Compcam steelrocker turned blue hot !! valve adjusting related
07-24-2007, 06:21 PM
#1
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Compcam steelrocker turned blue hot !! valve adjusting related
I had some poor performance after readjusting the rockers the last time, it was drive able but misfiring and ugly midrange,
the first time I set them at 1/2 turn (engine off /hot engine)
but then I recalled that when I set my other cars (totally stock old chevies) rockers at a fullturn as per original Manual, it sounded great and had great responce , I decided to readjust , worked ok until the day after the engine sounded bad and I actually though it was Carb or ignition probs ,,that type of sound ,
the Yesterday I read about you really should set valves at quarter to half turn or otherwise the valves may not close !? ok so I decided to set them at quart turn, and it sounds good again !
BUT the only thing was that one of the Compcam 1,52 steelrockers had turned blue between the push rod side and center (only that side) I checked it and the pivot ball they seemed ok ( the pivot ball was not blue )and no cracks or such (and no weird sounds when running) it seemed to have been so hot that some of the oil had actually been burnt on the rocker around that area when I popped the cover it was full of normally hot oil and no heat no sizzling etc a so I assumed this may have happened when I was driving the car a little hard the other day on the highway reving over 5K+ for a while
I wonder is it possible that the rocker has gone too tight somehow ?
is 1 full turn too tight and maybe really on the edge off too much in a set up like this ??
or maybe the lifter been damaged not pumping oil properly??
my engine has L82 cam 10,25 flattop pistons, Dart eagle iron 180cc heads, 1,52 rockers, chromoly pushrods, screw in studs, guide plates ( not too tight either from what I can tell)
any ideas ?
the first time I set them at 1/2 turn (engine off /hot engine)
but then I recalled that when I set my other cars (totally stock old chevies) rockers at a fullturn as per original Manual, it sounded great and had great responce , I decided to readjust , worked ok until the day after the engine sounded bad and I actually though it was Carb or ignition probs ,,that type of sound ,
the Yesterday I read about you really should set valves at quarter to half turn or otherwise the valves may not close !? ok so I decided to set them at quart turn, and it sounds good again !
BUT the only thing was that one of the Compcam 1,52 steelrockers had turned blue between the push rod side and center (only that side) I checked it and the pivot ball they seemed ok ( the pivot ball was not blue )and no cracks or such (and no weird sounds when running) it seemed to have been so hot that some of the oil had actually been burnt on the rocker around that area when I popped the cover it was full of normally hot oil and no heat no sizzling etc a so I assumed this may have happened when I was driving the car a little hard the other day on the highway reving over 5K+ for a while
I wonder is it possible that the rocker has gone too tight somehow ?
is 1 full turn too tight and maybe really on the edge off too much in a set up like this ??
or maybe the lifter been damaged not pumping oil properly??
my engine has L82 cam 10,25 flattop pistons, Dart eagle iron 180cc heads, 1,52 rockers, chromoly pushrods, screw in studs, guide plates ( not too tight either from what I can tell)
any ideas ?
Last edited by tomcat65; 07-24-2007 at 06:46 PM.
07-24-2007, 06:37 PM
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Sounds like you turned the rocker adjustment nuts in to far and the pushrods burned into the rockers. I bet you need new lifters, rockers and pushrods. You got lucky a valve didn't hit a piston. The correct adjustment is zero lash + 1/4 turn
07-24-2007, 06:58 PM
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I wonder is it possible that the rocker has gone too tight somehow ?
is 1 full turn too tight and maybe really on the edge off too much in a set up like this ??
or maybe the lifter been damaged not pumping oil properly??
my engine has L82 cam 10,25 flattop pistons, Dart eagle iron 180cc heads, 1,52 rockers, chromoly pushrods, screw in studs, guide plates ( not too tight either from what I can tell)
any ideas ?
