TDC detection (beaten to death topic)

[refit1701]

I'm adjusting the valves now and forgot how tedeus it is to keep track of TDC. I know about the plug above number six.

When watching the valves move, can I not just wait for them both to stop moving and then adjust? Or must it be TDC of the compression stroke?

It seems to me as long as both valves are at rest, it should be OK to adjust.

[Argie1978]

1 --> 5 --> 3 --> 6 --> 2 --> 4

Why are you using cylinder No. 6? Maybe I got you wrong.
Anyways, when you reach TDC on cyl No 1 you apply the mark in the balancer (I recommend 3 marks...). And that's it.
And yeah, I use TDC.

Sebastian

[refit1701]

I was told that 6 and 1 both reach TDC together.

How are you guys getting to the crank flywheel to mark it?

[Argie1978]

Don't laugh but long ago I used to have a long artery clamp for things like this when working on engines.
So I'd hold a small piece of white or yellow crayon and do the markings.
Note that I've never done this in the T245 and I see there's too little space.

Sebastian

[refit1701]

I'll have to puzzle this out. I'm not in a hurry. I'd rather not remove the radiator and I sort of added mission creep to this as it is.
The original goal was to replace the interface gasket between the two manifolds and fix the heat baffle. Now I am up to my arm pits in "nice to do" items.

[Cal_Gary]

Hi John,
I too will be doing my manifold gaskets, etc. in another month or two.
I've never trusted a valve "at rest" to adjust from that point as there can be some variances unseen with the naked eye. I always ensure that the valve lash is set by first moving the crank around to ensure there is no upward pressure. I prefer to set mine with the engine running; however, that's a hot manifold burn waiting to happen, and there are historical posts here showing the skin damage.
Gary

[NAM VET]

when Charles Talbert redid some of my engine, one of the things he did was to bolt the intake an exhaust manifold together, then have his machine shop surface both of them as one piece, so they mate perfectly with the block's surface. No leaks or gas cutting that way. Just a suggestion. Hal

[refit1701]

I did my best to mate the two manifolds together. I clamped the exhaust to my workbench, then placed the intake there and installed the bolts loosely. I checked the flanges with a straight edge and they were very close so I clamped the block flanges to another heavy piece of steel. After that, I tightened the four bolts and once done, checked the interface again.

They are very close, close enough to not leak. I'm not likely to have them ground to match until resources are available. So I did work on making them match.

[Elwood]

Old topic, but I've repeatedly seen this reference to "grinding" the flange faces of the intake and exhaust manifold to match a known flat surface, e.g. a surface plate or a machinist's straight edge. I understand that the term "grind" appears in TM9-1840A and is likely the source of the phrase, but as someone who has done a fair bit of machining work, the need to actually grind the two faces escapes me. Surface grinding is usually reserved for applications where the surface must be exceptionally flat and/or of a certain degree of smoothness, neither one of which would seem to be necessary on a manifold mating face since the gaskets have a degree of compression to them. Some gasket surfaces can actually be too smooth, as the gaskets need something to bite into to hold their place especially if pressurized.

The maximum allowable spec in TM9-1840A for variance of these faces is 0.010", which is a whole lot of non-flatness. Simply machining the faces on a good quality milling machine will easily produce a flatness with less than 0.001" variance, i.e. ten times as good as the spec.

Unless I'm missing something here, I think that milling the manifold assembly, if necessary to true the flange mating surfaces, is more than sufficient, and that grinding them is not needed.