quick and violent D Digit Knock, valve springs?

[ThikStik]

Happy new year to all. o2 are 820, blm 129, and knock around 3-4..but from a dead stop, the K goes to 15-25 sometime during first gear. And it doesnt always do it. I have never seen K that comes on so suddenly and so hi. I also can free rev motor, and at 4500 rpm, it sets off K detector. Sometoimes a 3rd gear romp will do it also. A romp from 2nd will not do it. Im suspecting the valve springs, they are recent Comp 980's with maybe 25k miles. But this motor is very noisy with forged CP pistons. Could valve float be it? or the pistons? I hate to complicate the issue , but i also have a turbo 700 trans, and am wondering if its big gear drop from 1st to 2nd is the problem. Still, it does do it sometimes on a hiway romp.

TIA
Thanks

 

[Gary Wells]

FWIW & IMHO:
You might want to consider bypassing the boost solenoid over on the passanger side valve cover by removing the vacuum line running to it and plugging the vacuum line. If anything changes, there is a good chance that the solenoid is shot. If that turns out to be the case, consider buying a RJC Hybird boost controller, or something similiar, as a replacement. Solved my issues.
This thread might help, unfortunately, it is on our sisterships site. The one that we cant mention, you know the place, HTH

http://www.turbo*****s.com/forums/showthread.php?t=43945

 

[Ormand]

It sounds like the knock detector is being set off by something besides knock. You won't get knock by free revving the engine, for example. Many of the aftermarket chips have a "delay" feature, to prevent the ECM from finding false knock in first gear. Have you looked for the normal sources of false knock, like the down pipe hitting the frame? Don't think valve float will set off the knock detector. Pistons, maybe, but doesn't seem likely. If it were pistons, they would do it the same in every gear, as would valve noise.

 

[Gary Wells]

Might also want to keep a close eye on this thread as it displays symptons virtually identical to yours. Sistership again. HTH

http://www.turbo*****s.com/forums/showthread.php?t=45049

 

[broke1]

http://www.turbobuick.com/forums/showthread.php?t=173320

One more time,WHAT KIND OF CHAIN YOU GOT IN THERE?

 

[ThikStik]

Thanks guys, Well the basics should be covered like mounts, d pipe. This prob has only been uncovered since I found my freaking egr valve was leaking vac/boost . That has cleaned up my rich o2's and sinle dig K , and blm's. But even then, I never had double dig, and sudden K. The boost is now more consistant, but, it does go beyond the set point (not sure if it does from a 1 st gear launch, mainly seems to after a long pull). So, it could be a case of sudden overboost-geez, it just seems like it would work its way up from audible pinging. btw-I dont hear a ping at any time. And it should be easier on motor from a dig, than from a hiway romp. It does actually do it on a 3rd gear romp sometimes-it depends on instant rpms. If there hi, it will set off K-but not always. Thanks Wells, I will check out that thread. I can say that the 4500 rpm free rev ALWAYS sets of k.
Drew, I think I got a Cloyes double roller...have you heard they have issues?
Thanks again guys

 

[ThikStik]

I blended in some race gas to get around 95 octane. I ran it out from a 1st gear start. It did fine. Did it again , and it went into the usual DDK. It has run fine a few times on 93 gas, so I have perhaps eliminated octane. I did notice that the boost creeps to 19-19.5 (Testa chip is an 18lb) on a good K free run. But I do know that it sets off the K at 14-15 (when it craps itself) so I dont know if its officially over boost. May need to try your idea, Wells.

I do suspect a tuning problem, because under very little load, it feels like a cylinder is missing intermittantly. Its just like a plug wire biting, but it must not be ign related or it would do it under boost. Im suspecting an injectoras my fp gauge bleeds down within 30 seconds. Its been this way forever, and i have verified its not the regulator. I can give it just a tad more gas and it runs smoothly. In a tuning corner as usual.

 

[ThikStik]

I found the famous #3 exh valve to be opening just enough less to be visible.
Barely less. Maybe thats driving up cylindr pressure on that cylinder and causing the double K. This motor killed the oe cams #3 lobe at 138 k. This is a comp 206/206 with around 14k so I guess its a goner. Far be it for a part to last more than a year or so.
Anyone know if this could trigger K? I know after they really wear down it will pop thru intake/.

 

[ThikStik]

I hate to resuscitate the old , but figured Id report that apparantly the K problem is solved. I put in a Full Throttle (Comp)206/206 roller and it is very nice with no K from a dig. I didnt even get K on gear change. I havent free revved it to test for un-loaded K as it did have. Old flat tappet Comp 206 had only 8 k miles and had 2 lobes going, and all of them were different in measurement. I still dont trust this to last long, and almost wonder if something got blindly fixed, but on this 98 degree day, I couldnt believe that there was 0 K on a 16 psi pull with old gas at that.
After buying 2 cams from Comp, I think I deserve it.