Understanding rockers - Page 2 - Pontiac GTO Forum
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post #11 of 17 (permalink) Old 04-12-2019, 07:06 AM Thread Starter
 
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Thanks Jim. Heads are off and the push rods do have oil channel through the middle. The current springs and cam seem to work fine, so I guess my my question is if I do the 1.65 swap, I need different springs even though the cam has stayed the same?
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post #12 of 17 (permalink) Old 04-12-2019, 06:32 PM
 
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Thanks Jim. Heads are off and the push rods do have oil channel through the middle. The current springs and cam seem to work fine, so I guess my my question is if I do the 1.65 swap, I need different springs even though the cam has stayed the same?
The oil channel through the pushrods do not necessarily mean that the engine oils through them. Look at the rocker arm studs and if they do oil through the studs, you will see a very obvious hole in them where oil would come out. Easy enough to convert to oiling through the pushrods during a rebuild.

I would install new springs while you have the heads apart or at least bring them to a machine shop/engine builder where they can test for spring pressure. It could be that you already have a good set of springs and may not need to upgrade to a stronger spring.

Here is another forum that may be of help and gives a spring recommendation. You will also note that you want to check and make sure that the spring retainer does not hit/interfere with the inside of the rocker arm (closet point on the stud side) at full lift, nor encounter any spring bind or the valve retainer hitting the valve guide. The general clearance needed is about .060" and as I recall, that is about a paper clip wire size, so you may be able to use that as your checking tool. https://www.yellowbullet.com/forum/s...ad.php?t=42201
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post #13 of 17 (permalink) Old 04-13-2019, 09:33 AM Thread Starter
 
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well i dont know what to think on this cam. i attached pics of 540 233 stacked, and as I mentioned, there are no poly locks so I believe its hydraulic cam. so big d, i think its contradicts what that wallace chart says. I took a couple pics of lifters if that will help any. let me know if any other thoughts.

Jim - i dont quite follow on the measurement piece. are you saying to measure the total amount of travel the lifter generates from lowest point of cam rotation to the highest? and maybe using top of lifter bore as a static reference point? on a related but simplistic note - I now understand the rocker multiplier (thanks big d) - so lets say lobe lift without the multiplier is .300. is that saying the lobe lift is .300 of one inch? so roughly 1/3 of 1 inch?
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post #14 of 17 (permalink) Old 04-13-2019, 10:58 AM
 
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well i dont know what to think on this cam. i attached pics of 540 233 stacked, and as I mentioned, there are no poly locks so I believe its hydraulic cam. so big d, i think its contradicts what that wallace chart says. I took a couple pics of lifters if that will help any. let me know if any other thoughts.

Jim - i dont quite follow on the measurement piece. are you saying to measure the total amount of travel the lifter generates from lowest point of cam rotation to the highest? and maybe using top of lifter bore as a static reference point? on a related but simplistic note - I now understand the rocker multiplier (thanks big d) - so lets say lobe lift without the multiplier is .300. is that saying the lobe lift is .300 of one inch? so roughly 1/3 of 1 inch?
"is that saying the lobe lift is .300 of one inch? so roughly 1/3 of 1 inch?" Roughly because it really is not 1/3 of an inch - 3 x .300 = .900. That's .100" short of an inch - which in cam lift is a significant number. So you cannot use the "inch" measurement to guess if that is what you are suggesting as you will not get an accurate reading. Inches are broken down in 1/16th's, a dial indicator measures in 10th's. You will need a dial indicator for an accurate measurement.

As I said before, I think the number shown is a manufacturer or even cam blank stamping, not the actual specs of the cam.

Hydraulic lifters will have a little "springyness" to them. When you push down on the center where the pushrod goes, it will compress and then return. A solid lifter will not be able to be compressed - thus a "solid" lifter.

Check out this discussion starting at post #34 which should make things a little clearer - https://www.gtoforum.com/f170/cracke...65/index4.html
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post #15 of 17 (permalink) Old 04-13-2019, 02:58 PM Thread Starter
 
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The mystery continues. Those lifters have absolutely no give/sponginess. Is it possible to have a solid lift cam with regular nuts screwing down the rockers? Cause it seems that is what I have. I am not suggesting The number 540 233 has anything to do with the specs of this cam. Initially I thought it was that 389 sd cam. And if this is a mechanical cam , maybe it is. But again no idea why the heads have standard nuts and not poly locks...

Also no oil via rocker stud.

Thanks for push rod thread. That helps
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post #16 of 17 (permalink) Old 04-13-2019, 08:36 PM Thread Starter
 
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update. I did find a lifter that has some sponginess to it, but most of them are rock solid with no give. Is that a problem in and of itself?
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post #17 of 17 (permalink) Old 04-13-2019, 09:20 PM
 
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update. I did find a lifter that has some sponginess to it, but most of them are rock solid with no give. Is that a problem in and of itself?
You probably have hydraulic lifters and cam. They may be hard to push down as they may be pumped up with oil. If you take one out and place on a bench, when you push down you will most likely see the oil escaping out of the small oil fill hole in the side of the lifter and it will collapse down.

Factory rocker arm nuts are simply torqued down into place - unless you had a solid lifter engine or the engine had the "Royal Bobcat" upgrade which included a nylon ring at the top of the rocker arm nut to keep it from backing off and the lifters where then "zero lashed." The poly-locks were an improvement over the nylon locking nuts.
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