice I've gotten  off of  .Probably just as well go w/an off the shelf stroker kit or some w/ moved ring lands for the  .Guess I'll save the exotics for the W/8 motor I've been fantacising about.Have access to the heads & intake but they are RAW castings.WHERE ARE MY 7 MAGIC NUMBErS?