blk89lx

ok so i bought a 306 short block from a friend but number 4 piston is bad. no damage to cylinder walls. im looking to buy a new set of pistons and rings and bearings. im looking to do it myself but it would be my first time. does it just come down to poping the pistons out and putting new ones on the rods and sliding them back in? or does it involve more then that i just dont want to screw it up. any info or advice would be greatt

mstngsule68

yep, just takin them to the local speed shop havin them take them off and puttin them back on.

blk89lx

when i took out the bad piston there was no clips holding the wristpin in does that sound right?

mstngsule68

not sure on if there is any clips, but your gunna have to take them to get pressed off. so id say just take it as is to them. should only cost 40bucks ruffly.

blk89lx

so lemme get this right i can just take eveything apart replace all bearing and slide pistons back in and torque everthing to spec and im done?

blk89lx

i just took the rest of the pistons and crank out and some of the rod and main bearing were like copper looking. those have to be bad bearings. is there sumthing that would cause that or is that just normal wear?

.boB

Sort of.

Pistons are attached to the rods with a pin. The pin is either press fit, or floating. It's easy to tell the differance. Move the rod back and forth. If the pin moves with the rod, it's a press fit. You need a shop press to change them.

Before adding new rings, you need to refinish the cylinder walls. You need a simple cylinder hone, run slowly with a drill motor. It's not difficult, just pay attention to the pattern you're leaving behind.

When installing the new pistons, make sure the ring gaps are in the right place, and the piston is oriented in the right direction. There is a "front".

mjr46

honestly the cylinder and piston need to be measured and specs compared to one another, meaning cylinder should be checked for out of round and taper and then measure piston to make sure there will be no inconsistencies that'll cause the piston to rock or sieze in the bore while it is running, also cylinder if found to be in spec should be honed

blk89lx

ok but what about the bad bearing i can just replace then with new ones, the same size? how much would a machine shop charge to clean up the walls?

mstngsule68

acculy you might need the crank ground as well if any of the bearings or surfaces were scratched up, simplest thing to do, strip the block, take the block, crank, and pistions/rods in and have them check it all. simple and done. not sure if you know how to mike a cylinder or check any of it and yea, just take it all in.