i cant turn my motor over at all with the new cam and heads. patrick g told me that there would be clearance issues so this is no surprise, and ill have the lindy on the way to my house early next week. my intake and exhaust valves hit the piston just BARELY before TDC on the upward stroke. this was using my dual springs with a solid lifter (that is correct right?). some of my unanswered questions are:

#1)im sure an incorrect pushrod length can effect P2V clearance? i cant check my pushrod length using the sharpie method because the motor wont turn over completely. i tried using the stock 7.400 pushrods to measure the P2V clearance. combo is a untouched Lq9 bottom end with ls6 heads. 2.02 intake valve with stock exhaust. heads were milled .027 from what i was told. stock 6.0 head gaskets (.053 compressed) 235/243 .610/.627 112+2 HUC lobes. the math that was explained to me shows a 7.400 should be about perfect but i cant verify. does 7.400 sound right to the guru's here? i buddy loaned me a pushrod length checker but he wasnt sure how to use it lol.

#2) how much should i cut initally before i can clay and measure? i dont want to go too little and do the job 10 times, and i dont want to go too far on the first cut lol.

3) how the hell do i check the degree on the cam? im checking it before doing any cutting. i have the tools but dont know how to use them lol. the dots are lined up right now.

sorry for the noobish questions. it seems like every time i break something i find myself even farther into unknown territory. i enjoy the learning experience though.

 

still looking to learn

 

There is an excellent article in Car Craft magazine in March 2011 on this very subject..using LS engine. They have high dollar tools but they are not necessary. Worst trouble I have is making homemade stuff to bolt on engine in places so I can use my Harbour Freight magnetic dial indicator base LOL. I think the cam makers also have instructions on their web sites.
You need to visualize the push rod situation. With a hydraulic lifter, the push rod operates with the end partway down in the bore of the lifter. In other words, once the engine has run and built up oil pressure, the lifters self adjust and take out all slack between the push rod and the end of the valve. The length of the push rod then determines where in the bore of the lifter the internal plunger rides. When you hear someone talk about a lifter pre-load of .030-.060, they are saying they have the length of the push rod set to have the internal plunger operate at .030-.060 below the top of the bore of the lifter (the spring clip that holds it together) The reason you have to check is because different cams have different base circles (lowest point of lifter travel) The problem with trying to check PTVC is you need to be able to check it basically like it will run. If you are going to run the factory 7.4 push rods, they could easily run down in the bore as much as .100-.125. If this is the case you can see that by just sticking a solid lifter in it, you are holding the valves open when you turn it over and could easily bend a valve! Be careful! It may sound crude, but here is how I do it. It takes a little time but costs nothing. I take a couple of used lifters and take the guts out and clean them so the plunger and push rod seat slide in and out freely. Reassemble without the little spring and drop in cyl#1. Put old gasket on and head with a couple bolts. Drop in the push rods you plan on using and bolt on the rockers.
You should be able to turn engine over now since the lifter plungers are at the bottom of their bores. Now turn the engine until the intake pushrod is at the bottom of its travel on the cam (valve closed) Now measure with feeler gauge or dial indicator clearance between valve tip and push rod and record. Do same with other valve. Divide these numbers by 1.7 (rocker ratio). Now pull back apart and disassemble the two lifters and put a small spacer between the plunger and the push rod seat in each one that matches the number you got when you divided by 1.7. Stick it all back together and see if you have 0 clearance at each valve when the lifter is on low point of cam (valve closed) Sorry..you may have to do this more than once Once you get it right you can check PTVC. You can put lite springs on the valves,and check with dial indicator. Check from 15* BTDC to 15* ATDC on the overlap stroke. You can also clay it and turn it over to check. Lots of work, but it actually mimicks the way the valves and lifters work when the engine is running. Sorry so long winded. Ron

 

thanks for the help. i have a pushrod length checker on hand. today my goal is to learn how to use it haha. from what i see so far, i put the piston at TDC and measure with a solid lifter until zero lash. then add in .070 preload. does that sound about right?

