Technical valve spring compression?

I'm really hoping to get my 331 Cadillac v8 engine completed by October but there still one thing I'm not sure on during this rebuild, I'm curious if I replace the valves would i need to recheck spring compression if i reuse the same springs and the same washers if there are any? my ***umption is if im just replacing the valves it shouldnt change the compression. thoughts? Thanks, Joshua

 

Are you planning to have the valve seats reground also?

Anyways...valve springs do get tired, and it's usually a good idea to replace them.

The shims (washers) are usually added to get the installed height right, which is specified in the shop manual for the car. Some guys add them to make up for weak springs...there is usually a specified force at the installed height that you can check with the proper tool, which machine shops have.

 

Are you planning to have the valve seats reground also? I didn't even truly think of it.

If I replace the spring i don't have the the tool to check the spring compression, i have to see what it would cost to have a shop do it. I just wanted to check if it was possible to do this without rechecking the compression, but it sound like it may be a bad idea. alot to think about. but it seems I may end up having a shop replace the valves

 

“Have to”, is a big question. Should you? Absolutely. If the valves are exactly the same then your spring pressure should be the same give or take the resurfacing of the seats. But that leads to the other question; Were they right to begin with? Imagine if they were just barely on the good side and you barely change it for the worse. You a check the pressure at the installed and compressed height by measuring and checking the pressure by compressing the spring to those distances on the bench. Something like this LSM tester isn’t overly pricey. https://shopfasttrack.com/products/...1a12aTtEuT_Oxw4PSNvnR5QrcKXDkHmIaArgKEALw_wcB

 

Did you change the cam?

 

no, this wasnt a complete rebuild, and originally I was just going to leave the valves but since the heads are off I feel nows the time

 

I appreciate your input, defiantly got me thinking because I want to do this right so I don't need to do this again. and thanks for the link

 

Why not get the heads freshened up? The checking is part of the process in a shop that does a thorough job.

I was introduced to the wonderful world of cylinder heads at the ripe old age of 18 when the basic head service was $22 per head, plus parts.

 

damn I'm 18 right now, and man do I wish it would only cost $22 lol. but I've done some thinking I'm going to bring it to a shop hopefully its not to expensive but by the sound of it its worth it

 

expect to spend several hundred bucks on a valve job these days...they'll probably want to do the guides, and just getting them cleaned well enough to work on costs a fair bit.

If you're just trying to get the engine running, and don't expect it to live for a long time (most old cars are hardly ever driven these days), then you can get probably get by with very little, but without some good pictures of what you're working with, it's hard for us to give useful advice.

I've done a few "old school" valve jobs by just cleaning things up, inspecting, and lapping the valves, and the car ran fine for as long as I needed it to.

We don't know what your plans are, though. The more info you give, the better your results could be.

 

Little "heads up" so your not blind sided , a complete valve job less parts is $500 & up . Too bad you didn't check compression before teardown. Before you do anything , find out about parts availability , a competent machinist can " save" valves that would otherwise be tossed . A low rpm cruiser doesn't need a serdi 5 angle valve job , new exhaust seats , positive valve seals & top shelf ( or even new springs) IIRC the caddy has to have stem height corrected after grinding valves , many modern shops don't know this .you can save yourself a bunch of money by doing the teardown & cleanup . Lots to learn

 

so the car ran fine but it needed new gaskets since it was dripping oil everywhere and the engine was just caked with grease, nothing to serious but after 74 years i guess that expected. now the most everything im leaving the same but since the heads are off and Ive read that if you install hardened valves you wont need a lead additive in the gas I thought maybe this is something I should do. but please let me know hat you think based off these photos

 

I haven't yet torn them down im planning on calling Tuesday to get a quote if its to much I may end up leaving the old valves but Im still trying to figure it out

 

The wear on heads happens at the valve stem, the valve guide, and the valve face and seat. You can't see these parts until you remove the valves, which requires using a valve spring compressor to compress the springs, then remove the two keepers, and the retainer, and spring. There is probably a valve seal of some type also, I don't recall how these ones work (been decades since I rebuilt an early Caddy engine). Once the valves are out and we can see what things look like, and suggest some further things to check, maybe we can tell what might need to be done to get a certain result.

