customblackbird

iTrader: (2)

99 5.3 with 150k, just slapped on a torqstorm supercharger and boy is it fun. But I have 20psi hot idle oil pressure and I'm prob going to be doing a rebuild/oil pump swap this winter. Its a stock motor with fbody oil pan/pickup/windage tray, LS6 blue Valve springs, stock pushrods and rockers. Stock 862 heads (pretty sure they have the notches). I'm planning on getting some fresh 862 heads without the knotches so I can run MLS gaskets. and do a smidge of port work to the heads.

Engine is staying stock for the most part, just want to upgrade the valve train and fix anything that needs to be fixed. Stock style 862 heads, stock cam etc

Here's what I got thus far
Straub bushing trunion upgrade kit (using stock bolts)
LS6 blue valve springs


Looking to get
LS7 lifters and trays
7.400" moly pushrods
Felpro Gasket set with MLS head gaskets.
GM HV oil pump.
New timing gear and chain.


Now I'm confused about the pushrod length?! LS7 lifters are now stock replacement for all LS1 style replacements as LS1 lifters are discontinued. But I read that they are the same height/cup is the same but then some say you need a slightly shorter push rod like a 7.350 vs a 7.400". I know your going to say use a pushrod checker but does that even matter if Im using all stock components including the cam (no base circle change)... its literally just lifters being changed. This is a street car so idle quality/noise matters... gotta hear that supercharger!

Mercier

iTrader: (15)

With all stock components, stock length should suffice. And yes, the disclaimer--always check. The pushrod tool is about $20. Get it. That being said, if you are freshening the heads or replacing them, you might be in for a slight mill to clean them up and that will change geometry a little. The hydraulic lifters should take up a bit of slack, though.

I think 853s could have notches but I wasn't aware of 862s with this. But I learn every day. If you do have 862s, you have a smaller intake valve compared to the rest of the cathedral port LS world. I think your better option would be to get some 241s or even 243s and have them milled to 862-ish chamber size or have the 862s opened up for the larger 2" intake valve and put some nice used LS1 valves in there. The larger valve will help, especially with your supercharger. Milling or opening up the valve job is probably only $100-$150 either way. Used 241s are about the same price as 862s..243s are a few hundred more but the casting flows better and they do start with a smaller chamber already.

Even a drop-in cam designed for a blower will net you a lot of power without causing a crazy idle. Call Cam Motion and tell them you want one that will be stock idle but net you more power with a centrifugal blower and they will cut something just for your setup. It's $400 well spent, especially when you are already pulling all the other pieces you indicated. Another hour and you've changed the cam. It really is easy. And most of all rewarding.

customblackbird

iTrader: (2)

Thank you for your response. If I didnt have to tear into the motor I would leave it as is, but since its got 150k on it i figure it would be smart to freshen some components. IVe done big HP builds, monster cubes (motor before was a 521 BBF in the same car) and although fun to brag about for dick measuring it means/does nothing for me on the street. I put 500 miles on my 521 in 3-4 years bc it was just stupid to drive around. Horrendous gas mileage, uncomfortable cam lope, having to baby it all the time. I never got to enjoy the motor for what it was worth on the street. The rule that I now live buy is its more enjoyable to drive a slow car fast and a fast car slow. Id rather be pegging my 5.3 at 4k in boost and going like a bat out of hell over my 521 at 3000 but having the economy and drive-ability that the stock 5.3 has at idle and highway.

