KCS

iTrader: (20)

Today I received my heads back from the machine shop, so I thought I'd post the before and after pics. I picked up these 862 castings locally for less $60 to go on my turbocharged 4.8L build They're NOT the Castech castings that are prone to crack, and they DO NOT have the notch in the deck, so no special head gaskets are needed. They looked like this when I got them.



I sent the heads off to my local machine shop and had the heads cleaned, milled, and the valve job cut for larger 2.00" intake valves and the stock 1.55" exhaust valves. They only skim cut the deck so the compression should be about 9.5:1 on the 4.8L. They look a lot better now.







So far, I have a whopping $330 invested.

cookseyb

I have a set of 862 with the coolant erosion really bad .Does that hurt anything they weren't leaking and the shop I took them to wouldn't try and clean them up (mill). I think I will try and weld them up if it is that important. Your thoughts?

KCS

iTrader: (20)

As long as it's over the water jackets in the block, I wouldn't worry about it. If it crosses over to make a potential leak path, then I would worry.

G Atsma

Nice heads, KCS! They turned sow's ears into silk purses! I like how they lapped the valves too. I didn't think that was done anymore. Kind of a lost art..

A.R. Shale Targa

iTrader: (2)

Awesomeness

KCS

iTrader: (20)

A lot of machinists use it to check the concentricity of the valve and valve job after it's been done. It's a nice visual for the customer to see too, IMO.

KCS

iTrader: (20)

I measured the venturi to see what the minimum cross section is. The handy little tool shows me the diameter, and using basic math, I can calculate the area.



The intake port is at 2.35sq in while the exhaust is 1.37sq in. I'll be opening the intake up to about 2.54sq in and the exhaust to about 1.52sq in.

Darth_V8r

iTrader: (4)

You thinking boost? 9.5 compression the reason I’m asking.

KCS

iTrader: (20)

Yup! Boost will be provided courtesy of a Huron Speed V3 AC T4 kit and a VS Racing 7875 turbo.

79_T/A

iTrader: (1)

Deburred chambers and everything. Nice, detailed machine work.

G Atsma

Plus, to me, it's about being thorough...
On edit, is it me, or did they even get a little bowl work done in there while they were at it?

ddnspider

iTrader: (26)

Welcome to the dark side where making power is easy and torque is abundant.

99 Black Bird T/A

iTrader: (4)

The heads are looking nice

Look forward to reading about the turbo build.

omc8

iTrader: (7)

What valves are you using ? Did the same cutter that cut the seats, cut the chamber walls.

KCS

iTrader: (20)

The intakes valves are 2.00" from a set of 243 heads, and the exhaust are 1.55". Good eye on the chamber scalloping; that is built into the intake and exhaust cutter profiles.

G Atsma

That should go a LONG way toward unshrouding the valves.

omc8

iTrader: (7)

That $ 330 does that include the cost of the heads , so you spent approx $270 in machine shop work ? So your going to take the throat diameter close to 1.80 intake ..... and the exhaust to 1.39 ?. Iirc I thought the exhaust should be approx 86- 87% of valve diameter , looks like your going close to 90% is that because it's going to be turbo ?

KCS

iTrader: (20)

I was always taught 90% as a good general rule of thumb, especially with a 45 degree seat, but some applications may like more or less. The exhaust bowl has an ugly lip in it just above the seat insert, so going out to 90% will usually help get rid of it.

The Postman

iTrader: (44)

Wow those cleaned up really nice, glad someone could put them to use!

KCS

iTrader: (20)

Another cheap and easy modification: drill the pushrod holes out to 1/2". Now there's plenty of room for a 3/8" pushrod.