07-24-2007, 07:32 PM
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Oh,, the studs are tight in the heads alright,
by not too tight I meant pushrod sideplay not too tight causing friction heat by guide plate, it has the same play as the other in the engine so thats not it,
,, I am thinking maybe the full turn adjustment actually might have made the rocker come too close to the stud arrangement ,, since they are thicker that stock rockers, btw I use the race doublelocking nuts so they are tight the pushrod looked ok really I started the engine now and it runs really nicely on idle maybe I just go ahead and change the rocker and pushrod and hope the lifter actually made it
07-24-2007, 08:21 PM
#5
"Burnt-blue" Rockers
Just a tip, but we've seen this numerous times over the years and I can tell you with reasonable certainty it caused by "late" (read that as VERY late) ignition timing.
This affects the "exhaust" rocker most times, it will not be visible on the intakes due to the "cold" air coming in! A very lean condition could also cause what you're describing by raising cylinder temp's, but most times it's the "late" timing issue.
This is one of the reasons you must be careful when "picking out" your C.R. and the fuel you'll be running. If you examine the other exhaust's you will PROBABLY see it happening to them as well. All this assumes that the unit has no other serious issues pertaining to one single cylinder.
You most likely will have to "dial-in" more timing! If you experience any detonation at that stage, with additional timing, the next step will be "mixing" some pump-gas and some fuel.
It's hard to make a call about your C.R., not enough info to evaluate. Would need part numbers, etc. If you have a "4-eyebrow" piston (5 cc notch's) and a 64 cc head, you are probably in the neighborhood of 9.8:1 with an .038" gasket! I assume the decks are not milled if you have the original "matching numbers" block!
The 9.8:1 with "iron" heads, if that's where you are at, is going to take some "sharp" tuning to run 93, especially with the "short" 224* cam inside. The short(er) duration actually raises the cylinder pressures, a slightly larger cam would have helped some!
Thanks, Gary in N.Y.
P.S. What you are actually seeing is the "tip-of-the-iceberg", more damage to the valves, springs, etc, usually follows suit if it's left as-is!
This affects the "exhaust" rocker most times, it will not be visible on the intakes due to the "cold" air coming in! A very lean condition could also cause what you're describing by raising cylinder temp's, but most times it's the "late" timing issue.
This is one of the reasons you must be careful when "picking out" your C.R. and the fuel you'll be running. If you examine the other exhaust's you will PROBABLY see it happening to them as well. All this assumes that the unit has no other serious issues pertaining to one single cylinder.
You most likely will have to "dial-in" more timing! If you experience any detonation at that stage, with additional timing, the next step will be "mixing" some pump-gas and some fuel.
It's hard to make a call about your C.R., not enough info to evaluate. Would need part numbers, etc. If you have a "4-eyebrow" piston (5 cc notch's) and a 64 cc head, you are probably in the neighborhood of 9.8:1 with an .038" gasket! I assume the decks are not milled if you have the original "matching numbers" block!
The 9.8:1 with "iron" heads, if that's where you are at, is going to take some "sharp" tuning to run 93, especially with the "short" 224* cam inside. The short(er) duration actually raises the cylinder pressures, a slightly larger cam would have helped some!
Thanks, Gary in N.Y.
P.S. What you are actually seeing is the "tip-of-the-iceberg", more damage to the valves, springs, etc, usually follows suit if it's left as-is!
07-24-2007, 09:20 PM
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Just a tip, but we've seen this numerous times over the years and I can tell you with reasonable certainty it caused by "late" (read that as VERY late) ignition timing.
This affects the "exhaust" rocker most times, it will not be visible on the intakes due to the "cold" air coming in! A very lean condition could also cause what you're describing by raising cylinder temp's, but most times it's the "late" timing issue.
This is one of the reasons you must be careful when "picking out" your C.R. and the fuel you'll be running. If you examine the other exhaust's you will PROBABLY see it happening to them as well. All this assumes that the unit has no other serious issues pertaining to one single cylinder.
