You are doing great. Don't get disheartened.

I don't see how the contact marks were left while assembling the engine. Something would have gone solid and you would have felt it.

Confirm the numbers given to you are for the cam timing you are using. The cam company can run thje cam profile in whatever software they use and get valve lifts at any crank degree at the Intake and Exhaust centerlines they suggest you use or are using.

What did the tool you are using show as the Intake centerline number? It would be something like 113° ATDC. the 113° is an example only. It could have said, 113.25° and the other side may have said 113.5°. Again, just examples.

Recheck you drop numbers. Ask the cam person again, for the valve lifts at the same crank degrees you use for the drop numbers. If you are using 20° BTDC through to 20° ATDC at every 10°, as for this valve lift numbers. Make sure they are valve lifts not cam lift. If they are cam lift, be sure to multiply into the valve lift the rocker ratio.

The repeat your math to get the clearance numbers. Once done, and everything checks out, you are good to go to re assembly with fear of anything touching. Then focus on the cam timing assembly. This is really easy and simple if you understand the process and remove the fear element.

Get to this point with all the checks and with the pistons somewhat down the bores, refit the heads, cam housings and camshafts. When you get to this point let me know. I am happy to guide you through the next steps.

Neil, thanks again for the help.

We reviewed some of our original measurements again today regarding the deck height we had when I pulled the engine apart. The deck height was actually .75mm (with a 1.0mm shim under the cylinders) and not the 1mm I thought I’d measured on initial assembly. The valves were just touching the pistons with this .75mm deck height which means (assuming everything was timed / setup correctly between pistons and valves) that any thicker shim combination would start to create clearance between the valves and pistons.

With that, even if I shimmed the cylinders with 2mm of shims (for a deck height of 1.75mm) I would still only have about 1mm of valve to piston clearance.

We rechecked to see if the heads have been surfaced and they are still at the factory thickness so it doesn’t appear I’m loosing anything there. The rockers are also stock ratio rockers so that’s not creating more valve travel either. The case was machined by Ollie’s to include surfacing the case halves and cylinder spigots but the shims should be compensating for the removed material.

I’ll continue to work the camshaft lift numbers with Dougherty (he’s been very helpful) and see if there’s something we’re missing. I’ll confirm whether those numbers are lift or actual valve travel numbers as suggested.

Dumb question: if everything was set up correctly in the valve train and camshafts were timed correctly, then I’m assuming we’ll need to go with thicker shims and / or machining the valve pockets. Is this correct?

Also, what’s the maximum deck height you could go (to reach the needed piston / valve clearance) before you’d need to look at machining the valve pockets? I’m thinking 1.5mm is probably about it for an 85mm x 66mm engine.

An update:

The lift numbers I got from the cam maker are the actual valve lifts so I should’ve had some clearance between valve and piston based on my calculations. I’ll review these numbers and see what I get a second time.

Upon remeasuring my heads they have been surfaced. They are not stamp as most rebuilders do so I didn’t even think to measure them when I initially assembled the engine since they were not stamped. They have about .40mm (.015”) removed from them which is a pretty large amount I think. The chamber volume was still around 68cc because they have a second plug and reground valve seats that have added back cc’s lost when the heads were surfaced.

Between the less than thought deck height and now .40mm of lost surface on the heads I’m starting to see that my pistons were really close to the heads. I obviously did not get an accurate reading when I tried the clay or solder methods to determine these specs.

I called JE and they say I cannot machine the valve pocket deeper so my only option with my current components is to shim the cylinders to compensate for the surfaced heads and the required 1-1.5mm of deck height.

With that, I’m looking at somewhere between 2.0 - 2.5mm of shims to set a deck height of 1.25 - 1.50mm and compensate for the surfaced heads. Will this work?

All of this should add about 1.25mm of clearance above what I had when I first assembled the engine. I’m still somewhat concerned since I had zero clearance (assuming everything was set up correctly) and this is still less than the required minimum valve to piston clearance.

Thoughts?

Bump.

