Valve Spring Differences

R

Rodney Racer

Junior Member
OK all you experts out there. Help Me Out Here.. I have a fresh fresh fresh 59AB. Done up by a "well-known" flathead builder. Runs terrible at idle. Passes compression test, has an NOS bone stock cam. Vacuum Gauge Needle bounces like crazy at idle. SO--- I pulled intake, checked valve adjustment, right on the money, loosened them up a couple thou. just to see what I would get.. Runs about the same.. Pulled heads and valves --- But in checking valve spring pressure---- Sure did seem VERY WEAK--- So I checked out two of the OTHER engines I have here.. One has a big cam and springs, yep, they have some real GOOD pressure.. The other has a spring with a larger wire diameter that what is in this stocker. I REALLY SUSPECT these "stock" springs are just to weak. But they are "new" --- Anyone care to express an opinion here?

The picture shows the spring I have in question on the left. The one in the middle is MUCH stronger and the one on the right is used with the Big Cam
 

Attachments

  • DSCN0115.jpg
    DSCN0115.jpg
    49.3 KB · Views: 88
50 lbs on the seat will work well.
What is the pressure @2" installed. The first spring should be all you need if they are 50lbs.

R
 
The complaint regarding idle behavior is not characteristic of weak spring pressure but more like sticking valves. The idle speed spring pressure could be 30 lbs. and operation shouldn't be faulty unless valve-to-guide problems exist.

What does the engine do when you rev it up? What is the installed length of the spring when valve is seated? What is the spring pressure at that length?
 
All installed spring heights are 2 1/8- MAX 2.180 I have no real true way to test installed pressure. BUT I can reach in with two fingers and open valves. Can do it on the other engines I have opened up. I know that the book says 30# low limit. Seems that I should not be able to open them by hand. Guides are new- valve grind fresh. All valve faces have light carbon on them..
 
Put a spring on your bathroom scale and hold it at 2 1/8". Look at reading. Do it several times to get a "feel". Much easier to do in a drill press with scales on table.

Again, what was engine performance when revved up above idle?
 
Just googled engine rebuilders in napa valley & come up with a pretty good list. One of these outfits should be able to test your springs.
just a few.:

L J's Speed & Machine Shop Inc

www.ljsspeedandmachine.com
Google+ page
https://maps.google.com/maps?oe=utf...a=X&ei=DrqpU7L8G8Pg8AWYnYKAAQ&ved=0CEcQrwswAw
954 Kaiser Rd
Napa, CA
(707) 255-4611



MCM Jobe's Repair, Inc.

www.mcmjobes.com
Google+ page
https://maps.google.com/maps?oe=utf...a=X&ei=DrqpU7L8G8Pg8AWYnYKAAQ&ved=0CE4QrwswBA
1824 Yajome St
Napa, CA
(707) 252-8802





Kragen Auto Parts

www.cskauto.com
1 Google review
https://maps.google.com/maps?oe=utf...a=X&ei=DrqpU7L8G8Pg8AWYnYKAAQ&ved=0CFUQrwswBQ
1685 Trancas St
Napa, CA
(707) 255-5266





Star Auto Services

www.[B]ca[/B]rrepairnapa.com
Google+ page
https://maps.google.com/maps?oe=utf...a=X&ei=DrqpU7L8G8Pg8AWYnYKAAQ&ved=0CFwQrwswBg
1162 Jordan Ln
Napa, CA
(707) 294-2364





Silver Auto Service

silverautonapa.wix.com
Google+ page
 
LJ's does all my machine-work. Been there this morning with a few parts to see what we could figure out.
Look REAL CLOSE at the photos. See the different valve spring retainers? Free spring height is about the same on all three springs. KEEP IN MIND, I have three engines I am working on, so I can compare parts. the photo shows the spring in the center to have a different (51 to 53) retainer. While at LJ's we tested spring pressure with the set as removed from this problem engine. Came up with 20# pressure with the 48 to 50 retainers... Not good enough! Changed the retainer to the 51-53 set from the other engine and got 48# pressure. So I headed home with the parts and installed one ex. and int. but the installed height was reduced to 1 7/8" There is no coil bind when valve is fully open. Shall I go for it with the 51-53 retainers? What am I missing here? BY The Way, the valve guides fit pretty darn LOOSE in the block..... Does this last statement change everything? REMEMBER, I really had almost NO closing pressure.
 
You need to test the springs without the retainers in the test.Shoot for 2" and get the reading.Do all the springs.After the pressure is discovered you then fool around with retainers,shims and locks to achieve the desired height(2") and the pressure will be at what you tested at.

R
 

Attachments

  • spring pressure.jpg
    spring pressure.jpg
    9.4 KB · Views: 16
Yes--- exactly as shown in your photo, I get 20# with stock spring at 2" (I am told this is a NEW spring set, but I have no clue where they came from) If I use the red springs shown in my picture, I get more than 30# at 2".
Add the 51-53 retainer, set the end of retainer to 2" and I get 48# with the black original "new" springs. In other words, pre-compress by .300 (or spring height 1 7/8") and I get the desired number.
 
We have two springs in inventory for "stock" Flathead builds, one, part #VS-393 for '48/'50 has a free-length of 2.437" and has "progressive" wound coils.

The other, part #VS-527 for '51/'53 has a free-length of 2.190" and has "conventional" wound coils.

Using the 2.000" checking height mentioned above the 2.190" spring has 25# pressure, while the 2.437" has 55#.

Keep in mind you always have the option of .050" shorter locks. This helps on setting spring heights occasionally!

Thanks, Gary in N.Y.

P.S. The '51/'53 use the two piece retainer which explains the "shorter" springs. Hope this helps some, good luck!
 
Thanks for all this help! yes, the 51-53 is a 2-piece retainer. the spring on that engine is about 2.20 free height with about .141 wire diameter. On the "problem" 1948 engine, the free height is 2.310 and wire dia. of .128. both are progressive wound. Gary, I was looking at parts suppliers for spring wire and height is listed, all suppliers I checked only show ONE spring part number for the flathead. Could be that when I place an order they then ask for more info, I don't know. Just for fun (yah-right) I put the red spring (2.20 with .141 wire) in the engine with the 48 one piece retainer and it still has MUCH more closing pressure that the small wire, taller springs that were in the engine..
 
Just to add a bit of information, I have one engine out there with a Max #1 cam and valve rotators. Using stock springs and a .030" shim. Been running niw for the past 10 years. I like the use of rotators.
 
You must log in or register to reply here.
Back
Top