You most likely will have to "dial-in" more timing! If you experience any detonation at that stage, with additional timing, the next step will be "mixing" some pump-gas and some fuel.
It's hard to make a call about your C.R., not enough info to evaluate. Would need part numbers, etc. If you have a "4-eyebrow" piston (5 cc notch's) and a 64 cc head, you are probably in the neighborhood of 9.8:1 with an .038" gasket! I assume the decks are not milled if you have the original "matching numbers" block!
The 9.8:1 with "iron" heads, if that's where you are at, is going to take some "sharp" tuning to run 93, especially with the "short" 224* cam inside. The short(er) duration actually raises the cylinder pressures, a slightly larger cam would have helped some!
Thanks, Gary in N.Y.
P.S. What you are actually seeing is the "tip-of-the-iceberg", more damage to the valves, springs, etc, usually follows suit if it's left as-is!
This affects the "exhaust" rocker most times, it will not be visible on the intakes due to the "cold" air coming in! A very lean condition could also cause what you're describing by raising cylinder temp's, but most times it's the "late" timing issue.
This is one of the reasons you must be careful when "picking out" your C.R. and the fuel you'll be running. If you examine the other exhaust's you will PROBABLY see it happening to them as well. All this assumes that the unit has no other serious issues pertaining to one single cylinder.
You most likely will have to "dial-in" more timing! If you experience any detonation at that stage, with additional timing, the next step will be "mixing" some pump-gas and some fuel.
It's hard to make a call about your C.R., not enough info to evaluate. Would need part numbers, etc. If you have a "4-eyebrow" piston (5 cc notch's) and a 64 cc head, you are probably in the neighborhood of 9.8:1 with an .038" gasket! I assume the decks are not milled if you have the original "matching numbers" block!
The 9.8:1 with "iron" heads, if that's where you are at, is going to take some "sharp" tuning to run 93, especially with the "short" 224* cam inside. The short(er) duration actually raises the cylinder pressures, a slightly larger cam would have helped some!
Thanks, Gary in N.Y.
P.S. What you are actually seeing is the "tip-of-the-iceberg", more damage to the valves, springs, etc, usually follows suit if it's left as-is!
the funny thing is I checked the TDC to match mark on damper and it was correct , I reset the distributor pointing at #1 cyl ,,and set idle timing to 12´bt accordingly, but it runs kind of hard at 12´ and it responds rather rough on throttle, when I eased off a bit on timing it revs up sligthly and idles real nicely and responds well to slight throttle , but then the diallamp mark is almost up beond the timing mark plate on idle and when rev up to 3k it s not even visible way over the top off the damper !!??
will the 2´advanced cam mess up any off this ? I heard that different engines having tdc marks at 12aclock,, but I checked the tdc and it matched the 2 aclock timing plate,
another thing that I thought off right now is that the distributor has some rather large endplay between the bottom gear and housing there is a little shim there but the play is about double than the shim is thick ,,hmm,,
I appreciate all help,
Last edited by tomcat65; 07-24-2007 at 09:43 PM.
07-24-2007, 09:42 PM
#7
Race Director
There is a paper describing what the endplay should be. Setting the endplay is not very hard to do. I believe the endplay should be around .007" or so. Let me see if I can dig up the paper on endplay. Maybe someone can chime in.
A few threads about endplay.
Thread 1
Thread 2
A few threads about endplay.
Thread 1
Thread 2
Last edited by Eddie 70; 07-24-2007 at 09:49 PM.
07-25-2007, 02:38 PM
#8
Melting Slicks
I had a whole set of the Comp 1.52's turn blue.Found out too late,(bent pushrods),and discovered the pushrods were only rated to 300 lbs spring pressure. My AFR springs push 360 lbs open.I upped the anti and went with .080 thickwall chromemoly pushrods,and full roller rockers this time.From what I can gather,the Comp roller tip rockers aren't much of a jump from stock,so if you're running big springs,toss the rockers and step up to something stronger.