i am trying to measure for pushrod size with my cars new set up and i running into results that i think are less than normal. im using a pushrod length checker but im still seeing numbers that are all over the place. just to let you guys know about the set up its a TSP 233/239 .595 .603 cam, 1.8 rockers stock heads stock head gaskets GM PP lifters. i have the car at top dead center with cylinder one fully extended and these numbers are all over the place. i measured every cylinder, intake and exhuast and here are the numbers

1I= 7.3 2I= 7.3
1E= 7.3 2E= 7.35

3I= 7.3 4I= 7.35
3E= 7.35 4E= 7.3

5I= 7.35 6I= 7.45
5E= 7.35 6E= 7.35

7I= 7.35 8I= 7.1
7E= 7.125 8E= 7.35

i thought cylinder 1 being fully extended that any other cylinder would at least have to be shorter or same size at worst but im seeing all kinds of results even after going back and double checking still.

 

Just check #1. Is the lifter pushed down firmly on the cam? You don't know position of any other lifter unless you push it down on the cam, and even then you can't measure them unless the lifter is on the cam base circle.

 

yes the lifter is pushed down on the cam. i only checked the others to see if the theory was correct about the others being shorter

 

You would need to be on the base circle on every cylinder, if you left it on #1 and did not turn the crank to get say #7 on its base circle of course your numbers are wrong.

 

i guess what im trying to figure out is if it s base circle or not, cylinder one has the longest reach due to it being TDC with all the valves being closed and such. how can i get a reading, even if the other cylinder is not correctly positioned, that is longer than cylinder 1's. i thought every other cylinder should at least read shorter than number one no matter what

 

How do you figure or who told you that the other cylinders should be shorter? That makes no sense. I think you are over analyzing this whole thing.

 

If the valves are supposed to be closed at tdc than you should than the readings you get should be the longest readings you aquire correct?
Isn't that why we get the readings from that cylinder, so we know what length the rest should be?

Well if he is getting the reading of 7.3 on both valves on cylinder 1 at tdc and he wants preload between . 060 and .1 than he will need 7.375 pushrods and settle with .075 preload.
Well say he put those in, what is happening to cylinder 7 exhaust valve and cylinder 8 intake valve at this point when it is all assembled?
Are you saying that .2 of play between the pushrods and the lifters is acceptable? I know if his readings were with the lifters completely compressed than they can compensate for up to .1 of differences, but what about that other tenth of an inch?
And cylinder 6 intake? Given his cam is over .600 lift don't you think he's pushing the limits of his ptv clearence?
He's not an idiot, just asking a logical question that has me confused as well, for I am also in the same boat.
Just because the other cylinders aren't an accurate gauge to check pushrod length doesn't mean you can't wonder what the hell it is doing at that point when the engine is assembled. That is our question.
Our goal is to understand, do you think you have some information to help us do that? He has provided all you would need to reach a correct pushrod length correct? If it is so easy than please tell us what length pushrod it is he needs and why.

 

Every cylinder has its own TDC. Number one cylinder is easy to get to, has been the main one to check forever, and is the one you would use to degree the cam.

If you check #1 at TDC and rotate the engine until #3 is also at TDC and the lifters are on the base circle of the cam you should get the same length measurement.

You can not leave it on #1 TDC and go around and check other cylinders, some valves are open, some closed, some in between.

Here is the procedure for tightening the rocker bolts from GM, as you can see, with #1 at TDC, it is the only cylinder with both of the valves closed at the same time.

Procedure
6. Rotate the crankshaft until the number one piston is at top dead center (TDC) of the compression stroke. In this position, cylinder number one rocker arms will be off lobe lift, and the crankshaft sprocket key will be at the 1:30 position. The engine firing order is 1,8,7,2,6,5,4,3. Cylinders 1,3,5, and 7 are left bank. Cylinders 2,4,6, and 8 are right bank.

7. With the engine in the number one firing position, tighten the following valve rocker arm bolts: Tighten

.....(1) Tighten the exhaust valve rocker arm bolts 1,2,7, and 8 to 30 N·m (22 lb ft).
.....(2) Tighten the intake valve rocker arm bolts 1,3,4, and 5 to 30 N·m (22 lb ft).

8. Rotate the crankshaft 360 degrees.
9. Tighten the following valve rocker arm bolts: Tighten

.....(1) Tighten the exhaust valve rocker arm bolts 3,4,5, and 6 to 30 N·m (22 lb ft).
.....(2) Tighten the intake valve rocker arm bolts 2,6,7, and 8 to 30 N·m (22 lb ft).