.086" Preload too much??
Thread Starter
Staging Lane
Joined: Sep 2004
Posts: 59
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From: arlington, wash
.086" Preload too much?? Read on here that .030 to .080 is an acceptable range with .060" being perfect.
I bought a set of pushrods on here being told they were 7.325, instead I was sent 7.350 which pushes me out to .086". This will have been the second set of pushrods I've been shagged on.
a thread on here pointed out that a particular GM engineer gives a range of something like 0.06 to 0.1 preload....
These are stock ls1 lifters..
Any feedback? I'm trying to get this thing running rather than wait another week.
Thanks!
I bought a set of pushrods on here being told they were 7.325, instead I was sent 7.350 which pushes me out to .086". This will have been the second set of pushrods I've been shagged on.
a thread on here pointed out that a particular GM engineer gives a range of something like 0.06 to 0.1 preload....
These are stock ls1 lifters..
Any feedback? I'm trying to get this thing running rather than wait another week.
Thanks!
The funny thing is, on this same forum, or the Corvette forum for that matter, you will hear that .030" is perfect. So is .020, .040, and probably someone has stated that the BEST is .032674".
I guess I'm curious why you are ending up shorter than stock? Stock cam with milled heads?
Typically the base circle of an aftermarket cam is smaller, requiring a longer pushrod. Milling the head takes it back the other way.
Just curious. I have a set of good 7.40" trickflows, but you are way shorter. I am in Oregon.
Perhaps you could detail how you arrived at your number?
Ron
I guess I'm curious why you are ending up shorter than stock? Stock cam with milled heads?
Typically the base circle of an aftermarket cam is smaller, requiring a longer pushrod. Milling the head takes it back the other way.
Just curious. I have a set of good 7.40" trickflows, but you are way shorter. I am in Oregon.
Perhaps you could detail how you arrived at your number?
Ron
Thread Starter
Staging Lane
Joined: Sep 2004
Posts: 59
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From: arlington, wash
It has jesel non adj. shaft mounts
According to Jesel, Install the checker and rocker and adjust the checker out until the rocker is fully seated and no rocking movement. I then added in desired preload.
According to Jesel, Install the checker and rocker and adjust the checker out until the rocker is fully seated and no rocking movement. I then added in desired preload.
.08x" will be fine. Did you measure them tip to tip with a dial caliper to figure out they were 7.350"?? Or were they actually marked on them as being 7.350"?
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Thread Starter
Staging Lane
Joined: Sep 2004
Posts: 59
Likes: 0
From: arlington, wash
They were marked as 7.350" I shouldve checked overall length.
I got it started ran it up to temp. Loud, loud sewing machine sound but ran well and idled. drove it up the street and when I was coming back, (all under 4000rpm) heard what sounded like it popped out of gear and was dragging gear. It was still in gear then died. Ill open it up tonight or in the morning to see if it was a spring?
I got it started ran it up to temp. Loud, loud sewing machine sound but ran well and idled. drove it up the street and when I was coming back, (all under 4000rpm) heard what sounded like it popped out of gear and was dragging gear. It was still in gear then died. Ill open it up tonight or in the morning to see if it was a spring?
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Verdad Gallardo They were marked as 7.350" I shouldve checked overall length.
I got it started ran it up to temp. Loud, loud sewing machine sound but ran well and idled. drove it up the street and when I was coming back, (all under 4000rpm) heard what sounded like it popped out of gear and was dragging gear. It was still in gear then died. Ill open it up tonight or in the morning to see if it was a spring?
I got it started ran it up to temp. Loud, loud sewing machine sound but ran well and idled. drove it up the street and when I was coming back, (all under 4000rpm) heard what sounded like it popped out of gear and was dragging gear. It was still in gear then died. Ill open it up tonight or in the morning to see if it was a spring?
Thread Starter
Staging Lane
Joined: Sep 2004
Posts: 59
Likes: 0
From: arlington, wash
Wasn't a broken spring. Now won't start. It's dumping fuel, this is on a .581 lift 225 duration cam. (Speed incs tu1) I'm extremely confident cam was installed straight up but it was not degreed. Possible ptv issues???
225 duration; doubtful that it's a PTV issue unless the heads are milled &/or thinner head gasket was used. Leak down test or just turn it over w/ the starter & listen for the sound of air in the intake or in the exhaust. If there's a bent valve you'll here the air passing it into either the intake &/or the exhaust depending on which valves may be bent.
Back to the original topic. Why did you install 7.350" pushrods when you needed 7.325"? This isn't a pre-load issue, it's a valve wipe pattern issue. If you measured 7.325" on a centered valve wipe pattern & then installed 7.350" pushrods, the wipe pattern is no longer centered.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
225 duration; doubtful that it's a PTV issue unless the heads are milled &/or thinner head gasket was used. Leak down test or just turn it over w/ the starter & listen for the sound of air in the intake or in the exhaust. If there's a bent valve you'll here the air passing it into either the intake &/or the exhaust depending on which valves may be bent.
Back to the original topic. Why did you install 7.350" pushrods when you needed 7.325"? This isn't a pre-load issue, it's a valve wipe pattern issue. If you measured 7.325" on a centered valve wipe pattern & then installed 7.350" pushrods, the wipe pattern is no longer centered.
Back to the original topic. Why did you install 7.350" pushrods when you needed 7.325"? This isn't a pre-load issue, it's a valve wipe pattern issue. If you measured 7.325" on a centered valve wipe pattern & then installed 7.350" pushrods, the wipe pattern is no longer centered.
1- Push rod length adjusts pre-load on lifters.
2- Shimming rocker pedestal adjusts wipe pattern.
Yah, duh, I f'ckd up
. Was relating it to my stud mounted PRW's w/ guide plates. Sorry about that livewire0201. Thanks for clearing that up PREDATOR.livewire0201, let us know what you find.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
No problem, used to happen to me a few years back, but since I have owned nothing but LS motors for the past 10 years, those flashback tech memories are much less frequent.
I'm not certain but I think the Compcam magnum rockers fit the description you gave on our motors. However I've never used those (I'm actually interested on some live feedback on those)
I'm not certain but I think the Compcam magnum rockers fit the description you gave on our motors. However I've never used those (I'm actually interested on some live feedback on those)
Thread Starter
Staging Lane
Joined: Sep 2004
Posts: 59
Likes: 0
From: arlington, wash
I have no idea when I will have the opportunity to tear down the motor. When I do turn the motor over you can hear a sucking/hissing sound. Sounds like fuel is being drawn into the motor. Bent valve??
The main question here is why did you use 7.350 pushrods when going to an aftermarket cam? Did you do heads and cam or just a cam? Are your heads milled and are you using stock gm head gaskets?
Thread Starter
Staging Lane
Joined: Sep 2004
Posts: 59
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From: arlington, wash
Just did cam springs rockers etc. I used jesel shaft mounts which could change the length. I measured something like 7.264 tip to tip per jesels recommendation. Adding in .06 preload gave me 7.324.
I ordered a used set from a member here and was instead sent 7.35's. The original question was whether or not this preload was too much with 7.35's
I ordered a used set from a member here and was instead sent 7.35's. The original question was whether or not this preload was too much with 7.35's
Thread Starter
Staging Lane
Joined: Sep 2004
Posts: 59
Likes: 0
From: arlington, wash
Finally was able to actually measure the 7.35's Tip to tip was actually 7.3625 giving me preload of .097. Are these opening my valves on base circle?