 

don't add the preload in...the way to see your ptvc is to use a solid lifter and then adjust the adjustable pushrod until it is at zero lash...you should be on the base circle of the cam(so no lift at all)...it does not have to be at TDC...

spin the motor over a few times, then check your clay...if using a dial slowing turn the motor over checking clearance every few degrees...start about 15* BTDC...

you should have clearance with that setup and not hitting the piston the way it sits...pm me if you have other questions...

 

7.400 seems about right, but it's always best to measure. When I flycut mine, we flycut .1 on the intake and exhaust. You can go up to about .110, and you should still be fine, but we went to .1 just to be safe.

When we did mine, we hotglued a piece of sandpaper on an oversized valve, and used a drill and dial indicator to flycut...

 

ok, so i measure P2V with a solid lifter and the pushrod length checker set to zero lash instead of the 7.400 pusrhod (7.400 would factor in preload)?

once putting the normal lifters back in and use the 7.400 pushrods, wouldnt the valve be pushed farther in once the lifters prime up?

 

No the plunger in the lifter depresses and absorbs the preload.

 

for clarification on what you didnt understand. when checking PTV clearance - i dont want to use the 7.400 pushrod with a solid lifter because it includes the preload that i would use in the end product right? i should measure with the adjustable pushrod on a solid lifter at zero lash...then add the preload to my zero lash length when i order my pushrods.

awesome. i think i have it all figured out now for the ptv checking part anyways.

adjustable pushrod at zero lash on the base circle of the cam with a solid lifter. turn the motor and measure clay. once i add the preload in the valve wont drop anymore because the lifter will absorb the preload. time to go re-check my PTV clearance. i checked it using a 7.400 pushrod instead of an adjustable at zero lash. hopefully doing this will let me turn the motor over

sorry about being redundant. just making sure i have everything straight in my head.

 

ok i got it right this time (thanks for setting me straight!). my motor will turn over now with the adjustable pushrod set at zero lash with solid lifters.

here's my math:
9.5 turns on comp adjustable pushrod to zero lash.

9.5x.050=.475+6.8=7.27+.075=7.345

sooooo if my math is correct, a 7.35" pushrod will be perfect for me right?

i still havent checked my PTV clearance. i need to get some checker springs and get the degree wheel hooked up. that method just seems more accurate than clay to me.

 

with some crude measuring techniques lol, i came up with .120 exhaust clearance and .070 intake clearance. after doing it, im not wild about the clay method. i gotta get some checker springs and figure out a way to mount this dial before i can have peace of mind.

 

I had 10 turns with mine and I came up with 7.380 after adding in .080 for preload and im going to use a 7.375 pushrod. So take .025 off for the 1/2 less turn and you get 7.355 which would require a 7.350 pushrod. I have a set of tsp 7.350 pushrods for sale. 70 shipped

 

ok, before i cut i want to be CERTAIN that i measured my PTV correctly. sorry if im being redundant but the numbers i got were off from my clay method. i feel much better about the new numbers.

i found TDC on the #1 piston (drivers side front). i measured 15 degrees each way on each valve. i found minimum PTV clearance at 9* on both valves.

i found .070 clearance on the exhaust and .020 clearance on the intake. this was using solid lifters with an adjustable pushrod set at zero lash.

for some reason, the exhaust side requires 1/4 more turn to reach zero lash using the same solid lifter and rocker. is this normal? has anyone heard of adding clearance to your measured numbers using the checker springs? i swear i read that somewhere.

 

SOB. i think i measured it backwords. i just read a post from predator that you measure the intake BTDC and exhaust ATDC. i think i did it opposite because thats where the valves started moving and where i got the tightest PTV numbers from. i wish i had someone to actually SHOW me how to do this instaead of learning the hard way lol