Lifter preload on my new setup...
Thread Starter
TECH Regular
Joined: Jan 2002
Posts: 414
Likes: 0
From: Orlando, FL
Lifter preload on my new setup... Here is the configuration...
-stock heads with 0.015" milled off - the combustion chamber volume measured in at 64.3 cc so the milling is accurate
-GM lifters
-XE-R 224/228 (actually 226/230 measured)
- 7.400" pushrods
Tonite I installed the rockers and gave the lifters time to bleed down (about 20 minutes). I checked the lifter preload on both #1 intake and exhaust. I got about 1 5/8 turns on the intake and 1 1/2 turns on the exhaust from zero lash.
With the bolt having a 1.25 mm pitch this equals 0.049" per turn. So I'm looking at 0.080" and 0.074" preload respectively.
1) Am I missing something here in the calulations
?
2) Should I go with 7.350" pushrods or keep the 7.400" pushrods? I'm leaning towards going to 7.350" pushrods.
Tim
-stock heads with 0.015" milled off - the combustion chamber volume measured in at 64.3 cc so the milling is accurate
-GM lifters
-XE-R 224/228 (actually 226/230 measured)
- 7.400" pushrods
Tonite I installed the rockers and gave the lifters time to bleed down (about 20 minutes). I checked the lifter preload on both #1 intake and exhaust. I got about 1 5/8 turns on the intake and 1 1/2 turns on the exhaust from zero lash.
With the bolt having a 1.25 mm pitch this equals 0.049" per turn. So I'm looking at 0.080" and 0.074" preload respectively.
1) Am I missing something here in the calulations
?
2) Should I go with 7.350" pushrods or keep the 7.400" pushrods? I'm leaning towards going to 7.350" pushrods.
Tim
Thread Starter
TECH Regular
Joined: Jan 2002
Posts: 414
Likes: 0
From: Orlando, FL
Re: Lifter preload on my new setup... Well in theory if a lifter were to pump up it can pump up to an amount equivalent to the preload. This would be a very very bad scenario if it were to happen.
I'm going to go to the 7.350s. Pumping up is still a possible scenario but I'd rather take my chances with 0.030" rather than 0.080".
As far a stock goes... GM never intended the engine to rev upwards of 7K.
Thanks for the responses.
Tim
<small>[ November 26, 2002, 10:12 PM: Message edited by: TimZ28 ]</small>
I'm going to go to the 7.350s. Pumping up is still a possible scenario but I'd rather take my chances with 0.030" rather than 0.080".
As far a stock goes... GM never intended the engine to rev upwards of 7K.
Thanks for the responses.
Tim
<small>[ November 26, 2002, 10:12 PM: Message edited by: TimZ28 ]</small>
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Re: Lifter preload on my new setup... I had always heard that the aftermarket cams are about 0.030" smaller base cercal.
With that taken into consideration, with your heads having been milled 0.015", you are still 0.015" UNDER the factory preload.
With that taken into consideration, with your heads having been milled 0.015", you are still 0.015" UNDER the factory preload.
Thread Starter
TECH Regular
Joined: Jan 2002
Posts: 414
Likes: 0
From: Orlando, FL
Re: Lifter preload on my new setup... Vince,
Yes the cam measured larger than spec'd 226/230 vs. 224/228. The advertised durations (@0.006") were 274/280 vs. 273/277.
I said upwards of 7K not over <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> I will probably be shifting around 6600-6700 atleast on the 1-2 shift.
Yes the preload may be ~0.015" less than stock but that doesn't mean it is right for this application. In a stock situation you won't exceed 6200 RPMs where there is really no risk of pumping up.
Tim
Yes the cam measured larger than spec'd 226/230 vs. 224/228. The advertised durations (@0.006") were 274/280 vs. 273/277.
I said upwards of 7K not over <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> I will probably be shifting around 6600-6700 atleast on the 1-2 shift.
Yes the preload may be ~0.015" less than stock but that doesn't mean it is right for this application. In a stock situation you won't exceed 6200 RPMs where there is really no risk of pumping up.
Tim
