I purchased a TS .228/.588 cam package for my 03 5.3L
It came with 7.4 pushrods. Which seem to be the same as the stock ones.

But now my lifter preload is very low.

Searching here I find for stock lifters they require .060" to .120" preload.

With the stock set up I had 1 3/8 turns preload = roughly .068" preload.
With the new cam I have only 3/4 turn preload = roughly .037" preload.

Stock cam base circle = 1.552
TS .228 / .588 base = 1.4615

.0905 difference /2 = .045"

So I should have .045 longer pushrods than stock to have the correct (same as stock) preload.

What does everyone else do? Or am I wrong?

Why would TS sell me those pushrods when I explained in great detail what I require? Its Sat and they are closed. So I guess I'll stop the assembly here and wait.


Any ideas????

 

what rockers are you using?

 

The stock rockers.
The engine is 100% stock.

Only doing a cam, springs, pushrod swap. All parts purchsed from TS.

I checked again on different cylinders. it always the same 3/4 turn preload. compared to 1 3/8 with the stock cam.

 

Have you called them? I would call them and see what they say, its their cam, they should and will know what works best with it.

Base circle makes a difference, I had to run 7.5's with my last setup utilizig AFR's and a custom ground comp cam.

 

TS recommended the package and sent me "everything I need".

I just thought for good measure I would "measure" the lifter preload.

I plan to call them.

It's just that I found this out last night. And I am sure many on here have performed a cam swap like I am. Stock heads, rockers etc..

I just hope to find someone that has done it before. And can comment.

Thanks.

 

Most people just stuff it in and and bolt it back together without checking...lol, your one of the few that actually paid attention to it and took the time to measure.


I havent run the combo so I cant really say for sure. BUT 1 and a half to 3/4 turns seems to be the standard with oem lifters and rockers.....

 

i've never checked... lol but! My lifters went bad shortly after the cam install.... as a matter of fact I am changing them right as we speak! *Would strongly Urge you to do the same thing*... pending what size cam you chose. I have an ms3 237/242 .603 .609

Good luck!

 

I've done several hundred installs of that cam and I normally see .045" of pre-load measured with a dial indicator. Being that the install is in an iron block that doesn't expand much if any, I would just roll with the ~.037" pre-load myself. I would rather be on the lesser side of pre-load than having too much.

The minimum I've ever run with stock style lifters was about 1/2 turn of pre-load which is a tad over .020" on a cold engine, and I don't like running more than 1 3/4 turns.

 

Congrats for measuring, Joseph is correct on being on the lower side, but not by that much. That is why I've been recommending at least 7.425 p-rods on XE-R cam only setup. IMO from experience at least .060 preload.
XFI and LSK lobes 7.450 (but 7.425 will work). 7.400 are too short and that is one main cause of sewing machine noise and sometimes even valve float.

As to why most vendors put 7.400 on most their packages, I've asked myself that a million times.
It is believed that hydraulic lifters will make up the difference, but I've found that to be inconsistent depending on oil thickness and lifter bleed down rate.

 

Beyond all that... Nice looking ride !

 

Thank you everyone for the help. It makes sense to measure with a dial indicator.

I am going to do that right now and I will report back.


When I think about it seems to me that checking by rotating the rocker bolt may not be too acurate because....

The valve spring will almost always move first, then the lifter slowly bleeds down. When you think of the 1.7:1 ratio or the rocker arm moving the spring first, it would give a false reading IMO.

 

I think your calculations and predators comments are correct although I like closer to .080+ preload for a quieter valve train. Get the 7.425s, you'll be glad you did.

 

OK.

I checked like in the pic below.

NOTE: Some lifters are tighter than others. They compress with more force. Must be that some have bled down more than others when I rotated the engine a few times.

With the tighter lifter I get .054" like in the pic. Indicator is moving CCW at the lifter goes down. It takes a few minutes to bleed down.

With the looser lifter I get .060" right away.



If I get 7.425 pushrods that would put me at about .085" preload.

Would that be too much?

 

So when I figure it all out.

I have just about .060" preload now,

The base circle radius changed by .045" with the new cam.

Stock lifter preload was .105" !!!

 

That would be perfect

 

OK Then.

Thank you very much for the help. I will call TS on Monday and get the 7.425 set.

 

Let me ask you... does that thing go over speed bumps very well? LOL...

What kit or MFG are you using? I have customer who wants something very similar for his Camaro. Air-ride o Air-link something like that. I need to get a lot more info on it.

 

Its a 2003 bought it new, drove it a bit, then tore it down and built the truck from scratch. Took 27 months to this point! Custom frame and suspension.
15K miles on it.




New


Rear set up.



Front set up

 

Nice looking truck. Good luck with the pushrods.

Bill

 

UPDATE:

Just thought Id close this subject.

At the suggestion of Texas Speed, I stayed with the 7.4 pushrods.

.060" measured Lifter Preload.

It's just as quiet under the valve covers as before. IMO.

Sound Clip!


http://www.youtube.com/watch?v=FmiK-Lea8cQ