A&Q about 350Z
Q:
Ahh... Slightly different form of hillclimbing to this one...
Try and get some engineers blue and a scribe (bit like a dentists tooth pick) from a motor factors and mark out inside the gaskets a line as a "max" to go too, though you should'nt to open out that far depending on yr measurements (especialy on the exhaust side).
A:
Have a "good" read of this before getting stuck in....
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Also worth a look here for some basic principals....
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Great thread... keep that info coming...
The article by vizard repeats some basic rules that he also puts forward in the tuning the a series book, but it's interesting to read in the context of a different engine...
A:
started by cleaning er up
before
after
had some trouble removing exhaust inlet bolts
so locked two nuts up and out they came
using wire brush on a drill wet n dry down to 800grit then autosol to polish
cleaned port face
got me spring compressors coming later so will have the valves out for a proper look
ive checked the faces are flat with a metal rule, just got to nuy the gaskets then ill start shaping the ports
thanks for the links above, some really good stuff there!
A:
be careful about removing too much material from the bends in an 8v head, the water galleys are not that far away.
tip for valve refurb..... caefully put it in a drill chuck and spin it against your chosen cleaning material. I got an almost mirror finish on mine with some wet and dry, got rid of all the cr'p that was stuck to them
A:
how far away?? i dont intend to take more than a couple of mm off will that be ok?
cheers for the advice on polishing the valves thats a good un, will mount them in the drill press
bolted gasket down and scribed it off
valves out
loads of crud in here
and a bit more shiny blingy
have now started cleaning the ports up ready to grind away and shape em!
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Just a quick question I cant get my head around, how do you get at the short turn inside the ex port?
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i dunno yet!!
probably thro the valve side, i need to get a dremel with extension really, but this is more of a long term project so that will have to wait till chrimbo!
A:
Just a quick question I cant get my head around, how do you get at the short turn inside the ex port?
It's fiddley but possible, and best if you use a round cutting bit, but use the opposite edge to what you would normally, if that makes sense.
A:
Just a quick question I cant get my head around, how do you get at the short turn inside the ex port?
A ball shaped stone on an iron head (a stone will clog with ally heads) so a ball shaped cutter would be ideal and attack it (carefully) from both sides.
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thanks for the links earlier, have re-planned the way im gonna shape the inlet ports now!
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i dunno yet!!
probably thro the valve side, i need to get a dremel with extension really, but this is more of a long term project so that will have to wait till chrimbo!
Before you start cutting away the ports, concentrate your efforts in the valve throat area. Ideally, have the guides pressed back so you dont damage the ends (or remove them compleatly if worn and fit new ones when yr porting is done) when thining down the guide boss.
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thanks for the links earlier, have re-planned the way im gonna shape the inlet ports now!
No probs...
Figure on an inlet port size of around 80% of the valve size, for the throat area (the bit below the valve seat), around 85% of the valve size will be big enough for road use.
On the exhaust side, work to a throat size of around the same (85%) with the port around 90% of the exhaust valve size. If it looks like neither size can be achieved without hacking out large lumps of ally then use some restraint.
I'd also leave the chamber alone for this exercise.
A:
there seems to be a natural lip just past the seat in the throat, removing that would put it around 85%ish. theres a lot of founding marks, really suprised at the amount tbh.
ive noticed the guides are at slightly different depths so will have them pressed out, and fit new as said.
the injector shroud cuts deep into the inlet by about 6mm, i know the injector has to sit well in, is it worth building up the port in front of that to straighten it out or does it provide the turbulence?
does the injector have to sit that far in?
ive noticed that some of the ports are not quite true, i know they pan in at an angle but one or two are slightly out, gonna measure the peak of the apex against the block and even them up,
im goin to extend the inlet port up and reduce the short turn radius so straightening it up a bit.
a theory....
if the exhaust manifold were stepped out to the block, it would create an area of low pressure after the exhaust leaves the block helping to clear the port.
what dya reckon?
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a theory....
if the exhaust manifold were stepped out to the block, it would create an area of low pressure after the exhaust leaves the block helping to clear the port.
what dya reckon?
It's true, better to have the ara of low pressure in the manifold after the port than an area of high pressure in the port before the manifold. always make the exhaust port slightly smaller than the entrance to the manifold.
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cool , thought it made sense tbh!
im currently working thro as much info as i can find b4 i start the porting, will update after the weekend
thanks all
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im goin to extend the inlet port up and reduce the short turn radius so straightening it up a bit.
what dya reckon?
DONT reduce the short side radius ! Take another look at the Popular hotrodding link to see why.
Good luck with the project.
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haha.... nearly!!!
ta
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Those valve seats look well recessed into the head. You're probably getting a lot of restriction from the step between the seat and combustion chamber at low valve openings.
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yep, tho the vavles are sitting about 1mm proud when fully closed.
think ill get the valves reseated, would that sort it??
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Willie, could you take some more pics of the ports and post them up please? just going by what i can see up there getting more flow out of that head could be done with a small file, lol. Those ports are p*sh.
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yep np
havent started any removal yet, but have cleaned em up ready
hth
cheers
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Cheers, can you take some more, straight into the ports and from both sides please. The pics should come out clearer if you take them under a light and switch your cameras flash off.
Sorry to be a rectal pain
A:
no problem pls bear in mind my digicam is about 18yrs old and held together by gaffer tape, pretty much like my car btw!
is that better......