The Stovebolt Site Forums The Shop Area Engine Shop How important is valve spring pressure?

Hi!

I found out that in my 235 (with 261 cam)all
intake valve spring have 3 mm less "preload" than all the exhaust valve springs (seems to be caused by the seat regrind)! Can this maybe cause my noisy valvetrain??????

All exhaust springs : about 45 mm
All intake springs: about 48 mm

Should I shim the intake springs to bring them to 45 mm?

What can too weak or too strong springs make for problems?

THANKS!!!!!

[ 11-20-2001: Message edited by: German235 ]

You need to find a book that gives the valve spring specs. as to lbs. of pressure at a given height. As far as making the valve train noisy if the springs do not have the correct pressure and height, it will not effect that but it could make the engine miss at high rpm. and could cause the valves to burn prematurely. If you are not going to be driving at high rpm's I wouldn't get too excited about it.

What year 235 do you have?

The 1954 Shop Manual states: "Springs should be compressed to 1 1/2 inches at which height the KMO-607 spring tester should read from 155-165 lbs on 235 engines and 175-185 lbs on 261 engines. Weak springs affect power and economy and should be replaced if not within the above limits."

The 261 camshaft has higher lift than in the 235 and higher load valve springs are used. The 261 also had stiffer push rods, rocker arms, and rocker shaft than the 235. The 261 also had exhaust valve rotators (used on the 235 Loadmaster engines but not used on the 235 Thriftmaster).

My books do not have any info on pre-load spring height. Sorry. If no one posts this within a few days, I will ask a local engine shop and post it here.

My guess is that you cannot have too stiff a spring (if you shim the 45mm springs) but too weak a spring could cause problems ("valve float" at higher rpm's -> problems as described by racecarldad).

I just bought a set of 12 springs for a 235 for $28 (from Patrick's).

Good luck,

Thanks for the info!

It´s a 1961 or 62 block...I have to look one more time...

But what about the hydrolifters? Doesn´t affect the spring pressure the bleed down rate? If the spring is too strong the hydrolifter will bleed down faster and starts ticking at idle, isn´t it????

I have a rocker assy from a 261 here and I did not found any differences to my new 235 assy! All parts are absolutely interchangeable!

I use the springs and the pushrods from my old 261 in my 235 (with the 261 cam)...so that should be ok...

My old 261 did not have exhaust valve rotators!

A last question: could this valve floating also come up at fast accelerating in the mid rpm range??? Or does it only depend on the rpms, not the load?

Thanks!

André

[ 11-21-2001: Message edited by: German235 ]

The correct installed valve spring height on a 235 or 261 is 1-27/32 or 1.84 inches.I have overhauled 2 of my 261's and a 235, the rocker arms and pushrods look the same to me.The rockerarm geometry is affected when the valves are sunk into the head, but i don't think that alone will make the valvetrain noisy.Andre, you were going to remove the noisy hydraulic lifters with the solids?

If you have it apart, go ahead and replace the springs. New keepers while you are at it.

Valve springs are easy to fix on a 235, drop a brick on the gas pedal and within 5 minutes at 5000 rpm, youll have no need for valve spring repair.

Well, there's at least two threads with smart-donkey advice- - - - -I predict your tenure here will short and unhappy. Most people here don't take kindly to dumb-butt comments.
Jerry

André, any engine will perform its best when everything is as close to spec as possible, and while you have it apart, you might as well do it right. I check spring heights, tension, set them on a straight edge and check them for being square. I also check the valve spring height. I would buy new springs and check them. Not all new springs are correct. I would also check the valves. The stem tips have to be ground to compensate for seat and face grinding. I know that there are machine shops in Germany that are very competent in doing this. I visit Germany quite often and have seen some of the machine shops. In fact, I will be in Germany later this week.

Jerry,
7 TIMES,so far.
Sounds like somebody,s got nothing better to do at O Dark Thirty,than play with this site and create HAVOC with old posts and WASTE SERVER SPACE,When Drunk or out of it!
regards,
steve sr.

Yep, some mouth-breather clowns grow a huge pair of C.O. Jones when they get behind a keyboard. Too bad they're only imaginary! I wonder if his mommy knows he's up past his bedtime? Don't feed the troll!
Jerry