Hello, have a lq4 with 243s cleaned up 5 thousandths. .051 gasket. Truck Norris cam 560 beehives. I believe I messed up by soaking the lifters in oil and not leaving them dry. If I�m using the method to measure pushrod by exhaust opening intake closing when I�m measuring I�m getting 7.3095 then add preload which seems very small for a pushrod when I see online most run over 7.4. Not sure where to go if I should just run like 7.375s

 

Sounds believable to me, in a general way... a little less than 2 business card thicknesses shorter than stock... although I can't imagine how you're getting measurements of that out to ten-thousandths of an inch, especially over a number of valves

 

Just the caliper I have had to order an 8in one overnight to measure them. Is less preload worse than more preolaod?

 

You can't really measure push rod length with a caliper. The lengths you buy are spec'ed by their "theoretical" length, i.e. as though the end was a perfect and complete sphere, but they're not that physically, so the measurement you get by measuring the physical object doesn't match what their spec says. They are shorter than that by some unknown and unpredictable amount, although you could probably get a "close enough" estimate by measuring the oil hole dia with drill bits and calculating the portion of the sphere that's missing. So if that's what you're doing, it's no wonder it's coming out weird. Probably more than .0005" worth of weird in fact. Garbage in, garbage out.

Right way to measure it is with an adjustable push rod. For example the Comp 7702. It's 6.800" fully screwed together, and has �"-20 threads, so one full turn is exactly .050". It's calibrated so that the results it gives are consistent with how you can buy push rods. (i.e. if you measure it with a mic it might be 6.750" because of the holes in the ends) With that tool, you might find that you reach zero lash at 10� turns out, which would be .525" longer than 6.800", or 7.325"; and you'd want to buy the closest length you can actually buy to that plus the desired preload, which if you want .080" of preload, you'd have to buy 7.405" which you can't, so you'd have to settle for 7.400". Hard to get closer and more consistent than .005" or so though, not that it usually matters all that much. It's always a good idea to measure the intake and exhaust on the cyls at the 4 corners of the motor, by which time you've measured half of them, so you might as well go ahead and measure the other 8 valves too; you'll probably find as much as .020" of difference between the shortest and longest, and might maybe not be able to use the same length in all 16. Meaning, carrying your measurements out to ten-thousandths of an inch, is kinda futile. Measure with micrometer, mark with chalk, cut with axe.

Butt if you're using typical LS7 lifters, i.e. stock replacement, they have about .150" or so of total travel, therefore something around .075" - .080" of preload is the center of that (depresses the plunger about halfway). That's a good target to shoot for. Not that it matters much; they're exactly like the old small or big block Chevy (in fact, you can use LS7 lifters in those if it's a factory roller cam block), where really hard-core racers would adjust to 1/16 turn, a "hot street" or "street strip" setting might be � or � turn, the "Chilton's" spec is � turn, butt the factory used 1 full turn. Take your pick. .080" on a LS7 lifter is about like � turn on one of those old ones; just, "typical".

Depends. In either case, it's bad if it takes you out of the range that the lifter expands to when fully extended or compresses to when fully depressed. In the former case it'll be extremely noisy; in the latter it will cause the valve(s) to hang open. In that sense, too much is "worse than" not enough.

Soaking the lifters makes no difference to this whatsoever. As long as the lifter plunger is fully extended while measuring, it'll all come out the same.

 

What lifters are you using.
Manton has you use a caliper to measure the pushrod checker. If you use only the checker your pushrods will not be the actual size. Mine was about .0017 off.
You can get away with using only a pushrod checker if you�re using a LS7 style lifter. .200 total travel with .100 preload.
If you are using a lifter that has a lot less travel like the Johnson 2116LSR .097 travel with .035 +/-.005 preload. You need to be measuring.
Another thing to keep in mind is the pushrods you order should also be measured. I measured with calipers and my Mantons where measured with calipers. They came in within .006 of what was ordered. Top end is quiet.

