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TT Cylinder Head Rebuild


Guest blacknight
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Guest blacknight

Hi All,

 

After getting the 2jzgte engine for the n/a to tt conversion a year ago, i decided to strip everything down and start rebuilding the engine with uprated parts. I am working on the head first, then moving onto the block.

 

After stripping the head i had it pressure tested and skimmed, then i cleaned the head and valve covers. Once that was done i removed the valve guides and started porting the inlet and polished the valve covers.

 

Next on the list is removing the valve guides on the exhaust and porting and polishing. I plan to have ferrea valve train bits with 272 crower cams. Heres a few pics of the progess so far: :)

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Guest blacknight

yes i've removed the guide boses as it is supposed to improve airflow in the ports, after reseaching i found that all cnc'ed 2jz heads have the guide boses removed.

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yes i've removed the guide boses as it is supposed to improve airflow in the ports, after reseaching i found that all cnc'ed 2jz heads have the guide boses removed.

 

surely that is only the case if the valve guide is also reduced level with the floor of the port, the boss is there to smooth the flow of air round the guide

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Don't like the thought of removing the valve boss as you will lose a lot of support for the valve, bet it will go through stem seals like no ones bussiness:blink:Personally i wont bother with the porting route and we have a top porter on site, personally for the agro and expense I would rather run another .1 bar of boost and get the same if not more HP gains. I had a discusion!!!! with the engine guy here and after a lot of arguing even he conceded the gains on a forced induction car are tiny compared to normally aspirated. Wiggly valves ....... not for me. I'll stick to the big valves and 280 or bigger cams:rolleyes:

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Guest blacknight

dude, just wondering what will be the reason for going through stem seals like no ones business, how?? and what you mean by 'wiggly valves??'

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dude, just wondering what will be the reason for going through stem seals like no ones business, how?? and what you mean by 'wiggly valves??'

 

If the valve is not supported it will tend to move around and wear out whatever is left of the guide and therfore the seal too, does no one think that Mr Toyota designed valve guides a certain length for a reason:rolleyes:

As i said i prob wont touch my head at all and i have a very knowlegeable expert here who would do it free for me!!! Now fancy valve jobs etc different kettle of fish and degreeing the cams etc

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Wiggly valves ....... not for me. I'll stick to the big valves and 280 or bigger cams:rolleyes:

 

Shortening the valve guides will inevitably increase the wear but if good bronze alloy ones are used and correctly reamed after instalation the clearances can be made tighter and if your going to all this trouble to port the head i dont think changing the guides again in a few years is going to be an isssue.

 

To say the valves will wiggle is a tad dramatic, my valve clearances were on the limit 4 years ago when i re-built my head so chances are they are now well outside Toyotas tolerances however the stem seals are still fine.

 

Porting if done well will increase the volumetric efficiency of an engine and can produce power and torque throughout the rev range unlike big valves and 280 cams (on a street car :taped:) which will sacrifice huge amounts of low/mid range power at the expense of peak power bouncing off the rev limiter :blink:, each to their own but i wouldn't touch big valves and cams with the proverbial barge pole, unless i was building a drag car :eyebrows:

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unless i was building a drag car :eyebrows:

 

 

That will be me then!!!:cool: The old car with 272 cams idled like a stock car, sorry you wont get me to agree with porting on a forced induction car, you will map out more lag easier and cheaper. The only way to prove or disprove the theory is to dyno before and after.

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I agree with Dude, the shortened guides are going to take a lot more load and so more wear, as the contact surface is reduced by quite a percentage. Even in a standard engine this would accelerate wear. With big cams, I presume you are going to fit duel springs so increase the loads even further. I think the gains in gas flow will be minimal in a force induction engine.

 

Big valves and big cams with porting on my engine and I get the the same sort of spool as guys in the states running my turbo on standard head with cams.

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Big valves and big cams with porting on my engine and I get the the same sort of spool as guys in the states running my turbo on standard head with cams.

 

really not disputing the accelerated wear but what compression ratio is that at Termy i dont think we are comparing apples for apples here are we ;), there really is no questioning that a decent porting job (i cant vouch for this guy :eyebrows:) whether that be n/a or forced induction will produce a more powerfull car, granted the bigger gains will be on crappy old school head rather than a modern 4 valve head but the principles still apply

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Guest blacknight

Just a bit of info really, i was not intending to shorten the valve guides. The porting work i have done on the head is nothing major, apart from removing the guide boss. I have matched the port opening to the manifold gasket, smoothed out the the overall port and blended the short side radius and valve bowl into the seat. I have then flapped the port with a 120 grit. While the head is off and a full rebuild is being done, why not port the head even if the gains will be marginal, there will be an improvement regardless.

 

I will be using ferrea manganese bronze valve guides with ferrea valve guide seals and i'm undecided with ferrea titanium or brian crower steel valves. The valve springs, i not sure at the moment between the single or dual. As for the seats i will be doing a full radius cut.

 

Good article, will come in useful when porting the exhaust side and sorting out the combustion chambers.

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Just a bit of info really, i was not intending to shorten the valve guides. The porting work i have done on the head is nothing major, apart from removing the guide boss. I have matched the port opening to the manifold gasket, smoothed out the the overall port and blended the short side radius and valve bowl into the seat. I have then flapped the port with a 120 grit. While the head is off and a full rebuild is being done, why not port the head even if the gains will be marginal, there will be an improvement regardless.

 

I will be using ferrea manganese bronze valve guides with ferrea valve guide seals and i'm undecided with ferrea titanium or brian crower steel valves. The valve springs, i not sure at the moment between the single or dual. As for the seats i will be doing a full radius cut.

 

Good article, will come in useful when porting the exhaust side and sorting out the combustion chambers.

 

i hate to piddle on your chips mate but the guide boss serves a major part in smoothing the flow of air past the valve guide which just sticks up in the air acting as an obstruction, the guide boss has no function in supporting the guide as theres plenty of meat for that, without shortening the valve guide you will probably have made matters worse from an air flow perspective, as a very minimum i would have the length of the protruding guide bulleted (tapered down) prior to instalation

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Guest blacknight
i hate to piddle on your chips mate but the guide boss serves a major part in smoothing the flow of air past the valve guide which just sticks up in the air acting as an obstruction, the guide boss has no function in supporting the guide as theres plenty of meat for that, without shortening the valve guide you will probably have made matters worse from an air flow perspective, as a very minimum i would have the length of the protruding guide bulleted (tapered down) prior to instalation

 

 

I was origionally thinking of getting the bulleted style guides and after what you have mentioned about the length and doing some quick research i realise what i have to do. Appreciate the advice, i will look deeper into a shortened guide.

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In my experience anything which protrudes into the port is best avoided or minimised. Sometimes valve guide support bosses are blended into the port to smooth the airflow around the guide, albeit at the expense of even more loss in flow area. However, since you want to avoid any protrusions into the port, if the guide boss is there, its probably there for a good reason.

 

Likewise, the valve guide will proabably already be as short as it can be to minimise protrusion. Support length issues aside, the guide acts as an important heat transfer path out of the valve, so the lerger the contact area between the valve and guide and the guide and head, the better.

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