Valve difference from CA18 to CA20

Just thought this was kind of interesting. Was looking up new valves for the CA20ET project in my SBI book, and I decided to check what the CA18ET was just out of curiosity. I was always under the impression that the heads were identical. Well, the exhaust valve has an S after it, so I'm like cool, that means it's a stellite impregnated valve, so it'll be stronger. So I called SBI to see if they could tell me what the difference in the intake valves was. Well get this: they list the exhaust valve as .100 shorter than the CA20, and the intake valve as .060 shorter than the CA20.

Wierd.... :dontknow:

So I figured maybe it was just they weren't compensating for the difference between the hyrdaulic and mechanical heads, so I measured mine, and they're only .040 and .030 different than the numbers he gave me for the turbo lengths... Well whatever, just thought that was kinda wierd. I'm going with turbo valves since they're close enough to work with and mine is a mechanical rocker anyway...

Here's the length he gave me for the turbo valves

Part # 10264 (intake) 4.165
Part # 10265S (exhaust) 4.203

Here's what I got when I measured mine:

intake: 4.205
exhaust: 4.235

Anyway, sorry for the ramblings. It's time to go home... :burnout:

Yeah there are a few differences between the hydro and mech valvetrains.

The late ca20es (with hydr.) have stiffer valvesprings too

Are the face sizes the same?

Well, the book listed the turbo valves as .003 smaller (head diameter) than the CA20, but .003 is nothing... That's the thickness of a piece of paper... :laugh:

the ratio of the rockers or what ever the proper name is is slightly different between the 2 thats why you have use noew ones from the ca18et when you use the euro cam on the ca20e

Can u still bolt a CA18ET head onto a CA20E, because of the different valves used????
My CA20 has Mech Lifters... and its a 1985.
What year did they change?

86.5 is when they changed, IIRC. Yeah, you should be able to use a CA18ET head on a CA20 with no problems...

the heads themselves are identical its just some of the valvetrain that is different