L99 Gasket thickness

[Inspiro]

Hi
I will be ordering AFM delete kit from Texas speed, they offer either the GM MLS Gasket or Cosmetic MLS Gasket(4.085" bore) in .051, .045 or .040" thickness
I was thinking of adding a little compression, so
-I have no idea what will each thickness of gasket in terms of compression ratio(all other components are unchanged)
- Which one you recommend using for a daily driver; I'm located in Dubai, I use Super Octane, which is believed to be 98RON, so (R+M)/2 should be theoritically around 93, it gets really hot here in summer sometimes reaching 120 F in summerdays

Thanks in advance

[christianchevell]

I would keep the stock gasket thickness as its steel and built to hold compression in and also your gain in compression will not be much at all in power and its a lot easier to figure the clearance for the valves with a new cam and have good PTV clearance; piston to valve clearance. So you go skimpy on the head gasket to get it closer and gain a hp or two and risk blowing the gasket IMO.... And as far as their cams for VVT go bigger or go home, as why spend money changing out the springs every 25k and have a cam that leaves a lot on the table....for a auto get a cam that requires a converter , they are not that bad and needed to make it really go faster...take it from a old motor head.

Replace all lifters at once also with a ls3 valley cover which should be in the kit and don't forget new baskets if they are not on the list as its a must for new lifters... Good Luck

[Inspiro]

Thanks for the advise
Do I really need to replace the springs regularly?!

[Redbird555]

Well any of those gaskets should be MLS just like the stock ones.if you have the PTV clearance and you should given that you look to be keeping the stock cam. Then I'd go with .040 gaskets.

It will bring you up to stock ls3 compression, .3 points but another benefit of a thinner gasket is a tighter quench which is actually better to fight detonation.

[frankwjr]

Use stock LS9 gasket and if you want to up comp, have the heads "decked", just enough of a mill to ensure flat surface and chamber volume equalization....this gives you a double win....and use ARP head bolts too...AND double check PR length AFTER putting it all together....

As for valve springs it all depends on lift, high lift will wear out the springs faster than a stock or near stock...over .600 I believe is the cut...good luck....

[christianchevell]

If your going with a higher lift cam yes you should replace springs regularly as even stock we have high lift being that its a roller cam its lift is beyond what you would think of in a good old hot rod being a stage 4 flat tappet race only type cam in a SBC/BBC .

Even stock our springs can wear becoming tired IMO before the end of the engines useful life long before the bores wear out, and for more lift than stock yes changing out the springs can be checked on checking closing pressure etc by a competent mechanic but generally the higher the lift you go the more often you change springs in racing when it comes to these high lift rates.

And the last guys right a ls9 gasket is not that much more and would be good addition in case you desire to go FI some day or nitrous, though even then you are always better off with forged pistons and rings made specifically on the pistons for the type of FI or power adder, one reason many only do mild boost. Different types of pistons, rings, spacing, gap, oil blow by so many things to consider for the "perfect" build.

Consider this; I order my oil specifically for my engine LS 30 from driven racing and pick it up my local Baxter auto supply. I use a high volume pump giving me at least 10 lbs more than the stock pump at hot idle and lots more usually when cold. L99's have a higher volume pump in them stock than the ls3. Your oil cooler is more of a oil heater should you ever want to block it off it does need to still flow oil through its path ways and there are posts on blocking it off should it be desired correctly..... Always run the a/c in the winter and the heat in the summer occasionally to keep them functioning for short periods of time as it does help keep the systems working ; some say you should run the a/c in the winter here every week...LOL

Depending on the lift of the cam installed as I said you will have to talk to a good mechanic to determine what the best schedule would be for replacing the springs if you want the springs to not someday fail by breaking or weaken and allow valves to hit from high rev valve float...IMO good luck.

[Inspiro]

THansk all for the tips