With that being said. Sure a small cam change might be worth some power, as well as better flowing heads but at the cost of money and tuning time etc. This is a street car that will prob never see the track but once a year, so power below 5500 is a must. Otherwise I would have went with a turbo or a larger supercharger but Im seeing positive manifold pressure at like 1800rpms which is great around town. A small cam and worked heads might now be worth it $$ to hp ratio wise and then I gotta still retune again. I was thinking of cleaning up the 862 heads with some DIY port work/cleaning up. I dont want to loose any compression as its already alittle bit of a dog out of the hole as is. But I would love to run the MLS style gaskets, not machine the block or heads and I might possibly leave the short block alone (maybe a cam if I really need to) but the car is already fun with 4psi and I still have 7psi to go . But the 862s are the ones with the knotches between 99-01 years. I Think I saw them when I had the motor upside down. So getting non knotched 862s even with the small valves will be a minimum for the MLS gaskets. Since I was going to do the heads I mainly for seals, guides and port work, I would do the 150k original lifters which my only option is the LS7s. I would love to keep the motor in the car as Ive been pulling it every winter the past 4 years.

Does the size of the intake valve really matter with the smaller displacement and stock 5.3 when you have 11psi going through it? lol. Doesnt that arise different issues with valve shrouding in the smaller bore?

MuhThugga

Not always the case.

I did a 5.3 with an LS2 cam, 862 heads, and LS7 lifters, and to get the right preload, the length was 7.325.

customblackbird

iTrader: (2)

Does the LS2 have a difference base circle DIA compared to the stock LS1 cams? I know OEM use smaller base circle and therefore usually require different length pushrods. I also read the LS7 lifter cup is taller than the OEM lifter but that this is actually just visual trickery as the lifter body is shorter thus making the cup look taller.

Mercier

iTrader: (15)

I said stock..LS2 cam in a 5.3 isn't stock, though it is OEM which is close and I understand why you made that interpretation. So I'm only being a little bit of a hair-splitting smart-*** here.

I would have guessed the same on LS2 cam in there too, though, if NOTHING else changed. Is the base circle different on a LS2 vs. LM7 cam? Did you use the exact same part number head gaskets? What's the travel on a LS7 lifter? Perhaps enough to soak up what you are reporting as a .075" deficit?

Mercier

iTrader: (15)

I think it does. Boost is a measure of backpressure; not power potential. Open up the valve, port the heads, install better intake or exhaust and don't change the blower configuration, you will make more power with less boost. Less boost = less heat as well, and more power again.

It occurs to me that GM wouldn't put 243s on a 5.3 factory if there were significant shrouding issues. I believe the 1.89" valve was more to preserve super low end torque..or maybe just sell some old stuff they had nothing else to do with. I think the small valve starts to cost pretty early..and especially if no cam, larger valve will act like a cam with more intake lift.

If you really are after maximizing a low boost setup, I think a cam is wise, especially when you have it apart. Will it set the world on fire? No. But it can optimize your investment in the blower.

MuhThugga

I don't know if there is a difference in base circles between the LS2 and the LM7. The 5.3 I used was an LH6, I believe: aluminum, Gen IV block. It could have just been the way the manufacturing tolerances stacked up between the block, heads, lifters, and cam. I have seen some cases where factory GM engines were running .100" of preload.

The only thing not factory with that 5.3 right now are the pushrods.

Mercier

iTrader: (15)

I always assumed that the stock lifters had enough travel and forgiveness to them that they would soak up said mfg tolerances.

Noted. I suppose I should practice as I preach. I have lost several of those pushrod length checkers in my garage and have two more on my desk for that reason. Just seems unreasonable to spend on aftermarket pushrods with a bone stock engine. I've got a few to put together over the summer and will surely watch this.

Venom33

I have a completely bone stock 5.3 lm7 that has some lifter tick that’s been getting worse and worse so I’ve been researching what lifters I should replace them with. I know the ls7 lifters will fit but I’m not sure what size pushrod I will have to change to in order to get them to run with a completely stock 5.3.

01CamaroSSTx

iTrader: (3)

I've heard they are stock replacements so no change to PR length would be necessary but I've also heard that LS1 lifters and LS7 lifters have different preloads so without having both of them in hand to put into an engine on the stand its hard to tell. Maybe someone in here knows this and can answer that question. How do you know it's the lifter that is the problem? Could be a worn out valve spring, pushrod, rocker arm or valve.