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#1
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Pattern on Valve Tip Opinion
Hi everyone, we are measuring pushrod length today, we made a hydraulic lifter solid by stacking it with washer, we then turned the engine until lifter was on back side of lobe, adjusted stock factory length pushrod to zero lash, tightened the poly lock, then turned the engine two full revolutions and this is the pattern we got. Looks awful wide to me, but we have never measured pushrod length using factory stamped steel rockers like this build will use, its always been full roller rockers in our past builds. Is this pattern normal for a stamped steel rocker? If so, how does it look? Heads are factory 6x4, just barely cleaned up to make sure they were flat, no more than .010" taken off deck, stock length 4.98" Ferra valves, Crower 68404 springs are set up at 1.550". Camshaft is a Voodoo 704.
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1978 Trans Am Pump Gas 461 Stroker |
#2
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For got to mentioned above, we will be ordering the .116" wall pushrods from Butler just as soon as we know for sure the length we need. We were just using the factory length pushrod to initially measure it with for a starting point.
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1978 Trans Am Pump Gas 461 Stroker |
#3
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Did you look up the Straub method to set your pushrod length?
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The Following User Says Thank You to tempest1964 For This Useful Post: | ||
#4
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I did, but the method they show is using a full roller rocker, which is next to impossible to figure out when using a stock stamped style rocker, do to no Trunion and roller wheel axle centerline to go off of.
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1978 Trans Am Pump Gas 461 Stroker |
#5
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Stamped steel rockers do swipe a bit wider than a roller tip variety but I've never had any quite that wide.
Did you vary your adjustable pushrod in both directions to see if it tightened up the pattern some?.....
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
The Following User Says Thank You to Cliff R For This Useful Post: | ||
#6
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Thanks Cliff, we haven't tried the adjustable pushrod yet, we just did it with a factory pushrod first to see where it was at, and this was the result. We will check it with the adjustable pushrod and report back.
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1978 Trans Am Pump Gas 461 Stroker |
#7
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Looks you need a longer pushrod from your first post. Not the second.
Try this: Set the lifter on the base circle of the cam. Now set the adjustable pushrod in place and adjust the rocker until there is zero lash. Now lightly rub the rocker across the valve tip to establish a witness mark on the valve tip. Inspect the position of the mark and re-adjust the pushrod length until the witness mark is roughly 1/3rd of the distance toward the intake side from centerline. Another reference, about 2/3 of peak lift the mark should be about center of the valve tip. Last edited by pastry_chef; 06-27-2021 at 07:37 PM. |
The Following User Says Thank You to pastry_chef For This Useful Post: | ||
#8
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Here is the pattern with the adjustable pushrod at 9.200"
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1978 Trans Am Pump Gas 461 Stroker |
#9
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I hope you had the tops of the valve guides topped for positive seals because this is a picture of the not enough retainer to guide clearance you will have at only .500” lift without the guides topped.
This shown is with a stock length exh valve and a stock retainer like I see your using, and this is on a 6X head also.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! Last edited by steve25; 06-27-2021 at 07:37 PM. |
The Following User Says Thank You to steve25 For This Useful Post: | ||
#10
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Quote:
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1978 Trans Am Pump Gas 461 Stroker |
#11
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👍...
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
The Following User Says Thank You to steve25 For This Useful Post: | ||
#12
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Here is what it looks like the the pushrod adjusted to 9.100"
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1978 Trans Am Pump Gas 461 Stroker |
#13
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Here is the witness mark with the lifter on the base circle, lifter at zero lash, pushrod adjusted to 9.100"
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1978 Trans Am Pump Gas 461 Stroker Last edited by TransAm 474; 06-27-2021 at 07:55 PM. |
#14
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Witness Mark with lifter on base circle, lifter at zero lash, pushrod adjusted to 9.150"
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1978 Trans Am Pump Gas 461 Stroker |
#15
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Witness Mark with lifter on base circle, lifter at zero lash, adjustable pushrod set at 9.200"
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1978 Trans Am Pump Gas 461 Stroker |
#16
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The pattern is wide even when you are not moving the rocker across the lift range.
That explains much. |
The Following User Says Thank You to pastry_chef For This Useful Post: | ||
#17
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Here are the two witness marks, one on the base circle, the other at 2/3 lift, both with the lifter adjusted to zero lash, and the pushrod adjusted at 9.200"... to me, the 9.200" pushrod seems to be the best so far. What do yall think?
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1978 Trans Am Pump Gas 461 Stroker |
#18
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Ok, we tried one more time, this time with the pushrod adjusted to 9.250". These ARE two different marks, one with lifter on the base circle, the other mark is at 2/3 lift. Lifter was set at Zero Lash(No Lifter Preload) for both.
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1978 Trans Am Pump Gas 461 Stroker |
#19
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So, reviewing and comparing all of my above pictures, am I correct in thinking that it seems that it may like the 9.200" pushrod the best, especially since .050" or so of lifter Preload still has to be added? The 9.200" witness mark above, at 2/3 lift, appears to be just a tad towards the exhaust side from the center of the valve, so I'm thinking by the time the lifter gets .050" or so of preload, it will be right in the ball park?
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1978 Trans Am Pump Gas 461 Stroker Last edited by TransAm 474; 06-27-2021 at 09:38 PM. |
#20
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With the photos above, I'd agree.
I think it was post 7.. full sweep of 9.2 . Getting closer than I'd like to exhaust side of valve tip. I'm curious how 9.15 full sweep might look compared. I do like where the 9.2 begins |
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