Pushrod lenght and preload
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Teching In
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Pushrod lenght and preload Ok so I have searched for countless hours and I am getting numbers ranging all over the place.
Some say .020 preload , some say .050, some say between .080 and .0100.
Which is it ????????
I have a 2004 lq4 stock bottom end and pistons. 799 heads milled .006 for a clean up. Fel pro stock thickness head gaskets, PRC dual springs and titanium retainers, Texas speed Tourque V4 cam.and new ls7 lifters.
With the comp cams pushrod lenght checker (6.8) i get 10 1/4 turns. I checked a few intake and exhaust and I get the same measurements.
So 10.25 x .050 + 6.8 = 7.3125
Now I need to add preload to the 7.3125. The cam package came with 7.4 pushrods. So 7.4 - 7.3125 gives me .0875 preload.
Is this ok ?????
Thanks.
Some say .020 preload , some say .050, some say between .080 and .0100.
Which is it ????????
I have a 2004 lq4 stock bottom end and pistons. 799 heads milled .006 for a clean up. Fel pro stock thickness head gaskets, PRC dual springs and titanium retainers, Texas speed Tourque V4 cam.and new ls7 lifters.
With the comp cams pushrod lenght checker (6.8) i get 10 1/4 turns. I checked a few intake and exhaust and I get the same measurements.
So 10.25 x .050 + 6.8 = 7.3125
Now I need to add preload to the 7.3125. The cam package came with 7.4 pushrods. So 7.4 - 7.3125 gives me .0875 preload.
Is this ok ?????
Thanks.
I just looked up that preload needs to be between .050-.100, so I think you'd be fine with .0875.
A couple things, though. I'd be looking for something better than LS7 lifters with a big cam and high pressure springs. And do yourself a huge favor, get a set of 8" calipers to measure the length of your pushrods more precisely. The turn method isn't as accurate and your 7.4" pushrods will vary - they're not exactly that length. Heck, you could even go to the local auto store and borrow theirs I bet.
A couple things, though. I'd be looking for something better than LS7 lifters with a big cam and high pressure springs. And do yourself a huge favor, get a set of 8" calipers to measure the length of your pushrods more precisely. The turn method isn't as accurate and your 7.4" pushrods will vary - they're not exactly that length. Heck, you could even go to the local auto store and borrow theirs I bet.
Thread Starter
Teching In
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Texas speed recommended the ls7 lifters with the cam package.
Also the checker seems to be pretty accurate. If I stand the checker and the 7.4 pushrod side by side and use my 6" calipers like a depth gauge the difference between the two is .087 with 10 1/4 turns out.
I will definatley buy some bigger calipers to confirm.
So I should be ok with .087 preload then ?
Also the checker seems to be pretty accurate. If I stand the checker and the 7.4 pushrod side by side and use my 6" calipers like a depth gauge the difference between the two is .087 with 10 1/4 turns out.
I will definatley buy some bigger calipers to confirm.
So I should be ok with .087 preload then ?
I've bought almost all my parts from them, so I know they would know better than me, but I see other experts on here almost always recommend going with an upgrade on such an important piece of the equation. I'm sure tons of people have success that we never hear about. People pretty much only speak up when there's an issue (ie: the cam I run). Just up to you obviously.
I would think so based on what I've read. Search Google rather than just this site. Call TSP and confirm since they sell and recommend them. It would make me feel better personally, and if I was in your position. They answer all my questions on the phone, or email me if they need to talk to the engine builder first. Good luck!
I would think so based on what I've read. Search Google rather than just this site. Call TSP and confirm since they sell and recommend them. It would make me feel better personally, and if I was in your position. They answer all my questions on the phone, or email me if they need to talk to the engine builder first. Good luck!
In testing years ago, Morel found that shortening the recover distance that the check ball traveled allow the lifter to recover quicker and in turn the higher in the rpm the the lifter was stable. Morels with pre-load set between .035 and .065" is a good range depending on cylinder head and block material.
