Cylinder Head Upgrades on a Budget
#1
Cylinder Head Upgrades on a Budget
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.
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.
#2
TECH Resident
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?
#4
TECH Senior Member
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..
#7
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.
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.
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#8
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You thinking boost? 9.5 compression the reason I’m asking.
#11
TECH Senior Member
On edit, is it me, or did they even get a little bowl work done in there while they were at it?
#16
TECH Senior Member
#17
TECH Fanatic
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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.
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.
#18
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 ?