speedtigger

iTrader: (16)

I don't see anything in your formula that represents the thickness of the metal. Any expansion rate will be X amount of expansion per x amount of thickness. To be specific, you have not taken into consideration the distance between the camshaft and the rocker arm saddle. The longer that distance the more measurable expansion.

Havoc40

You used your head and accounted for expansion. The point to my post was about cold setting preload and not accounting for thermal expansion. Which seemed to be the path people were pushing regarding short travels and preload. A .004" cold set would equate to lash after the engine warms up.

Salemetro, thanks for taking the time to isolate the cam/springs change and the lifter swap. This thread should have some good information come from it!

ETA: kenp, I didn't see the 1st part about you agreeing with me, I read right over it I'll still leave my response anyway

CHADsterss

Here is what my engine sounds like with morel linkbar lifters

http://www.youtube.com/watch?v=noG0b9wL7_8

salemetro

iTrader: (5)

[QUOTE=CHADsterss;16055302]Here is what my engine sounds like with morel linkbar lifters


I F'n hate you, Man! lol Seriously though, mine will be there soon enough.

Johnnystock

iTrader: (6)

Nice n quiet sound! Im glad I went with Lunati street link!

5.3LJimmy

iTrader: (10)

[QUOTE=salemetro;16054385]If the heads have been milled then you can subtract that amount from the 7.450"

There has been alot of debate about the different height of LS7 lifters. Shane from Thunder Racing had a post comparing them to a stock LS1 lifter and found the distance from the wheel tip to where the pushrod sits to be identical. The body of the LS7 lifter was slightly taller. Even if some are measurably taller from cup to wheel GM used them in thousands of truck engines without changing the pushrod length. I think that the taller ones you speak of have more travel and are happy using what we would measure and think to be excessive preload.
I had a set of the early LS7 lifters and came up with a 7.350" pushrod length after measuring. The engine sounded almost as bad as yours so I swapped to a 7.4" pushrod and the engine was much quieter. For reference this engine had heads milled 0.030" and an 0.040" gasket. From my personal experience the LS7 lifters do not require a shorter pushrod.

The comp trunnion kit will not change the fulcrum point of the rocker.

The LS6 is the only engine that had the special lightweight and longer stem valves in the 243 head casting. If the heads weren't factory installed on a Z06 or CTS-V then they have the same valves as any other LS1.

There is some other talk in here about the thermal expansion of the block and heads. This is absolutely true. I have learned this from working on LS motors with solid roller cams. If the lash is set with the engine cold and the the engine is warmed up to full operating temperature and the lash checked it will be .015-.020" more than the cold lash. When I measure pushrod length I always add .010-.015" to compensate for this expansion.

Lastly: if you are using a dial caliper to measure the end to end length of a checking pushrod then you will always get a shorter than desired pushrod length. The length of a pushrod is not measured from the flat spot of the oil passages. It is measured to the hypothetical arc that would be there if the oil passage did not exist.

speedtigger

iTrader: (16)

[QUOTE=5.3LJimmy;16057690]This would be the logical design, but no one that I know of has actually measured this to confirm. However, if Havoc is right which I suspect he is, that is not the issue and there is no universally correct preload.

thunderstruck507

iTrader: (18)

[QUOTE=5.3LJimmy;16057690]I'm guessing this is why if I measure my 7.4" pushrods they appear to be closer to 7.375"?

salemetro

iTrader: (5)

As I thought.

I've read elsewhere on this site that 799 castings have the same valves as the LS6....only no hollow stems on the intake side. ???

Good info.




Interesting. My comp pushrods appear to measure 7.350 in the dial caliper...just as it is stamped on the pushrod?? Also, Manton and SmithBros. measure end-to-end on their ordering pages...so I'm not sure what's up with that.

At any rate....let's be conservative and say that I was OFF by .020 when I had them set to ".080".....which is a stretch of the imagination. They were STILL noisy as hell at a theoretical .060.

speedtigger

iTrader: (16)

Stock pushrods measure 7.385 with calipers.

5.3LJimmy

iTrader: (10)

So were mine(noisy as hell at 0.060"). When I switched to the 7.4" pushrods this made my measured preload .110" and they got quiet.

5.3LJimmy

iTrader: (10)

[QUOTE=thunderstruck507;16057770]Yes sir.

Havoc40

Figured I'd post some pictures of the total travel of an LS7 lifter. I'll try to track down some older parts for comparison later on today, when I have some time.

I zero'd the indicator with a 2.500" stack of gage blocks, then took measurements over a Dia. .3125 ball. Which this particular ball is actually smaller by .0005", this measurement isn't that critical.

Zero


Extended


Collapsed


measurements: 2.6511" extended length over a .3125 ball; 2.4478" collapsed over a .3125 ball. Total travel of .2033"

salemetro

iTrader: (5)

So you had to go .030 beyond GM recommended spec? And still other people in other threads claim .030 LESS than GM spec solved their problems. According to Havoc40, this is just putting a band-aid on a bigger problem......and IMHO, this appears to speak volumes of the factory tolerance issues.

RonSSNova

iTrader: (3)

And my 7.40" Trick Flows also measure 7.4" on the calipers.

salemetro

iTrader: (5)

Seems logical to me. When I used the adjustable pushrod, I just set it to zero lash, then measured end-to-end on the final adjustment....then added desired amount of preload to the measurement...then ordered new pushrods. Doesn't seem difficult to me, and I got exactly what I ordered.

thunderstruck507

iTrader: (18)

I admit I did not use calipers, but a straight edge. I didn't measure the Trick Flow 7.35" to see if they had the discrepency, but the Comp 7.4" look .025" short (they are stamped 7.4").

Could be a manufacture difference?

Havoc40

I measured a few more lifters from various manufacturers and dates. All with the same zero and .3125 ball. For this post I'm not going to include all the measurement pictures, but I will if somebody requests (I did take them).

Here's a picture of the group. I had 2 more parts to measure, but the pistons were locked in the bodies from sitting around for god knows how long. I'm using part number 17122490 to describe an "LS7" lifter.



From left to right on the picture...

Sample part #1 (part 1): 2.6588 extended length; 2.4565 collapsed length. Total travel of .2024"
LS7 sample #2 (part 4): 2.6562" extended length; 2.4486 collapsed length. Total travel of .2076"
Sample part #2 (part 5): 2.6491 extended length; 2.4565 collapsed length. Total travel of .1926"

joecar

Gauge length and actual length are defined differently, see attached pic (from another ls1tech pushrod length thread).

salemetro

iTrader: (5)

Yep. They are. But when you order an "LSX" pushrod from any of the manufacturers that have them listed as such....after having used an adjustable pushrod that was designed for an "LSX" engine....using OEM rockers, you should have no issue. The cup dimensions should have been taken into consideration by the manufacturer. The only other consideration might be to double check the cups of (in my case) the aftermarket lifters that I'm going to install. Unless I'm missing something?