Measured lifter preload-strange results
Thread Starter
Joined: Jun 2004
Posts: 2,279
Likes: 1
From: Napoleonville, LA
Measured lifter preload-strange results What I have: TSP 347, Stg 2.5 5.3 heads milled .030, Cometic 0.040 gaskets, MS4 cam, Caddy lifters, and 7.4 pushrods.
Measuring with a dial indicator on the pushrod side of the rocker arm(I used one of the intake bolts to secure the indicator to the engine). I measured the preload by setting each lifter on the base circle, bringing the rocker to zero lash, and then tightened it down till it stopped. The intake came in at 0.120 preload and the exhaust 0.160. So to get to the suggested preload of 0.060-0.080 I need 7.3 pushrods for the exhaust and 7.35 for the intake. Which is a bit shorter than I would have expected the results to be.
I was thinking 7.4 - 0.03(heads) - 0.016(difference in gasket thickness)= 7.354. Which I know is all theoretical measurements. Anyone else think a 7.3 pushrod seem short for this setup?
Measuring with a dial indicator on the pushrod side of the rocker arm(I used one of the intake bolts to secure the indicator to the engine). I measured the preload by setting each lifter on the base circle, bringing the rocker to zero lash, and then tightened it down till it stopped. The intake came in at 0.120 preload and the exhaust 0.160. So to get to the suggested preload of 0.060-0.080 I need 7.3 pushrods for the exhaust and 7.35 for the intake. Which is a bit shorter than I would have expected the results to be.
I was thinking 7.4 - 0.03(heads) - 0.016(difference in gasket thickness)= 7.354. Which I know is all theoretical measurements. Anyone else think a 7.3 pushrod seem short for this setup?
Last edited by 5.3LJimmy; Aug 31, 2007 at 08:54 AM.
I think that's way too short. Stock PR is 7.380" and an MS4 has a .0565" smaller base cirlce (radius) compared to stock. Theoretically, to keep the same plunger depth as stock, you'd need a 7.4365" PR before you consider the milling and thinner gasket. Subtract the .030" milling and the .014" thinner gasket and you should be around 7.3925". Hard to believe that your setup would want something THAT much shorter. Of course, we're talking about modified heads with valve stem heights that are different from stock and may possibly vary between intake and exhaust.
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
I ended up with 7.35 pushrods on a MS4. But I also shot for .025-030 preload on the morel lifters. Measured with checker springs and adjustable pushrod.
.043 gasket and and unmilled heads.
.043 gasket and and unmilled heads.
I'm running basically that same combo. Heads are TSP stage 2.5 5.3L milled to 59cc, .040" gasket and MS4 cam. With my LS7 lifters I used 7.350 pushrods both intake and exhaust and everything checked perfect. The valvetrain is as quiet as stock - no joke!
Some people set the Caddy lifters up at stock .100" plunger depth, while others like to set them closer to .050". Both settings are fine.
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
