Bent Valve..

[Jdfnq]

ahh yes i know wat you mean now.. dont think i actualy have any feeler gauges

ah well i dont think ill get anything out of them anyway.. and i'd rather not have them touch the head again.. i really dont wanna get assf**ked twice by them was costly enough the first time

I have some that you can borrow mate

[Swiper the Fox]

I have some that you can borrow mate

clearance should be 0.45mm for the inlet and 0.38mm for exhaust side. Only use two gauges and come in with them from opposing sides to obtain correct measurement.

[rb26s13]

sweet we'll have to do it one weekend joe

Edited December 27, 2007 by rb26s13

[Jdfnq]

Any Sunday or Monday in the next 8 months is good wazz..... after that, well, you are going to need permission from you know who

[rb26s13]

and thanks paul for the specs

[STATUS]

can you post a clear pic of the combustion chamber around the bent valve?

[rb26s13]

can you post a clear pic of the combustion chamber around the bent valve?

i will when i can get ahold of a decent digi cam.. the pics in first post were taken on my mobile.

[rb26s13]

anyone else..

[datsqik]

Could have been a number of things cause this.

The pics aren't really clear but my guess would be that it may have broken part of the guide off which has either caused the valve to get stuck down and cop a wack or the part of the guide has stuck between the seat and valve causing it get stuck down and cop a wack.

It seems unlikely to me that the head place would setup the clearances with one valve having a lot less clearance than all the others causing it to come in contact with the piston.

I would also check the guide to valve clearance as most exhaust guides get flogged out due to the heat that gets passed thru them due to the sodium type valves. Some machine shops use the old knurl method and insufficient clearance may result. K-liners can also be used but dont seem to suffer from galling with tight clearances.

Ive seen a few GTR heads with a bent valve recently. One was built by some self proclaimed gtr head gurus from qld which had the vg30 valves installed which are like 0.5mm bigger head size,2.6mm longer and use the 6mm stems on the exhausts. The valve spring pressure were weak as piss and they had also ground the tops off the valve and ground the shims right down to get the correct clearance. Doing this also meant they had to use a die grinder in the guts of the retainer so the shim would sit far enough in to actually touch the valves. Unfortunately they didnt check all the handy work with the die grinder and some of the shims were sitting on the retainer and not touching the valves when they set there clearances. This cause the retainer to be pushed down first until the shim came in contact with the valve, the retainer was pushed down enough that a collett came out causing all sorts of destruction. Another gtr had recently been rebuilt and it appeared that they had knurled up the exhaust guides as they are usually worn. The exhaust valve on No.6 must have got jammed thru lack of guide to valve clearance which wouldn't of been helped by the fact that they usually run quite hot/lean on that cylinder causing the valve to get wacked by the piston.

[rb26s13]

to me the valve guides appear to be steel? or do they have another material inside them that could potentially break off?

[datsqik]

Factory valve guides are generally a cast iron sintered alloy. Sometimes chunks these can break off which is usually more common in engines that have higher combustion/exhaust temps and lots of rpm. But sometimes when people port heads they heat the head and knock the guides in and out of the way whilst they port then knock them back in when finished and sometimes this can cause cracks in the guides that can break at a later time. You should be able to see if a chunk has broken off the end of the guide.

[Beer Baron]

how much did the head job cost?

[rev210]

how much did the head job cost?

you didn't just say that......go stand in the corner for an hour and don't talk to anyone.

[shanef]

i paid the quoted price upfront before the head had arrived

no shop should ask for this, ur a silly man for paying full price upfront!

if u want a no bs quality head service i use john hill of jhh engineering in brisbane. he's also done noel's (the old fella on sau) head so theres local proof of the quality/service

P.S once again hard luck mate

[rb26s13]

no shop should ask for this, ur a silly man for paying full price upfront!

if u want a no bs quality head service i use john hill of jhh engineering in brisbane. he's also done noel's (the old fella on sau) head so theres local proof of the quality/service

P.S once again hard luck mate

yer i know.. i didnt understand that asking for the money upfront specially considering it took them 3 f**king months

jhh was one of my original choices.. which i had of gone with them in the first place but oh well cant really go back and change that now can i

i dont know wat ill be doin with it for the time being.. goin to just start saving up and buying parts slowly for the rebuild i think.. and decide who will do the head work after that.. i have someone in mind.. but will wait till later down the track

[Roy]

Begs the question. What is wrong with a std RB26 head? Sure anything can be improved but perhaps its time to just throw on a std head and the get the thing running and have some fun. Also gives you time to think about who you can use in the future.

Tough luck...but hopefully you will get it sorted. Im scared senseless at the moment as i want to get a head cleaned up and match ported to manifolds and i know of too many cases where ported heads work worse then std. To date the only firm alternative is a place near where i lived in Sydney out west, but the cost of the work is above what i really need

[Adriano]

Have you spoken to the head shop in question, ive had 2 heads ported by them, and numerous other machine work. They have also never asked for money up front, maybe it was because you are from interstate?

[rb26s13]

no i havent spoken to them.. and more than likely wont.. specially considering there match porting effort i gave up on them after that..

regardless if im interstate.. i have to send the head to them.. which is worth more than cost of the job.. so its simple.. head doesnt leave workshop till its paid for

[proengines]

Talk to the shop who did the job first. As for the Port match, the exhaust gasket means very little, if they matched it to the gasket you have shown your head would be completely f**ked. Port match doesn't mean a match to a gasket, particularly if it's that much bigger. As for the intake, it's not real close, did they have the manifold to match it to?

With one valve being bent, are you sure that all the shims were sitting properly in place when the cams were bolted in after you fitted the head? I've seen similar damage because of this.

[bnr#@]

I would assume the cams were already fited to the head when it was bolted on? They dont need to be removed to bolt the head on...