+1mm valves

[TLicense]

I've just spoken to Ferrea about an unusual valve wear pattern I've been seeing on the valve stems of my +1mm valves and they've said they think it's due to the valve seat not being concentric to the valve guide.

 

I explained that it could well have been that when I got a local machine shop to cut the seats for the +1mm, they could have got it slightly off. They then said that the stock seats were too small to be machined to +1mm, and that if you were going to fit +1mm valves it would require the head to be machined and aftermarket seats to be fitted as the seat becomes too thin and is then liable to move slightly which could cause the non-conentricity issue.

 

I've spoken to a couple of machine shops now, and they both think it's very unlikely that this would be the case, so I was wondering if anyone had experienced anything like this, or if I'm being led up the garden path?

[Scott]

No experience with the issue but I do have a machining background. It sounds to me that you are being led up the garden path... however I will reserve judgement for now.

 

What thickness/material are the stock seats?

[TLicense]

I've had a few chats with a couple of machine shops and they seem to concur with thinking that the valve wear is more likely to do with having very stiff valve springs (Ferrea double springs) and that associated with a 'high lift cam' (HKS 264) it's causing the valve to be pushed over to the side and rub against the guide.

 

It all sounds plausible except for the fact that many many people have run the same combination as I have with absolutely no problems observed.

As I said to them both, HKS do a moe aggresive camshaft and Ferrea do a stiffer spring than I am using. If the combination I have is causing issues, then if you were running says a 274 or a Jun camshaft and the high stiffness springs from Ferrea, you'd be having very serious issues, very quickly.

[Scott]

I would be very surprised if that was the case. As you have pointed out the most likely scenario is that the guide isn't perfectly concentric.

 

Is the wear to the one side? Is it on both the intake and exhaust? Are they all on the same side? Were the springs checked for squareness?

[TLicense]

The wear is spiralled around a good 90 degrees of the valves from the head to the tip. It's worn by about a thou on both intake and exhaust.

The springs were checked and were out of square by about 1mm. The tolerance in the manual is 2mm.

It's not all the valves, just some of them which to me, reinforces the concentricity theory.

[Scott]

The wear is spiralled around a good 90 degrees of the valves from the head to the tip. It's worn by about a thou on both intake and exhaust.

The springs were checked and were out of square by about 1mm. The tolerance in the manual is 2mm.

It's not all the valves, just some of them which to me, reinforces the concentricity theory.

 

What about the guide being worn? If it was oversize that would cause what you describe? No? Also, when machining I take it the guide is used to bring in the con? I'm guessing you had them changed though.

 

By the manual do you mean the Toyota manual? Just thinking out loud but surely if the springs were much stiffer the tolerance on the squareness would need to be pulled in? Saying that you would think 1mm would be fine if the original limit was 2mm.

[Terminator]

Watching for the verdict here, slightly nervously. 280 cams Ferrea everything double springs, +1mm valves, guides etc.

[Chris Wilson]

The seats are cut piloted on the guide, or should be. I wouldn't have anything less than a low hours Serdi do mine though. The Yanks just love mega stiff, poor quality valve springs though, as they are still thinking huge valves, pushrods and roller followers. Many haven't quite got their head around DOHC multi valve engines with light valve trains yet Why are you running such stiff springs on an engine that turns sod all revs and runs a tame cam profile though? A seat is either fixed or loose, however if the wear was just an unusual SEAT pattern on the exhaust valves and seats you might conclude the seats could be warping, due to being too narrow and not dissipating heat properly, but they'd soon fall out and make the problem obvious. Get someone with a Serdi to check their concentricity and to check the guide to stem clearances. Get rid of those springs and fit the HKS or stock ones, too. Are the valve top hats stock height, and are the valves stock length? If not do they use stock valve spring installed height? If fitted height is none stock you might be stuck with none standard height springs Are the springs you use designed to use rotators? Unless building something ultra big HP fitting oversize valves are just hassle, same as fitting steel main caps, avoid it if at all possible.

Edited August 9, 2010 by Chris Wilson (see edit history)

[TLicense]

What about the guide being worn? If it was oversize that would cause what you describe? No? Also, when machining I take it the guide is used to bring in the con? I'm guessing you had them changed though.

 

By the manual do you mean the Toyota manual? Just thinking out loud but surely if the springs were much stiffer the tolerance on the squareness would need to be pulled in? Saying that you would think 1mm would be fine if the original limit was 2mm.

 

The guides are stock and the entire head was brand new when it was assembled.