What we need to do is machine the heads to a total of .50mm then make .50mm steel head gaskets like they use on the turbos etc, this would bring it back to stock height.

Craig

Based on what you wrote above about the current deck height measurement, it does look like you'd need add shims to get both the piston to head clearance, and the piston to valve clearance.

One thing though - in post #22 you mention that with a 1 mm spacer/gasket under your cylinders, and that you had .75 mm of deck height. Adding another 1 mm spacer would yield 1.75 mm deck height (which most would consider to be too much), but then in post #23 you mention that you'd have 1.25-1.5 mm deck height with 2-2.5 mm of spacers. Are you thinking that the .4 mm machined from your head sealing surface changes your deck height? Unless I've misunderstood what you are doing, it should not.

The machining done to your heads does bring the valves and combustion chamber closer to the piston and would contribute to the valve to piston contact of course ...

Craig, thanks for the reply.

Stownsem, yes, that’s what I thought the solution was. I was thinking shims to create the 1.25mm head space and add back the .40mm of material would solve my surfaced heads and machined spigots. I’m obviously not correct?

With that, it sounds like I’d need to have a spacer (from cgarr) added to the bottom of the head and then shims to set the headspace. Would that solve my issue?

Craig's solution will bring the head back into proper orientation/height compared to the cylinder, and give you .4 mm of deck height which will fix that problem. You'll still have to solve for more piston to valve clearance though, adding back .4 mm won't be enough there. Depending on whom you ask, you may hear .060" min on the intake and .080" min on the exhaust.

Something seems off re: the piston to valve clearance. Are these off the shelf JE pistons? Normally they'd cut the valve pockets with plenty of clearance ... which yours clearly don't have. DC40's are a common cam for your motor, not exactly off the charts with lift and duration. Did they say why the pockets can't be cut?

I’m measuring about .25 - .40 mm of head material that’s been removed. It’s hard to get a consistent reading but it’s at or slightly above .25mm. Will a head gasket / shim work on a 2.2L cylinder?

The heads are JE shelf pistons (bought from L&N) and JE says these particular pistons are already as thin as they can be in / under the valve pockets. I’d have to read the email again on why but this determination was made by the JE engineers when I emailed their tech guys with the piston part number.

When I measured valve drop with the 1.75mm of head space, valve lifts that the cam producers provided measurements for show 2+ mm for both intake and exhaust. With those numbers, I can’t see why the valves touched the pistons even with half the head space.

You're using standard early CE style head gaskets? I think Craig may be referring to using a later style head gasket, perhaps he can elaborate.

Gotcha re: the pistons, the crown may not have enough meat to cut further without making too thin.

Weird that now you get enough valve drop. When you say 1.75 mm of head space, do you mean 2 mm of shims under the cylinder and 1.75 mm deck height (top of piston to top of cylinder at TDC)?

Stownsen, that's what I mean. Based on my reading I thought I could use shims to compensate for both the deck height and the surfaced heads by simply using shims under the cylinder base.

Thinking about it now, it obviously wouldn't work since the deck height would still be 1.75 (flat of piston to top of cylinder) with the 2mm of shims regardless of how close the cylinder head was to the actual piston dome. I would need to find some form of shim to compensate for the surfaced heads since the chamber volume (squish?) with the head at TDC would be less than an uncut head given a fixed deck height of 1mm - 1.5mm.

The cylinders and heads are from a 2.2 / 2.4 motor so they have a ring / spring sealing shim in them that sits in a groove in the top of the cylinder barrel.

I agree that my valve drop measurements seems to indicate there would be enough valve to piston clearance but the valves touched the pistons. From an earlier post it seems that my timing was correct since both valves in all 6 cylinders were hitting there respective pistons and not just intake or exhaust valves.

Hey stretch,

Did you ever figure out why you were having the P to V interference, if your actual measurements as per Neil’s instructions (those were super helpful thanks Neil!) showed plenty of clearance?

Cheers,
Lukas

Those pistons look a lot different from JE 10.5:1 I’ve seen. Much higher dome.

JE makes a couple different pistons for 911’s.