QuickSilver

iTrader: (22)

Ok guys i am trying to check for the correct length pushrods.
I have the comp cams length checker that goes from 6.800 to 7.800.\
Each turn of the checker is .050.

I am checking an exhaust valve. I watched the intake valve open, so i know the exhaust is on the base circle.

Here is what i came up with.
had to turn out checker 9 full turns.

9 turns @ .050 a turn should be ----------.450
Push rod lenth checker closed -----------6.800
total with no preload--------------------7.250
add in about .065 preload(LS7 lifter)-----7.315 pushrod over all length.

This seems way off from what TFS recomends for their heads and cam package, they reccomend 7.500

Car had a TFS cam, TFS 205cnc heads and stock rockers.

Please let me know if I am doing something wrong.

TIA
Josh

PREDATOR-Z

Did you measure on the base circle of the cam and was the rocker at 0 lash

QuickSilver

iTrader: (22)

Yes rocker was at 0 lash.
Measured exhaust valve with intake valve open, so that whould have been on the base circle of the cam.

vettenuts

iTrader: (4)

Push down on the adjustable and make sure the lifter is on the cam. New lifters will stick in the up position. Check intake, it should be similar.

QuickSilver

iTrader: (22)

lifter was all the way down on cam.
I will check intake to make sure figures are correct.

vettenuts

iTrader: (4)

What rockers? Rocker pushrod cup position will also make a big difference.

QuickSilver

iTrader: (22)

stock rockers

dtroike

iTrader: (4)

I am assuming you have the heads torqued down with head gaskets installed. Try measuring the push rod with a caliper to make sure it is accurate. You cant always use what is recomended thats why you use a pushrod checker. Also I believe trick flow rocomends using roller rockers so the length may be different for stock rockers.

DaddySS

I don't know what lifters you are using but .080 to .100 is the recommended preload for LS1 lifters .075 to .120 is the range. so 7325 or 7350 would work. you can also double check by tightening rocker arm bolt to 0 lash then you should be 1 to 1.5 turns to 22 ft lbs.

vsocks1

iTrader: (6)

Not sure that the length is way off at 7.3X.
There are lots of variables and as long as you measured should be ok. Don't go by TFS 7.500" recommendation. Didn't work for me either - little different setup but I am running 7.37 with TFS heads.

DuronClocker

iTrader: (25)

Why don't you do it the right way and make sure the motor is at compression TDC?

QuickSilver

iTrader: (22)

either way "should" be correct. I am going to double check it on compresion TDC next.

Intake stroke- intake valve open then closes to compression stroke. so check exhaust
exhaust stroke- exhaust valve opens after compression stroke so you can check intake.

vettenuts

iTrader: (4)

Curious on your intake measurement. Any results?

QuickSilver

iTrader: (22)

I need to double check everything but the intake measurement was coming up at like 7.400. I must have not been on the base circle on the exhaust.

I have been trying to bump it over and watch the valves myself. I will have some help tonight or tomorrow to try and get it right.

DaddySS

I find #1 TDC compression stroke first, mark the dampner, then mark it at 90* intervals. Now turn the engine by hand and follow the firing order for each 90* turn.

vettenuts

iTrader: (4)

If you are bumping with the starter, it can be hard to position. I ended up making a special wrench to turn it over by hand.