slant valve springs

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1930

1930

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I purchased some engine builder valves from E-bay item no 380919173128

I am also considering these 340 valve springs E-bay item no 390854240085 but I am thinking for a non high revving engine I may be wasting my money, that the stock valve springs will do just fine.

From what I have read a stiffer spring will put extra wear on valvetrain components and I am going for longevity with the engine. Not a racer.

What is your opinions on this?

Also can someone share with me how they test their existing valvesprings at home or is this something a machine shop can only do.

Recently D.I ( over on slant.org ) wrote within one of his posts about finding a couple of weak valvesprings on an engine/head he was working on and so Id like to also find the same potential problem if it is there.

Is it recomended to just change out to all new stock valvesprings when re-building an engine and if so are these springs still avail for a good price?
 
No, I would not change the springs.

You can do a rudimentary check by measuring spring free length; any that are way off from the others are suspect. But the only right way is to compress to a specific length and measure the spring force with a spring tester. My old manual for solid lifter /6 lists:
78-88 lbs @ 1-11/16"
170-184 lbs @ 1-5/16"
 
Do you plan to run a hot cam? If so run the 340 springs.
 
Consult with some of the Slant 6 guru's on Slant 6.org. "Doc" Dutra is one of many invaluable resources who frequent the board there. They are a wealth of knowledge on Slants and the issues and intricacies that surround their operation. Lake anywhere, they have there share of rude know-it-all's, but they are in the minority and the vast majority are eager to help.
 

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I would stay w/ stock springs. Stronger springs would not only limit life, they could wipe out a cam lobe on the initial startup if you don't do everything correct. As long as the spring is strong enough to return the valve with no gap between the cam, it is doing all that is needed.
 
Thanks guys, I ordered a coupe of sets of the 340 springs. I am considering buying a spring tester as well.

4o bucks a set I thought I am not losing much either way and one of the guys on .org recommended them.
 
BillGrissom said:
I would stay w/ stock springs. Stronger springs would not only limit life, they could wipe out a cam lobe on the initial startup if you don't do everything correct. As long as the spring is strong enough to return the valve with no gap between the cam, it is doing all that is needed.
Click to expand...
Exactly....well explained!
 
for spring pressure recommendations,, I would go with what the cam supplier recommends.
A custom cam grinder like Oregon will have in house experts,, a major cam supplier like Comp will have a Tech line. They would be familiar with the ramp rates and what it will take to control the valve. Modern cam profiles can have pretty fast ramp rates,, that is how they increase performance, the valve opens opens and closes (ramps) faster,
The risk with too low of a spring pressure is that there can be valve bounce at the seat when closing. That shock is not good for either the seat or the keeper grooves.

If your cam supplier is not concerned over spring pressure,, you have either a conservative cam profile or the cam lobe was made from an older master with slow ramp rates.
 
I checked our stock solid lifter slant springs just to see what they had @1.600 they barely made 50. That was a 71 engine with 90,000 miles on it. It's no wonder you cant over rev them Lol. I ended up with 75lbs seat @ 1.615-1.620. Theese were standard 318 springs.
 
Not many people are aware of this, but the factory installed slant six springs are weaker then the factory installed 318 springs but If you ordered slant six springs from the dealer or aftermarket, you would get 318 springs. This was true even back in the '60's and 70's.
 
for a valve spring compression tester,, you can use a sturdy drill press and a bathroom scale,,, force is force...

put the scale on the base of the drill press, insert the nose of the chuck into the spring and compress the spring to the installed height, read the scale...

be sure the spring is secure and horizontal,, if it would pop free it would give you a nasty hit. You would definately want safety guarding and a clamping fixture to check valve open pressures...
 
and I have a fish scale that reads in ounces, mounts in a drill press chuck and attaches to a distributor spring mounted firm to the drill press base, this time the chuck is retracted a set length,,pulling a spring to a set length,, allows one to determine spring tension, puts some level of predictability into the selection of springs for setting distributor mechanical advance.
 
video of the distributor spring tension tester..

cheap / light garage sale drill press, fish scale that reads in ounces..

[ame="https://www.youtube.com/watch?v=Pha1T4kQt9E"]YouTube[/ame]
 
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