 

The seats are cut piloted on the guide, or should be. I wouldn't have anything less than a low hours Serdi do mine though. The Yanks just love mega stiff, poor quality valve springs though, as they are still thinking huge valves, pushrods and roller followers. Many haven't quite got their head around DOHC multi valve engines with light valve trains yet Why are you running such stiff springs on an engine that turns sod all revs and runs a tame cam profile though? A seat is either fixed or loose, however if the wear was just an unusual SEAT pattern on the exhaust valves and seats you might conclude the seats could be warping, due to being too narrow and not dissipating heat properly, but they'd soon fall out and make the problem obvious. Get someone with a Serdi to check their concentricity and to check the guide to stem clearances. Get rid of those springs and fit the HKS or stock ones, too. Are the valve top hats stock height, and are the valves stock length? If not do they use stock valve spring installed height? If fitted height is none stock you might be stuck with none standard height springs Are the springs you use designed to use rotators? Unless building something ultra big HP fitting oversize valves are just hassle, same as fitting steel main caps, avoid it if at all possible.

 

Hi Chris, thanks for looking in on this.

Basically I'm trying to grab a little bit of the best of both worlds. The turbo's I have are pretty laggy, so everything is right up the at the top end. The intention was / is to have a high revving engine (max rpm dictated by where it'll make power - currently it looks like it'll make peak power around 8000 - 8500 rpm so I was targetting a 9000 rpm rev limit).

In order to try to bring the torque and power curves down the rev range a chunk, I've then fitted the milder cams. Sure it'll restrict it higher up, but I'm willing to sacrifice a little bit of peak for a bit of area under the curve.

So due to the high rev limit, I've gone for the stiffer Ferrea dual springs.

 

To be honest though a lot of people have this set up - or a more severe version with the longer duration cam, and haven't had a problem.

 

Valves are stock length. By top hats I presume you mean the spring seats? If so yes. As they're dual springs they have a secondary spring seat, but that just brings the inner, second spring to the same height as the standard length outer springs, which seats on the stock spring seat.

 

Ferrea recommended a US company called CHE precision. I've just spent half an hour on the phone to them, and they seem to think that the valve seat could be causing a lot of problems. They recommend replacing the seat with a copper based one, that is at least 2mm larger diameter than the valve, and if space allows doubling the depth of the seat to allow better heat transfer. Obviously this all needs to be positioned to be concentric to the guide. I've heard people say the concentricity needs to be within 1 thou....

[Chris Wilson]

I'd want concentricity at least as good as to .001 inch I disagree on the dual springs and high seat pressures, and I also disagree on different seats being needed unless you are unable to get 1 mm bigger valves in machined stock seats without either sinking them, or there being so far on to the periphery of the seats that you can't get the seat angles and widths right. All this heat transfer stuff is rubbish, IMHO, I bet the engine's hardly broken sweat yet, has it?

 

 

I would NEVER mix valve springs from source A with cams from source B. I always recommend you run the valve springs, seat pressures, timings and clearances the cam makers suggest. With respect 264 cams will be useless at the sort of revs you are trying to spring the valves for. I have 280 degree cams in my shorter stroke RB26 and even they are running out of puff at 8500. I think you will solve your problems with checking concentricity on a Serdi machine (I know someone with a modern and well cared for machine that does race heads and knows what tolerances are required, in Manchester), and running stock, or if HKS list them, their own springs for these cams. I would also chuck the valves up in a lathe and check them themselves for run out. Finally check with an independent valve specialist if the material your valves are made from are compatible with the material the stock guides are made from.

[Tricky-Ricky]

Have to ask, i presume that the lifter buckets and there bores are of good tolerances? high spring tension coupled with high lift cams take there toll on the lifters, and i would have thought that

any misalignment of force will be passed on to the valves.

 

Do you have an increased rev limit?

[bromy]

Tony, you must have a cmm in your quality department....get them to check valve guide to seat concentricity. I would rule out dodgy machining first.

[TLicense]

I'd want concentricity at least as good as to .001 inch I disagree on the dual springs and high seat pressures, and I also disagree on different seats being needed unless you are unable to get 1 mm bigger valves in machined stock seats without either sinking them, or there being so far on to the periphery of the seats that you can't get the seat angles and widths right. All this heat transfer stuff is rubbish, IMHO, I bet the engine's hardly broken sweat yet, has it?

 

 

I would NEVER mix valve springs from source A with cams from source B. I always recommend you run the valve springs, seat pressures, timings and clearances the cam makers suggest. With respect 264 cams will be useless at the sort of revs you are trying to spring the valves for. I have 280 degree cams in my shorter stroke RB26 and even they are running out of puff at 8500. I think you will solve your problems with checking concentricity on a Serdi machine (I know someone with a modern and well cared for machine that does race heads and knows what tolerances are required, in Manchester), and running stock, or if HKS list them, their own springs for these cams. I would also chuck the valves up in a lathe and check them themselves for run out. Finally check with an independent valve specialist if the material your valves are made from are compatible with the material the stock guides are made from.

 

If you could send me their contact details Chris, I may well give them a call as I'm struggling to find anyone local with anything like the experience required.