 

RB- So I am using the adjustable pushrod checker 6.8-7.8. So your saying I�m better off just starting at let�s say 7.3 then count my rotations untill zero lash? I just watched a video witch used the intake open method where he would put adjustable pushrod in place somewhat close then torque to 22 then hold rocker up spin the pushrod untill you hit zero lash. Then take a mic and measure end to end? I know on a normal pushrod you lose material because of the oil holes, but the checker is two flat ends no? I�m definitely going to just count my turns out to 7.3 then go from there I�m just curious why the other way wouldn�t work. The reason I was worried about presoaking them was because I was reading in a book where it says do not pre soak them as it would mess the pushrod measurement up.



Jason- they are ls7 lifters

 

You do BOTH. Actually, you start out by doing a third thing: rotate the engine to the point at which the cam lobe operating the valve you want to measure, is on the "heel" (lowest point, directly opposite the "nose").

"Torque to 22" is not particularly important to the process. All "22" is, is the approximate equivalent of the "standard" design torque of that size fastener, which is 30 N-m � about 4. That metric torque actually converts to about 21.7 ft-lbs � 3 (that is, the acceptable range is about 19 to 25). All you accomplish by doing that, is to make sure that the whole system is "assembled" because the bolt is "tight". It won't make even .001" of difference to your measurement if the torque on that bolt is anywhere from probably 12 or 15 ft-lbs, on up until you get to a point where it's SO TIGHT, that you strip the threads in the head or break the bolt or something (although of course when you final-assemble it, it's best to be somewhat reasonably precise). It's not like head gaskets (which must be compressed to a particular thickness) or rod bolts (which are supposed to be torqued until stretched a certain amount). "Torque to 22" on the rocker bolts is just, yeah, they're put together now.

DO NOT "spin the push rod". Doing that NOT ONLY produces WRONG results by depressing the lifter plunger, BUT ALSO destroys the turns count. Put that OUT OF your vocabulary permanently.

DO NOT try to measure the adj PR with a mic. That measurement will be WRONG because of the oil hole and the fact that PRs in the marketplace ARE NOT measured that way. Put your mic away and DO NOT pick it up again during the procedure.

The procedure is:

