Cylinder and bearing condition on a 350- what to be concerned about?

[msg]

As I have been breaking the 350 down I have been checking the cylinders for wear and hoping not to have to rebore and buy new pistons. I do see what I would think is the normal vertical lines but this is my first time working on an engine so I wanted to check with the crowd here. I found in 3 cylinders some areas that look a little pitted, like corosion may have worn an area. Does this signal to you guys that its so bad it should be rebored and all or pretty normal looking?


Also I have gotten a palstigauge set to see the clearance levels on the rod bearings and the first I looked at shows wear but I dont know how to distinguish too much vs normal wear. As a start how does this one look to you guys?

[geezer#99]

With pitting like that you’re likely gonna need a bore and new pistons.
A quick pass or three with a ball hone won’t do it.

If the block is standard bore you’ll be able to likely use it. If it’s been over bored it might not clean up and you’ll need another block.

[YoungPup1977]

from the pic of the top of the piston you provided doesn't show any numbers, when a oversized piston is used normally the oversize number would be on the piston top. It maybe a standard bore, measure it and see if its 4.00

Also on your bearings,(main and Rod) look on the back side of the bearing it will indicate if its a STD bearing or if its oversized as well... this will tell you if the crank has ever been ground/turned.
Good Luck

Looking at the pic of the crank, if you run your finger across the journal does your finger nail catch. From the pic, I would go ahead and have the crank turned so you go back with a nice piece.

[YoungPup1977]

If you look at the pic provided it shows a STD on the back of the bearing in the pic. Its sort a hard to see but this indicates this crank is at standard size.

I am not sure you need plastigauge at this point to measure your old bearings, they are worn out and needing replacing. Take your crank to the machine shop of your choice and either they can polish it or turn it based on the wear the crank may have. Ensure you have your rods re-sized as well with new bolts. this process trues up your rod bearing cap to ensure proper bearing clearance. Its part of rebuilding the engine.

[msg]

Posting a few more pics, the bore ranges with my caliper a bit. The bearing I looked at was the 2nd from the front here. Photo of each end

[Dead Parrot]

Is this a "Just trying to get it running" or "Do it proper" rebuild? Wanting extra power or just running decent? Lots of motors have given lots of service with less then a full proper do over.

What made you think it needed to be opened up?

If just trying to get it running, IIRC - there are some file to fit piston rings that might give a better seal then just buying the standard size rings. Matched with a good hone job, will probably give many thousands of miles of service.

I think you can get thicker then normal bearings to match the wear on your crank. As good a having the crank properly machined? No, but if this is a just need it to work build, might be good enough.

I would get a basic valve job and new valve seals.

Whatever you decide, get firm estimates for everything before having anything done. Nothing worse then getting halfway done and running out of money. Leave a budget cushion. Something always pops up and wants more money.

[truckster]

Using Plastigage with old bearings is, in my opinion, a waste of time, unless you think you're going to reuse those bearings, in which case I wouldn't have torn the engine down. Plastigage with new bearings will tell you a better story of the condition of the crankshaft.

You're going to have to bore the cylinders. That damage is too deep to hone. I'm curious - did the engine sit with water in it at some point?

[msg]

Thanks for the reply, I had removed this engine as part of the restoration I have been doing since 2014. It ran fine, wasnt smoking but I seem to remember a little ticking sound that I was wondering about. After doing the compression check I pulled it and took a few pics and shared them with the members here in this thread that photobucket dumped on.

http://67-72chevytrucks.com/vboard/s...d.php?t=669346

At that time I was only wanting to tackle some simple "you have it out, at least do this" kinda things. Not having experience myself I knew Id be biting off more than I could chew if I cracked it open, but years later I got to talking to a friend who was experienced, interested and willing to help me do the more complex stuff. The thinking then became " well you have an opportunity to learn a bit more with help and take any guessing out of what the condition really is internally, before you put it all back together."

I would like to avoid spending too much of course, the most I want to spend on engine repair/conditioning would be $1500 in "jeez this is awful..replace or fix that" situation. Not looking for a hot rod powerhouse just an engine that is in good running shape and can likely see 25000 more miles or better. This is not a daily driver, just a take out for maybe 100 miles a week at the most I would think to enjoy.

Here are some pics when it was removed

[msg]

Originally Posted by truckster

I'm curious - did the engine sit with water in it at some point?

It has been sitting on a stand in my garage since I removed it in 2015 while I have been doing all of the body work. Just getting things back together now and the engine is getting close on the list of things to complete.

[YoungPup1977]

Have you considered what a lot of people on this forum have done with regards to a LS swap. Go out and get a used LS engine, clean it up, replace external gaskets, so it looks new and call it good.

Or buy a cheap crate engine for less than 2000 bucks..


Jegs:

https://www.jegs.com/webapp/wcs/stor...rsistYmm=false

[msg]

The restoration I had in mind was to make it look fairly stock. The crate motor direction I thought would be higher than $3000 so I havent really looked into it. I was hoping to keep what I had with a few updates that wouldnt tip too far into the direction where a crate motor made more sense. Maybe the years that it sat has caused some problems, just bums me since it was running before.

Ive never shopped for a crate motor. I wouldnt know who made a good one and who to avoid. I know Id like it to be orange though.

On the fingernail test on the journal, it didnt catch but it wasnt gliding. A little texture with the fingernail drag. The plastigauge on that read between .002 and .0015....closer to the .0015 width.

