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P&G Valve Gapper User's Manual

 
Old 02-06-2010, 11:05 PM
  #21  
mechron
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Originally Posted by jtranger View Post
I assume this approach is done hot. Can the Duntov also be adjusted this way, until the clacking stops?
jt--> and all you other guys poking fun at me...:cheers i love a good joke. i need to elaborate. a complete tune up on any solid lifter c-1 or c-2 always included a valve adjustment. valve adjustment was always done last (yes, after the engine warmed up and everything else was adjusted JT). i never had a vette driver who actually knew which cam he had.
BY EAR until the clacking stopped was not the adjustment, but would get you close enough to positively identify the cam. at that point you could adjust the lash with a feeler gauge. they are called "feeler gauges" because you can feel the drag as you move it in and out between the rocker and valve stem to do the adjustment, and yes, they are extremely accurate if used right. what worked for me was to just back off the valves until each one started clacking then tighten until the clack disappeared one at a time at idle. this put you on the clearance ramps designed into any solid lifter cam. at this point shut the engine off and adjust the valve clearance with a feeler useing the IE method. hope this clears up my previous post guys...

JT, any solid lifter corvette or after market race cam including the duntov can be identified this way...
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Old 09-05-2016, 11:27 AM
  #22  
vortec710
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Just to add fuel to this fire, I owned 1967 Chevelle SS 396/375hp in 1967, bought a P&G gapper they offered for the solid lifter BBC's. Hooked up a remote starter switch, a bumper, if you will, under the hood, would warm up the motor to operating temp, shut it off, remove the valve cover, slide the P&G under the rocker and onto the retainer and bump the starter over until a reading was obtained, adjust and recheck until right. If the P&G gave different varied clearances, it was time to change the valve keeper to prevent the valve from pulling out and into a piston. Saved my motor on more than one occasion and was worth every cent I paid for it. Feeler gauges could not do this and that was why I relied on the P&G.
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Old 09-05-2016, 02:24 PM
  #23  
wmf62
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I also could use a copy of the P&G manual; I bought one 50 years ago to adjust the valves on my factory 426 wedge Dodge (done with engine cold...)

tried it once with my chevy engine (running) and it was a mess.

haven't used it since.

Bill
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Old 09-06-2016, 12:49 PM
  #24  
SWCDuke
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Originally Posted by mechron View Post
no offence, but i never had any use for one, they are slow as can be. on solid lifter C2s feeler gaugers are way faster. but adjusting all the C2 solid cams i just listenend to them, they were way faster to adjust when the ramps quited downed, you never had to figure if they a 12-17 or a 20-20 or a 30-30 cam, you just adjustede them until the clacking stopped... then you knew you were on ramps of the cam. now days hydrolics and hydroc roller lifters makes solid lifter cam lifters obsolite
No matter how accurate the adjustment procedure, if you use the wrong spec, the result is wrong. And why do the procedure multiple times "by ear" when you have access to a spec, which is based on a dynamic analysis of the lobe data on the engineering drawings (in inches to five decimal places every cam degree) that very accurately identifies the top of the constant velocity clearance ramp and takes into account rocker ratio behavior, which varies throughout the lift cycle.

Under all operating conditions, the valve should be lifted off the seat and seated at no more than clearance ramp velocity to ensure maximum valve float speed and be easy on the seats.

The attached procedure guarantees the above result! A properly adjusted mechanical lifter should be barely perceptibly louder than a properly adjusted hydraulic lifter... maybe some guys can't even tell.

All the OE settings are too loose because they didn't take into account the fact that the rocker ratio is less than the "theoretical" 1.5 on a small block, and it's minimum at the lash point.

Duke
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Old 09-06-2016, 05:20 PM
  #25  
W Guy
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Originally Posted by vortec710 View Post
Just to add fuel to this fire, I owned 1967 Chevelle SS 396/375hp in 1967, bought a P&G gapper they offered for the solid lifter BBC's. Hooked up a remote starter switch, a bumper, if you will, under the hood, would warm up the motor to operating temp, shut it off, remove the valve cover, slide the P&G under the rocker and onto the retainer and bump the starter over until a reading was obtained, adjust and recheck until right. If the P&G gave different varied clearances, it was time to change the valve keeper to prevent the valve from pulling out and into a piston. Saved my motor on more than one occasion and was worth every cent I paid for it. Feeler gauges could not do this and that was why I relied on the P&G.
It's interesting that you mentioned this. The next time I use my P&G, I'll cycle the lift events a few times and see if I get any variation.

The thing I like about the P&G is that once you install it on the retainer, it snaps in place and stays put. You don't have to keep putting it in and out to get readings. When the rocker is on the stem, just zero the dial. If you're starting with lash already, just pull up on the heel of the rocker until it hits the valve and set the zero. The spring in the tool keeps pressure upward under the rocker tip, so as you bump the cam around all you have to do is watch the dial for a reading. If it gets higher than you want, just tighten down the adjusting nut. Keep doing that until the reading starts to decline, and you're all done with that one.
If you go through the whole event and the reading never reaches the lash you want, you'd have to go around again but that can be avoided by loosening the nut before you start. You merely squeeze the barrel down with your thumb when you install it so the lift fingers slide in under the tip of the rocker. Easy Peasy.

Verne
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