Cylinder head questions

[sujitroy]

This is a new thread. I took my head to a shop and they determined one head is warped. (I recall he said is was warped by about 2 thou. ) What amount of warpage can I get away without having it resurfaced?

They can fill in the indentation of the fire ring. The local shop here in US will charge me $100 to resurface it. I asked it the cam shaft needed line boring but he said from the measurement no, but said to remove the cam shaft and valves, re-clamp cam shaft down and see it it binds. If so it needs some work.


I plan to strip the head myself and the shop said if I run into trouble they can help me out. for a charge which I'm OK with as I I'd really like to learn this whole process.

Before I pull it apart, should I measure the valve gaps?

One I get it apart, I'm sure I'll have more questions.

Sujit

[new to this]

Are you reusing the valves and guides cam buckets, if so put them in separate containers so you know we're they came from

Dave

[sujitroy]

Plan to and yes am aware of keeping then I'm the right order

[Mark Serj]

I would leave it alone with .002" total bow

[sujitroy]

Hello Mark. I will reconfirm with the shop. however I still have to deal with the indentation from the fire ring as that is very visible.

[flying farmer]

If the 2 thou was down the entire length of the head I probably would not bother getting it re faced, but if it was between adjacent stud holes I definitely would. Since you also have the fire ring groove I think refacing is probably the best option, but for only 2 thou I would go down the plate glass and wet and dry route.

The link in the previous thread posted by dasadrew with the pictures shows exactly what is required.

Personally I always check the cam for alignment when I am rebuilding a head. Bolting the cam back into a stripped head is a sure way of finding whether it is tight or too loose, but I always start by seeing if the cam can be rocked from end to end when resting on the head before the caps are bolted on. If the cam does rock the high bearings can be carefully rubbed down with an appropriately sized socket wrapped in 600 grit wet and dry so the cam is touching all the bearings. The cam bearing caps can then be faced on a flat surface using more wet and dry to reduce the clearances, I use a one and a half thou feeler gauge for this as it is the thinnest in the set.

The last pair of heads I did both had tight cams and the warping was actually sideways, it appeared that the ends of both heads had pulled inwards. I reckon it took about 2 hours work to sort out each of the heads but cost nothing except a few sheets of wet and dry.

I have lost count now, but I think I have done 5 or 6 pairs of heads like this over the years

Neil

[sujitroy]

I took my head to another shop. The warpage is about 5 thou and mainly concentrated in the middle. Since he has to deck it about 5 thou, the gouge due to the fire ring will be gone.

so here are some other questions

It seems the minimum a head can be is 112.45 inches. Was this number based on using a standard thickness head gasket of 40 thou being used?

If so, if I use a thick gasket, I should be able to reduce this number, 112.45 inches, by another 20 thou since a thick gasket is 60 thou?
If I have to remove more than 20 thou below 112.45, then I need to use a saver shim and or a thick or thin gasket?
Am I correct here and have I missed anything?

If a new head is 112.64 mm 4.4364 inch and a max skimmed head is 112.45 mm 4.4271 in
Then the (.19 mm = 0.00748 )seems a rather small amount before the head is useless.

When a head warps for the first time, what are typical amounts that need to be removed to make it flat again?

There is talk about having the same or similar amounts taken off each head to prevent undue load on the crank. I'm not planning on racing my Stag should I worry?

Sujit

[Ian928]

There are also a "head saver" shim available. You attach this to the block with Wellseal and fit the head gasket as usual. I have two of these that I may or not choose to use. Some info I received from them:

"We supply 0.020" 0.040" and 0.060" thickness shims for the Triumph Stag's. Whist they are the thicknesses we stock we can manufacture them up to 3.00mm Thick."

I bougth it from these guys:http://www.gosnays.co.uk/acatalog/index.html

[flying farmer]

I would not worry too much about the actual numbers. As a rule of thumb as long as the valves do not protrude above the head face when closed you can still get away with a standard thickness gasket. If the valves protrude higher than the head face you can move to a thicker gasket.

The main problem I find with heavily skimmed heads is that the timing chain tensioners run out of adjustment, and the cam timing can end up retarded. The cam timing can be corrected by re-drilling the sprockets.

The inlet manifold might also need skimming as the mounting faces get closer together as the heads are skimmed.

If you only need 5 thou taking off one head I wouldn't bother too much about altering the balance of compression between the two heads, the variation in volume between chambers in the same head will be more than that.

I can't say I would be too keen on using the head saver shims unless the block has been skimmed first to ensure it is flat, I have seen far too many warped blocks for my liking.

Neil