Can to much preload cause valve float.

[Mike Licht]

springs lose tension after a couple hard passes, you should not use spring cups with those springs, .035 is on the bottom end I would use more than that if it were my car. I used to run .060 on mine with no issues up to 6400 and it was quiet too.
Mike

 

[forcefed86]

Appreciate the info! I picked up roughly 2mph dropping to the bottom of spec on my NA sbc with no other changes. Worlds apart I know. Even at .034 which was my preload on these custom push rods prior to the HG change I did not have excessive valve noise. These new “custom” pushrods are used and $24 for a complete set of 16. I can always go back to my others if they are noisy. Comp tech guys were no help they are suggesting a LS1 type beehive spring. With 106 closed and 290 open. I’m of course looking for the easiest drop in replacement.

 

[bison]

Appreciate the info! I picked up roughly 2mph dropping to the bottom of spec on my NA sbc with no other changes. Worlds apart I know. Even at .034 which was my preload on these custom push rods prior to the HG change I did not have excessive valve noise. These new “custom” pushrods are used and $24 for a complete set of 16. I can always go back to my others if they are noisy. Comp tech guys were no help they are suggesting a LS1 type beehive spring. With 106 closed and 290 open. I’m of course looking for the easiest drop in replacement.

The good old lt1 will usually be around 110#@1.700. I'd get a box of 16 from anywhere and measure them all and take the closest 12 and shim to 110# and call it a day. The spring comp suggested is an better choice and will be more stable at less pressure. Comp 981 can be shimmer to 110# also. As far as dropping on without checking. Good luck with that. Too much room for variation that will leave you scratching your head wondering why it still has a problem.

 

[forcefed86]

The info I found is showing the Lt4 springs at 100# closed. And Lt1 at 85# closed. This is at 1.78" installed height.


LT1 vs LT4

Looks like these VS739R autozone cheapy springs would work. Or the 981 comps. I'll probably start on the weaker autozone springs. Testing them of course.

OD(in.) Closed# Open# Rate(#/in.) Part number

(Sealed Power numbers)

> 1.20 80 200 267 VS677
> 1.23 85 230 295 VS1615
> 1.264 105 277 350 VS739R

(Comp Cams numbers)

> 1.24 80 200 267 CC 979 -
> 1.23 85 230 325 CC 980
> 1.25 110 285 ? CC 981
>

 

[forcefed86]

I have a nasty habit of not responding when everything works out. Anyway here is an update.

Installed all new springs. PN VS739R. Tested them all and they were all suprisingly close. Also tested my old springs of unknown brand/origin. THey tested exactly the same as the new springs until around the 1.0 of compression on the drill press. The new springs tested roughly 10psi higher than the old springs from this point on.

Went out for a test drive and had the same issue! This time I threw a code 42 so I knew something was odd. I started probing wires and found an open going to the coil pack. Come to find one of my recent nice t-brake launchs tore the driver side motor mount in half. This was allowing the engine to torque over far enough to pull the wires out of the coilpack module plug. Opened up my shrink wrap and found 2 wire pulled completely apart. Repaired these. Installed new mount. And installed torque strap. Car runs great. (cracked pedestals and all!)

 

[TurboDave]

Get you a set of H R Parts N Stuff motor mounts and NEVER suffer this issue again, and get rid of the ugly "strap".

 

[BlackBandit]

Get you a set of H R Parts N Stuff motor mounts and NEVER suffer this issue again, and get rid of the ugly "strap".

I agree with this 100%. At least get one for the drivers side. Of course, I'm assuming you're using buick mounts.

 

[joey316g]

if you were preloaded too much, you would see noticable idle problems. .060 is not too much if you think thats what you have...I would look for another problem like perhaps a broken valve spring...Ive experienced this alot on the 1.25 diameter single valve springs when used in services over 5500 rpm. Check thesprings very good and look for a broken coil or damper or both.

 

[BlackBandit]

if you were preloaded too much, you would see noticable idle problems. .060 is not too much if you think thats what you have...I would look for another problem like perhaps a broken valve spring...Ive experienced this alot on the 1.25 diameter single valve springs when used in services over 5500 rpm. Check thesprings very good and look for a broken coil or damper or both.

Read post #25.

 

[forcefed86]

I was checking out those poly mounts, they do look sweet. In all fairness those mounts were 6+ years old at least. My current "strap" consists of 1.5" thick wall steel tubing flattened on the ends and bolted to the back of the driversside head, and then to the frame. Almost like a rear mounted motor plate.

This engine is being replaced by a turbo LS1 this winter. I'm cutting costs where possible on the buick setup. Feels amazing up top compared to alst year I must say. We'll see if the 2" in tire difference( 26 to 28") improves the 10.24 or not. It may be to much to get out of the hole properly on the glides 1.76 first gear. Also the 100+ degree weather around here may put a stop to any new personal bests.

 

[joey316g]

Read post #25.

I saw it after I posted this....didnt see that it was fixed but thanks.

 

[forcefed86]

No problems with rockers... just went 10.14! :biggrin: