jfl1960

OK as the title says I am rebuilding my ORIGINAL 305 that came in my 1982 Camaro, the only thing I am going to do is port the heads, bore the block +30 and put a better than stock cam in to make it a bit more fun to drive, I am running a T5 5speed and love driving this car, don't want a 350 as it's too much engine for the T5. Anyway the crank is gone in the 305 is the reason I am doing the rebuild, I was wondering if using a set of 350 rods and a 350 crank was possible as I have those here, if not I will buy a new crank, rods and of course +30 pistons. I have heard of people using the 305 crank and rods in a 350 but not the other way around, as I understand it the rods after 86 are the same for 305 and 350, but earlier years are different weight for the rods, kinda green on this type of build so I thought I would ask here for some experienced advise, just didn't want to spend $3-500.00 if not necessary. Any help is appreciated.

Prodigious

Don't quote me on this, but I'm pretty sure the crank and rods are the same specs between the two engines. I thought the only difference the 350 had was a bigger bore. So theoretically you should be able to use those parts in your rebuild, I would either do some googling or wait for somebody more knowledgeable to reply though. The 305 and 350 have the same stroke though, and that's why I believe you can use those parts.

If you're gonna bore the motor .030 over, you might as well finish the job by stroking it out with a 400 crank. You'll still have the factory 305 block, and it's not really taking much more originality away from it since you're already gonna be running bigger pistons.

jfl1960

Thanks for replying, I knew the stroke of the crank and rod lengths are the same between the two motors, it's the balance I am concerned about, I could go into detail of what I know (actually have read) and unfortunately the info I have gotten from googling is kinda of sketchy, with about a 50/50 yes and no type of answers. I am hoping an experienced engine builder can help me out, thanks again for the reply.

Orr89RocZ

iTrader: (20)

Rods and crank are same so thats no problem. Chances are the 350 crank is balanced for slightly heavier bob weight due to larger diameter pistons

jfl1960

Thanks for your response to my post, I understand the 350 piston is heavier than the 305 piston due to physical size and from what I have read the pre 86 350 rods are heavier than the 305 rods, not 100% on that but did read it somewhere and approx 1 ounce heavier was mentioned. I expected that the rotating assembly would need re-balancing to use the 350 crank and rods in a 305, my query is could they re-balance the assembly to work in a 305???? Has anyone ever done this before and what were the hurdles and results?? Thanks again for responding all info is appreciated.

On a side note I understand the L69 used something called a "X" Rod that was also heavier than the regular"0" rod used in stock LG4 305's anyone got some additional info on that and please correct me if I am wrong. My motor is a 1982 LG4 with the 416 casting head, suppose that was standard for that year, going to port those heads a bit for flow.

ASE doc

As long as you are having the assembly balanced, the weight difference is not an issue. The machinist will determine the needed change in bob weight for the different piston weight. The affect from changes at the piston end of the rod is much less than the affect from changes at the crank end.

I would urge you to also have the block line honed, decked and honed with torque plates and the entire assembly clearanced as well, while you are having the crank balanced and the block bored. This will include resizing rods as needed. The value of thorough machine work is priceless for a long lasting reliable engine build. My machinist gives the block and assembly back cleaned, bagged and ready for assembly.

Orr89RocZ

iTrader: (20)

Alot of machinists wont let parts leave half done. They will require a complete clean and machine job on the block and balance the assembly. They wont hone or bore bores only and not check everything else