Guess my L67s varnish is "bad"

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Shannow

Shannow

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Dec 12, 2002
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'Stralia
Got a tax refund this year, first in ages, so decided to do a few things out of the norm.

Plastic rocker covers on the L67 have been a bit drippy, so lashed out and bought a set of polished alloy ones...and thought that while in there I'd put some higher ratio rockers in...inlet only.

Straight bolt in mod, to augment my 10psi pulley.

Varnish with the rocker covers off was worse than my fill hole pics, quite seriously. Red/Brown, and quite rough in spots...no pics, but I do have the old covers, and will post a pic of them in my varnish thread.

Put the new rockers in, and ended up with every inlet valve cracked open...apparently the lifters refused to bleed down to accomodate.

Will be contacting the supplier to make sure that they sent the right bits...but in the absence of that being wrong. looks like there might be enough gunk, despite all my flushing efforts to have kept the lifter from running full stroke...maybe.
 
Originally Posted By: splinter
SOTP improvement with the new rockers?


Lost a lot of performance...wouldn't start at all with no compression due to the inlet valves not sealing...back to stock.

the 10psi pulley was marked 'though. Will wheelspin on kickdown at 55MPH if the road's a little damp.
 
You change the rockers ratio and this changes the geometry of actuating the valves. The push rods are now too long for your new geometry. The manufacturer should have the info, but if not you'll need to 'mock up' some hardware with correct rod end ball sizes to find the required length. The easiest may be to just source adustables to accomodate-for your aplication they'll probably be the cheapest priced.
 
Originally Posted By: Shannow
Lost a lot of performance...wouldn't start at all with no compression due to the inlet valves not sealing...back to stock.

the 10psi pulley was marked 'though. Will wheelspin on kickdown at 55MPH if the road's a little damp.

That's too bad. You've always struck me as a 'clean oil' gent.

Yeah spinning the supercharger a bit faster (with IATs in check) is almost always a good thing!
 
Originally Posted By: Shannow
Originally Posted By: splinter
SOTP improvement with the new rockers?


Lost a lot of performance...wouldn't start at all with no compression due to the inlet valves not sealing...back to stock.

the 10psi pulley was marked 'though. Will wheelspin on kickdown at 55MPH if the road's a little damp.



Nice.

I'm supercharging my charger this spring with my taxes. A twin screw is an option right now however I'd like to keep mds,so a snail might be my only choice.
Boost is awesome. I ran nitrous for years but boost is on demand and no tank to fill.
 
Originally Posted By: Clevy
Where's the pics?

What kind of teaser thread is this?


IMG_20141227_131722.jpg
 
Originally Posted By: Lapham3
You change the rockers ratio and this changes the geometry of actuating the valves. The push rods are now too long for your new geometry. The manufacturer should have the info, but if not you'll need to 'mock up' some hardware with correct rod end ball sizes to find the required length. The easiest may be to just source adustables to accomodate-for your aplication they'll probably be the cheapest priced.


Confirmed before purchase that these are direct bolt in, nothing else required...thus my going back to them Monday to reconfirm that this is the case.
 
Often longer rocker studs solve this problem, surprised your performance parts dealer did not recommend them along with pushrod guides. Shannow, I assume you are at the end of adjustment for the new rockers but the valves remain partially open with lifters on the cam's base circle?

The L67 does use adjustable rockers (like more OHV GM engines), right?
 
Originally Posted By: splinter
Were you able to catch up with your vendor to help get this squared away?


They are on a shut over new year...you get that.
 
Originally Posted By: Lapham3
You change the rockers ratio and this changes the geometry of actuating the valves. The push rods are now too long for your new geometry. The manufacturer should have the info, but if not you'll need to 'mock up' some hardware with correct rod end ball sizes to find the required length. The easiest may be to just source adustables to accomodate-for your aplication they'll probably be the cheapest priced.


NO, the pushrod location on the rocker is a little closer to the pivot point (the rocker stud) which provides a higher ratio lever arm . I'm more familiar with SBC stuff but from the looks of these Buick rockers he could probably put a washer between the rocker and head to fix this or just send them back and get the proper rockers.

ra_fixture.jpg
 
Last edited:
turtlevette, hi for starters and happy New Year.

Yep, you are correct, in that they are fixed, they fill the existing hole, and machine a new one closer to the fulcrum giving the ratio.

Problem is that a head full of rockers are on a single aluminium "girdle" (???) that runs the length of the head, and has matching concaves for the convex of the individual "shafts" (just under the cap-head screw on the jig that you have shown.

I've shimmed and filed for rocker alignment and lifter preload before on Holden sixes and eights that I've owned, so have a little appreciation of the issue.

Sold to me as a direct bolt in, will see what they say when open in a week or so...or I have the varnish issue, which I've still not discounted.
 
IMG_20150124_153430.jpg


Turns out that when the pushrod hole is moved closer to the fulcrum, the pushrods run into the "u" shaped "guides" in the girdle, and ride up in the pushrod hole.

They sold me a set of modified plates at mate's rates, and I fitted them today...Lifters bled down, but have still a few issues on warm-up, with what sounds like an occasional sticky valve.

Will suck it and see, but the throttle opening at 100km/hr has changed.
 
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