Case 188D Valve-to-Piston clearance

Does anyone know what the valve-to-piston clearance should be at closest encounter on the 188D?

How about expected head gasket crush?

These values would be nice to know in advance of an overhaul this summer.

Otherwise I guess I'll have to try to measure what exists currently in mine & go from there. Sounds painful, but I have the patience of a saint...

thx, Bill

60 foot pounds is your torque for the head.I have to ask why are
you concerned with valve to piston clearance when the valves
are recessed 1 .060 ex and1.000 intake? Head gasket crush is
what it is.Has the head been milled?

He wants to know DIESEL head valve specs, not gas. Diesels have valves close to flush with the head deck surface, but do vary from slightly below to above the deck surface depending on piston top design.

Thx for the responses!

That's right gents, it's the diesel.
Valve protrusion/recession I think I've already got a handle on.

From what I can glean from the forum, I know the valve-to-piston clearance can get pretty close, even to the point of collision. Especially if one starts shaving the block.

So I'm wondering is a miss as good as a mile or what?

Or, is it the mysterious .060" that mEl refers to once in a while? :wink:

I have seen generic recommendations for gas engines that say .080" & .100" (intake & exhaust I think), but pretty sure that doesn't apply here. Low RPMs on these puppies.

And even just gasket crush makes a difference on this spec.

What number would make you comfortable if it were your engine?

Bill

Thanks for the info on that . My service manual lacks the diesel specs. Thanks for clarifying Diesel tech! CM

(quoted from post at 20:45:12 01/21/22) Thanks for the info on that . My service manual lacks the diesel specs. Thanks for clarifying Diesel tech! CM

Click to expand...

additional note, cyl head studs w/flange nut torque is 90to 100 ft lbs.CM

I would use a mag base and indicator , and zero it out on the head,without the gasket applied, then move the base and indicator to the piston, and bring the piston to TDC.That should give you the clearance of the head to motor block. CM

Jumping off Chucks post here to answer Wilbury, in the past I indeed did use the .060 figure for valve protrusion, I have no idea where I got that figure but it was in error so I must clear that up. that being said, not ideal of course but I have seen nice running engines with the valve face print indented into the piston valve relief, maybe there was a history of a cam key failure allowing an out of time sequence, I have done several cam key jobs on 188s and would recommend replacing standard keys with hardened if working in that area. Not trying to minimize the possibility of collisions on the top end but think about this, at that part of the stroke cycle the piston is near a dead stop as the crank swings over TDC,so any collision is very slow motion.

Years ago I had all new valve seats installed in a Continental HD 277 head, and thought I could get away with the intake valves flush with the head deck surface. The
exhausts were raised also far as the energy cell would allow as head is a power cell design like the Case 30 series. I was hoping the head gasket thickness would furnish
the clearance I needed at the TDC exhaust closing/intake opening cycle. All valves spec is .014 inch hot, but when checked at .016 cold the intake valve opened JUST quick
enough as piston started back down that I only had .015/.020 valve/piston clearance. I pulled the head and touched the intake valves and seats to drop them all another
.010 inch. It was still close, but it ran fine as I never ran the engine over 2000 RPM.

Hehe, glad you know a joke when you see one mEl but I [i:dd2c2eb5ac]was[/i:dd2c2eb5ac] kinda hoping you were thinking clearance. Thanks for that outstanding tip on the woodruff key, you won't find that one in the manual! Good point about piston speed too but I'm not sure yet where in the stroke closest approach is. No one's offered to give me a cam profile yet. :roll:

I'm clear on the valve recession now though two months ago I never even heard of it. If you guys haven't seen it yet, I laid out the math to prove .005" valve recession (both valves) = 0.1 compression.
https://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=case&th=359682

Dieseltech- Funny, I was thinking .020 would be scary & mebbe .030-.040 minimum. I don't know squat tho. I can see me squishing the clay pretty thin in there! Probably gonna cost me an extra head gasket too. No way I'm just going to leave it up to the machine shop & hope for the best.

Chuck - I think I'll have to measure it all up before I even tear it down. Measure valve stroke with everything still intact, then install weak test springs on at least a couple valves with an indicator on the stems & crank through the degrees on the overlap stroke. That'll at least tell me what I've got now. AND with new timing gears (priced a cam gear lately?), cam w/bushings, lifters, valves & seats, that'll just tighten things up even more. Praying this engine is a 61 year-old 7000+ hr virgin. :shock:

Speaking of parts & gaskets etc., is Reliance the only game in town or should I be looking at Mahle?

Again, thx for all the input so far! Bill

This post was edited by WilBury on 01/21/2022 at 06:30 pm.

Read John Sailes Post below Believe me.CM

I read it over & over Chuck.
"As long as the pistons don't touch the valves, you can't go too far."

He's probably dead right about that but jeez, give me at least .020"... There'll be carbon that deep in there... eventually. Or maybe they're meant to kiss the carbon off the pistons!! :shock:

I won't know how much will have to come off the block deck until it's in the machine shop. That'll give me the new compression ratio. From that I get the desired valve recession. Tack on the desired valve-to piston clearance & Bob's yer uncle, I'll know where to seat the valves. Oh crap, still the crushed gasket number to get...and yes, I'll have to make sure there's enough adjustment left on the rocker arms for any changes.

It's not like I need more power, I'm hard enough on machinery as it is! :twisted:

Any criticism is most welcome! Bill

This post was edited by WilBury on 01/22/2022 at 05:03 pm.