Now im trying to make sure im on the base circle on the intake side...I placed a pushrod on the exhaust side and turned the motor clockwise until the pushrod came all the way up then slightly started to go down. Im not sure which is the correct way. Im finding contradicting info. I found another video on yt where one person said once the pushrod in the exhaust starts to go up that the intake valve is on the base circle.

 

but if I am on the base circle on the intake side it's looking like the stock pushrods are too long

 

Remind us, what have you done to the heads/valvetrain? In other words, what thickness gaskets, have you had the heads milled, etc. When checking if you're on the base circle, I generally watch the exhaust rocker and when it begins to open, I turn the crank another 5-15 degrees ( the tighter your LSA, the less you need to turn ) and that should put you right on the base circle of the cam.( When checking the exhaust valve, wait until the intake valve is nearly closed and you will be on the exhaust base circle.) Insert the pushrod checker, torque the rocker arm down, and turn the top of the checker until it takes up the slack between the pushrod cup in the lifter and the rocker arm. Do not use any force to twist the checker as the slack is taken up, as you can begin to compress the pushrod cup in the lifter. Remove the checker without disturbing your measurement, and use a set of calipers to measure the end to end length ( this is not entirely correct due to the radius of the pushrod and the oil holes, but it works ). Once you have the end to end length, add .100 to the value and choose the pushrod that is close to that value ( but not over ). For example, I just built an engine recently where my direct measurement was 7.237". I used 7.325" pushrods in that build. Hope this helps.

 

THIMK about how an engine works.

It has 4 strokes: intake, compression, power, and exhaust. In that order. You can "start" with any of them, but they all follow in the same order.

The intake valve opens just before the intake stroke begins, with the piston at TDC. It reaches full open somewhere around halfway through the intake stroke, with the piston around halfway down. It closes somewhat after the end of the intake stroke, shortly after the piston reaches BDC. Therefore, since it's fully open at half the int stroke, i.e. the peak of the lobe is under the lifter at that point, the "heel" of the lobe, where the lifter is on the cam base circle, is 180° of cam rotation away from that; IOW on the opposite side of the lobe. 180° of cam rotation is 360° of crank rotation. Since there are 4 strokes total in one cyl's cycle, that means that the "heel" is under the lifter exactly 2 strokes away from the middle of the intake stroke; which is, halfway through the power stroke, after the other TDC event, at which the cyl fires. The exhaust opens a bit before the beginning of the exh stroke and stays open through the exh stroke much like the int valve does during its stroke. "A bit before the beginning of the exh stroke" is the same thing as "near the end of the power stroke"; which is, JUST AFTER the int has reached the base circle on the cam. Therefore, measure the intake valve JUST BEFORE the exh starts to open (the "EO" of "EOIC"). You could for example watch for the exh to open, and as soon it starts, back the crank up 20 or 30° or so, and that'll get you to about the middle of the power stroke, directly opposite the middle of the intake stroke. Too easy.

Apply the same logic to the exh lobe's location, and you'll come to the conclusion that the exh lobe reaches its base circle JUST AFTER the int valve has closed, i.e. as the compression stroke is beginning. That gives you the "IC" part of "EOIC".

At each one of those 16 points in the engine rotation you get to measure ONE valve for push rod height. Put your adjustable push rod in THAT ONE valve, adjust it to take up all the VERITCAL play in the PR & rocker ONLY (DO NOT try to use the "twist the push rod" malfunction, you're looking for VERTICAL PLAY ONLY); and that's the length of the shortest possible push rod you could use, i.e. with NO preload at all. Add your desired preload to whatever that length is and place your order. For LS7 lifters you might shoot for .070" - .080" or so longer than your adj PR, and since you can easily order PRs in .025" increments, you should easily be able to get all 16 valves between .060" and .090", which is plenty close enough. Other lifters may require some different preload and maybe more precision, or you might choose a different number like .100" if all your parts are brand-new and you're expecting a bit of wear right away such that your preload will open up at first but then stay there afterwards, but the process and logic will be the same. You might not need to measure all 16, but I'd FOR SURE measure both valve types at all 4 corners of the engine since that's where machining tolerances will show up the most, and since by that time you've already measured half of them anyway, might as well just go ahead and do em all especially since you're rotating the engine in 90° increments to begin with which lands on all of em as you go along anyway, and make sure you have no surprises.

Not that hard really.

What makes this even easier is that any given event occurs on all 8 cyls at exactly 90° of crank rotation apart from each other, in the firing order. That is, if you find, let's say, the base circle point for #1 intake, then you can turn the crank exactly 90° (¼ turn) and the NEXT cyl in the firing order, #8, will now be at ITS intake base circle point; then 90° more, and the NEXT one, #7 will be up, and so forth, for all 8 intakes. Meaning, you only have to find ONE valve's EO or IC, and then run through the firing order measuring that kind of valve, all 8 in a row, 90° apart. Too easy. So eeeeeeeezzzzzzy even I can do it, and I'm a moron, so surely someone as smarrrrt as you can knock it right out.

