The Stovebolt Site Forums The Shop Area Engine Shop Valve spring question(s)

54 235 848 head w/std valves:

1) with valves fully closed, should the springs be able to be turned some by hand? Mine can.

2) I'm finding differing specs on a 54 235 spring free height. Trucks call for 2.16" and the Vette and BelAir call for 2.25". Both w/o rotators.
Any problems w/the 2.25" spring in a truck 235?

3) Would changing to exhaust rotators be a drop in?

Dave

Here is the 1954 Chevrolet information packet, look at the engine section almost at the bottom and you will find valve spring specifications.
https://www.gmheritagecenter.com/do...hevrolet-Trucks/1954-Chevrolet-Truck.pdf

Incase you don't look, here it is,

62 to 68 pounds of pressure with valve closed. You could rotate these by hand.
155 to 165 with valves fully open, these you should not be able to turn.

Valve closed, spring hight is 1.821" Valve open, 1.505" Free length 2.156"

Lobe lift, Exh - .2111", Int - .1991" Rocker ratio 1.477:1
Valve lift, Exh - .3118", Int. - .2941"

A taller spring will increase spring pressure all around, but also increases pressure on the cam lobes. Just be sure to check for coil bind if you switch. Coil bind is maximum compression of spring where the coils touch each other. If this is well beyond maximum valve lift, you are good to go. .050" would as close as I would let the get to coil bind.

Joe

Thanks Joe
Looks like my springs are either shot or too short, even tho the head rebuilder indicated they were OK. I pulled a couple and measured their free height and got 2.06" on both. The exhausts have the roto caps so that settles those questions.

Research at Rock Auto has turned up a couple differing options.
The truck 235 doesn't detail roto caps and has a 2.16" and 2.156" offerings.
The Vette & Bel Air 235 does detail a spring for the roto cap. It is listed at 2.281", Another offer is listed at 2.25" but doesn't indicate if it's for a roto cap. One other is listed at 2.156 and is the same part# as the truck spring and it indicates that it is not for the roto cap.

So I'm looking at either a 2.281" or 2.25" spring set which is considerably taller than whats in the 848 head now.

The reasons for checking the head is basically due to erratic vacuum readings and a leakdown test that showed leakage in the valves. The engine is freshly rebuilt and the head has new exhaust valves and hardened seats, new intake seats, recut intake valves and new guides. Relapping has got all but #4 & 5 exhausts sealing up good. 4 & 5 exhaust will weep alittle gas after 30 secs or so when the port(s) is filled with gas.
The head rebuilder claims the valves will eventually seal with use and has rechecked the head and says it's GTG. We've both relapped them now. Before I slap it back on I'm going to replace those springs and hope he's right, just got to decide which length.

Other than putting a little more stress on the cam lobes, slightly stiffer springs won't hurt. Just don't get into a coil bind situation. Check the spring tension at the "valve closed" dimension and you'll get the amount of pressure holding the valve closed. The spring tester I used for a lot of years had a "click" noise that could be set to indicate when the "valve closed" dimension was reached, and I could read the tension at that point on a flex-beam torque wrench. More sophisticated ones I've used since then have a positive stop system and a scale to read spring pressure rather than using a torque wrench.
Jerry

While I was at the GM Heritage Center looking at the '54 truck information, I looked at the '54 Corvette as well. It didn't list valves spring but said the engine was pretty much the same as the truck except, lifters and three carburetors.

Here is the '57 parts manual listing,
http://chevy.oldcarmanualproject.com/1929_57chevyparts/57cmpc0138.htm

It shows Corvette's using the longer 2.250" springs.

Some Corvette 235 differences (by end of the "run" in 1955):

- intake system
- exhaust system
- carburetors & air cleaners
- generator (with tachometer "sender")
- camshaft (261 style)
- some valve "train" parts
- (color and "Blue Flame Six" decal)