Rockers, adjust or replace
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Cross-Country
Joined: Apr 2018
Posts: 96
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From: Texas
Rockers, adjust or replace
Rockers / lifter rattling. Pulled one rocker. 1979, all original.
Rocker adjustment, start at TDC, set for 0 lash then turn in 1/4 turn. Correct? Have cam / carb aspirations at end of year (Schneider / Crower in the 200 to 210 @ 050 range). I'm ok with replacing rockers now, would prefer to do it when pull head and install cam.
Searching posts for rocker arm advice on replacements. See some say HS 1.6 way to go (drop in). Others say 1.7 BBC, others 1.7x Chev 6, etc. What is current consensus?
Comp cams 1.6 are only listed up to 1978. Was their difference from 1978 to 1979?
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Joined: Nov 2015
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In 1978 the rocker studs became non-adjustable by going to a smaller 5/16" treaded top section where you ran the nut down till it stopped on the 3/8" stud body.
The reason the Comp rocker set won't work is because the nut that comes in the set is 3/8" and the stud needs the 5/16" nut otherwise all the other parts are fine to use.
The Melling and the Sealed power rockers come with both the 3/8' and the 5/16" nuts
The old rockers look very worn and need to be replaced and you need to be sure oil is coming up through the pushrods to oil them.
The Chevy 250 six 1.75 ratio rockers will fit to add some lift to the stock cam. Same situation with needing the 5/16" nut.
You don't need roller rockers till you get near .500" valve lift in which case you will need to pull the stock press-in studs and drill and tap for screw-in studs.
The HS rockers are the only roller rockers that give you the correct rocker geometry.
The BBC rockers are .050" too long and have to be moved far down on the studs to get the roller tip to track across the center of the valve stem tip.
The reason the Comp rocker set won't work is because the nut that comes in the set is 3/8" and the stud needs the 5/16" nut otherwise all the other parts are fine to use.
The Melling and the Sealed power rockers come with both the 3/8' and the 5/16" nuts
The old rockers look very worn and need to be replaced and you need to be sure oil is coming up through the pushrods to oil them.
The Chevy 250 six 1.75 ratio rockers will fit to add some lift to the stock cam. Same situation with needing the 5/16" nut.
You don't need roller rockers till you get near .500" valve lift in which case you will need to pull the stock press-in studs and drill and tap for screw-in studs.
The HS rockers are the only roller rockers that give you the correct rocker geometry.
The BBC rockers are .050" too long and have to be moved far down on the studs to get the roller tip to track across the center of the valve stem tip.
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Cross-Country
Joined: Apr 2018
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From: Texas
pmuller
Thanks for prompt response. I'm positive oil wasn't coming through the push rods for several years. Puled the valve cover when I bought the truck and it was obviously on the "Optional" oil change schedule. One of the days will put a long post of how badly beaten this truck was. But still runs!!! With good compression even.
Got a set of 1.75 250 3/8 rockers in shopping cart, do a quick browse to check price <$70 for complete set.
To verify, when I get these it's a straight up bolt down while turning crank to TDC for each cylinder?
When do change the cam, will be adding 4bbl (390 CFM) and swapping over to DUI (off brand HEI currently installed). Already have, upgraded radiator, fan, HEI ignition. Currently putting in FI exhaust, Y pipe to 2.5" single with Magnaflow. Best to just have cam ground to accommodate 1.75 rockers? Not interested in spinning 5000 RPM. Have 2.75 rear end and 30" tires. Only things important are torque under <3500 RPM, decent mileage and bullet proof.
Thanks for prompt response. I'm positive oil wasn't coming through the push rods for several years. Puled the valve cover when I bought the truck and it was obviously on the "Optional" oil change schedule. One of the days will put a long post of how badly beaten this truck was. But still runs!!! With good compression even.
Got a set of 1.75 250 3/8 rockers in shopping cart, do a quick browse to check price <$70 for complete set.
To verify, when I get these it's a straight up bolt down while turning crank to TDC for each cylinder?
When do change the cam, will be adding 4bbl (390 CFM) and swapping over to DUI (off brand HEI currently installed). Already have, upgraded radiator, fan, HEI ignition. Currently putting in FI exhaust, Y pipe to 2.5" single with Magnaflow. Best to just have cam ground to accommodate 1.75 rockers? Not interested in spinning 5000 RPM. Have 2.75 rear end and 30" tires. Only things important are torque under <3500 RPM, decent mileage and bullet proof.
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Joined: Nov 2015
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If you have the 5/16" rocker stud nuts you simply tighten them down till they bottom out on the stud.
Having the piston at TDC for the compression stroke where both valves are closed for the cylinder you are working on makes it easier.
If you change to the Crower 19212 cam you will need to change to the Comp 903 valve spring.
You will need to swap out the exhaust valve retainers for a set of stock intake retainers to accommodate the Comp spring.
The stock exhaust retainers have a rotator section that will not allow the Comp 903 spring to be installed at the correct height.
Also the rotators can come apart at the higher spring pressure.
If you go with the Crower cam you don't need the extra lift from the Chevy six rocker. It would push the lift to .490".
I would go back to the Ford 1.6 ratio rocker
Having the piston at TDC for the compression stroke where both valves are closed for the cylinder you are working on makes it easier.
If you change to the Crower 19212 cam you will need to change to the Comp 903 valve spring.
You will need to swap out the exhaust valve retainers for a set of stock intake retainers to accommodate the Comp spring.
The stock exhaust retainers have a rotator section that will not allow the Comp 903 spring to be installed at the correct height.
Also the rotators can come apart at the higher spring pressure.