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So I just got my LQ4 running 3 days ago. I have ported 799 heads on it, and a LJMS stg 2 turbo cam in it, and LS7 lifters. My heads were wacked I think .010 and I have LS9 headgaskets. I am running 7.4 .080 pushrods in mine, and it has just over .050 preload. It's pretty quiet, and seems to run great so far. I think you will be fine with 7.4. JMO
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Verdad Gallardo Thread Starter
Teching In
Joined: Nov 2015
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Texas Speed got back to me today. They said usually between .060 and .080 on the ls7 lifters is good. They said me being at .0875 wouldn't be a problem.
Thanks everyone for the help.
What kind of power would you guys think this combo would make ??
Lq4 bottom end freshened up ( new rings rod bearings crank bearings cam bearings, cylinders honed)
New timing chain and oil pump.
Torquer v4 cam (231/234 629/615 111 lsa)
799 heads (valve job, milled .006)
Prc dual valve springs
Stock head gaskets
Edelbrock performer rpm carb intake
Holly 750 carb
Msd 6ls
Full lenght headers, 3 inch exhaust.
I'm hoping to at least see around 400 hp
Thanks everyone for the help.
What kind of power would you guys think this combo would make ??
Lq4 bottom end freshened up ( new rings rod bearings crank bearings cam bearings, cylinders honed)
New timing chain and oil pump.
Torquer v4 cam (231/234 629/615 111 lsa)
799 heads (valve job, milled .006)
Prc dual valve springs
Stock head gaskets
Edelbrock performer rpm carb intake
Holly 750 carb
Msd 6ls
Full lenght headers, 3 inch exhaust.
I'm hoping to at least see around 400 hp
Thread Starter
Teching In
Joined: Nov 2015
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Ok so I took the advise and went out and bought a set of 8 inch calipers.
Kind of glad I did, as now I have a problem.
The pushrod checker comes out accurate at 7.325. However the 7.4 Texas speed pushrods are not exactly 7.4. I measured a few and they are all around 7.417
So now 7.417 - 7.325 gives me .092 preload now. Seems a bit high.
Guess I will exchange the pushrods.
Kind of glad I did, as now I have a problem.
The pushrod checker comes out accurate at 7.325. However the 7.4 Texas speed pushrods are not exactly 7.4. I measured a few and they are all around 7.417
So now 7.417 - 7.325 gives me .092 preload now. Seems a bit high.
Guess I will exchange the pushrods.
Call Texas Speed and go over the numbers with them first. I think there's some difference in measurement between the caliper (end to end of pushrod) vs the turn method of the adjustable pushrod.
So you could actually be fine is what I'm getting at. Plus, ordering new ones will still give you varying lengths and you can't even order an exact length of some odd number. I think they offer lengths in increments of .025 or .050.
Best case, you'd be ordering 7.375 would probably give you somewhere in the 7.390 range (.065 preload based on your numbers). Worse case, you'd have to order 7.350 (7.365 range, yielding .040 preload).
Those are all just round numbers for the sake of easy math. If you get new ones, measure them to confirm and the preload may change at that point. You have a wide margin for error with your preload.
Side note: I mistakenly read your first post as using the MS4 cam instead of the Torquer 4, which is the only reason I brought up an upgrade over ls7 lifters. I don't think it's as crucial now that I know this, but personally went with Morel 5315s on my Torquer 3 cam FWIW (but mine uses the older very aggressive lobes).
So you could actually be fine is what I'm getting at. Plus, ordering new ones will still give you varying lengths and you can't even order an exact length of some odd number. I think they offer lengths in increments of .025 or .050.
Best case, you'd be ordering 7.375 would probably give you somewhere in the 7.390 range (.065 preload based on your numbers). Worse case, you'd have to order 7.350 (7.365 range, yielding .040 preload).
Those are all just round numbers for the sake of easy math. If you get new ones, measure them to confirm and the preload may change at that point. You have a wide margin for error with your preload.
Side note: I mistakenly read your first post as using the MS4 cam instead of the Torquer 4, which is the only reason I brought up an upgrade over ls7 lifters. I don't think it's as crucial now that I know this, but personally went with Morel 5315s on my Torquer 3 cam FWIW (but mine uses the older very aggressive lobes).