Somehow the heads survived the last 4o years without leaded fuel....so maybe you can get away without having different exhaust valve seats installed?

I've spent thousands of dollars to rebuild old engines, and I've spent hundreds...and the wild variation in cost is all to do with the condition of the engine, and how long I expect it to last. There is also the question of how much money is available, and how much time is available before the car has to be running again. Right now, all of this info is not available to us, so we can't really offer the best advice about what to do.

 

I've been using a lead additive on my drives before I tore it down the. as for money thats why ive been doing all this at home since Im trying to save as much money as possible. like ive mentioned before part of me wants to keep the original ones just because its the cheapest and easiest thing to do, and im only panning on driving this car on nice days this is never gonna be a daily driver I just want it to be reliable during those Sunday drives. hopefully this info help out a bit more in giving me some more advice because im all ears

 

If it were me....I'd take the head apart, and clean it up and inspect, and check the guides and valve stems for wear, and see how wide the valve seats are. And I'd likely just lap the valves and put it back together, but that depends on how much wear there is, and we can't see that until it's apart.

just for fun, read a little of this thread....

https://www.jalopyjournal.com/forum/threads/doing-a-valve-job-the-old-way.1102526/

 

There's also the school of thought that says if you do a good valve job you should also do a re-ring, which also means at least pulling the pistons and honing the cylinders. The concern was that by sealing the combustion chambers better, you'll end up with more cylinder pressure trying to get past the piston rings. How much more pressure is the point of debate.

If the cylinder walls weren't scored, the rings aren't stuck or broken and you're not oil fouling the plugs, it's probably not a real concern. And just a valve grind isn't going to give you any real "seat of the pants" improvement unless you had an existing valve problem before you tore things down.

Your best bet might just be to leave well enough alone, look into replacing valve seals on the intake valves at least, get all your oil leaks fixed and give it a quick paint job.

 

What really happens is that the rings were already worn out, and the person didn't have enough money to fix more than the heads. Fixing the heads didn't fix the problem, so they get blamed for suddenly making the rings go bad...but they were bad all along....

But yeah, just fixing the oil leaks with new gaskets and seals may be all the engine really needs, to meet your requirements. Replacing rings can be relatively inexpensive, if you are careful, and things aren't worn out too far. We don't know how much oil it was using, maybe you don't either?

 

yea I truly don't know how much oil it was using, but I like these past suggestions much more. I guess its something to sleep on

 

My first engine overhaul was at age 14, this was long before the internet...I found a series of articles in Hot Rod magazine, and read them over and over, and also read a Chiltons manual about it. And I was able to get the engine working again better than it was before. So yeah, I've been there....

but this was back when you could take a pair of heads to a machine shop and give them $25 to get a valve job, which consisted of a good cleaning, grinding the valves and seats, checking the springs and shimming as needed, and re***embling with new seals. And the Sears and Montgomery Wards catalogs sold rings, bearings, gasket sets, etc pretty cheap, so the total cost for the overhaul was not far from $100. Ah, the good old days!

 

wow 14 that crazy, very cool! I highly doubt I could have been doing this at 14. "$25 to get a valve job "Ah, the good old days!" your not kidding I wish it was that cheap today

 

Of course I never had $25 to my name back then, so dad subsidized it....

 

lol that's nice

 

If you have a drill press and a bathroom scales check the springs yourself, chuck a valve in the drill use a 6 inch scale for checking height stock springs should be 140 @ 1 21/64

 

If you take the valves out they should be marked as to which guide they came from. Then measure the stems and guides to calculate the clearance to see if it's in spec.

 

If the springs are the correct free length the "pressure" should be pretty close.
All the same height in an encouraging first step.
The sides of the coils need to be square to the faces also.
And rust free when the gunk is rinsed off. Blasting to remove rust doesn't really remove the deadly stress concentration caused by a rust pit on a spring's OD.

