20v Head Work

[Vaughn]

Hey Guys,

Planning on taking the head off my Blacktop 20v and had some Questions:

What do you guys in the know' do?

Was wondering about:
Porting/Port matching?
Polishing?
Do any of you guys do it by hand?

I was thinking Tomei Pon Cams: In 264 Ex 256, 9mm lift on both to retain VVT, What cams do you guys recommend to retain VVT?
Worth doing springs whilst im at it?

What are your opinions on running an adjustable cam gear on the exhaust side?

Get head skimmed or running a thinner head gasket? How thin of a head gasket would you run .05?

Please put your knowledge below

Regards
Vaughn

[Matt]

The TRD gaskets that sam q stocks are a good one to use and bumping the compression a little makes a fairly noticable difference.

I recommend keeping vvt unless you are chasing power at the end of the rev range.

Not so sure about the head work, but the blacktop head is pretty good out of the box

[Jimmee1990]

You would need to surface the head anyway when you're taking it off, I would reccommend taking as little off for it to clean up flat as possible and to use a thinner gasket like Toda/TRD etc as well.

With port matching you need to be careful as a lot of people just match near where the head meets the manifolds and end up with a small port then a much bigger opening at the manifold face then smaller again into the manifold which is terrible for flow. Polishing I would only ever do on the exhaust side and it's really unneccesary anyway, on the inlet side you will see a gain in flow on the flowbench but in reality it will be less as the slightly rougher un-polished surface finish will stop the fuel running down the port walls and throws it back up into the airstream helping with atomisation. Doing it by hand you really need to know what you're doing otherwise you will go backwards, especially so with 20v's so I wouldn't reccomend you do it yourself.

I would say to do valve springs as these engines are getting older and considering you have the head off anyway it's easy to do and cheap insurance.

As far as VVT goes with the adjustable exhaust cam gear I'm unsure as all 20 valves I've worked on have used the standard gears. I would imagine you would lose the extra torque through the midrange without though.

[Matt]

bit of a hijack, but could someone recommend a tool to remove the valve springs on a 20v head?

http://www.ebay.com.au/itm/ENGINE-VALVE-SPRING-COMPRESSOR-UNIVERSAL-AIR-HOLDS-new-/150635358467?pt=AU_Car_Parts_Accessories&hash=item2312912903

or is there something better?

[Gunner]

With a complete engine I recommend this style, in a decent brand not ebay shit like this is...

http://www.alfabb.com/bb/forums/attachments/engine-rebuilding/65346d1177947050-valve-spring-compressors-1.jpg
http://www.ae86drivingclub.com.au/dcimages/3/5/513734.jpg

Or this type if it is apart...

http://www.chain-auto-tools.com/pics/AMR032V-INS.jpg

The first lever type can be made quite easily, Buy some crappy socketsm use a socket extension, and some steel and off you go.

[Vaughn]

Cheers Guys

James, what cams have you used on engines to retain VVT?

Also Gunner what have you got to say sir?

Though you would know a but about this topic?

[Jimmee1990]

The cams I used where a very mild grind loosely based of TRD I think, got them from Clive Cams in Ferntree Gully but I didn't source them myself so not 100%. I would talk to Sam-Q about what 20v grinds he can do as he plays around with them quite regularly I think.

[SamsTA22]

Not so sure about blacktop, but the silvertop head has big casting marks down the sides of each intake port.

And the dividers on the intake look like they could be improved somewhat. But its a pain in the ass the get in there with a die grinder.


And, I though you could run 272 cams with vvt still working... Or am I mistaken?

[Vaughn]

Cheers James, I have emailed Sam Q and he will reply here for everyone.

SamTA22, Not sure about cast marks on Blacktop intake ports and according to Sam Q you can run 272 and keep vvt :)

[Gunner]

Also Gunner what have you got to say sir?

Though you would know a but about this topic?

Didn't feel the need to comment, the guys covered it pretty well. Retain vvt, debur ports, machine head, do valves, springs and retainers (if springs are old, so is everything else) Supposedly you can run upto 2808 cams with aftermarket management, Ive only ever seen 260* grinds used.

I can sell you a built bottom end though lol

[pen15]

i have blacktop with big cams and my power is very good through the rev range if you look in my build thread i am running toda 288 in ad ex 9.2mm lift with good ports by good i mean big if you are going to be doing any work the first thing you should do it valve springs just get supertech valve spring not the retainer and spring kit just the springs at work we do race blacktop heads all the time

my recomendation is get some kelford d spec cams and some supertech springs tidy up the ports ie address the short turn radius in the intakes and polish the exhaust with a light skim and a trd .5mm or .8mm gasket the motor will be sweet also get some gears run something like a 100 deg lobe center on the exhaust and like any where from a 92 to 96 deg lobe center on the intake and you will be verry happy with the motor very usable power

i should know my car makes 110rwkw and im doing alright in a drift comp atm against cars with 3 times my power

cheers
mat

[Vaughn]

Cheers Mat
I was looking at keeping VVT, Also why do you just go springs not the kit? you find only springs are needed?

[pen15]

the kit is money wasted the springs alone give you 60 lbs seated the kit ups it to 80 and that is way over the top unless you are going to be running about 30 psi of boost and the extra spring pressure saps power due to the extra effort the motor needs to operate the valvetrain if your going to keep vvt small cams are the only ones that work in your favor but you will be disappointed in the results

[Delazy]

Matt speaks the truth...I have the supertech springs and the old Kelford D cams (288/10mm)...yet to run the motor, but it should be a good thing :)