Ok so I took the advise and went out and bought a set of 8 inch calipers. Kind of glad I did, as now I have a problem. The pushrod checker comes out accurate at 7.325. However the 7.4 Texas speed pushrods are not exactly 7.4. I measured a few and they are all around 7.417 So now 7.417 - 7.325 gives me .092 preload now. Seems a bit high. Guess I will exchange the pushrods.
Glad you checked. Yeah the pushrods actually measure put a bit long every time. That said, 092 preload is on the long side but would be ok
Thread Starter
Teching In
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Ok so I'm just confusing myself more and more.
I measured a bunch of the Texas speed 7.4 pushrods with calipers. I got 7.422 with most of them. (Some were +- a few thousands)
And I measured the pushrod lenght checker at 10 1/4 turns out with the caliper which gave me 7.325
So now the 7.422 - 7.325 gives me a preload of .097
I think that's a little high.
So best bet would be to get the 7.375 pushrods. BUT this poses another problem. If the 7.4's were actually .022 longer, how much longer are the 7.375's going to be ??????? Maybe 7.390 ?????
I messaged Texas speed as I would like them to actually measure the 7.375's before ordering them.
I measured a bunch of the Texas speed 7.4 pushrods with calipers. I got 7.422 with most of them. (Some were +- a few thousands)
And I measured the pushrod lenght checker at 10 1/4 turns out with the caliper which gave me 7.325
So now the 7.422 - 7.325 gives me a preload of .097
I think that's a little high.
So best bet would be to get the 7.375 pushrods. BUT this poses another problem. If the 7.4's were actually .022 longer, how much longer are the 7.375's going to be ??????? Maybe 7.390 ?????
I messaged Texas speed as I would like them to actually measure the 7.375's before ordering them.
I think you're right. That's the same example I gave you, which would be the right preload.
If you want to re-measure a few cylinders to confirm, I would not even count checker turns. Just adjust it where it needs to be and measure end to end. I never once counted turns, because the stupid thing would turn so easily I couldn't be sure it was accurate (well, and because Darth told me not to). Others have put teflon tape on the threads to keep it from spinning so easily, but still - don't count turns, just measure.
Good luck man!
If you want to re-measure a few cylinders to confirm, I would not even count checker turns. Just adjust it where it needs to be and measure end to end. I never once counted turns, because the stupid thing would turn so easily I couldn't be sure it was accurate (well, and because Darth told me not to). Others have put teflon tape on the threads to keep it from spinning so easily, but still - don't count turns, just measure.
Good luck man!
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From: Monroe,NY
They should end up measuring the same amount more as the 7.4's. When i measured my btr pushrods with the calipers the all measured between .017 to .024 more than advertised length. That is the gauge length. So the your 7.375 should measure 7.397.(give or take a few thousands)
Another issue with running too much lifter preload is with lifter pump up. If you have say .080 preload and get lifter pump up this can cause piston to valve contact once you consider rocker arm ratio. I just went through this. I had .100 preload and everything was fine. All of a sudden i get a tapping noise and think I killed a lifter. Pulled it apart and there was piston to valve going on, on one piston on the intake side. I have .082 piston to valve clearance with my cam. But this one lifter wasvall of a sudden pumping up an additional .065. I was able to tell this once disassembling the lifter and looking at the witness marks. So the additional. 065 x 1.7 rocker ratio = .1105. Aka enough to overcome what piston to valve clearance I had. I was using 7.4 manton push rods and went to tsp 7.35 pushrods and now have .058 preload. Now even if the lifter pumped all the way up it would only be .058 x 1.7 = .0986. It could still touch but no where near as bad.
Yes 7.4s aren't 7.4 but longer because most manufacturers use gauge length which starts measuring a little ways down from the end. Another reason I like Manton push rods. You measure, add pre-load and they make the push rod to the length you want without figuring out gauge length. I even had them make several different length push rods to balance my pre-load between valves. The girl on the phone said they have a variance but she'd put a note on to get them close. They were all with .001-002" of spec.