I can't forsee there being that much of a variance between valves that the lifter won't be able to make up internally. Pushrods usually go up .025 in length (ie: 7.4, 7.425, 7.45, etc.), and if there's a .025 variance from valve to valve, something is wrong IMO. Still, as Joe mentioned, you should check the pre-load at each valve, just in case there is such a variance that should either be corrected or adjusted with the proper length pushrod.

 

Like an exhaust leak...

The only thing I want to hear is my turbo's spool and my passenger gasp

Rick

 

I thought I'd have some info for you this weekend but the heads are still at the Machine shop. I was going to swing by Saturday am and pick them up but they still needed to be cc'd. With Thanksgiving this week, it looks like I'll be slapping on the heads next weekend.

Rick

 

Hirdlej is getting a little too technical for a regular build. If youre not spinning the motor to 8K there really isnt a need to get that technical. The wipe pattern of stock rockers doesnt vary very much anyway. The only way to get everything perfect is to run a set of adjustable rockers, get an average for pushrod length then check wipe pattern and adjust your rockers accordingly.

I do agree however, with the newer lifters you need to check and make sure you are using the right length rods. I found this out the hard way on a motor I built last year. The valvetrain noise was very loud and for the life of me I couldnt figure out what was going on, since I built the standard setup. LQ4 shortblock with a set of stage II 243s, patriot springs and 7.4 rods. Turns out the owner gave me a set of caddy lifters to put in the motor(they were just in a bag not marked), once I found that out and searching on tech turns out I needed a 7.35 rods and all the sudden the motor was much quieter.

You've got a pretty big range to play with on preload anyway, and if youre not quite in the perfect range and on the loose side you can make up for it with a heavier weight oil to keep the lifter pumped up a bit more to help with excess valvetrain noise.

Im currently building another LQ4, Im wondering if I should spend the money for some caddy lifters or just roll with the stockers(no idea what year so Ill have to check prod length). The caddy lifters are quite a bit lighter than the stockers, but then again Im not going to be spinning this thing more than 6K anyway.

 

Too technical? Hmmm

 

The word that I heard, and this if from Roger Vinci, is to stay away from the Caddy lifters...the conversation basically went like this (this is when I ordered my cam from him)...

Roger: "Do you need pushrods?"

Me: "Yes, but I don't know what size yet as I will be measuring when I put the engine together"

Roger: "OK, that's good...what lifters are you using...you're not using the Caddy lifters are you?"

Me: "No, I will be using the stock replacement LS7 style lifters"

Roger: "Good, I've seen too many problems and failures with the Caddy lifters"

Me: "****, there's my boss....sorry gotta go Roger...I'll be back in touch"

So that's as much info as I was able to get due to the circumstance, but I trust Roger Vinci as he has always been straight up with me in the past, and I have ordered parts and tools from him more than once through the years. You can take it for what it's worth, I'm sure that there's a lot more info on Tech about the Caddy lifters...

 

Hadnt heard that, but I pretty much answered my question as I typed. There really is no need for me to upgrade, im just going to disassemble my current lifters and make sure they're in good shape.

 

FYI, just built another run of the mill LQ4 yesterday and ended up needing 7.35 PRs. Thats with the new style lifters, .051 headgasket, gt2-3 cam(smaller base circle) and .04 preload. Im on the light side but Ill make up for it with a little heavier weight oil, I like the heavier oil for the bearings anyway so it works out

I used regular cheapo fel pro gaskets, Im interested to see if they hold up as well as the regular GM MLS that Ive always used if I didnt use a cometic or titan gasket.

 

Here's a good tech article about lifter preload from Crane Cams: http://cranecams.com/?show=techarticle&id=2

 

Good article. I like the straight edge technique for measuring preload. Seems pretty foolproof.

Rick