Engine: How to know which bearings to order for 289 engine rebuild.

[jostanton1]

It's been 30 years since I rebuilt an engine and I finally got me a 64 GT. It has a 289. I am doing a rebuild and need suggestions on how I measure the crank, rods and pistons to order the correct size bearing and rings. I see they come in several sizes. Should I have a good mechanic measure them or can I do it if someone explains the best procedure. Thanks in advance and it's sure great to once again own a Studebaker!

[tsenecal]

Yes, I would have a machine shop mic the crank for both size, and roundness of the journals. They will have access to specs, and can tell you if it can be used with standard inserts, or will need to be turned.

[rusty nut garage]

IMHO the first step is buy the STUDEBAKER shop manual. All of the vendors carry them. Read and re read the engine section, especially the install and setup of the crank endplay and the removal and installation of the piston wrist pin pinch bolts. There is an oil galley plug that is often forgotten in the distributor tower area. , familiarize yourself with it. If you leave this plug out during reassembly you will experience near zero oil pressure and the plug is almost impossible to install once the engine is assembled. buy the special tools you'll need. For example the correct puller installer for both the cam gear and the crank gear. Find a machinist that does good work. After tear down take him the parts to him for cleaning and inspection. don't skimp on the machining process. Don't trust the machine shop to clean the parts, don't reassemble your engine without a thorough parts cleaning after getting the parts from machinist. Dont' assume the machinest measured the parts correctly. Check and recheck clearances and dimensions during your reassembly. Take your time its not an inexpensive endeavor.

It's been 30 years since I rebuilt an engine and I finally got me a 64 GT. It has a 289. I am doing a rebuild and need suggestions on how I measure the crank, rods and pistons to order the correct size bearing and rings. I see they come in several sizes. Should I have a good mechanic measure them or can I do it if someone explains the best procedure. Thanks in advance and it's sure great to once again own a Studebaker!

[PackardV8]

First decision is the budget. Never order parts before an machinst has determined what is needed.

Yes, CASOs often used to replace bearings on worn crankshafts and get more miles out of the iron.

No, I've never pulled down a Studebaker V8 in which the crankshaft was completely within Shop Manual specifications to be reused without a regrind.

Maybe, discuss budget with your builder. There's just keep it running or cheapest possible rebuild or better-than-new rebuild and every thing in between.

It all begins with the block; it should be thoroughly cleaned, pressure tested and checked for cracks. Once the machinist has determined the block is sound, he can bore and hone the cylinders. Then, the correct pistons and rings can be ordered.

Then, move on to the crankshaft. Have it reground. The shop doing the work will remove the smallest amount of material to make the journals round and straight again. That will be .010", .020" or .030". Only then can one order correct rod and main bearings. They're both usually the same undersize, but can require different size to clean up.

Next, have the rod bearings, rods, pistons, rings front damper, flywheel, pressure plate or flexplate rebalanced. The engine will be smoother and last longer.

jack vines

[jostanton1]

Thank-you to everyone who responded. Everything is coming back to me now. It's been since 1993 that I torn down a Studebaker engine! I appreciate all your help and advice.

[Jeffry Cassel]

S'pose it all depends... I have often, successfully, reinstalled a crank after a polish with standard or .001 OS bearings. The key is that you want .001 to .0015 clearance between the crank and the bearing and you must USE PLASTIGAGE!!. I am reluctant to play Russian Roulette with a hard to find crankshaft. Yes, yes I have had some machine shop moron destroy a crankshaft (as well as just about any other thing you can think of) Be very very careful in selecting a shop . Ask several club members. You can balance the crank and by weighing each balance the piston-rod bearing assembly, but if it runs smooth now it won't help. It will give the 'shop' another opportunity to mess up your motor! Balance rodbearings??? Ya gonna cut off a hunk if its too heavy?? To determine the crank journal size you will need a good calibrated micrometer. If you are not familiar reading them you may opt for a digital one - they are super nice - but cost more. You need to mic it twice on each journal north-south and east-west to be sure it is perfectly round. The journals need to be smooth as a baby's butt. If not you might want to go .010 over. NEVER go any more than needed. If you go .010 over and they screw it up (Not At All Unlikely) you still have a little iron there to work with when you find a respectable shop. Good Luck and Happy Wrenching!

[PackardV8]

Balance rodbearings????Ya gonna cut off a hunk if its too heavy?? ?

Editing to clarify. In a set of rod bearings, they'll always weigh the same, so no, material is not removed from a bearing.

All the big ends of the rods are weighed and material is ground off the balance pad at the bottom until they all weigh the same. Then, all the small ends are ground to the same weight, all the pistons are machined to weigh the same.

Then, two rod bearings plus the big end of the rod are weighed and 100% of their weight, plus 50% of the weight of the small end of the rod, the wrist pin, the piston and the rings are added up to determine the bob weights bolted onto each crankpin when the crankshaft is spun up to balance it.

Balancing has long been standard procedure in performance engine building. We balance all our engines and they run noticeably smoother.

jack vines

[Jeffry Cassel]

was not aware that anyone ever did any thing like that..seems strange, time consuming and unnecessary.

[Bo Markham]

was not aware that anyone ever did any thing like that..seems strange, time consuming and unnecessary.

Totally!!!

[tsenecal]

Most stock, factory engines will run fine without being balanced, but a balanced engine will run smoother, and any vibration that is eliminated, will make the engine last longer. When I built the 289 for my Hawk, I used flat topped pistons, that were much lighter than stock. The machinist weighed each piston and rod, then removed weight from the crank throws to compensate for the lighter pistons.

[64studeavanti]

Balancing the rotating assembly is a normal procedure especially if any of the revelant parts have a different mass than stock - for example pistons. I always have mine balanced during a rebuild.

[64Avanti]

was not aware that anyone ever did any thing like that..seems strange, time consuming and unnecessary.

This is very important if you are building an engine that you want to turn 6,000 rpm or higher. The engines as built by Studebaker were built to have some degree of balance based on piston, pin and ring weight. Aftermarket pistons are likely to different in weight and you will most likely have a worse balance than the original engine as built. Bottom line, spend the money to have your engine balanced!