free hit
overhauling a 907 engine - Engine & Ancilliaries/Gearbox - The Lotus Forums Jump to content
Sign in to follow this  

overhauling a 907 engine

Recommended Posts

here a topic for overhauling a 907 cilinderhead (912)


or better say: 2 lotus 907 heads, because i am overhauling 2 engine's




first i remove the cilinderhead from the engine,

then i put the cilinderhead inside a industrie cleaner (to get all the oil and dirt off from it)



when i came out, i take the valve's out and clean them,

after cleaning i can see how the valve's look like (and yes some of them are burned..)

so the burnd ones i can throw away


i have a other cilinderhead in case if i need parts from a other head,

so now i need 3 exhaust valve's


after that i grind/cut the valve's so they have a new layer to put inside the head,  (cut under a corner from 45 degrees ofcourse)


after that, i clean inside the cilinderhead, so i can take a look to the "sessions" (i hope i will use the right word) (the round thing when the valve is closed and where it rest on it)


somethings the sessions are gone, because it gets to hot, or just old and many miles, or maby bad valve timing, it could be so much things, but this time i had luck and the look good, (not really good, but i dont have to put new ones inside it)


the valveguide's where also good, only 2 where broken off, so next week i get to others to put back in, so it complete agian,


thats what i did today, the next time i will do the rest, and all the info and pictures will come also,


here  some pictures:





on this picture you can see really good the sessions, the first on the left is done, and the right not yet, (you can see the difference)






here a valve after cutting/grinding and "sand in" inside the session




with this machine i can see if the valve's are closed, because it makes vacuum on the port,




this is the meter i can see if its good or not good with the valve's (2 each port) and this one is good closed! so i can go to the next port





all work is done at my dad his own overhauling company, i did all the work, (he owns also a lotus, a esprit turbo se) and thats why i love lotus so much because he has it allready from 1995...


Edited by Vulcan Grey

Share this post

Link to post
Share on other sites
Upgrade today to remove Google ads and support TLF.

Great work, Tocus!  I think the word you are looking for when you say "sessions" is valve seat.


I've never seen the vacuum method of checking a valve is sealing properly before.  I guess it checks the valve stem seals as well or do you put some oil on the stem to help it seal for the test?

Share this post

Link to post
Share on other sites

Yess thats the right word! but you know what i mean,


without oil i test it...


it just work like this, when i should use oil, the meter will become higher,

because its also more closed.. when its not yet good, i must sand it in agian, to make it better,

Share this post

Link to post
Share on other sites

Don't know if you are using a machine for lapping the valve seats. I used to do it by hand. Quite a few over the years, come to think of it.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this