1. Put the cam lobe for the valve you want to measure on its "heel". I.e., zero lift. The EOIC method is plenty good enough for this, for a hydraulic cam: you rotate the motor in its normal direction until the exhaust is just beginning to open ("EO") to measure the intake push rod, and rotate until the intake is just arriving at fully closed ("IC") to measure the exhaust one. Obviously this is easier if you put some random push rod in the valve that's your "indicator" and also install its rocker, so that you can see its motion. A quick shortcut is, once you get the right location for a given valve and finish with it, you can rotate the motor exactly 90� and you'll be at the right spot for the next one in the firing order, so you can just go through the engine like that. Such as, find the right spot for the #1 intake by watching the #1 exhaust just beginning to open, measure its PR, rotate the engine 90� and do #8 intake, another 90� and do #7 int, and so on through all 8 intakes; then repeat for the exhausts. Saves the time trouble of futzing around with watching all of them without sacrificing any accuracy whatsoever.
2. Install the rocker for the valve you're measuring, with the adjustable push rod. Install it fully, including ... tightening the bolt.
3. While jiggling the rocker & adj PR, unscrew the adj PR until all free play in the rocker & PR is taken up. Take up ONLY "free play"; DO NOT allow the PR to depress the lifter plunger. It doesn't make any difference whatsoever if the lifter has oil in it or not, as long as its internal spring is able to push the plunger all the way to the top.
4. Remove the rocker. Remove the adj PR without turning it. Screw the PR back together, counting the turns carefully.
5. Multiply the # of turns times .050". Add this number to the screwed-together length of the adj PR; 6.800" for example. So as an example, you might end up at 10� turns; that, times .050", is .525"; add that to 6.800", which gives 7.325".
6. Add your desired preload to that. Since they're LS7 lifters, the total travel of their plunger is about .150" or maybe a bit more. Half of that is about .075" or .080" or so, which is why you see people recommend a setting somewhere around there. But like the SBC/BBC example above, the exact # isn't particularly critical, as long is it's greater than 0 and less than .150", since the one condition leaves lash which will be very noisy and not open the valve quite all the way, and the other will never allow the valve to close all the way. It's MUCH more important that it be consistent with your usage of the engine, and consistent within a reasonable tolerance throughout the entire engine. The lifter is "self-adjusting" within the range of the plunger's motion. To give you an idea of the precision you're working with, i.e. how "accurate" you need to be before the tiny errors get lost in the overall "noise" of uncertainty, an aluminum block and heads will expand by somewhere around .010" - .012" (half of a marketplace push rod length increment) going from cold to fully hot, thereby losing that much preload; the preload will vary by that much just between a cold start and 15 minutes later. So there's no need, with THOSE lifters, to get all wound up with getting it down to the closest thousandth. So, if you come up with 7.325" as the length of your adj PR, and you want .075" - .080" preload, your "marketplace" PR choice might be 7.400", because that's the closest increment you can buy, and puts the lifter solidly within the range you want it to be, which that range, is already .150" (plunger travel) wide. If you get within half of the market PR increment (.0125) on every PR, you're golden.
7. Repeat for AT LEAST both valves on all 4 corners of the engine, since variations in block and head machining that affect this, are most likely to be greatest on those cyls. But by that time, you will have measured 8 of the 16 valves; might as well do the other 8 anyway. You never know until you KNOW, whether maybe some 1 or 2 or however many valves is different from the rest; or whether all the intakes are one length and all the exhausts some other; or who knows what. Eliminate guesswork, "assumptions", "I put it together and now it makes noise and runs terrible", etc. etc. etc. You might have to buy a set at one length, and 1 or 2 at some other; or 8 & 8; or whatever. Get the lengths you need in the most cost-effective way you can. That's the WHOLE POINT of measuring.
8. WRITE DOWN AS YOU GO which valve needs what length. Especially important if they turn out different.
9. Buy. Install. Tighten the rocker bolts. Doesn't matter whether the valve opens as you tighten the rocker; that makes less than 2 ft-lbs of difference on the bolt. Meaning, if a valve doesn't open or opens just a little, don't worry about it, and tighten to 22; if it opens all the way, tighten it to 24 ft-lbs; if it's open halfway, tighten it to 23. It doesn't matter that much. The bolt is tight, is all that matters. "Measure with micrometer, mark with chalk, cut with axe."

Custom PRs (Manton et al.) are absolutely not necessary in a motor with LS7 lifters and those springs. That's the very image of "measure with micrometer, mark with chalk, cut with axe." Off-the-shelf PRs such as from Texas-Speed are ENTIRELY adequate.

 

And I should have mentioned, that if you buy PRs that are marketed as 7.400", they will NOT measure 7.400" with a mic, because of the oil hole. They will measure somewhat less, maybe .015" - .020", because the oil hole part of the "theoretical" perfect sphere on the end that the market spec is based on, is MISSING. You have no idea how much of it isn't there; only, that a PR that you buy as 7.400", will mic LESS THAN THAT. Likewise, if you try to mic a PR and then order what you measure, the thing you get will be LONGER THAN the measurement you gave the supplier. A mic is THE WRONG TOOL for PRs.

And also, if your heads have been ported or if they're aftermarket, or even just to be safe, use thread sealer on the rocker bolts for the intakes during final assy, because the bolt hole can break into the intake port. DO NOT use silicone of ANY kind because it dissolves in fuel. Use the "hi-temp automotive thread sealer with PTFE" from Permatex/Loctite.

 

Yes I totally understand the Mic now it was throwing me out of whack. So I counted 11.25 turns which would bring me to 7.4225 with my calculator. I must of been going too tight with the adjustable PR as that seems big as the 243 were milled 5 thou slightly smaller gasket than the .055 stock ones. But I believe that is all irrelevant because it depends on the cams base circle correct?

 

Milling the heads or the block, or using a thinner head gasket, will affect the PRs. Those things will all bring the rocker closer to the lifter, thus shortening the PR. .005" on the head and .005" on the gasket, for example, will make the PRs want to be .010" shorter than otherwise.

