Smallport vs Bigport

[B1NZ]

Had a search and also tried google, Seems there is alot of info on the inlet sizes obviously being different but are the exhaust ports the same size?

From what I have read maybe they are all the same from the 1st gen bigport right through to the 20v? and manifolds are swappable but if your using a 20v manifold on the 16v the 2 end bolt holes need modificaction to fit?

So gaskets between the bigport and smallport will be the same?

[B1NZ]

ooh, also, Flywheels: The silvertop and blacktop flywheel, are they a straight swap on a smallport engine? Are either of them lighter, is it worth getting one and swapping over?

[jakesae101]

20v exhaust manifolds are interchangble blacktop are bigger im told just the 2 end holes need to be slotted blacktop flywheels are the lightest and will swap over

[Bling]

This site has a bit of info:

http://home.clear.net.nz/pages/phil.bra ... lation.htm

Bottom of page for exhaust info. I assume its all correct but who knows

[B1NZ]

Cheers, I did find that site but doesn't 100% say that the ports are the same size for gaskets etc....

But Im guessing if the manifolds are interchangeable then the ports must be the same

[Mr Revhead]

16v exhaust's are the same
Can't remember if the silvertops are the same as 16v but I think they are
blacktop's are larger.

I would use the gasket to suit the head, make it easier to fit the bolt pattern. Just do the usual when port matching and it'll be fine.

Blacktop flywheel is lighter than the silvertop one. both are bolt ons to any 4age

[Bling]

Cheers, I did find that site but doesn't 100% say that the ports are the same size for gaskets etc....

Well i'm not saying the site is 100% correct, as I have no way to check, but it said this at the bottom. In saying that Revhead says blacktop exhaust ports are larger so... yeah

All 4AGEs (including the 20 Valve) have identical exhaust port dimensions and spacings. The 20 Valve has 4 into 2 factory tubular extractors while the remainder have 4 into 2 cast manifolds. The 20 Valve head manifold bolts at the extreme ends are in a slightly different location to the 16 Valve engines, however, the 16 Valve manifolds can be modified to fit quite easily, and vice-versa.

[B1NZ]

Blacktop flywheel is lighter than the silvertop one. both are bolt ons to any 4age

Is the silvertop one an upgrade from the smallport 16v one or are they the same?

[Lurkin]

I have some unused blacktop extractors in the Garage if you need to have a lookse...

[QikStarlie]

Blacktop flywheel is lighter than the silvertop one. both are bolt ons to any 4age

Is the silvertop one an upgrade from the smallport 16v one or are they the same?

same thing

[pc]

I have 1 x blacktop, 1 x smallport, & 2 x bluetop flywheels.
The blacktop one is the lightest and has the weight removed from the outside which is good, the downside is that the pressure plate is bigger... so no re-use of clutch parts and i'm not sure if the bigger diameter pressure plate negates the less weight of the flywheel.