If you go with the Crower cam you don't need the extra lift from the Chevy six rocker. It would push the lift to .490".
I would go back to the Ford 1.6 ratio rocker
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Cross-Country
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From: Texas
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Every once in a why we see mystery combinations.
When you install the new Chevy rockers its would be good to have the side cover off so you can see the lifters and check for preload.
When the lifter nut is tighten down the lifter plunger should move down .050" to .075" away from the retaining clip.
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Thread Starter
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Cross-Country
Joined: Apr 2018
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From: Texas
Got at least 1 bent push rod.
Started it up with valve cover off. Intake rocker on cyl1 and cyl5 not getting oil up to rocker arm. Pulled push rod, oil drained out of it, not making it up to rocker arm. Push rod is not plugged.
All other rockers get oil pooling around lock nuts at slow idle, cold engine.
Started it up with valve cover off. Intake rocker on cyl1 and cyl5 not getting oil up to rocker arm. Pulled push rod, oil drained out of it, not making it up to rocker arm. Push rod is not plugged.
All other rockers get oil pooling around lock nuts at slow idle, cold engine.
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Cross-Country
Joined: Apr 2018
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From: Texas
Ok. Parts store, need few cans carb cleaner.
Got your advice and looked at couple other old posts and other message boards. Ordering a set of 1.75 C250 rockers and 10.136 5/16 push rods (both Comp Cams).
Going to pull all rockers and push rods and troubleshoot the oiling issue.
Should I pull and clean all lifters or just the suspect ones? Looked up how to take apart and clean, doesn't look too tricky as long as you don't shoot the springs across garage and keep each seperate, putting back in original position. Doing 16 instead of 2 makes me 8 times more likely to drop, break or loose a part.
Next, assuming cleaning up lifters solves the oil issue, when I install new rockers and push rods, read a post that talked about using hardened washers over rocker pivots and double rocker nuts on non adjustable stud mounts. The washers push down on rocker pivots to remove that little bit of lash that can remain, using the double nut to set position and keep it from backing out. Ever try it?
Got your advice and looked at couple other old posts and other message boards. Ordering a set of 1.75 C250 rockers and 10.136 5/16 push rods (both Comp Cams).
Going to pull all rockers and push rods and troubleshoot the oiling issue.
Should I pull and clean all lifters or just the suspect ones? Looked up how to take apart and clean, doesn't look too tricky as long as you don't shoot the springs across garage and keep each seperate, putting back in original position. Doing 16 instead of 2 makes me 8 times more likely to drop, break or loose a part.
Next, assuming cleaning up lifters solves the oil issue, when I install new rockers and push rods, read a post that talked about using hardened washers over rocker pivots and double rocker nuts on non adjustable stud mounts. The washers push down on rocker pivots to remove that little bit of lash that can remain, using the double nut to set position and keep it from backing out. Ever try it?
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Should I pull and clean all lifters or just the suspect ones? Looked up how to take apart and clean, doesn't look too tricky as long as you don't shoot the springs across garage and keep each seperate, putting back in original position. Doing 16 instead of 2 makes me 8 times more likely to drop, break or loose a part.
Next, assuming cleaning up lifters solves the oil issue, when I install new rockers and push rods, read a post that talked about using hardened washers over rocker pivots and double rocker nuts on non adjustable stud mounts. The washers push down on rocker pivots to remove that little bit of lash that can remain, using the double nut to set position and keep it from backing out. Ever try it?
Next, assuming cleaning up lifters solves the oil issue, when I install new rockers and push rods, read a post that talked about using hardened washers over rocker pivots and double rocker nuts on non adjustable stud mounts. The washers push down on rocker pivots to remove that little bit of lash that can remain, using the double nut to set position and keep it from backing out. Ever try it?
The washer on top of the pivot is an old used car sales trick.
You shouldn't need to do it but if you can't get preload on the lifter go ahead and play used car salesman.
When it comes time for the cam replacement and a head rebuild remove those pressed in studs and have the head drilled and tapped for screw in studs.
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I second what pmuller said on cleaning all 12 of them. I've done it, and it takes a few hours, but well worth it.
Also, with all 12 pushrods, make sure you can lift them up and see all the way through them. Point them at a light, or similar. If you can't see a clean hole all the way through, clean them out until you do.
Also, with all 12 pushrods, make sure you can lift them up and see all the way through them. Point them at a light, or similar. If you can't see a clean hole all the way through, clean them out until you do.
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Cross-Country
Joined: Apr 2018
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From: Texas
Yep, bonehead the 16 comment. I grew up on V8s. Thinking back to past life. Got few more items for cam, intake but save that for another post, keeping eye on current situation.
Pulled all rockers and push rods. Going to replace all of them. Iv'e got 5 that I can't tell if they're bent.... and 7 that clearly are.......so, yeah. Tried attaching video for amusement.
Next question, Speedway has Comp Cams push rods 10.136" OAL, Summit has Sealed power push rods at 10.140" OAL. Any preference?
Pulled all rockers and push rods. Going to replace all of them. Iv'e got 5 that I can't tell if they're bent.... and 7 that clearly are.......so, yeah. Tried attaching video for amusement.
Next question, Speedway has Comp Cams push rods 10.136" OAL, Summit has Sealed power push rods at 10.140" OAL. Any preference?
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Joined: Nov 2015
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The Comp is cheaper and both are about the same quality. Neither one is heat treated for guide plates. Get the Comp.
If you want a quality pushrod for later get an .080" wall heat treated pushrod.
Stock pushrods are .060" wall and soft.
If you want a quality pushrod for later get an .080" wall heat treated pushrod.
Stock pushrods are .060" wall and soft.