2.0 Cylinder Head Questions

[P.J. Romano]

I purchased this 2.0 cylinder head on German eBay. During detailed inspection I noticed that the cooling channels are quite shallow, especially at the cylinder No. 1.
1) Is it normal or this head was milled? Can somebody please confirm this, based on the attached picture?
2) I measured 102.3 mm head thickness (at both ends). What is the standard thickness of 2.0 head?

[RallyBob]

Originally Posted by P.J. Romano I purchased this 2.0 cylinder head on German eBay. During detailed inspection I noticed that the cooling channels are quite shallow, especially at the cylinder No. 1. 1) Is it normal or this head was milled? Can somebody please confirm this, based on the attached picture? 2) I measured 102.3 mm head thickness (at both ends). What is the standard thickness of 2.0 head?

The head *may* have been angle milled. I say this because it normally takes a ton of milling to make those coolant passages that shallow, but the head does not look heavily milled near the edges of the valves to me. I would measure the head from side-to-side to see if the total heights are the same.

[P.J. Romano]

Spot on, Bob! One side measures 101 mm, another one 104 mm.

I noticed in one of your recent threads that you recommended angle milling.
What do you achieve with angle milling vs. parallel milling?
One more question (last one, I promise): Should I carefully grind down those shallow cooling channels and make them deeper or just leave them as is?

By the way, the cylinder head seems to be mildly portet. Possibly visible on the photos. No visible cracks but I will get the head magnafluxed before putting new valves and springs.
I am building 2.0 street engine, Combination cam (hyd. lifters), DSD Webers, Sprint manifold, Compufire. This cylinder head will fit nicely.

[RallyBob]

Originally Posted by P.J. Romano Spot on, Bob! One side measures 101 mm, another one 104 mm.

Lucky guess!

I noticed in one of your recent threads that you recommended angle milling. What do you achieve with angle milling vs. parallel milling?

You increase the compression without massively weakening the head itself by making it uniformly thin. You also only retard the cam timing half as much as usual....if you mill the head 2 mm flat, then the chain slop increases and timing is retarded. If you milled it 2 mm on an angle, then the center of the head (where the cam is located) is only 1 mm closer to the crankshaft, and timing is retarded only half as much. However you get nearly the same compression increase because most of the relative volume of the chamber is near the spark plug side of the head. There are also some other (slight) changes such as a shallower valve angle (better cylinder head breathing), and a slightly inclined intake manifold angle, as well as a slightly better exposure of the spark plug to the air/fuel mixture.

One more question (last one, I promise): Should I carefully grind down those shallow cooling channels and make them deeper or just leave them as is?

I have typically ground a little bit of cast iron away to connect these two sides of the coolant passage to avoid steam pockets.

Bob

[P.J. Romano]

Bob, thank you once again. We are so lucky to have you. Hope this thread was useful to others as well.

[GTJIM]

Make sure that the spot under the head bolts has been re-machined square to the angled head face.

You may also need to relieve the holes the head bolts go through to allow some clearance around them as the original drilled holes are now at an angle to the head/block face.

[P.J. Romano]

I was also thinking about this, Jim.
It appears that there is enough "slack" between head bolts and their holes in the cylinder head to compensate for the angled position of cylinder head.

Regarding area under the bolt head, my calculation shows that the height difference between sides is approx 0.4 mm.
(Cylinder head width 140 mm, angle milled 3 mm, the width of the area under the bolt 20 mm. 140:3=20:X=60/140=0.4)

Ideally, this area should be parallel to the bottom of cylinder head but I wonder if the machining is needed for such a minor difference?
Any experience here?

[RallyBob]

I've never had to clearance the bolt hole ID's for the head bolts, they've always had plenty of room.

However I have always had the tops of the bolt holes spot-faced parallel to the cylinder head deck. The head bolts are one of the most critical fasteners in the engine, so I didn't want to risk side-loading and potentially damaging them. I would imagine that the torque values would be skewed otherwise.

[hrcollinsjr]

Originally Posted by P.J. Romano I was also thinking about this, Jim. It appears that there is enough "slack" between head bolts and their holes in the cylinder head to compensate for the angled position of cylinder head.

I would tend to think you are correct in this statement with the exception of radically angle milled heads.

Ideally, this area should be parallel to the bottom of cylinder head but I wonder if the machining is needed for such a minor difference? Any experience here?

I would think this is fairly important for proper torque and the bolts maintaining the proper torque.

Harold

[P.J. Romano]

Well, it is clear now that the area under the bolt head should be machined to match the angle of the cylinder head. Actually, the person that angle milled and ported the head might have done it but as I have no mean to check it, I am off to the machine shop as we speak.

[GTJIM]

It is critical that the area under the bolt heads is parallel to the head face.

Think of it like this - If the spotface is at an angle then only one side of the under-head will be in full contact ... and that will put only one side of the bolt in tension by 'bending' the bolt. This reduces the strength of the bolt by somewhere near 70% ... I have had the short bolts along the outside of an angle-milled SB Chevy 'pop'; breaking off at the jucture of the thread and shank ... NOT GOOD!

Also, only one side of the thread in the block is 'loaded' - this severely damages the cast iron and ends up with a stripped thread.

The bolt touching the side of the hole will also 'push' the bolt off-square - that is why I mentioned checking clearance there too.

Good idea going off to the m/c shop to get it checked!

[wrench459]

Originally Posted by P.J. Romano Actually, the person that angle milled and ported the head might have done it but as I have no mean to check it, I am off to the machine shop as we speak.

Can't we level the head on a flat surface?
Or even use feeler gauge's to flatten it out?
Don't give up too early.