3TG valve problem - help/advice needed

[jb_22]

Mike, first thing I checked after measuring excessive valve clearance was the shim didn't come loose, the lifter and shim were unmarked.

As for the lifter OD & the sleeve ID I haven't measured them, but the lifter will very slowly slide into the sleeve when coated in oil & I can't feel any play through my fingers.

[cubic_cleveland]

Mate if your going to replace the guide, you might have trouble getting the valve to seat properly. You might be ok, but a lot of the time you won't, and it probably won't be damaged, maybe just worn. Did I read somewhere that you were thinking about reusing the head gasket? DON'T...

You could try a leak down test with the cams out to eliminate variables. See where your comp is going before getting too involved.

Does the bucket fall under its own weight, or do you add pressure?

[MorGo]

Anytime when installing new valvequides the seats HAVE to be cut!
No matter how good the quides but how they sit in the head.
And G-head cannot be properly ported without removing quides.If anyone tell otherwise quit and go somewhere else who knows his stuff.
I have a habit to make a "X" in the wall when I receive a G-head with straight valves.. there is 2 crosses in the wall..
So simple engines but so easy to bend the valves..

[jb_22]

Yes if the guide is damaged then I'll be going to all new guides & valves - of course the valves will need to be reseated because there is no way to ensure the new guide is perfectly parallel & concentric to where the old guide was installed.

How do I do a leak-down test with the cams out? I'll have to remove the upper timing chain to do that? At the moment there is no compression on #2 to leak

The bucket will fall very slowly into the sleeve under its own weight, all of the buckets are like this. However, on the #2 exhaust bucket, there is what looks like some chemical staining??? It doesn't look like any sort of wear marks. Once I pull it down I'll put a pic of it up here so you guys can see what you think.

[jb_22]

SO I pulled the head off today, here's a photo of the valve from both sides:



A: Shows wear marks on one side, carbon build up on the other side.
B: Carbon build up on back of valve, other side is smooth with much less build up.
C: You can see the bare metal from the valve seating on one side, while the other has carbon build up.

A, B & C are all aligned with each other, so that spells bent valve even though there's no chance I could see it with my eyes.

Oh & here is the chemical stains on the lifter:



Don't know what caused it, it's only that one spot on #2 exhaust lifter.

Ghetto valve remover - G-clamp & a bit of water pipe:



Magnet tool to catch the collets so they don't go walkiebouts

[MorGo]

Simply go with that valve to the machine shop and ask them to check it on grinder.If it's only a small amount wiggly and trues by light cut use it.But never try to knock them straight!! Those OEM exhausts are two piece items and WILL snap to two it trying to bend them back.
Intakes and most aftermarket SS exhausts are one piece and there moderate straightening is acceptable.And no,if they were available every parts store cheap they should not be straightened but get new ones.

And one thing with those magnets;they are extremely handy picking up small missing parts but snapping a strong magnet on hardened steel part..
Check that if you are able to pick-up small steel parts with those buckets.Not a good thing that parts collect all the wear particles to them.

[jb_22]

Hmm good point with accidentally magnetising the parts, but wouldn't the 110-120C heat in the motor at operating temp kill the magnetism? The magnet tool has an outer shell that protrudes past the magnet, so the magnet doesn't snap too much when it reaches a magnetic surface. As for the collets, surely the valvetrain shock loading would be enormous amounts higher than the collets getting pulled ~10mm onto a magnet?

I'm getting a replacement head to pull valves from, so I will just use a straight one rather than getting the bent one recut.

[71TA22]

jb_22,

Its a bit too late by the time engine heat reduces the magnetism - the rubbish has been picked up and ground in.

FYI here is a picture showing reground very slightly bent valve on the right v straight on the left (the only giveaway was low compression - the engine idled ok but misfired/back fired badly with revs).

Put the valve in the grinder and got that out of true tink, tink, tink noise till the high spot was ground off. For obvious reasons I would not reuse it.

[MorGo]

I didn't think about using magnet picking the buckets before Sierra Cossie factory manual warned against of it.First I think that "what the hell!? why not?" Then the idea clarify and it was "of course!"
I use (somehow) magnetized screwdriver (just strong enough) to pick up the valve locks.For the buckets I use valve lapping suction cups.
Probably it is not a big issue but something to think about.

Very few used valve run true when put in valvegrinder;there is slight bend almost everytime.
That valve is out of game;will need bigger cut to clear the seat surface.

[jb_22]

You say pretty much every used valve is bent. How would I go with swapping a valve out of a spare head & lapping it into mine without grinding?

I will use the valve lapper suction tool for the buckets from now on, I only bought one yesterday.

[71TA22]

jb-22,

If you can get a lapped finish like on the valves below you are good to go. See the narrow lapping line on the bright recut area.


Personally I always regrind valves and recut seats when replacing. Its cheap insurance for head life. I also polish valve stems and ream valve guides as necessary to get correct oil clearance.

Attention to detail should give you good power gains and long life. Dust and grit is also the enemy. Keep you work covered up or in plastic when your not working on it.

[jb_22]

Sweet! pic is worth 1000 words Mike! I also got a bit of advice to check the seat after lapping with pencil graphite in 4 spots on the seat and give the valve 1/4 turn to see how the pencil lead smears around the seat.

[jb_22]

All sorted! Car is back on the road again & hoorah! no more backfiring through the carbs I got a spare valve that had been recut but never ran, so I lapped it in & put the head back on & motor running in under 4 hours. Happy camper! Also feels heaps better with the new LSD I only just got to try out cuz of this valve problem. Thanks to everyone for all the advice on this thread, it helped big mobs!

[71TA22]

Well done. Its all worth it. Much better grip with the LSD eh. Lot less tyre squeel.

[jb_22]

Or much more tyre squeal depending on how you operate the clutch, hehehe.. But yeah, heaps more traction to power out of corners - it's like night and day compared to an open legger