I'm looking for recommendations for an overhaul kit for my '71 455 (SX). The build will be stock, and I'm looking to upgrade any weak areas such as the timing chain set-up. The block will be cleaned, checked and receive any required machining. Should the kit also include a new cam and lifters?

 

Mike,

What's prompting the overhaul?
Any performance issues, noises, leaks other?

George

 

George,

This is the original engine which was pulled from the car by the previous owner. (the car currently has a '70 455 replacement engine) From what I can see, the timing chain lost the nylon teeth, and the timing chain jumped the sprocket. So far I haven't found component damage, and this block has sat in (AZ) storage for many years. My goal is to rebuild and install this engine for worry free cruising. This will be a stock rebuild with improvements as needed.

 

Well, in that case....I haven't seen any rebuilt motors with over 300,000 miles on them, sometimes it's just better to leave stock alone if you're looking for a cruiser. Maybe just the oil pump, timing chain, cam, lifters, valvetrain. Leave the bottom end alone. If the heads are still attached, leave 'em. I've just never seen rebuilt engines last as long as factory ones.

 

Mike,
Why did the previous owner replace this motor?
You mentioned the block will be cleaned and machined where necessary.
I would begin with having the crank, rods, bearings, rings and cylinder bores checked.
The bottom end comes first. I would not buy any parts or do any machine work on the heads until you know what shape the bottom end is in.
From there you can make plans for a valve job and perhaps cam & lifters.

George

George

 

George,

Sounds like good advice, thanks. This is my first engine rebuild, so I want to proceed carefully.

From what I was told, a replacement engine from a '70 Delta 88 was installed at some point in the cars life. I also got the original numbers matching engine when I bought the car. No story was provided on the '71 455, but found the timing gear missing the nylon teeth and the chain had jumped.

I pulled the main caps on the '71 engine last night and found some light surface rust on the main journals. (probably from sitting outside under a tarp) Besides that, the bearings had minimal wear which leads me to believe this was a low mile engine. The rotating assembly won't spin, and it's difficult to access the rod caps at this time. I want to tear it down further and have the block and heads cleaned and magnafluxed to see if I should keep going.

 

Mike,
I think that's an excellent plan.
Is your machine shop familiar with olds engines?
Not a trick question, they are a little different.
Are you going to re-assemble the bottom end yourself, presuming the check out and required machine work goes to plan?

George

 

George,

The shop I'm using only does engine rebuilds, and did another Olds just last week. Some of the shops I've checked with are familiar with Olds motors, but not sure who's the 'expert'. As for the build, I'll go as far as my Chassis Service Manual and mechanical skills will take me. I've worked on my own cars for many years, but this is the first time I've done any engine work.

Mike

 

Mike,

I'm not an expert myself. I'm having help with my build cause I've not rebuilt a bottom end before. Lot's of stuff on the CO forum on olds specific mods (e.g. improved oiling- an olds weakness) and re-assembly "best practice" for good results.
Best of luck and I'd say before each major step, float a specific question out here. If you put the subject in the thread title, you'll usually get some advice quickly.

Best of luck.
Keep in touch.

George

 

George,

What sort of questions would you ask a machinist to determine if they're knowledgeable about Olds engines?

 

Olds engines need a little more bearing clearance than chevy. Ask Olds engine expert, they will agree. As much as we Olds fans would like to think our engine of choice is indestructible, the engines are kinda weak in the main bearing area. I'm guessing this is due to the way the engine mounts bolt to the side of the block, right where the main bearing caps bolt in. If you don't provide a little extra room, things will "clearance" themselves! At the minimum, you need to open up the bearing clearance to the factory maximum. Have the main bearing caps align-honed, have the rods resized. Install a high volume pump, and careful machine and assembly should be all it needs for your application. If the shop wont machine it the way you request then keep looking.

 

Anyone in the Glendale AZ area have an Olds machine shop recommendation
for Mike??

 

Mike,
I found two links on the internet.
Let me know how they work out.

George

https://classicoldsmobile.com/forums...hoenix-az.html

http://www.azoldsclub.com/recommend.shtml

 

George,

Thanks for finding both of those links. Fred is a great resource for Olds stuff, and both shops are close by.

Mike

p.s. Thanks to matt69 for the specific machining tips.

 

Mike,

You're welcome.
Please drop a few notes and or pics along the way.

Good Luck.


George