Figuring out what the the springs actually are, to determine their correct free length should be can be challenging

Found a 1955 shop manual. Would have been a 331 I think.
https://www.oldcarmanualproject.com/manuals/Cadillac/1955/Shop Manual Supplement/index.htm

Engine specs, including valve spring length and "pressure" ( actually force) at two different lengths.
https://www.oldcarmanualproject.com...Manual Supplement/10 1955 CAD-Engine Mech.pdf

 

An Engineer has a paper somewhere that explains leaded fuel and seats

He worked with car makers to figure out what was happening to some engines and not others when they removed TET from fuel

His explanation was the TET with the cast iron and heat hardened the exhaust seat

These engines survived unleaded fuel, the new engines started having eroded exhaust seats

I would clean the heads, mark everything as said above... drill holes in a box or a piece of wood to put the valves in and mark what head and where they came out of

If the valve face and seat look ok, I would use 800 or finer lapping compound on them to see if there is a mark 360 degrees and see how wide the pattern on the seat is

I have the original springs on my 1965 352 engine with a 1969 390 2 barrel camshaft
I dont turn the engine over 3500 RPM so they work fine

All in the application, if you are just going to cruise around

If you are looking for performance and want to rev it, I would listen to the advice above

The guys wont lead you astray, I have read some of their posts and they know what they are doing

I bought a Mopar 360 engine from a junkyard, the car was pulled out of Galveston Bay

Hammered the pistons out with pieces of 2x4 and a sledge hammer
Broke the rings into pieces with a small chisel and ball peen hammer
Used an ice pick to pry the pieces out of the ring lands then ground down one of the ends of the pieces flat and at an angle to s****e all the **** out of the ring lands

Ball honed the bores with a water hose for lubricant

Did the heads as I posted above, used 600 grit sandpaper cut to the width of the main and rod journals ..... wrapped a really long leather shoe string around the sandpaper using water as a lubricant and worked the shoe string up and down till the journals were shiny

Daddy let me use his various mikes and such to check for clearance

He also showed me to look at the main/rod inserts to see if they looked good or had some sort of damage

I installed a General kinetics camshaft and full length headers, a 727 out of a van

An old Edelbrock 4 barrel intake and $10.00 600 Holley from a swap meet

Put it in a 67 notchback Barracuda shell I traded a nice 70 Duster with no engine for

Drove it for 2 years and ran it hard till I sold it, then found a rusted 340 all apart

I was 17, grew up in the country and had little money so we did what we could do with what we had

Do it and post progress please


Ricky

 

The more you learn , the more you realize how little you know . Take your time .

 

I was a dirt poor kid, my 1st valve job on a '64 Olds 88, the shop costs were $57 and I had to dig that up. All in with gaskets, it was $90. I had a part time job and the car ****ed all that up.

Since then, I have found rebuilt heads as an exchange in some machine shops. But a 331 Caddy... like hen's teeth and I haven't seen an exchange service in many years.

Most machine shops have a cafeteria-style pricing on basic services. The standards plus add-ons. Speed costs money, how fast do you want to go?

 

Here's an idea of the levels involved. Cheap to full rebuild.
Take them off, clean everything and reinstall - gasket set, fluids, basic tools and a torque wrench, and the info to do the job. You are here. You can simply reinstall and run it. It's at this point you have to decide if you can go deeper and still get it back to a running engine.
Take them off, dis***emble (valve spring compressor), clean and measure components. Replace any broken or worn parts, lap valves. ***emble. Everything in the first step, plus parts and the compressor and valve lap stuff.
Take them off and take to a machine shop. This is where it can vary from a few hundred to thousands.
The shop will clean the parts, measure, and inspect.
Valve springs will be checked for free height, squareness, and pressure. Shim or replace as needed.
Valves can be checked for installed height and wear. They will be reground or replaced.
Valve seats can checked for depth and roundness and be reground or replaced.
Valve guides can be checked for wear, then cleaned, knurled or replaced.
Retainers and keepers can be cleaned or replaced. Not as common.
Any threaded holes can be cleaned, and if needed repaired.
The head surface should be checked for flatness and if needed, machined.
Each engine has these standard parts and wear issues to be inspected and repaired. Each brand/size engine will have unique known problems or areas that require more attention.
As said, refreshed heads on a used short block often will improve the running, but is not going to run as well as a complete rebuild. It won't fix overheating unless it was a head gasket failure, ring and cylinder wear, crankshaft bearing wear, timing chain and cam wear.
You also must avoid causing any issues during re***embly. Make sure everything goes back together properly.