Does anyone know if the forged late connecting rods can be bushed for floating wrist pins ? I know the early rods have a smaller diameter pin bore so I don't believe they would work. My plan is to use forged 351w pistons with floating pins but I haven't really heard of anyone using floaters with the stock rods??? Any help greatlly appreciated !

 

You could do it, but it's just one more thing to go wrong. By the time you get the rods bushed and buy 6 individual 351W pistons you probably aren't far from the cost of custom pistons. What are you looking for in a piston? KB/Silvolite has 6 or 8 300 pistons listed on their website with various dome configurations.

 

I'm looking for light weight and floating pins with flat tops for raised compression ratio +.040 forged

 

If you want a lightweight forging you need a custom piston anyway.

 

I don't believe that's the case, with the bushed late forged rods I believe the 351w as well as FE (390) pistons will work just fine. The early rods seem to have the same pin diameter (for press fit) but I'm going to see if I can't get a set of late model forgings bushed as they have a larger small end diameter which might be perfect for running bushings. I think it may be a simple matter of sellecting the right compression height using "off the shelf" forged pistons........this is just a guess on my part based on a few measurements I've taken so far. The forged pistons will be heavier but from what I've gathered it's not a problem to offset the added weight by drilling lightening holes in the crank rod pins.......I think my biggest headache is finding a "GOOD" machinest in this 1 horse town I'm living in, LOL.

 

You could use an off the shelf piston, but if you're building a 300 that legitimately needs a forged piston you will have spent a considerable sum of money on the engine. Why compromise on a component that is vital to the performance and longevity of the engine? 6 351 or 390 pistons will probably set you back about $250-300. Then you're looking at another $25-30 each to have the rods bushed and fitted. You've got $400-500 invested in a set up that may or may not be exactly what you want. Custom forged pistons from BME, Probe and several others start at under $400 for a set of 8 (you only need 6) and they save 60-70 grams each in reciprocating weight just from the pistons. Also, if you get a custom piston you could change the pin height and use a 240 rod. If it was my engine and my money I would spring for the custom slugs and make sure I had exactly what I wanted.

 

Hey SS. Do you know if the wrist pin gets into the oil ring land on a long rod 300 by chance?

 

There are lots of variables in that question. The ring stack, desired rod length, pin diameter, etc. all come into play. The stock 300 has about 1/4" between the pin bore and oil ring, maybe slightly less. We'll call it 0.200" for arguments sake. A racing piston typically has the top ring closer to the deck than a stock piston unless it's for artificial aspiration, so you might gain another 0.100" there. There is also a large gap between the top and second ring where another 0.100 might be gained. If you use a 0.912 pin you gain roughly another 0.030. The stock rod is around 6.4" long (I don't know the exact number, but this is close), so you could add roughly 0.250 without getting into the oil ring, which would be a 6.65" rod. You might find a long rod for a 351W about that length (it's a shame the 400 has larger rod journals, its rods are 6.58) and run a 302 piston fairly inexpensively if the widths are close enough. Silvolite lists a 300 piston on their website (#1147) that has a 1.57 compression height, which would gain you 0.200 over a regular piston. If you do a custom rod and piston you could also go to a 0.832 pin to gain another 0.040. Another possibility might be a 5.4 rod at 6.657" and with a rod journal of 2.086" if it's wide enough. Big block Chevy rods are popular for the 460. 6.535 is a popular length for them. I guess the real issue with any off the shelf rod is width. You might get a 240 rod in there without invading the oil ring land with the right ring stack, but it would be close if it fit. Ford Six is building a ling rod 300 and can probably tell you for certain.

 

I think a stock 300 rod is 6.2". If custom pistons are that cheap, that's the route I would definately take. Thanks for the info. The gears are turning!!!!!

 

I just went out and measured one I had laying around and it's right around 6.375. The piston is still on the rod, though, so it might be off a little.

 

Here's another idea, but it's kinda crazy. Start with two 300 blocks. Cut the top 2 or three inches off of one of them and have both sides surfaced, then attach it to the top of block two. Install sleeves in each bore and you've got a tall deck block that could handle roughly 400 cubes with about a 1.6 rod ratio if everything clears the cam.