Valve Spring Shim Measurement Help

[ukkid35]

I am really struggling to understand the cylinder head build instructions in the AJP8 WSM

Here are the two pages describing valve shims measurements, I am stuck on Step 2





The image appears to show a Spacer in place of the Spring, with the Gauge on top measuring the height of the valve stem

However, in the calculation example the spacer size is shown as 59.72mm which is significantly less that the height of a fitted spring

How is the gauge measuring the 7.86mm given in the example?

I would have expected the spacer to have to be significantly taller than the spring in order for the gauge to sit (precariously) on top

I am imagining a gauge where the measuring tip protrudes about 20mm or so from the gauge body

Have I completely misunderstood?

[Mignon]

Why do you care what the garbled destructions say when this is kiddy level maths homework? Find a 12 year old to work out the calculations for you and bung him a fiver.

[ukkid35]

No so worried about the maths

It's more that I don't understand what they are measuring in that photo

However I realise now that the spacer in their example is actually longer at 59mm than the uncompressed spring which is 55mm

So perhaps if the gauge has a special collar that allows it to sit on the spacer, then it would work as shown

Obviously the gauge I have has nothing of the sort

Edited by ukkid35 on Wednesday 1st August 14:17

[Mignon]

You don't want a dial guage for this in the first place. You want a digital VeryNear caliper. Put valve in hole. Measure down hole from spring seat to tip of valve. Take valve out and put cap on. Measure from tip of valve to underside of valve cap. Subtract. You have fitted spring height. If too large add shims. Job jobbed. Complete waste of time doing this anyway unless your valve seats have been cut deeper by some ridiculous amount.

To facilitate this job on race engines where it actually mattered I made a tube on my lathe long enough to go over the valve stem and protrude above it. Then measure down tube to valve tip and subtract from the length of tube to get valve tip height. The tube needs to be bored large enough and deep enough at the bottom end to fit over the top of the valve guide. 10 minute job on a lathe. Not so easy if you don't have one. A length of 15mm copper plumbing pipe should do if you can cut it square.

[ukkid35]

Mignon said:

Complete waste of time doing this anyway unless your valve seats have been cut deeper by some ridiculous amount.

Very tempting to leave it, but since there is so much variation in the lifter shims, that must mean there's a lot a variation in the spring height, and that's before the seats were cut

I really don't want to do this job, but since it is a track car engine (rather than a race engine) and it is fairly high revving for a V8, it would seem foolish to leave this unbalanced

I only had time to check two intake valves yesterday, but they were 0.1mm different from cap to tip (2.15mm vs 2.25mm)

So there's more variation there even before the seat wear is taken in to account

I admit I didn't keep the retainers and keepers numbered when I took them off, probably a mistake

I also need to find a source of shims

[99hjhm]

ukkid35 said:

Very tempting to leave it, but since there is so much variation in the lifter shims, that must mean there's a lot a variation in the spring height, and that's before the seats were cut

I really don't want to do this job, but since it is a track car engine (rather than a race engine) and it is fairly high revving for a V8, it would seem foolish to leave this unbalanced

I only had time to check two intake valves yesterday, but they were 0.1mm different from cap to tip (2.15mm vs 2.25mm)

So there's more variation there even before the seat wear is taken in to account

I admit I didn't keep the retainers and keepers numbered when I took them off, probably a mistake

I also need to find a source of shims

0.1mm is 4 thou! You won’t be able to get shins thinner than 10 thou. It’s not worth worrying about. Have you checked the poundages of all your springs?

[ukkid35]

99hjhm said:

0.1mm is 4 thou! You won’t be able to get shins thinner than 10 thou. It’s not worth worrying about. Have you checked the poundages of all your springs?

Understood, I was just saying that the variation in the retainers adds to the overall variation, I hadn't realised that

I haven't checked the springs, but I have taken the precaution of buying a new set

I need to find a supply of shims 0.25mm as you said, with OD 34mm and ID 15mm

Based on the variation in the valve shims I am going to need a lot of spring shims

It would be nice to have about 20 or so to hand

That is assuming that I don't have to match Intake with Exhaust, and I just have to match all Intake and separately all Exhaust

Any suggestions for a supplier?

