red83

iTrader: (64)

i know this has been covered before, but there are no for sure answers, so i decided to measured the lifters today and there is .060 difference in plunger depth. betwwen the two. the newer ls7 lifter according to my measurement will need the following------for example---if your using a ls7 lifter you will need a a 7.340 pushrod plus your pre-loadif your replacing a ls1 lifter and 7.400 pushrod. it is also a big visual difference!

the main difference that i see is that the lifter cup retainer is made different. the old style ls1 lifter uses a piece of stamped steel that hold the lifter cup down. and that retainer is thicker than the newer style ls7 lifter that is made of wire. that is what i believe the difference is. i know there is internal differences in the lifters, but i am talking about cup depth only. hope this helps someone that is replacing lifters!

A_VAS

iTrader: (16)

Thanks for the info...just to confirm:
the LS7 lifter plunger is .060 higher than a stock LS1 lifter?

raven154

iTrader: (14)

yes, hence the shorter pushrod

Demonicbird00

iTrader: (17)

i didnt know that..good info.....but....

when i had my first cam a year ago i had ls7 lifters w/ the stock pushrods and had no problems.

since going to the cam i have now w/ the size of it i now have 7.4s

-brandon

red83

iTrader: (64)

i talked to scoggins-dickey tech today. and the ideal ls7 lifter preload is .060 . that is what i was told.

and yes that is what my ls7 lifters measured against my stock ls1 lifters

but i also know people add anywhere from .030 to .100 for pre-load. so stock pushrods could work. i think.....but i am not building your engine. so just to clear myself...........check with your engine builder.

4psi

iTrader: (5)

I was going to use my comp R lifters but after listening to a few people I decided to change over to the ls7 lifters.

Texas-speed told us to use the ls7. Will the 7.4 pushrods be fine?

red83

iTrader: (64)

really you just need to order a 20.00 pushrod length checker and be sure. 20.00 dollars is cheap insurance vs. having a super loud valvetrain or a valvetrain that is to tight! imho.

4psi

iTrader: (5)

My engine is in the machine shop. They use a adjustable PR to check. I guess we will see.

ls2 bait

iTrader: (11)

hmmm. good info. i wonder about the caddy lifters that i have.......

red83

iTrader: (64)

here is a link to a cam site. more good info

http://www.cranecams.com/pdf/151g.pdf

405HP_Z06

iTrader: (11)

Here's some information from Katech concerning lifter preload on Gen III/IV LSx engines. They recommend .075" - .100". https://ls1tech.com/forums/showthrea...ghlight=lifter

I observed the same difference in plunger depth on my recent cam/head install. I'm not sure the difference in lifter cup depth would change pushrod length IF the internal plunger depth is modified to compensate for this change. If you compare an old LT1 lifter to the LS1 lifter, the difference is even more drastic, on the order or .120"; yet, GM specifies the LS7 lifter as the replacement.

BIG_MIKE2005

iTrader: (116)

I'm running LS7 lifters in my set-up with zero issues. My heads are milled .018", I run a stock LS1 FelPro head gasket, 7.4 TR pushrods & stock rockers. It's very quiet & hasn't given me a single issue.

red83

iTrader: (64)

i talked to cam motions. thats whos cam i have installed and they recommended .040 to .065. which from my measurement of 7.335 at zero lash + .065 preload= 7.400. that equates to me saving 100.00+ on pushrods........lucky me.

on another note i also seem were tony mamo @afr recommeded .050 to .100 fro stock style rockers

405HP_Z06

iTrader: (11)

Are you using Cam Motion lifters? If not, why would you follow their recommendation for lifter preload?

vettenuts

iTrader: (4)

They sound about the same height as my Morels. On another note, I thought the LS7 lifter was the GM replacement lifter for the LS1. That being the case and the LS1 lifters I have measured being near 0.100" preload from the factory, wouldn't there be a service bulletin on this as I would think the stock pusrods and stock cam would result in a problem.

BIG_MIKE2005

iTrader: (116)

The LS7 lifters are GM's replacement for the LS1 lifter. So if you take your car to a stealership for a collapsed lifter, they will replace them with LS7's. You can't even buy the older ones anymore unless you get them used.

A_VAS

iTrader: (16)

I'm sure some of you here know this, but the less preload you run, you'll pick up torque....of course too little and you'll have chatter when cold. Personally I'd shoot for the lower numbers mentioned here

405HP_Z06

iTrader: (11)

I agree. There is a relationship between plunger travel and the pushrod cup depth that would result in a net 0 change to pushrod length. What GM did with the LS7 lifter was exactly that. For pushrod length checking purposes, you should use the components that will be in service so the correct stack up height is achieved. On the flip side, I would not change pushrod length when changing lifters.

red83

iTrader: (64)

because everyone is all over the board with the recommended preload. i called scoggins-dickey for the recommendation on gm ls7 lifters and they told me that crane recommends xx or xx. so therefore i could not find no one that could tell me the correct ls7 preload specs.

405HP_Z06

iTrader: (11)

Gotcha This is from the link above from Katech on lifter preload:

1) The only way to properly check (and know where you are in the travel) is
to use a special checking lifter or completely compress a stock lifter.
a) Checking lifter consists of a lifter that has been disassembled
to install shims that lock the plunger at the top of travel in the lifter body.
If using this method you would add length to the checking pushrod to put the
final pushrods into the middle of travel of the plunger.
b) Using a stock lifter, you must make certain that you have pumped
all the oil out of the lifter. To do this leave it at valve full open (highest
spring load) for a while with an indicator on the pushrod side of the
rocker. Watch to see when the indicator stops moving (when the plunger is
fully compressed in the lifter body). Once you have compressed the lifter
rotate the engine to close the valve, extend your checking pushrod to full
length. Using this method you will subtract length from your checking
pushrod to put the final pushrods into the middle of travel of the plunger.

2) Typical plunger travel on Gen 3/4 lifters is 0.150 - 0.200 depending on
the manufacturer, year, etc. We recommend 0.075-0.100" from the bottom of travel (using method 'b' described above) or 0.075 from the top of travel (using method 'a' described above). That will generally put you close to the middle of travel. While there are many different strategies for where to put the plunger, for street use we strongly suggest that near the middle of travel is the safest for durability.

3) The more precise method of checking is 'a' because you are not guessing
that you got all the oil out.

Vinci recommends two full turns when using Crane adjustable rockers, which equates to approximately .084". This is what I am using and have no issues.