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Old 07-17-2007, 09:26 AM
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Smaller valves on same head?

Question: Can 2.02/1.60 valves be replaced with 1.94/1.50 valves in the same head? Thanks! JG700

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Old 07-17-2007, 09:34 AM
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In some cases, yes. But you'd have to sink the valve job quite a bit.
Could also replace the valve seats to allow a new smaller diameter valve job.
Why do you want to do this?
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Old 07-17-2007, 09:34 AM
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Quote:
Originally Posted by JG700
Question: Can 2.02/1.60 valves be replaced with 1.94/1.50 valves in the same head? Thanks! JG700
Yes but not cheaply. The entire seat has to be machined away. Then a hard seat insert is pressed in under high pressure and a temperature differential, really cold insert (-100F) and a warm head. Once stabilized a new seat is cut into the insert.

Between the cost of doing this and a set of valves, you can buy a set of 060 Vortecs.

Bogie
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Old 07-17-2007, 09:46 AM
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So they cannot just be swapped out without machining?
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Old 07-17-2007, 09:57 AM
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Quote:
Originally Posted by JG700
So they cannot just be swapped out without machining?

A lot of expensive machine work. You would be better off to sell those heads and buy a new set of Vortecs. I think you will be money ahead. Or even a set of aluminum heads.
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Old 07-17-2007, 10:04 AM
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Quote:
Originally Posted by JG700
So they cannot just be swapped out without machining?
No, the 2.02 seat hole is too big to cut a 1.94 seat at the proper location in the existing casting. It could be done, but it would cause the valve to be sunk into the head as a result of chasing casting diameter suitable for the seat which is smaller as you pass just above the seat area. The sunken valve would greatly inhibit breathing and would result in a substantial reduction in power. Additionally, the valve would now sit high on the stem side which would require major "adjustments" to the valve spring, rocker, and push rod to accommodate what looks to those parts as a long stem valve.

I guess the basic question is why are you considering this?

Bogie
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Old 07-17-2007, 06:20 PM
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I sent my engine out for a rebuild, top and bottom. On the invoice the shop manager wrote "installed new 1.94.1.50 valves." But my engine (1980 Corvette L-82 engine) had 2.02/1.60 valves, so there are 2 possibilities: he wrote the information down incorrectly, or he swapped heads with ones he thought were correct. From what I've read here he couldn't have mistakenly inserted the smaller valves into the old heads without considerable work -which obviously would had lead him to see the valves were wrong. He's on vacation until next week, but I will definitely follow up on this.
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Old 07-17-2007, 06:31 PM
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Sounds like it's time to contact the shop to see what that's all about. Did you mark the heads you brought in to be sure they were YOUR heads you got back?
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Old 07-17-2007, 09:27 PM
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hmmmmmm, might be some larceny afoot......
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Old 07-18-2007, 04:55 AM
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I don't think chevy produced any engines in 79/80 with 2.02 valves.
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Old 07-18-2007, 10:20 AM
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Yes, the L-82 Corvette high performance engine had these valves. I checked the head casting number and it is C210: the block casting number is C280, so I'm guessing these ARE my original heads and the shop manager simply wrote it wrong (I hope, since it doesn't sound like he could remove the larger valves and simply reinsert the smaller ones without realizing it, yes?)
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Old 07-18-2007, 12:10 PM
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Quote:
Originally Posted by baddbob
I don't think chevy produced any engines in 79/80 with 2.02 valves.
That is what I was thinking. Chevy performance was very lackluster at that time and horsepower numbers were very low. I didn't think they had a smallblock that could have benefited from 2.02's.
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