X16XE Bent valves, what next??

[jeremy fisher]

Hi all,

I'm after some opinions on how far to go with sorting a couple of bent inlet valves in my X16XE.
Basically, after a day thrashing round Donington I finished a bit early after bending an inlet valve or two in No3. I was working it pretty hard for around 30 mins at a time, rev limiter set to 7,150 but only retards timing and I've seen 7,900 on a data log before, not sure if that was on a down shift or missed gear. Wasn't running any logging on the day it happened so no idea what I was hitting.
I haven't got the valves out of the head yet so don't know the full extent of the damage but the piston top has some damage around the cut out, the top of the bore and edge of combustion chamber have a small amount of damage also, but I think all of that can be cleaned up with a bit of work.
One of my mates thinks a spring has broken but I'm thinking the valve stuck in the guide. If there is no apparent damage to the guide then would just chucking some new valves in be a good idea? I have been considering bronze guides? What do people think about those? Lots of different opinions out there on those.
I also have some high lift cams and double valve springs to go in. Should I have confidence that with the standard guides and better springs there will be less chance of this happening again? Or will a few more revs make it more likely?
What sort of revs are seen as safe on these engines? I still have standard rods, just with arp's.
Should I shell out now and hopefully have a reliable engine or just get it back together?? I also have a day at curborough planned for 1st November... so time is a factor... or I just forget that and do the work over winter.
So many questions!!!!
Thanks!

[mowgli]

buy a replacement head. give it a recon & fit the new cams & springs. quickest & cheapest fix imho

[jeremy fisher]

That's not a bad idea. Made slightly more complicated by the fact that I have welded up all the egr related stuff on the head though. Which means a bit more work. But nothing I've not done before.

[staggy_gsi]

If the guides look ok Id just chuck a couple of valves in your existing head so you can get it back together and get out in it come november.

no harm in buying a replacement head too though, and fitting bronze guides and the fancy springs to that, then swapping heads over winter.

[jeremy fisher]

Well I got the head stripped down, and it's only one valve that'd gone. It snapped at the collet. I happen to have a metallurgy lab next door at work with an engine specialist so I thought I'd ask him about it. The valve had fatigued and there was several cracks coming together to cause the break. He also wasn't too impressed with the machining of the collet grooves and suggested that's what started the cracks. Although he did then compare it to a valve apparently from a Porsche and said that was no better so not sure how much can be taken from that. So I think the rest of my valves will follow given chance. That also means that it wasn't the valve sticking in the guide that caused the problem.
I think I will chuck this one back together without the cams for the short term, ordered a valve guide and have a used valve that'll do. And yes, I think doing another head over winter is a good idea although after doing a bit of reading and with the above info, I'm not so sure about the bronze guides. There are a lot of contradicting arguments about. Also, is it the norm not to use stem seals with bronze guides? More knowledge required methinks.

[craig green]

I cant really add much advice, but I'm inclined to add that these engines do have their weaknesses exposed when increasing the revs. luckily the engines are pretty cheap to source so heads & bottom ends are almost consumables. The rods are weak at the kind of revs you are seeing also.

[staggy_gsi]

Dont really know anything about the use of bronze guides, but I dont like the sound of not using stem seals!

[mowgli]

always always always use valve stem seals.


also, i am not surprised that the porsche valve wasn't any better..... they are probably made in the same factory, for the same money

[jeremy fisher]

Rods are also on my list, thrown one of those before so know all about that... mind you I thought I had ARP bolts fitted but the guy who built my engine forgot to fit them... which was nice of him.
I did think that not running stem seals sounded a bit strange.
Am I right in thinking that one of the main reasons bronze guides are used is because they won't break up and drop bits into the combustion chamber when damaged?
I may be inclined to not bother with rods or much work on the head and just buy more engines as required, but I've had a few and they normally smoke a bit and I like to rebuild before using them, which makes them a bit more expensive!
I would like to make a reliable engine but I'm starting to wonder if that's possible!!

[philip]

Few lads have run 8k + on std rods with arps.


Head wise were you on std cams or uprated when valve dropped and what springs/retainers? As ive had several std retainers spkit on normal road goibg cars with atd rev limits. Quite weak imo.

Ive ran 20xes with no stem seals on colsibro guides. Done the engine no harm juat keep an eye on the oil. Depending on the double springs id watch using hydraulic lifters too. Quite abit more pressure on a follower and can cause early failure.

Also bronze/colsibro is hardier so generally if a belt goes. The guides stay in one piece. But doesnt mean they 100% will.

[jeremy fisher]

8K?? I thought the rods didn't like too many revs? Maybe I can save a few quid there then.
Everything in the head was standard, not fitted my cams yet. I have springs (Kent doubles) and retainers with the cams when they go in. Did consider solid lifters but I think after doing a bit of reading up I decided they weren't for me. Although my I now plan on getting a bit more track time so may be worth looking into.

[philip]

Good choice too get tje springs/retainers. What cams habe you got? As hydraulic and solid profile cams differ. So if you were on hytaulic you would need too run app 4thou inlet 5thou ex if put on solids. Possibly thou less. Also if doing lots of trackdays and seeing revs the double springs would hammer hell out of the hydraulic lifters, squeeze oil out and cause tapping or potentially cause a lifter too jack up and drop a valve.

[jeremy fisher]

They are custom Newman cams apparently but very similar to VUXT/288/420H (http://www.newman-cams.co.uk/Newman-Cams-Vauxhall-Opel-CorsaTigra-16-Valve-Tarmac-RallySprint-Camshafts-VUXT288420H-PH3_25260_22_3623_18928.jsp) I was told. Made for a rally engine but only used to run in then plans changed. The info for the cams in the link say they are hydraulic profile so can only assume my cams are also. I think I will have to weigh up cost and my requirements. If you were to supply the necessary parts to go solid lifters then what would it cost me?