hey guys rebiulding a 350 and have a good set of connecting rods but not sure if they are for a 350 or 305 or what how would i check if these are what i need the id numbers
is on one side gmc and the other is 970 do these ring a bell any info would be helpful
thanks, scott

 

Both the 305 and the 350 have a 5.7" rod. The only 350 that doesn't have a 5.7" rod is the corvette LT5 motor which has a 5.74" rod. So you can use your rods for either a 350 or a 305.

------------------
Wayne Best
Best Racing
67 rs Camaro

• 355 cu in Chevy
• 12.5:1 compression
• 10.90s @ 120 mph

87 Formula 350 w/388cu.in. motor

www.geocities.com/best_racing

 

thanks for the info i appreciate it its my first full rebiuld from the bare block so some stuff is still new to me. thanks

------------------

 

Doesn't the 400 have a 5.7" rod, too? Rod and main journals might be a different size though, dont really know....

 

400 rods are 5.565"

 

OH damn thats a small rod to stroke ratio then, does the LT5 stuff have the same journal sizes as a standard 350 SBC?

 

Did/do any motors come stock with 6.0" rods, or are they only an aftermarket option?

 

400 Chevrolets do have a short rods, 5.700 and 6.000 are not a standard rod for a 400 but can be used with a piston change. (piston pins are in different locations on the piston for different rod lenghts ). Rod journal diameters are the same for a 350 Chev. or a 400 Chev. in round numbers 2.100. Main jourmal sizes are different, a 350 has a 2.449 Dia. and a 400 is a 2.649 Dia. You could offset stroke a 400 crank .090 to a stroke of 3.840 by using an early 283 / 327 connecting rod. The crank rod journal would now be a 2.000 journal instead of a 2.100, and won't change oil hole location. If you de-stroke the crank going to the 2.000 rod journal the oil holes will change location and may move too far to the outside edge of the rod journal to the point the rod bearings may not get enough oil from leakage along the outside edge of the bearing and cause rod bearing failure.

 

Funny you mention that, the 383 in my '81 was actually a 389 cu.in. for that very reason. The crank had been machined (someone prior to me had built the stroker motor) and the stroke it had was 3.8125" (3-13/16"). That, coupled with a .030" over-bore = 389 cubic inches. I couldn't tell you what kind of rods it had though? At the time, I assumed they were either stock 350 or 400 rods??

...man, do I miss the torque of that motor.

 

Although 350 and 305 con rods are the same length, they are not the same weight. If you're going to go mix and matching different con rods from different engines (providing they're all the same length), you're entire rotating assembly needs to be rebalanced.

The best thing is to find a set of the lightest con rods to use then have everything balanced.