[ukkid35]

AccuGroup looked like a good bet

But the closest sizes are

35mm x 25mm

32mm x 22mm

Thickness range is huge from 0.1mm to 2.0mm

Approx £1 each

Perhaps the 32mm would work, but the ID is much larger than I really need

[Mignon]

ukkid35 said:

Very tempting to leave it, but since there is so much variation in the lifter shims, that must mean there's a lot a variation in the spring height, and that's before the seats were cut

I really don't want to do this job, but since it is a track car engine (rather than a race engine) and it is fairly high revving for a V8, it would seem foolish to leave this unbalanced

This is not an issue of "balance". As long as all the springs have enough poundage to reach the rpm the power curve needs then none of them give a rat's arse what any of the others are doing. This is not like piston weights or crank balance. If it used to rev high enough and nothing much has been changed then leave the bloody thing alone.

ukkid35 said:

I only had time to check two intake valves yesterday, but they were 0.1mm different from cap to tip (2.15mm vs 2.25mm)

0.1mm?? Are you for real or if I look up the term "anal retentive" in an online dictionary do I get a link to your name?

[227bhp]

You can't knock him for trying to do the right thing, IIRC his last attempt was a bit shoddy so he's taking extra care this time.

OP try Gosnays for spring seat shims and tools to measure, although the tool won't be worth buying for a one off.

[Kccv23highliftcam]

@ukkid35

I have a Mitutoyo digimatic micrometer that goes down to 1 thou of a mm or v.00005 in if you want...

gonna be a bugger getting the shims down to that mind!

Seriously, despite the banter, some good advice here .

[ukkid35]

227bhp said:

You can't knock him for trying to do the right thing, IIRC his last attempt was a bit shoddy so he's taking extra care this time.

OP try Gosnays for spring seat shims and tools to measure, although the tool won't be worth buying for a one off.

Thanks

I'm going to be buying the shims from Stephens Gaskets, made to order £2 ea but with a minimum order

My dad is making me the holder for the Dial Gauge

I've been measuring the valve spring retainer to valve tip, almost 0.5mm variation overall

[Mignon]

ukkid35 said:

Perhaps the 32mm would work, but the ID is much larger than I really need

The I/D is irrelevant as long as they fit over the guide. The only thing that matters is the O/D being a snuggish fit in the spring seat bore so they can't move around too much and the I/D being smaller than the I/D of the spring itself so the whole spring is fully supported.


Dura-Bond Bearings in the USA list dozens of them in 15, 30 and 60 thou thicknesses and a huge range of O/Ds.

https://www.dura-bondbearing.com/Portals/3/2014%20...

[ukkid35]

Mignon said:

Dura-Bond Bearings in the USA list dozens of them in 15, 30 and 60 thou thicknesses and a huge range of O/Ds.

https://www.dura-bondbearing.com/Portals/3/2014%20...

Thanks - Part #1095 looks to be just right at 34mm x 15mm x 0.38mm

Minimum order looks like it would be 100, so I think that would make it more expensive than the 'local' option of Stephens Gaskets

[stevieturbo]

ukkid35 said:

Thanks - Part #1095 looks to be just right at 34mm x 15mm x 0.38mm

Minimum order looks like it would be 100, so I think that would make it more expensive than the 'local' option of Stephens Gaskets

They're like $15-20 for 100

Summit sell tehm

[Mignon]

https://www.summitracing.com/int/parts/dur-3095/ov...

[ukkid35]

Mignon said:

https://www.summitracing.com/int/parts/dur-3095/ov...

Thanks, that is much better value

Unfortunately I really need them quicker than they can supply

summitracing said:

The part DUR-1095 will be shipped directly from the manufacturer. Tentative pickup date: 9/13/2018 if your order is placed today.

[stevieturbo]

ukkid35 said:

Mignon said:

https://www.summitracing.com/int/parts/dur-3095/ov...

Thanks, that is much better value

Unfortunately I really need them quicker than they can supply

summitracing said:

The part DUR-1095 will be shipped directly from the manufacturer. Tentative pickup date: 9/13/2018 if your order is placed today.

If you'd ordered them on Friday via an expedited service you'd have them Monday..maybe Tuesday.

Obviously now the weekend that changes... but it still states "Estimated International Date: Monday 8/27/2018"

Same date applies for most of the 1.33" OD shims if that is what you need

https://www.summitracing.com/int/search/brand/dura...

[stevieturbo]

Or if really stuck I've a load of them here, although these would only be sent out either on the proviso I get them replaced ( ie you buy and send me replacements of whatever is used ), or they will be sold at a cost where I can replace them as I'm not leaving myself without stock.

I should have 15, 30 and 60's

[ukkid35]

stevieturbo said:

Or if really stuck I've a load of them here

Many thanks - you have PM