Can you replace a Valve spring in a 48 Plymouth without removing the head?

[auburnseeker]

Ok I've been joy riding in my 48 Plymouth a little too much I guess as I just broke a valve spring today a couple of miles from my shop. I consulted the factory shop manual but it only has info on valve replacement. Is it possible to replace a valve spring without removing the head. I figured I would ask before trying something that was impossible. Of course it's the spring on cylinder number two so it's more buried than the the back ones. If I have to pull the head I will replace them all. Just trying to avoid pulling the head right now as that will mean an engine detailing that will take way longer than I plan it to. I was just trying to stretch my season a little more before getting into that project.

Steve_Mack I told you I was just getting the bugs worked out for you

[c49er]

You can do this job easily without pulling the head. Remove the sopark plug. Use a thin rod slightly bent to hold the valve head down. Pull the side cover. Tap on the valve spring retainer to break it loose from the 2 keepers- this makes it easy to lift up just the valve spring and retainer. Sometimes the retainer gets stuck to the two valve stem lock retainers. Use the side valve spring compressor to raise the spring and retainer while holding the valve head down. DO NOT let the two small valve stem keepers fall into the pan! I suggest not rotating the valve either. You will have to raise the valve and possibly need to back off the adjuster to pry the old spring out.

[auburnseeker]

Thank you. I wanted to know it could be done before I tried it for half a day only to realize it was impossible. I'll get the spring out tomorrow and go from there. Thanks again, Randy

[ply33]

I'll be really surprised if you can actually get a new spring in with the valve stem in the way... Not a big deal to pull the head on these engines, you just have to restrain yourself from feeling obligated to detail everything when you do it.

[c49er]

Maybe later today I'll go out to the shop and pull one on a parts engine. I'll post pics.

[wmsue]

I read about a different way to change the valve spring without pulling the head.

Make sure the piston is at the lower end of its travel. Pull the spark plug and feed as much rope into the combustion chamber as you can make fit. Then tap the starter or hand turn the flywheel till the piston compresses the rope. Change the spring. Turn the flywheel a bit to lower the piston and pull out rope. Sounds like it would work....but I never tried it.

I used compressed air to hold the valve closed many years ago. If the rings aren't worn to bad and the valves aren't leaking, it works great. Just got to have (or make) the adapter and enough room to screw it into the plug hole.

Good Luck

[Chris Bamford]

I'm thinking Ply33 is correct... here are a couple shots of my '47 Dodge lifter gallery and it looks very difficult to remove the valve spring without pulling the valve.

The third picture is the same engine, fully rebuilt, proving it is possible to pull the head, and more, without detailing before reassembly.

Edited November 17, 2012 by Bamfords Garage (see edit history)

[Mark Simmons]

If that's the '48 seen the the picture I owned a '47 just like it same color and all. It was a great car, I also owned a '52 coupe. I don't remember enough room to insert a new valve spring in the motor with the head on. The area between the adjustment on the lifter and the bottom of the valve guide is to short. This is from a decades old memory. As stated above the heads on these motors are not hard to remove while in the car. So do it the right way,it's really not all that much time or trouble. The detailing can always be done later. Just my two cents worth. M ark

[auburnseeker]

I pulled the inner fender and wheel. Tried doing it without taking them off and it was too hard to get into it. I had to take the tappet adjusting screw out and had no problem getting it out. I just took my small magnet and stuck it in the spark plug hole which when stuck to the valve You can pull it up and it will stick to the side of the spark plug hole as well, both being metal. Looks like it will be easy to get the new one in As long as I can get the screw started with the new spring in place. Now I searched through all my inventory and realized I wholesaled anything that I had in NOS parts like that. I even looked through a few bags with loose ones I have been saving for who knows why and no matches of Course. I do have some access to a Desoto engine which according to my Mopar master Catalog (all 41-57 atleast 6 cylinder engines take the same spring. Went to the NAPA store, that was kind of a joke as they insist there are 2 different types and the exhaust and intake are different. Unfortunately someone must have forgotten to Mention that to Mopar when they printed the parts catalog in 1957. Even if I knew which one to order according to there books. I won't have it until middle of next week at the soonest. I hate to pull the one out of the Desoto (1950) but I may do that just to get to drive it a bit more. That engine isn't slated for anything and it's no longer in the car.

[Mark Simmons]

Bamsfords Garage Thanks for posting the pictures. That's the way I remembered the spring areas looking in my cars all those years ago. Now if I could just remember a few more things that clearly like..................what was I saying. Mark

[joe_padavano]

I read about a different way to change the valve spring without pulling the head.

Make sure the piston is at the lower end of its travel. Pull the spark plug and feed as much rope into the combustion chamber as you can make fit. Then tap the starter or hand turn the flywheel till the piston compresses the rope. Change the spring. Turn the flywheel a bit to lower the piston and pull out rope. Sounds like it would work....but I never tried it.

I used compressed air to hold the valve closed many years ago. If the rings aren't worn to bad and the valves aren't leaking, it works great. Just got to have (or make) the adapter and enough room to screw it into the plug hole.

Good Luck

What you describe works great on an OVERHEAD valve engine. Unfortunately the car in question is a flathead with the valves in the block.

[c49er]

I did a DeSoto 236 a long time ago with out pulling the head. It had a broken valve spring. Saves a ton of time not having to pull the head and do all the clean up plus a new HG and coolant too.

Some pics of doing one an hour ago on a engine in my shop. The head was on. You screw the tappet adjuster down all the way to be able to remove the spring-not enough space to remove the screw on this 230 engine. Then push/hold the valve up while unscrewing the spring off the stem and along side of the adjusting screw. Took 1/2 hour to R&R the spring off and on.

Bob

Edited November 18, 2012 by c49er (see edit history)

[R Walling]

WMSUE, I love the idea of stuffing rope in the cly. and then bringing the piston up to firmly hole the valve in position.

I once used air pressure to hols the valve in position whyle changing springs on a Chrysler Hemi... Opps!, lost air and the valve dopped into the cylender... O S*#!

I saved the day though by using a small round magnet through the valve stem and a larger one through the spark plug hole. Only took an hour and had the valve back in the hole..

[JohnnyMaryjo]

Thanks for the advice 

But there is no way i could ever do this 

my flat head 6  in my 1941 P-12 Plymouth

is there anyone out there in the ohio , or pgh. pa area that can found out if my engine needs work done on the valves and or pistons or anything in the engine why it is causing it to choke  when given full throttle

thank you

Johnny

[plymouthcranbrook]

I would suspect a vacuum leak or a problem with the carburetor.  Is your accelerator pump working?  You can check that by taking the sir cleaner off and while looking down the carb with the engine off open the throttle. You should get a spurt of gas into the bore. If not the pump could be bad.  The leather sometimes dries out and then it will not work correctly.