Originally Posted by Haulin327
Pistons can be lighter with a longer rod but they may rock in there bores a little more... We have to keep a eye on rod weight as to not cancel out the bob-weight savings...crank counter weights can be lightend at that point and with a light flywheel or small dia. converter faster than normal engine response can be anticipated...
6.125 or so is about it for a 3.75 crank in a stock deck block... I would go 6 inch as you are not using super-shorty pistons.."tend to rock,burn oil,Race only...
Keep rod weight as lite as possibe...
all in all long-rod combos work in theary but to take full advantage You will have to have a stout wallet
Without the lite crank lite flywheel, and low gears and trick bob-weight style of balance job , the rewards of a trick long rod motor may not be met.....GO FOR 5.7 RODS.....
We builds a lot of 6.250 rod engines and there not burning any oil and if pistons are rocking in the bore that much would they make some noise and we have 2 engines with 6.300 rods in them and no problems.
If a pistons is fitted to the cylinder right there should not be any problem with pistons rocking in the bores, Remember the pin is higher in the piston not lower and if there was this problem with oil burning and pistons rocking in the bores you should see signs of this on the skirts over shorter rod pistons or if they are rocking that much they would break.
If these problems you speak of were true the piston companies would not build them as the engines builder would stop using them if there was a problem with burning oil and pistons rocking.
Right now after 30 years of building eignes we have not seen any problems you speak about with using long rods.
Curious what engines do you build that are having these kind of problems with long rods??
I have some new pistons on the shelf I will look and see if there is a warning about this problem of oil burning and pistons rocking in the bores on long rod pistons.
We buy alot of rods and there is no differance in price from a Crower 5.7 to a 6.0 rod and the same with the pistons we can buy a Mahle piston for a 5.7 or a 6.0 rod for the same money.