I’m planning on doing cams and a new valve train this spring
to do it, will the head need to come off?
and if so, should I get a headgasket that will raise the compression? Some of the Cometic ones will apparently raise it 0.4
I have a b20z, with 9.6:1 comp, so then it would be an even 10:1 comp
just mill the head while its off and use an oem headgasket. o and yea you need to pull the head to install valvetrain.
You don’t need to pull the head to install valvetrain, you can use compressed air to stop valves from dropping.
Milling is not reversible. If you are going to raise CR the cheap way (without using pistons), a thinner headgasket is a reversible, cheap way to do it.
but why would I want to reverse it?
Pistons will come later, but not right now.
For that reason exactly.
If you decide to go with a high compression pistons, the milled head may bump the CR too much. You also may run into piston/valve clearance issues depending on the size of your valves, cam timing, and cam profile.
stupid canadians. dont mexican up ur valvetrain. also a nice headgasket like an inline pro costs more than head milling. and technically if you wanted to lower the cr later on you could go with a new valve grind. so all u did in that post was make me grumpy when i woke up. :thumbdown: also piston domes come in differant sizes too, if you mill your head alot you might want to go with a slightly smaller dome.
well, that was uncalled for
sorry lol didnt relize u were too.
Ignorant assholes like you give this board a bad name.
I try to offer advice (much better advice than you are offering) and this is what you come back with. If you have something to add, at least do so in a courteous manner.
And you’re trying to tell me you CAN’T swap valvetrain with the head on? You’ve got a lot of learning to do.
So, let me get this straight. Your compression ratio can be raised or lowered depending on your valve GRIND, but you can’t change valvetrain without pulling the head… lol.
Remind me to not ever come to you for advice. 
I can’t get over some of the shit that I read on here, and how confident the ass clowns are that make these statements.
What the hell? You’re joking right? Not even you can be this stupid.
ok guys, let me get this straight. you can change valve without pulling your head? maybe you should be my new mechanic. i know you are saying you can change the springs and retainers without pulling the head, but why waste your time. maybe im ignorant for wanting to do shit right, or maybe because when i buy a valvetrain, i actually buy a valvetrain not just springs and retainers, but i’m sure the biggest reason is prolly for not using my 10+ year old valve guides and seals. so if i grind material off my head in the combustion chambers larger this wont lower my compression? its a shame that im labeled the ignorant one.
ps that last question is rhetorical.
The whole purpose of changing the springs and retainers without pulling the head is to save time, not waste it - not to mention save you from purchasing another head gasket. You would know this if knew what the process involved.
…maybe im ignorant for wanting to do shit right, or maybe because when i buy a valvetrain, i actually buy a valvetrain not just springs and retainers, but i’m sure the biggest reason is prolly for not using my 10+ year old valve guides and seals. so if i grind material off my head in the combustion chambers larger this wont lower my compression?
This is not the correct way to “do shit right”. Read what I quoted you originally. You stated that you could lower the CR by changing the valve grind. If you take more material out of the valve seat area - diameter wise at least - for a new grind in an effort to lower your CR, you have to put bigger valves in which would bump it back up a bit. And if you were to remove material from the combustion chamber, it most likely would never be enough to lower the CR by the amount that you you added by milling the head, not to mention changing the flow/swirl characteristics. You used economy as a reason for milling a head to raise the CR, but if you had to lower the CR back down by the methods you described, it would cost a whole lot more in the end.
I appologize for my defaming statement in my last post, but please be more objective and try to think about the best solutions to problems, not just short-term fixes that may be regretful later on. I’ve seen a lot of posts lately offering bad advice to newcomers, and I think you could have thought out more about what you said - you just sounded like someone who has hasn’t actually worked on engine internals by your advice given earlier.
so how important is it to get new valve guides and seals?
first off there is no reason you should need to make up for the extra c/r added by milling the head. like i said posts earlier pistons come with differant sized domes depending on the cr you want. there is on average .2 differance in compression between pr3 head and p72, i would say a differant valve grind is a fairly large contributer in your compression ratio. i dont know where you heard you need oversized valves when you get a valve grind either. when you buy a valvetrain it comes with valves and they even let you can choose if you want dished or flat topped valves, which can also change the c/r. im not sure putting springs and retainers in a car qualifies as installing a valvetrain. i would just install a complete valvetrain or leave it stock. there are so many contributing factors in compression.
o so now milling wont change ‘flow/swirl characteristics’?
not too sure on the condition of your car but when i had my ls. the valve guides were completely shot so i had a head built. real basic, mild valve grind, mild p+p, new seals, with stock valve train.
This is getting a bit redundant.
Have you ever looked at how dramatically different the shapes and sizes of the pr3 vs p72 combustion chambers are? The p72 is MUCH smaller, and raises CR by, as you said, approximately 0.2 points. 0.2 POINTS. Considering the major differences in the combustion chambers, that’s a pretty minimal jump in compression. And, you still try to say that a valve grind is an effective way of lowering compression. Come on.
If you are using STOCK VALVES (i’m not getting into OS valves, flat top, etc.) with a different grind (say 5 angle), if there is any compression ratio change whatsoever it will be so minimal.
If you took 5 minutes to think about it, I’m sure you’d realize what you are saying is pretty unrealistic.
Yea… but if I am going to change to some high performance cams, I need to upgrade my valve sprigns and retainers.
Unless you’re burning oil, changing out guides and valve seals is something that can wait. And yes, with the proper tools you can change springs and retainers with the head still on the car.
See Link: http://217.160.249.230/forums/showthread.php?t=96264
1 its not .2 its around 1.37 ,flat top valves from REV add .3 alone.
2 sounds like you have #2 and #4 quotes mixed up with each other.
3 when putting bigger cams every body knows you need springs &
retainers. changing valves is not so important unless you are doing a
specific set up for nitrous ,turbo, etc…
joe alanis actually perferres using stock valves when doing a valve job.
especially on his all motor 10 sec competition heads. that tells you stock
valves are good out the box for all motor, but for not nitrous or turbo.
4 i say piston size, cylinder bore, and stroke is a large contributor for
compression.
valve grind/ profile/ valve angle or what ever we call it definitely changes
flow characteristics, i dont want to get in to flow and all that. we could get
in discussion about it for days.
im not trying to flame you or make you feel bad bro. youre a thinker and thats good. i just dont like seeing mis information thats all.
Anthony
efi101 certified
www.EFI101.com
special tuning services available
2NDGENTEG whats up man heres a valve compression tool you can buy if you dont already have one or have access to it.
its universal but works good on b-series $77
similar if not the same to the one DAN has posted in his pic.
Anthony
efi101 certified
www.EFI101.com
special tuning services available
thanks for the heklp guys
its a 99 b20z… burning ZERO oil, so if I do do cams next spring (ha… I said dodo) I won’t need to replace the seals, etc