my 73 w a 396 started runnin rough, found a broken valve spring when i pulled 1 of the valve covers. havent pulled the other cover yet, but a local highly regarded machine shop says they can freshen up my heads w new springs and seals for appx $350/pair. more obviously if i need guides, valves etc. im guessin if one spring broke, all of them are probably tired. ive had the car for a couple months, id rather not spend a ton of cash on this engine - my long term plan is to build a strong street 454, but thats a ways off. i dont have a spring compressor, and dont know how these can be changed without removing the head if i chose to simply change the springs. ive heard it can be done, im assuming it requires pressurizing the cylinder w air.

i dont want to spend unnecessary $$ on this engine, but id like it to be reliable for a year or so of driving till i get around to building something else. thoughts? should i have the heads done, or simply change the broken, or all the springs and run it? can anyone recomend the tools id need to change the springs?

also, what books are decent basic guides to building a big block? id like a relatively simple one to start, just to begin studying. something that covers basic assembly, checking valve train geometry, and anything else i need to have some working knowledge of. i figure i need to learn the basics before i get into the complex stuff, which ill get a book for later. heck right now i dont know what questions to ask, never mind having any answers.

that said ive worked on equipment all my life, i can fix durn near anything once i have the info. got a decent pile of basic tools and a warm garage

thx for any help!!

lear

 

You should be able to rent a valve spring compressor and if you dont have air another method I have heard of is pushing rope into the spark plug hole to fill the cylinder and prevent the valve from falling in.

 

I guess it would be possible to replace the valve springs with the engine in the car....but not something I would look forward to due to the tight quarters, especially those rear cylinders.....

Every manual spring compressor I have used ends-up bending the spring fork that go under the spring and slips off. Now the one my machine shop has.....uses a HEAVY DUTY air powered press....could hold that spring down forever and never bend.

Do not get a cheap one....

I suggest the machine shop path....that way everything can be cleaned-up and checked-out.


Good luck.

 

I've never tried putting fresh heads on a tired bottom end, but I've heard at least a dozen times over the years that doing so will blow away what little ring seal remains in fairly short order. Don't know for sure if that's true but I can certainly see the logic. If it was me and I was planning on a total rebuild in the not too distant future I would look into just replacing the broken spring(s) on the car...my $1.380

 

http://www.google.com/search?tbm=isc...985l0.9.3l12l0

For $350 for the pair, let the machine shop do them.

 

I replaced all of my springs in the car about a year ago, took me about 6hours, but i am slow and it was my first time. No books, just cruised the internet for awhile and read what's there. Access is a bit tight on a few and I used a couple different types of spring compressors. Compressed air to the cylinder is a good idea.

 

I might add that I knew what my cam was and what I was looking at as far as coil bind and seat pressure, etc.

 

heres a couple pix, after thinkin how much time and money ill have in gaskets, r&r, and cleanup im leaning towards replacing the springs only. its those terms like coil bind and seat pressure that worry me though...

 

The most important step is to know the spring rate that matches your camshaft, next is to check the installed height. two years ago I had a horrible valve float that occurs as early as 4000 RPM and after MANY hours of diagnosing and talking to some engine building experts, I found that my spring height was only .050 too long, I was shocked how this .050 could change the life of that motor! .. of course checking coil bind is also very important, try getting that book, for me it was the best engine building book for beginners, I know that because I'm hardly a beginner.

BTW, you sure can replace the springs with the engine in the car, I did that many times before on big and small block chevys.
http://www.amazon.com/How-Rebuild-Yo.../dp/0895861755

 

So it's a broken inner spring on what looks like a pretty stock engine with the exception of headers and what? based on that and you not wanting to throw a bunch of money at this old dog, buy one of these:

http://www.ebay.com/itm/KD-912-Valve..._Tools&vxp=mtr

It works real well for me on any head that has studs and it's cheap. Use compressed air (easy) or the rope trick (little tougher). depending on the location of the affected spring, you may have to remove the carb or misc. parts to get a clear shot. Use a small magnet to capture the keepers and buy a set of valve seal o-rings while your at it.

This one is not my favorite and it's more money, but others have used it with some success:

http://www.ebay.com/itm/KD-2078-Univ..._Tools&vxp=mtr

If it is fairly stock, you won't have to worry too much about the spring pressures, just get the same length & style of spring and you should be fine. Now on your new engine, your going to have to educate yourself so you don't end up with a pile of incompatible parts!

 

you dont need to pull the head, however it may be in a difficult spot...its still not a bad job...Go to your local independant parts store and ask for help...with any amount of savvy they should set you with the necessary parts and tools...not at a chain store though as most chain stores dont know there *** from a hole in the ground........


the above KD tool will work

 

got the 2 broken springs removed(yep found another one), talked w the machinist nearby, he agreed no sense in spendin the money at this point since im planning a build. got the new springs from him, got them installed. will finish her up tomorrow and go from there.

i have someone close by who is talkin like they want this engine, and ive got my eye on a 454 block nearby.

thx for the book recomendations, got one comin.

thx! everyone

 

[QUOTE=learje;1579054292]got the 2 broken springs removed(yep found another one), talked w the machinist nearby, he agreed no sense in spendin the money at this point since im planning a build. got the new springs from him, got them installed. will finish her up tomorrow and go from there.

i have someone close by who is talkin like they want this engine, and ive got my eye on a 454 block nearby.

thx for the book recomendations, got one comin.

thx! everyone


I personally would keep the original block unless you plan on keeping it for ever

 

I would too as those 396's were pretty rare in 73.

 

hehe yea ive got the only ls3 396 corvette ive ever seen mentioned here...just jokin 68/427, the engine is from a 71 chevelle.

it acually ran great up to this point, hopefully it will continue to, id like to keep driving the car while i research building the 454.

 

That was fast. What tools did you use to replace the 2 springs?

 

bummed one of the crank type spring compressors, and did the rope trick

tomorrow mebbe ill get to start it up. spent today fixin the POs' bubba'ed pwr steering and alternator brackets, belts and hoses...hehe they had everything shimmed w nuts and washers, took all that crap off, cleaned and painted the brackets, started to put them on like the aim shows, looks like everything will line up...no idea what they were thinkin

 

Big blocks are hard on valve springs. I would get just the one replaced with the compressed air method. Takes about 15 minutes. Then just take it easy on it until you're ready to rock a new monster motor.
The shop isn't going to pull the heads and redo everything for 350$ are they? I'd be very weary about a shop that promises a deal like that! They may be setting you up for a major big bill.
"Well sir, now that we have the heads off, we found this and that, and this is the best time to do it all".......