I am in the process of rebuilding my 1968 302 and I have a doubt regarding the Full Floating pin clearance on the stock rods. A few of the guys I have talk said that .001 overbore it's about correct for any application and recommended to drill a hole on the top and bottom of the rod to benefit from splash oiling. another guy that worked in a now disappeared machine shop said that .002 it's the exact overbore and to cut a .010 slot at each side of the bore. and a few others have said that the rod must be bored .050 and the install a .025 wall bushing and hone the bushing for a .005 clearance. Are any ones of these guys correct? Maybe none of the above?
The pistons are new KB115 with 0.9122 pins and are for Floating or press pin installation ( Spiro Locks included) the specs for the pistons mention that they expand less than a conventional piston under the same amount of heat due to the special casting process and materials used, the rods are Ford OEM replacements .
Now, Cat performance has a replacement OEM style rod 5140 part num CR302 that has the following clearance specs.
Small end has 0.0009-0.0015" clearance for floating type.
Small end is 0.0006-0.0009”smaller than pin for press fit.
Side clearance 0.015-0.025".
The rod is a steel non bushed type and is for both applications, press fit and bushed. Maybe this spec will work for my Ford OEM Rods? I will hate to have a small clearance and have the pin lock in to the rod after the heat expands the wrist pin.
Now, assuming these specs apply to my new rods I will deduct that the actual bore size of the new rods can be anywhere from 0.9113 to 0.9116. If we were to bore the new rods for a floating pin 0f 0.9122 we will have to make that bore 0.9128 minimum and .9137 maximum. My question is, with such a small overbore will the rods weaken a lot?
My main reason for opting the Full Floating approach is the easiness of repair when changing rods/pistons or pins.
Thanks for all the help you can provide.
The pistons are new KB115 with 0.9122 pins and are for Floating or press pin installation ( Spiro Locks included) the specs for the pistons mention that they expand less than a conventional piston under the same amount of heat due to the special casting process and materials used, the rods are Ford OEM replacements .
Now, Cat performance has a replacement OEM style rod 5140 part num CR302 that has the following clearance specs.
Small end has 0.0009-0.0015" clearance for floating type.
Small end is 0.0006-0.0009”smaller than pin for press fit.
Side clearance 0.015-0.025".
The rod is a steel non bushed type and is for both applications, press fit and bushed. Maybe this spec will work for my Ford OEM Rods? I will hate to have a small clearance and have the pin lock in to the rod after the heat expands the wrist pin.
Now, assuming these specs apply to my new rods I will deduct that the actual bore size of the new rods can be anywhere from 0.9113 to 0.9116. If we were to bore the new rods for a floating pin 0f 0.9122 we will have to make that bore 0.9128 minimum and .9137 maximum. My question is, with such a small overbore will the rods weaken a lot?
My main reason for opting the Full Floating approach is the easiness of repair when changing rods/pistons or pins.
Thanks for all the help you can provide.