RedVenom48

So, I finally pulled the oil pan off my Gen 3 4.8 that I recently picked up. To my surprise I found Gen 4 rods in there! So I got one of those weird Gen 3.5 engines... very cool. I didnt get a chance to pull a piston out yet, but Im excited to know Ive got the beefier rods.

Which brings me to my question: If the wrist pins are indeed press fit to the pistons, how much power can they (piston and wrist pin) hold? Can these Gen 4 press pin rods be used with a new set of pistons with floating wrist pins or will the require machine work?

Thanks!

SwapStang

Another of the mysterious gen 3.5 engines very interesting. Seems to be more and more of these popping up lately. Given the better rods I'd imagine you'll get about the same power as a gen 4. Keep the tune safe, free of detonation and gap the rings and I doubt the weak point will be the pistons or wrist pins. Someone with more experience with these will have to chime in but that's my .02 Good luck.

RedVenom48

I appreciate the reply!

Took some pics and wanted to post up what I found. Looks like I kinda hit the jack pot. Gen 3 config with Gen 4 rods and full floating pistons.... SCORE!









My biggest concern so far is the rod journal. The rod bearing looks rough, but no chunking of the babbit. The journal isnt polished and looks like the rod bearing surface. Im hoping that I can get the journals polished up if they all look like this. If the journals need more than a polish, should I just look for another crank? The wrist pin cam out with a bit of tapping but nothing of significant resistance. Actually, there doesnt seem to much of any play between the wrist pin and rod bushing.

This motor lived a hard life with poor maintenance if the sludge is any indication in the oil pan. Though, for as rough a condition it is, theres nothing that tells me I cant recondition the engine, save for the crank. Thats my biggest concern. Theres some crosshatching still left in the cylinder though, no obvious scoring of the walls. If the rest of the cylinders look similar, definitely going to hit it with a softball hone to restore the crosshatching, new rings and bearings. Gotta get the timing cover off and disassemble the oil pump. That might just get replaced, but Im interested to see how it looks.

If any of you guys see anything in these pics or might have seen this in your own teardowns, post up and let me know.

theunderlord

Nice! I would send the crank and the block out to be hot tanked and then micd and then if the shop says things look good, they can most likely polish the crank and then lightly hone the block to get all bores to the same exact size. Definitely tell them your plan is to reuse your entire rotating assembly with new rings and bearings, you don't want them to bore your block to a size that then renders your pistons useless.

SwapStang

You didn't really say what your goals with the motor were. I always start with that and a budget in mind and I have to be honest to drop a ton of money into a run of the mill gen 3/4 motor is a hard pill for me to swallow. I would re-bearing that motor (if need be), ball hone it, maybe clean it up a bit and send it. Machine work can get expensive and near me these motors are $200-$400 all day long so just don't end up in a rabbit hole throwing cash at this thing. Most of the time just a ring gap and these things handle a ton of power. Again just my .02 but just have some fun with it and don't think everyone one of these motors always needs a rebuild.