 

Have to ask, i presume that the lifter buckets and there bores are of good tolerances? high spring tension coupled with high lift cams take there toll on the lifters, and i would have thought that

any misalignment of force will be passed on to the valves.

 

Do you have an increased rev limit?

 

lifter buckets and bores are all good. Rev limit was just 7200.

 

Tony, you must have a cmm in your quality department....get them to check valve guide to seat concentricity. I would rule out dodgy machining first.

 

Unfortunately we're on a 2 week shutdown at the moment, and even when we're not the CMM's are pretty much flat out.

[Chris Wilson]

How the hell does an F1 team department shut down mid season?

-

B&J Motors, Trafford Park, Manchester. Speak to Bob Jones, the owner, and say

I sent you.

 

I think Dave at Performance Unlimited may have a Serdi, too. Again, feel free to mention my name. They are at:

 

Unit 3, Chessingham Park

Dunnington

York

North Yorkshire

YO19 5SE

England

Telephone

+44 (0) 1904 489332

 

 

I know Engine Developments (Judd) have the gear, of course, but they are eye wateringly expensive and flat out right now.

[TLicense]

How the hell does an F1 team department shut down mid season?

-

B&J Motors, Trafford Park, Manchester. Speak to Bob Jones, the owner, and say

I sent you.

 

I think Dave at Performance Unlimited may have a Serdi, too. Again, feel free to mention my name. They are at:

 

Unit 3, Chessingham Park

Dunnington

York

North Yorkshire

YO19 5SE

England

Telephone

+44 (0) 1904 489332

 

 

I know Engine Developments (Judd) have the gear, of course, but they are eye wateringly expensive and flat out right now.

 

Cheers Chris.

 

It's an industry wide thing to do with cost cutting. All the teams have to have a mandatory 2 week factory wide shutdown at the beginning of August. Something to do with the Italians not liking work at this time of year.

[Chris Wilson]

Cheers Chris.

 

It's an industry wide thing to do with cost cutting. All the teams have to have a mandatory 2 week factory wide shutdown at the beginning of August. Something to do with the Italians not liking work at this time of year.

 

Oh, right, never realised that happened. The Italians seem to keep their ice cream vans on the road all summer with no complaints though Good luck with the head.

[TLicense]

lol.

 

I've spoken to Bob and the head is going on it's holidays to the North tomorrow.

 

I'll let you know how it turns out....

[dandan]

If you need it put up on a CMM give me a shout Tony.

[jagman]

If there was any concentric difference , would not the valve seat be altered rather than the stem ?

would there not be a greater effect at that end of the valve as the forces are higher (impact) and temps higher and the stem is the effective pivot point .

Which is the harder surface, the stem of the valve or the valve guide?

seems odd to me and more oil lube/seal related or clearances on the stem/guide

[TLicense]

If the seats have been cut to one side of the guide, unless it was miles out, then there's no reason why it would see more excessive wear at the seat then it would in a normal condition.

If the stem is being pushed ever so slightly against the guide, then this would be seeing a lot more wear than it should in a normal condition.

 

It could possibly be an oil issue. All I can say was that there was plenty of oil there, but who's to say that it was enough? I would say though, there's certainly no immediately obvious cause for there to have been an oil issue. It was a new pump that was certainly generating good pressure.

 

I've checked the valve stem OD and valve guide ID, and they're all within tolerance.

[TLicense]

If you need it put up on a CMM give me a shout Tony.

 

Cheers Dan, it's already on it's way up North, but I may tap you up in the future

[TLicense]

Interesting bit of information here from HKS....

 

I e-mailed HKS about what springs and seat pressures they recommend.

They've replied saying that ALL HKS camshafts for the 2JZ-GTE are stage 1 camshafts (?) and are designed to be used only with stock springs and seat pressures.

Stage 2 camshafts (presumably not available for the 2JZ-GTE) would require increased seat pressures.

 

I think I may well end up switching back to the stock springs when the head gets rebuilt and see how I get on. Pity as I think I may have junked the old ones.

[Chris Wilson]

It's always better practice to fit new ones, especially on an old engine that's being asked to turn more revs than stock on a more aggressive profile cam lobe.

[TLicense]

True. They're not paricularly expensive. £90 for the set.

[TLicense]

A bit of an update to this....

 

I've spoken to Bob at B+J, and he's fully inspected the head and valves.

He doesn't think that the wear on the valves are anything to worry about, and thinks that it looks a lot worse than it is. "The wose thing you can do is open up an engine that hasn't done many miles and take a look at it, as it always looks terrible where you've got some bits still looking brand new and some bits showing slight wear" were more or less his words.

 

He has also checked the valve seat concentricity to the guides, and they're out by 5 thou at most. I've asked him to re-cut the seats to put the installed height closer to the stock nominal (putting me closer to the centre of the shim range) at which point he will also obviously correct the concentricity.

 

He's said he'll do that on Monday, so I should have it all back by the end of the week.