4 bolt main?

[cfan10]

Took the oil pan off of my 84 which I was told when I bought it in '08 was a 305...I am no expert but I've never seen a 4 bolt main 305. I'm in the process of replacing all the connecting rod and main bearings. A few have a tick and moves slightly band aid fix I know but I just need it to haul scrap within 40 miles on the weekends. Without a feeler gauge what size bearings should I buy also a pretty decent brand, and the oil looks really good no chunks of metal despite the broken dipstick in found in the bottom.

'84 c10 305(350)/th350

As always thanks for replying!

[geezer#99]

Rare but possible.
Only in 77-79 Canadian blocks.
https://www.mortec.com/castnum.htm

If you don’t measure them don’t change them out. You’ll need a micrometer to measure with.
No telling what’s in there.

[homemade87]

If all you are doing is to get by just look at the back of the bearing . Should have stamping and it will tell you whats in there and put the same thing back in . Most likely your bearing have some wear and this will tighten it up some . Not the ideal thing to do but sounds like it may do fine for what you wanting to do . No need to buy expensive bearings for this . Something like a seal power or even a summit brand would do . I dont know what weight oil you run but I would run a heavier weight oil as well once done .

[cadillac_al]

I would try a .001" undersize bearing and plastigauge it

[andyh1956]

Does the "Tick" you describe get louder or quitter as the engine warms up? The problem you describe sounds like piston slap. If it gets quieter then it's prolly the pistons expanding & if it gets louder then it could be excessive brg clearance. What does your oil psi say at operating temp? When you pull your brgs look & see if the brass is showing thru the babbitt.
If you have a 305 they are notorious for piston slap & even breaking a skirt off a couple.