Don't jack around with abuncha calipers. That's just extra w ... w ... wo ... wor ... [ppppppppuuuuuuuuukkkkkkkkkkke] sorry, can't bring myself to utter nasty 4-letter words like that without making myself sick. Just count the turns on your adj PR. They're all some particular length when fully screwed together, most are 6.800"; then since the threads are ¼"-20, 20 threads per inch, each turn is .050". (1" ÷ 20 = .050") Again, TOO EASY, and you only need ONE tool, namely, the adj PR. So, say you happen to have a 6.800" adj PR, and you unscrew it 11 turns to take up the preload; its length at that point is then 11 × .050" (.550") + 6.800", which is 7.350"; add .070" to that, you get 7.420". You'd buy 7.425", which will give you .075" preload. Perfectly within that .070" - .080" window. You might find your engine wants 8 of one length for intakes and 8 of another for exhausts, or all the same except one or 2 which you could then buy a set and the couple of extras, or whatever. Easy. Keep it simple and buy stuff off the shelf. Don't outsmart yourself with calipers and "calculating" and all that; just count the turns.

 

Nothing has been done to the cylinder heads other than the valve springs and valve seals. Im running stock apex mls head gaskets, the heads have not been milled. The 7702 pushrod checker arrived the other day Im going to try to find a digital caliber at hf

 

Don't bother, you don't need it. (at least not for this) The 7702 is all you need for this task.

 

I have all the tools at my disposal, so I figure why not? Math hurts. Lol.

 

Me too...

But the OP does not. Granted, a good caliper is indispensable when building, or even just ASSEMBLING, motors; he SHOULD have one ANYWAY given that he's trying to do that, I'm not trying to tell him he doesn't need one at all; only, that he doesn't need it for this specific task. The 7702 will tell him exactly what he needs to know, and his next post won't be something like "why does the 7702 say one thing and the caliper another" when the 7702 number is the only one he needs to begin with because it uses the same measurement method by which PRs are sized in the marketplace, being made specifically for that specific purpose by a PR mfr.

I do disagree however about math. It's one of the easiest things there is, actually.

 

All this math and geometry!! I never was good in either LOL. After measuring the intake and exhaust on the first cylinder they both measured 7.3xx. could any of the other valves need different pushrods...kind of time consuming when I get the measuring I found myself doing it over and over especially with the 7702...I tried both methods using the digital calper and using the count-turn method. 7.3 and counting the turns it took 12

 

12× .050" (.550") + 6.800 = 7.4 + x =

 

12 × .050" = .600"

6.800" + .600" = 7.400"

Doesn't get much simpler than that

Yes, absolutely possible

 

here are the measurements using the digital caliper

driver side pistons

1.intake: 7.333
exhaust: 7.311

2.intake: 7.317
exhaust 7.317

3.intake: 7.317
exhaust 7.317

4.intake: 7.315
exhaust 7.315

I found a FAQ on Speedway Motors where someone asked if the stock PR could be used with SS2. Tech responded stock pushrods will work but always check. if my measurements are around 7.3 and I add a .100 im in the range of stock pushrods which are 7.4?

 

Sure. Assuming you're using LS7 or other similar stock type lifters.

​​​​​​​You could even use stock ones themselves if you like the idea of having PRs made out of rubber tubing.

 

LOL nope I dont like that idea.I am going to upgrade them to hardened pushrods later I just want to know if the stock PRs will handle mostly idling and a little bit of neighborhood/highway driving until I get everything together.

I I measured all of the passenger side cylinders they came back in the range on 7.31X.. If I do order the hardened pushrods would I just go with 7.400 .080 or do I need to have a precise measurement

 

You order closest to what is exceptable for your preload requirements.

Only expetion would be like a johnson short travel or something similar that requires a tight spec. Then you can order specific lengths. But the cost is atleast 2x as much as standard hardened pushrods...

 

You'll be fine with 7.4s.

 

Could I get away with running stock pushrods with my build until I get the engine running?

I don’t plan on pushing it over 6000 rpm until I upgrade the pushrods. Mostly want to idle and do a little bit of local driving

 

I myself wouldn't do it, pushrods are cheap. Stock ones are not meant for the aggressive ramp rates of aftermarket cams. Watch videos of pushrods on Spintron machines, they're flexing and moving around like crazy.

 

Does the valve spring pressure change with RPM? Then what difference does that make?

I believe somebody mentioned

Just... don't. No point in ruining whatever else you have going on, by cheeeeeeeeping out on something that trivial. DO IT RIGHT. Quit trying to cut every corner you come to.

 

As for the pushrods What brand of hardened pushrods do yall consider that are not expensive?