I have a nice set of Rods with big pins
I want to build a lo compression stroker
4150 and 6760 rods
Not too much on shelves for piston selection
All seem to be 990 chevy size

Any recommendations ??
Or past build criteria

Will be iron heads
So lo comp a must ..

Thanks in advance

Pick you poison... Have pistons made to order or buy new rods...

KB251 pistons. with no major mods you can build a pump gas stroker with open chamber iron heads. play with the quench dome a little and compression can be upped. I've been thinking about doing this.

Bush the 1.094 for a .990 pin.

Would that make it top heavy ?

Oops , did i forgot to mention stroker crank ..

All searches lead to 990 chivy pins
At 9.5 cr
Not sure can even feasibly do 1094 pins

kb251's are for a 4.15" crank in a RB block and open chamber heads.

I'm sure any of the better race piston makers will build you a custom built piston with those wrist pins included
Let us know what you do, several options already pointed out about changing the bushing to use a smaller, lighter wrist pin also

if you have 1.094 rods and that's what you want to use, then use them. you can get lighter than stock 1.094 pins. a couple years back I bought some from JE that were in the less than 190gr range. 190+gr are common and that's noticeably lighter than stock. pistons are going to be a factor of pump gas or race/blends and how much money you want to through at it all.

Top heavy? Just think about it, going from a 1.094 pin to a .990. That is .104 smaller in diameter on a steel pin, much lighter. You would loose quite a bit of weight at the top.

The thicker bushing would add some grams to the small end but the .990 pin would more than make up for it.

The deal breaker might be how much will it cost to have bushings made and fitted vs new .990 rods.

I guess if your rods say Carillo or Oliver on them and your build is better served with a .990 pin, I'd bush them down. If they say Scat or Eagle on them, maybe not depending on machining cost.

Kevin

Oh fiddle sticks
Ok
If we all agree that a 1.09 rod is lighter than the same .990 rod. Bigger hole
If we all agree that a 1.09 piston is lighter than the same .990 pin piston. Bigger hole
then Most .990 pins that come with shelf pistons are 2.930 long
then most 1.09 pins that come with shelf pistons are 2.750 long
Guess which one has less bobb weight????
Check the gram weight on the pins that come with the pistons you are ordering. Those light weight .990 pins are not CHEAP but can be had.
Diamond will make any change to any shelf piston for 40 bucks. In this case a pin size change. No customs required.
Todd

Try ROSS Pistons. They made the custom dished pistons in my old 451 Stroker engine (stock 440 LY Rods.)

My 493 has a set of their reverse domes. 34cc dish IIRC. .990 pin tho.

They were a shelf stocking item at 440Source towards the end of Ross being the supplier there. Ross might have some.

Kevin

Well when you put it that way... lol.

This would also have to assume a .990 rod and a 1.09 rod use the same forging blank, agreed?

Also is the OP's 1.09 rod a BBC journal or Mopar journal and would they share a common forging?

In any case the $40 upcharge is the simple solution to the problem.

Kevin

Didnt know it was just 40 bucks
Ty !
Lol is that per piston ?

Always found it funny the weight savings some folks think they get with the 0.990" pin.

Like the proposed low cr iron headed stroker will even know the difference between the .990 pin vs 1.094 pin.

And just to be argumentative.......

JE and SRP use 2.93” long pins for both .990” and 1.094” applications....... with the 1.094’s being 20grams heavier.

Icon uses a 3.00” long pin for both sizes in some BB Mopar applications.
The equivalent piston is 1 gram difference for the pin bore, while the pin weight difference is 32 grams.

The Eagle catalog shows the 6.760 .990 pin rods weigh 5 grams more than the 1.094 version, but the 7.100 long rod for the 2.200 journal and .990 pin is 35 grams lighter than a 6.760 x 2.500 x 1.094 rod.

So, when you really care what the stuff weighs, you use the crank with the 2.200 journals, 7.100 rods(which makes the piston shorter and lighter by about 80 grams) and .990 pins.

is it a juggling act? pro's and cons to both.

Just need to be careful in how you choose to pick your catalog data. Catalogs are generally not a great source for this info. Using catalog info, you could also conclude that there is only a total of 5 grams difference and that's using the same length pins. But I don't necessarily believe that either.


The question simply comes to this, all else being equal, do you really think that piston and rod manufacturers are actually forging and machining different pistons and rods (obviously not including the pin holes) based on a 0.990 verses a 1.094 pin?

The weight of materials is well established, and the math is simple.

I do agree that thinking strategically on the overall combination, coupled with shopping for the parts with an eye to parts specifications can yield meaningful weight savings.