Club G40 Forum

Technical => Engine and Transmission => Topic started by: Agent47 on September 05, 2017, 05:45:48 pm

Title: Rebuild after 2 years away, a few questions.
Post by: Agent47 on September 05, 2017, 05:45:48 pm
Hi guys, i've been away for 2 years building a MX5 turbo and now that it's at a "finished" stage i've decided to pull the G40 out of the shed and do a rebuild. I'm starting with the head and have stripped it down and am shopping for parts, got gaskets and oil sensors but am struggling to get hold of valve springs, so any ideas?
Valve collars seem available through Shrick but can't seem to find standard retainers, the ones i've taken off are damage free so should/could i use these again?
Valves themselves look good, could do with a clean, any tips on that? Inlet number 030601BT-T39153 - is this the right valve? Exhaust number 030611BT-T14531 - correct?

I know lots of pieces were obsolete a few years back so this could be tricky but any help would be awesome. Missed driving the saloon!
Title: Re: Rebuild after 2 years away, a few questions.
Post by: randombadger69 on September 08, 2017, 07:30:23 am
I bought springs from DBilas, they are slightly shorter than OE and come with washers to fit between the head and spring. Work fine. Think Regal were distributors for them when I bought them; but should be available on their website. As for cotters and other associated parts such as valves I would recommend speaking to Nick at RS Engine supplies 01233 629982. He will be able to tell you what OE would have been and supply at a far more reasonable price. He can also supply elring head and block sealing kits.

Quickly looking here it seems the cotters are available, not sure about retainers.

As for cleaning the valves soak them in something like parrafin then fit them into the chuck of a battery drill and clean with red scotchbrite or similar with plenty of parrafin to loosen the carbon.
Title: Re: Rebuild after 2 years away, a few questions.
Post by: Agent47 on January 06, 2018, 07:17:23 pm
Thanks for the reply.
I ended up going to Germany and buying everything. Had the head pressure tested and it's all good despite a few cracks but no where near any water ports. Should be good to go back together.
Now just sat here looking at parts and considering my 1w lump sat in a shed.....
Title: Re: Rebuild after 2 years away, a few questions.
Post by: Agent47 on January 09, 2018, 05:44:40 pm
The questions continue...

I bought a head many moons ago, and when i did my chassis swap i finally got to putting it in. It's had a fair bit of porting (could be an understatement) and when it was all up and running i saw boost figures of 5-7psi on an OBD stage 2 fresh charger. This is with a gt inlet and 51mm TB. Now it's coming to putting things back together and im looking at gaskets and ports and wondered how much matching i should do.

Inlet manifold - 33x28mm (height x width)
       gasket    - 36x28mm
       head      - 35x28mm
So, do i take out more from the manifold (im thinking yes) but is it possible to take a bit of the gasket off. With the bolts in there's a bit of wiggle room and could, if not aligned perfectly, block some flow. Also need to know which way round the gasket goes.

Exhaust manifold - 39x39mm
            gasket    - 32x32mm
            head      - 30x28mm
This im pretty certain i'll leave alone, the gasket and head match quite well with a bit of wiggle allowed for the gasket. My small concern is with the manifold being so large, that gas may get caught up behind the gasket and potentially leak or block flow.

Thoughts and comments welcome, all figures are within 0.5mm.