7.4225 on the adj PR sounds kinda long. That's gonna end up wanting about a 7.500" PR which is unusual at best. I'd be very careful to assure that the lifter plunger is not depressed, i.e. DO NOT use the "twist the PR" malfunction, ONLY "jiggle vertically up and down"; and do several more valves the same way to see if it's consistent.

 

The 7.425 was with preload added I�m headed back to the garage I�m not going to tigthen the adjustable PR where it�s cranked on the rocker just enough where there�s a tiny bit of up and down and see what I get.

 

So you say it�s normal to have variation? How much is normal? Did drivers side average 10.75 turns from 6.8
other head 10-10.25 turns. So 7.3375 other side 7.3 7.3125. I�ll just run 7.4s and see what happens lol

 

Yes, absolutely. Castings aren't all that precise; then once machine work has been done, that can introduce more variation; valve jobs introduce ALOT, since different valves and seats can end up needing different amounts of grinding. The amount you're getting, and the pattern of it, seems fairly normal to me: 2 individual heads, each head is more or less consistent with itself, but different from the other.

This is why we measure in the first place. If there was no variation, we wouldn't need to bother with it.

Sounds MUCH better.

So on that side you're at 7.3375 before preload.

That one, you're at 7.300" - 7.3125" before preload.

That's .025" or more different between the 2 sides. Equal to or greater than one market increment

7.400" PRs will put you at 0.6625"ish preload on the one side and 0.875" - 0.100 on the other. Seems kinda ... not the same.

I think I'd get 8 and 8 if it was mine. 7.400" on the one side and 7.425" on the other would be about right, given the measurements you got. You'd end up with .065" - .070" preload, more or less, all the way around.

 

we�ll I really appreciate all your input. I wouldn�t be totally opposed to just running 7.4s with minimum preload at .065. My worry is the maximum being .100 seems deep? I�m running I believe .075 now on current build isn�t that noisy. Can�t wait to tear it down and see why there�s a ton of aluminum in my oil

 

Either preload would be OK; either the .065"ish, or the .090"ish. Not a problem there. I wouldn't want a motor that was half-and-half though. Esp not since it's possible for probably $5 or something, to get all 16 to be about the same. Which would mean, half 7.400" and half 7.425" for the lesser preload, or half 7.425" and half 7.450" for the higher.

.100" is toward the high side of "typical" but not to the point of being a problem. Just as .060" would be rather toward the low side of acceptable. I'd rather have either though. than .030" - .040" difference between valves. Consistency is more important than the absolute number as long as it's within the range.

 

So Installing the pushrods I realized I did the passenger head backwards smh. So it�s 10.5-10.75 all around so now I�m worried these 7.4s I got aren�t going to give me enough preload on ls7 lifters

 

Take a guess at what my Comp 7702 pushrod length checker measures when fully closed on my digital caliper gauge? If you guessed 6.8 inches you'd be correct. Very simple procedure to determine pushrod length

1.) With the lifter on the base circle of the camshaft install the 7702 Comp Cams tool onto lifter
2.) Install rocker arm and tighten down hand tight.
3.) Adjust the 7702 tool to take up all the slack "This is known as zero lash"
4.) Remove rocker arm and carefully remove length checker tool and measure with a caliper gauge
5.) Add desired preload and order OAL "overall length" pushrods closest to measured length
6.) Install into engine and torque stock rockers to 22 ft lbs..Drive and enjoy..

Those hydraulic lifters have a wide range they will operate in. High side preload can shorten lifter life and low side can cost you minimal power but longer lifter life so find the spot which is in the middle say .040-.050. Too long of a pushrod can cause valves to hang open and too short will tick tick tick.. Find the sweet spot for the lifters and you're good to go..

 

I use Manton pushrods exclusively and they ask that I use my caliper to measure lengths. They know how to adjust for the length given. It’s pretty simple really figuring Theoretical length vs Effective length, etc.

 

Yeah I�m just going to stick with the 7.4s at .063 preload. I was just mentioning there was no variation as I made the mistake of reversing my valves on the passenger side as exhaust is to the right there so first valve and on driver it�s the second valve while putting intake on base circle.