355z28

iTrader: (8)

So i bent some valves and im in need of some new ones. I was looking at the 2.02 and the 1.56 valves but the machine shops ive called says it requires them to cut the old valve seats out and put in bigger ones because the stock valve seats cant be ground enough to accept the larger valves.

Just wondering if anyone else has had this done and this is true? If so i guess ill just go with the 2.00 and the one 1.5 to get me by for awhile until i can get a decent set of heads.

1997bird

iTrader: (2)

2.00" intake & 1.56" exhaust valves are more or less the best choice on the stock valve seats. You could also use the Lsx 2.00" int & 1.55" exh valves for better flow until you get a different set of heads. You will have to change out your valve guides and mill the valve spring pocket in order to make these work in your stock heads. You will also need to buy new retainers and keepers to match the valves also (11/32" vs. 8mm). This last option may be more than you would like to spend right now though.

355z28

iTrader: (8)

what size are the stock valves? arent they 1.94 and 1.5's??

1997bird

iTrader: (2)

Yep!!

hyperzone

curious about the answer to the original question about gains. I imagine its just another one of those "well it depends on......" kinda answers though.

Formula350

iTrader: (3)

I would probably get the heads done and then get 2.02/1.60s instead of just the small upgrade of 1.54. The 2.00 isn't that much less, but I dunno. I'll have to check but I should still have a set of 2.02/1.60 stainless, and I think the exhaust are sodium filled (it is sodium isn't it? Something that keeps heat down). If you're interested PM me and I'll dig around.

96capricemgr

iTrader: (1)

The stock castings are the right heads if reworked by the right people and most of them use 2.00/1.56 valves.

SincalT/A

iTrader: (16)

You can go 2.00in. 1.56ex. on stock seats that are cut to fit.2.02 in. 1.60ex. is a diffrent story yes you will have to put new bigger seats in all together.(Unless you plan on doing a full port job stick with the 2.00 in. 1.56 ex. make sure the valve stems are undercut and swirl polished imho).

355z28

iTrader: (8)

Im still wanting to know about the gains, Is it technically worth it? The reason im asking this is because I just had my heads redone about 1200 miles ago, and If theres no significant difference I think ill just press my other good valves in out of my spare set of heads.

1997bird

iTrader: (2)

Less port restriction by the smaller valve stem. The 8mm valve guide ID (0.3135") is only .001" OD larger than a 5/16" valve guide ID (0.3125"). A 11/32" valve guide ID is 0.3437". There is also about a 10-12 gram a valve differance in weight as well.

355z28

iTrader: (8)

so would it be worth it in my situation?

1997bird

iTrader: (2)

Depends on what your near future goals are for your car. Will it help your flow numbers? Yes, throughout the whole lift range. You will have to figure the cost effectiveness of things for the cost of the work being done. You should be able to pick up a set of stock LS1/6/2 valves pretty cheap. Then depending on the valve springs being used, getting the matching 8mm retainers and the keepers. The guides will run in the neighborhood of $100-$125 plus machine work. But also depending on the wear of your stock valve guides you might have to change them out anyways. The valve size increase will definately help which ever way you decide to go. The last part would be what your budjet looks like for porting your heads in the future. If you have a good local head porter then I would say the advantage is with the LSx valve combo, but if you are just going to buy a set of cnc heads later from someone else I would stick with the stock valves. This is a decision that you must make, me personally I know what I would do.

355z28

iTrader: (8)

Well since my heads only have about 1200 miles on them, i think ill just pull them off check em out and pull the good valves out of my other set and lap them into the fresh heads i have on the car. Thanks for your help and opinions! appreciate them. I think eventually i MIGHT go with an AI combo. It just depends, at the shootout ill decide lol