25 replies to this topic

[Siret]

Between 2 & 3. When i was taking the valves out of the head, the first 3 valve springs from the TB side were missing their seats. Once the valves were all out i noticed that every intake valve guide was cracked. To my mind having 3 springs sitting lower than the other 5 would put the geometry of the valve train out possibly pushing the valves through the guides at an incorrect angle and causing guide failure. I've spoken to a few people and some agree, and some seem to think it would make no difference. Just wanted to see what you guys thought.

 

Also the machinist had to take 30 thou off the bottom of each lifter to get the right clearances. Does anyone know how thick the bottom is on those things or how much can be taken off safely?

[MDK87]

I'd say they wouldn't make a difference. Pretty sure the spring perches are there to better distribute the compressive force of the spring to prevent the steel embedding itself into the alloy head.
At worst it would cause you to have a lower seat pressure. Perhaps you're thinking too much into it. Just make sure you install all 16 them when you put it all back together.

Also these engines came with hydraulic lifters which should not require manual clearancing (all other things being equal). Unless you're running solid ones, you just bleed them and re-install. 
I once had to grind one down to get my daily running because the valve seat had become badly recessed. 

[jack be nimble]

Someone before you did a timing belt and stuffed a heap of valves. When the valves bend the guides get broken too. They replaced the valves and not the guides.

There is prolly dents in the piston tops still, lol

[doo doo]

In my opinion :

 

Spring height won't determine valve height, the valve seat does that. If the valve sits too far into the head/too far above the guide then the adjustment to make (to restore rocker arm geometry is to grind a bit off the tip, or install new seats/or new valves/or both. As MO suggested, grinding the lifters shouldn't make a difference if they're hydraulic as they pump up to where the valve sits anyway, agree with him on the seat pressure too. Reckon Jack's on the money for the reason for cracked guides.

Edited by doo doo, 22 September 2015 - 08:02 AM.

[jack be nimble]

100% doo and mo ^

[Siret]

Yeah i know a timing belt has been done before, 3 pistons have score marks. The reason i was speculating was i find it hard to believe that the previous owner didn't repair the head properly. Means i've done 27k kms on a rooted head.

 

Do the lifters have a maximum height once they're pumped up? Mine are hydraulic and if they pump up under oil pressure sort of seems like grinding anything off them would be redundant.

[brisvr4]

If it was me I'd be tossing the ground lifters out and buying a new set.
Also, if the machinist can't spot a hydraulic lifter from a solid one I'd be considering a new machinist too!

[jack be nimble]

Id take 30 thou of the end of one of his fingers with a potato peeler and see it that makes a difference

Edited by eJackulator, 22 September 2015 - 11:45 AM.

[jack be nimble]

Yes, a lifter pumps up. Its maximum height is the same as when you put them in. They should compress slightly (maybe 1mm?) On the base circle of the cam.
they need to do this or they will rattle as they cant take up the slack.
you might machine the bottom of the lifter if you have a cam with a huge base circle that bottoms the lifter out. Or lifters from something else. Ive never heard of it on a mitsi

[jack be nimble]

Guys doing v8 run 030 PRELOAD on hydraulic lifters (.8mm) so 1mm was reasonable guess.
now old mate has dressed your lifters, you need to make sure you still have some preload, or replace them. Or put 030 shim under lifter.

[jack be nimble]

One good thing is the hg wasnt caused by the valve guides.
prior owner may not have seen the cracked guides, its not that much extra to replace them. You will now need to reface valves and relap them in new guides. They may have been rocking around in the guides and not seating properly, knocking about the faces

[Siret]

One good thing is the hg wasnt caused by the valve guides.
prior owner may not have seen the cracked guides, its not that much extra to replace them. You will now need to reface valves and relap them in new guides. They may have been rocking around in the guides and not seating properly, knocking about the faces

 

Valves have been checked and a new 3 angle job on the seats has been done. Would the cracked guides explain why there is oil inside the intake manifold?

 

If it was me I'd be tossing the ground lifters out and buying a new set.
Also, if the machinist can't spot a hydraulic lifter from a solid one I'd be considering a new machinist too!

 

He was doing 2 heads for meek the same week i had mine there and he knew perfectly well they were not solid. I'm happy to buy a new set but what should i be looking out for to know for sure? I should get the car running today but you guys have got me worried now. Is it safe to turn over, and is there anything i can check beforehand?

 

Guys doing v8 run 030 PRELOAD on hydraulic lifters (.8mm) so 1mm was reasonable guess.
now old mate has dressed your lifters, you need to make sure you still have some preload, or replace them. Or put 030 shim under lifter.

 

Funny you should say that, the guy who did it is part of a top fuel team.

[evo-gsr]

So essentially...he should know what he is doing then?

[Siret]

Yes.

[jack be nimble]

Oil inside manifold? I see. Is it inside tb also? Is it inside intake side of turbo? Does dipstick pop out after boosting? Does it smell of burnt oil, blow smoke under power, have a dirty bumper on exhaust pipe side? Burns oil between oil changes?
Prolly is....

its blowby from the crankcase. Either worn rings or no catchcan. Have you done a compression test?

Top fuel 'i know boats' mechanics. Pffft!

[Siret]

Oil inside manifold? I see. Is it inside tb also? Is it inside intake side of turbo? Does dipstick pop out after boosting? Does it smell of burnt oil, blow smoke under power, have a dirty bumper on exhaust pipe side? Burns oil between oil changes?
Prolly is....

its blowby from the crankcase. Either worn rings or no catchcan. Have you done a compression test?

Top fuel 'i know boats' mechanics. Pffft!

 

Yes. No. No. No. No, no, no, a little bit maybe 100-200ml every 3-4k. I have a catchcan. Around a year ago i had 160psi across all four. Before i took the head off a week ago 2 & 3 were at 60, 1 & 4 were 158.

 

I'll start her up today and see what happens.

[jack be nimble]

Hope its all good now

[evo-gsr]

Oil inside manifold? I see. Is it inside tb also? Is it inside intake side of turbo? Does dipstick pop out after boosting? Does it smell of burnt oil, blow smoke under power, have a dirty bumper on exhaust pipe side? Burns oil between oil changes?
Prolly is....
its blowby from the crankcase. Either worn rings or no catchcan. Have you done a compression test?
Top fuel 'i know boats' mechanics. Pffft!

I did say "essentially" he should know.

[Siret]

Started her up and it's running well. Valvetrain seems to be a little noisier. Will see what happens after i've driven it. Either way i'll be replacing the lifters. Doesn't sit right with me keeping them in there after what you guys have told me.

 

Just to go back to the oil inside the intake manifold, hypothetically, is it possible for a crack in a guide to extend up into the top of the head, below the stem seals, and allow oil to seep onto the back of the valves in the ports?

[jack be nimble]

Sure. A guide will pass more oil if its cracked. But the engine will suck the oil into the engine, not push it into the manifold. Its normally shown as carbon black fluff on back of affected valve.