[cadillac_al]

Your engine will run as is but not as well as a newly rebuilt one. I am running a tired engine every day in my truck. It has 180k miles and a humongous ridge at the top of the cylinders. It still fires up every day and hauls down the road but it is tired and down on power. A $1500 crate engine may be in the future unless I decide to fix up my other truck.

[PGSigns]

The one bearing shows 010 on it so that looks like a 10 over bearing. The best thing to do is pull it all the way apart and take it to a machine shop and have it cleaned and checked. The can properly measure the crank for size and out of round. The can also measure the cylinders for size, out of round and taper. That information will tell you what you need to do to the bottom end. Then let them clean and check the heads. This will give you the full condition of the engine and what it will cost to fix it. Now you have the what you need to see if a crate engine is in your future. Here is a link for reference on some of what is out there and the cost. https://www.summitracing.com/search/...rder=Ascending
Jimmy

[msg]

The pistons have a 30 stamped on them if that helps to know. The plan as of last night was to go through each bearing and measure with plastiguage for the sake of having some specs to share with machine shops for the assessment...as well as me getting some experience. If the machine shops can share a price list of things they do then I could add things up before removing the pistons and make it a have to redo situation. If the estimated total gets crazy then I may just leave it be and see how many more miles I can get and pocket the dough for the AC, new wiring harness, headers, exhaust, bench upholstery etc.

[YoungPup1977]

Originally Posted by msg

The restoration I had in mind was to make it look fairly stock. The crate motor direction I thought would be higher than $3000 so I havent really looked into it. I was hoping to keep what I had with a few updates that wouldnt tip too far into the direction where a crate motor made more sense. Maybe the years that it sat has caused some problems, just bums me since it was running before.

Ive never shopped for a crate motor. I wouldnt know who made a good one and who to avoid. I know Id like it to be orange though.

On the fingernail test on the journal, it didnt catch but it wasnt gliding. A little texture with the fingernail drag. The plastigauge on that read between .002 and .0015....closer to the .0015 width.

The key word you used in your first sentence is RESTORATION..... what is the definition of restoration.... take it to the machine shop and actually rebuild/restore the engine back to where it was when it was new. Restoring does not mean to do "Just trying to get things running" approach. In my opinion, people who cut corners end up with unwanted issues down the road, you have it torn down, do the right thing and restore/rebuild the engine right or go with a crate engine. How many years have you been working on this vehicle, it takes time and money to restore so for some these two things are hard to gather up. Again just ones opinion.....

[geezer#99]

Just another thought!
Mid seventies saw thin wall blocks being used. Safe overbore was .o40. Your block is already .030 and needs to be cut enough to clean up the pitting.
You might be looking for a new block anyway.

[msg]

The restoration for me was more on the cosmetic side to begin with. Loads of rusted panels. Bunch of caked on crud. The engine I pulled to make those repairs happen and thought since it was running without issue it was a spruce at best. I am learning as I go throughout this restoration or whatever the right term is in my case. I'll definitely continue to price out and look to budget the engine issue. Not giving up and really dont want to kick the can on this. Its hard to gather up the time and money like you said, I'll do my best to make the right call.

[YoungPup1977]

Originally Posted by msg

The restoration for me was more on the cosmetic side to begin with. Loads of rusted panels. Bunch of caked on crud. The engine I pulled to make those repairs happen and thought since it was running without issue it was a spruce at best. I am learning as I go throughout this restoration or whatever the right term is in my case. I'll definitely continue to price out and look to budget the engine issue. Not giving up and really dont want to kick the can on this. Its hard to gather up the time and money like you said, I'll do my best to make the right call.

Sounds like you know what you want, Good Luck with your adventure !

Take your engine to a machine shop and let them tell you what it will cost, assumptions are being made but you will get the actual cost analysis from the machine shop. Just be careful of who does your work.....

[truckdude239]

Thinkid buy one of the 1500 gm crate 350s and throw in it

[msg]

Originally Posted by YoungPup1977

Sounds like you know what you want, Good Luck with your adventure !

Take your engine to a machine shop and let them tell you what it will cost, assumptions are being made but you will get the actual cost analysis from the machine shop. Just be careful of who does your work.....

I really appreciate the help and advice and encouragement! I asked the custom shop Ive take my truck to over the years who they recommend and this shop was the one and only candidate so far.

http://www.scottsautomachine.com/

Originally Posted by truckdude239

Thinkid buy one of the 1500 gm crate 350s and throw in it

for $1500 what engine brand and type should I be considering? I know nothing about who produces quality new crate engines vs a rebuilt.

[truckdude239]

https://www.jegs.com/i/Chevrolet-Per...429-R/10002/-1 sorry they like 1800 now

[PGSigns]

You have an engine that has been done once with an unknown amount of miles on it and what looks like by the bearings and cylinder walls that is was run hard and put up wet. The wet part is showing up as the rust pits in the cylinder walls. That leaves you less options than than a stock engine with a standard bore and crank. As I said above the machine shop is the best place to take it and get a true assessment of what you have. If you had more experience with rebuilding engines and all the tools needed you may be able to save a little over a crate engine. If you have long term plans for a motor with a bit more power and still keeping the old school engine a 86 and up one piece rear main roller cam style engine would be my choice. Then after that the L31 crate engine from GM with a cam swap. Now you are getting into the price range of an LS swap. Then there are the used engines out there that show up at times that are a pretty good deal if you know what to look for. So lots of choices based on time money and long term plans.
Jimmy