I'm thinking this is an easy question,I have a 383 short block sitting on the engine stand,motor has 80k miles on it.The #3 cam bearing is starting to flake apart.Can the cam bearings be replaced without taking the motor apart? 2 local machine shops told me no,the motor needs to come apart to do them.Is this true,I really don't want to dis-assemble this.Any input,Thanks,John

If you're down to a short block you should be good to go as long as the rest of the engine is in good shape.

I have the tool and have replaced them with the engine assembled. In fact I bought it because I had already assembled the engine before I realized the machine shop botched the bearing install and I didn't want to tear it down or take it back to them.

You will have to have access to the front and back of the engine with my tool so I actually did one in the car and others on the crane or bench so the engine stand wasn't in the way.

It is important to align the oil holes so I used a sharpie to mark the block and the bearing. I checked it afterward with a mirror and flashlight.

Just make sure the oil holes are aligned and no shavings get in the block. Shaving are a bad sign they usually mean the bearing didn't go in straight and the bearing is ruined. At least that has been my experience.

I've done several in the car. it really helps to have the open valley In th ecar one has to be careful not to disturb the rear plug. This can be accomplished by A: using a spacer to limit the depth of the bearing mandrel / installer. or B: if you have access to a lathe have a shorter mandrel made.

are you feeling REALLY LUCKY?
I would at least take the # 3 and 4 and # 5 and 6 rods and pistons out to provide some working room for access to that #3 cam bearing boss.
I have been installing cam bearings for a long, long time, make sure that the cam slides in and rotates smoothly before starting to reassemble the motor. If it doesn't rotate easily and smoothly get ready to carve on the new bearing with a bearing knife to fix it

I agree with Cab. I’ve install all my cam bearings as well.

I've never installed a set of cam bearings that the cam would fit in without scraping the bearings. (E-Booger claims the factory bored the installed bearings) This is why I wouldn't install them in an assembled short block...too much risk of shavings in the oil galleries.

How were you able to get the rear bearing out without taking the rear plug out?

All of the cam bearings except the rear #5 are easy to drive out, that one needs to have the rear plug removed to change it

I've done so by "hooking" the oiling hole and "Rolling" the bearing out like a freeze plug

Just wanted to update this post.We were able to replace the bad cam bearing #3 along with #'s1&2. We did not due 4 or 5 because they looked to be in good shape and didn't want to make more problems that I already had.All went smooth,got the old ones out without any problems and the new ones went in nice as well.Cam turns smooth as it should and now I'm able to move forward with this.Thanks to all that replied..

Wimp on 4 & 5 LOL

Sounds like a ex Chevy racers comment to me

Only one and it was because the motor was free and money was TIGHT!!!!