Austarion

I've noticed the SOHC 4g64 heads have 3mm larger intake and exhaust valves, but they also have a larger combustion chamber and I won't be able to get the compression ratio where I want it with one... Plus they're tricky to find.

Has anyone had any experience fitting larger valves to the SOHC 4g63 head? Ive got one on the workbench at the moment, and there doesn't look to be much room, without going further into the head, which is suspect is exactly what is going on with a 4g64 head.

Soooo, has anyone had an decent head-work done with their SOHC 4g63 head? Keen to hear experiences or see some pictures.

Cheers.

None of that "just go twin-cam" crap please. Yes it would be better, even easier probably, but SOHC is what I've got to work with, so it's what I'm sticking with. Plus, SOHC rocker covers are way prettier ;-).

Zac I had my SOHC ported and polished with 3mm os exhaust and std inlets.and the ex ports were widened 3mm which made them exactly the same as a 64 head ex ports.
My single cam3000k old stroker would still be in my jb if I had not sent it to be dyno tuned and sadly ended up detonating the top off a plug,bending valves,scoring the bore and damaging the gt3076 turbo at QR Derek = Starion VR4 was there when it happened :glare: :x ( Derek the faces are not 4 u )
From memory it put out 300hpatw.
FYI Kit =Garys 2.0 63 puts out over 300 on a hub dyno and there is a bit more space around a single cam as well :) :)

Rad, that is exactly what I wanted to hear! Cheers :).

Don't suppose you have any pictures of the work kicking around do you?

Honestly your better going with a 4G64 head & getting custom forged pistons, the 64 head is better & yes it has a bigger combustion chamber... but its for a reason... the flow from the valve into the chamber is much better on the 64 head.

Installing 3mm bigger valves in a 63 head will never give the same flow as a 64 head. :beer

Fair call, but If i was going for a build that involved the budget required for custom forged pistons, I'd just go 16v. Not trying to do stuff on the cheap, but not going to spend a bajillion dollar either :).

ProZac wrote:Fair call, but If i was going for a build that involved the budget required for custom forged pistons, I'd just go 16v. Not trying to do stuff on the cheap, but not going to spend a bajillion dollar either :).

That's understandable.... how much do you want to spend on the pistons... I have a contact at ROSS Pistons.

No one does oversize valves for the 4G63 sohc any more. Only option is modify "blank" valves. Very expensive.

Let us know how you go.

TOMSUN wrote:No one does oversize valves for the 4G63 sohc any more. Only option is modify "blank" valves. Very expensive.

Let us know how you go.

Yea... I can do that too :beer

I want to spend the $174 I've already spent on the low compression non-turbo pistons from ACL, 4mkry8028's. There was a set at a Repco branch up north, and they're on clearance at all Repco's (I keep my one weekend day job there so I can still get the staff discount).

Although it's looking like they wont really get me near the 8.5:1 compression ratio I'd like. I measured the combustion chambers this eve, and they're around 25cc, which equates out to around 7.6:1. If I take 1mm off the head I should be in the 8's, and I'm pretty sure the valves will still clear :).

Possibility of fitting 4g64 exhaust valves to the 4g63 head? I suppose the collet grooves are at a different height due to the deeper combustion chamber though.

ProZac wrote:I want to spend the $174 I've already spent on the low compression non-turbo pistons from ACL, 4mkry8028's. There was a set at a Repco branch up north, and they're on clearance at all Repco's (I keep my one weekend day job there so I can still get the staff discount).

Although it's looking like they wont really get me near the 8.5:1 compression ratio I'd like. I measured the combustion chambers this eve, and they're around 25cc, which equates out to around 7.6:1. If I take 1mm off the head I should be in the 8's, and I'm pretty sure the valves will still clear :).

Possibility of fitting 4g64 exhaust valves to the 4g63 head? I suppose the collet grooves are at a different height due to the deeper combustion chamber though.

I have a feeling they are too short (need to confirm). There are not many options for 8mm valves.

Yeah, that would certainly make sense. I'll see if I can get some into work to have a look at.

Bah, I should just give the head a quick smooth out, put stock valves in it, get the cam ground and stop 'internet racing' :).

Zac get in touch with Merv with the rally car, Jas should/might have his number. He did quite alot of head work and suggested it was hardly worth going mpi without doing it.

Cheers mate, thats a really good idea, Will do, I'm sure they'll have his number at work.

I can get valves, let me know what length & diameter you want..

The valves will still clear on the 64 head as the chambers are that much deeper...even after taking 1mm off it... They are a different shape too and bear in mind when comparing Starion 63 heads with L300 63 heads, the L300 has a smaller combustion chamber to the Staz one.

For more information, I built my engine using the L300 64 head with Galant VR4 pistons, and the crown was 12cc from memory instead of 14cc for standard Starion pistons (I had the high comp pistons originally in the Jap/NZ GSRIII one, also around 12cc).