So, after some thread searching and parts searching, I am going to assume the I head is the better of the 2, considering eta heads are going for ~$35, and I heads are around $150-$200. I can visibly see from the intake gasket I removed the ports are MUCH bigger in the I head.
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My first E30, its taken apart....help pls.
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So after a little research it appears that both the "E" and "I" heads have the same size valves. 42mm Intake and 36mm exhaust. Is it just the ports that are different? Could I port the shit out of the eta head and get the same results as I would out of the I head, or is there other factors that make them different, like combustion chamber sizes?
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Before you get too far off on a tangent, verify exactly which head you have. Look at the casting # on the intake side. If it ends with 200, it is an early eta head, with smaller combustion chamber, valves, and ports. You don't want this head. If it ends with 885, it is either a super eta head or a "i" head. They are identical. (Same ports, same valves, same chamber size.) If it is a 885 head, the differences between the two are valve springs (the "i" has duals, the s-eta singles), and cam (the s-eta has a 256 cam, the "i" a 264, if I remember correctly.)
If it turns out you have the s-eta head, add the inner valve springs, and change to a "i" cam and you're set.
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The 200 head from an eta is wrong in so many ways for your car. First, it has a 4 journal eta cam, not the 7 journal one for your "i". Second, it has the wrong size intake ports (smaller as you mentioned), and will not match properly with your intake. Third, smaller valves, 40mm intake and 34mm exhaust. Forth, the combustion chamber is different than what you need for your pistons. (And smaller too!)
So the answer is no, it won't work. I suppose it might (emphasis on might) work if you were stranded in the Mojave. But to go through all that work to get the head installed correctly (porting, chamber reshaping, etc), it still would be a dog.
Find a "i" head or even a s-eta head (cheaper option). That way you'll know it correctly connects with your other pieces.
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Originally posted by vr2jetta View PostSo, I am guessing I cant put a 24v head on my m20 bottom end, huh? I havent seen any posts about this and I seen a couple in the classifieds and they appear different.
The differences between the motors (M20 & M5x) would require substancial creative engineering to solve fitment and drive issues. The first and formost on my mind is the M20 is belt driven, while the M5x is chain driven.
If I remember correctly, a few M20 24 valve prototype heads were made once upon a time, but haven't seen the light of day in many years.
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Here's your solution... http://www.r3vlimited.com/board/showthread.php?t=137595 (if you can find a way to get it to you.)
The question to ask is do you still have the old head? If so, you can use it's cam & springs to upgrate the s-eta head. Otherwise, a quick search on Ebay found an 885 head starting at $20 with a Buy it now of $200.
Keep looking... The parts are out there.
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Originally posted by jmc1590 View PostSure you can... It's called an M50 swap.
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Originally posted by vr2jetta View PostI thought an M50 was a complete motor. I may have to look into that. I submitted a thread request for noobies like me who dont know the "lingo" yet but I guess the moderators dont think it is important enough to post. All I know is I have an E30 with an M20 motor, anything beyond that is still unknown to me. I know they are all codes for year/engine model but I am still unsure as to what they are. I will be headed to the junkyard in the next few days so I will have to see what I can find. Thanks for all the help!
The M20 is about the easiest motor I have ever worked on, outside of the aircooled VW motors.
If I were you, since you need a head anyway, buy an M20B25, AKA the "i" motor. Pull the head off, taking a ton of pictures, take the head off to the maching shop, get it inspected/cleaned and replace the valve guide seals, plus a fresh resurface.
GL!
Luke
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Originally posted by StereoInstaller1 View PostYou have a pretty steep learning curve ahead of you, bubba.
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Got the head set today and finished port matching the intake/exhaust manifolds. Friday I should be able to commit to buying a decent i head, and when I get it, a port job and valve lapping will be in order. After that is all assembled I will pick up the water pump and timing belt and (hopefully) get this running! Cant wait!!
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