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3.9 Engine Build

Hi Harv,
I'm sure I've seen a post on a 3D splitter somewhere but a search didn't find it, it didn't even seem to find your post(?!?!?). It would have been within the last few months as I've only had my car since June!
 
Finally I have my engine cases back fitted with their new 99.5mm full wet liners and the machining really is a thing of beauty.





Lots of measuring, gapping piston rings for each and cleaning to do before cases can come together.
 
Nothing useful to add but watching with interest.

Very impressive. :worship:
 
Looking good Harv! Liners look meaty and strong.

Dave Martin is a good old boy :thumb: Good luck with the rest of the build, will follow with interest.
 
The heads are finally built up ready to be fitted.

Recut intake and exhaust seats with multiple angles, refaced mounting faces (5thou off each) to remove slight distortion. Cambers measure out at 50cc

New set of exhaust valves and intake valves re-faced, very lightly lapped in to check contact patch.

Exhaust ports slightly modified.

New valve stem oil seals







More soon hopefully


:thumb:
 
Awesome work Harv, really liking this thread. An overall cost breakdown of the parts, machining and balancing would be great... if you don't mind sharing of course. This is something I plan to do in the future, hopefully not too soon though.

Keep up the excellent work,

Paul
 
Managed to get some more done on the build and into the real fun of assembly now.

Sorry for late response Wav, I've not done a cost breakdown as yet but suffice to say I'm doing this on a tight but reasonable budget not including my time I will try and get some figures added at the end. I suspect about 4k as I have been lucky with some bits and bought others a vastly reduced cost with the luxury of time as spares came up for sale and suppliers put up discount codes and offers.

Thanks to Dyno Mike for loan of the piston ring end gap tool and happy to say all ring end gaps are really exact, measurements taken at same depth in each bore :thumb:

Lots more washing and cleaning of parts, gapped ring set kept with bores 1 thru 6 respectively and fitted to pistons.

Rods fitted to pistons 1 thru 3, gudgeon pins and clips fitted, rotated to same position and triple checked, assembly's inserted into cylinders for lefthand case, pay attention to which way up rods run and markings on piston crowns point towards flywheel.



Crank carrier built up with rods for cylinders 4 thru 6, new ims timing chain, guide, new tensioner arm, oil baffle housing, gaskets, cam chains. Check everything multiple times



Another new ims bearing fitted, had about 5k on old new one but think I nicked it's somehow on removal for cleaning as no longer felt buttery smooth, peace of mind for £8




Carrier lowered into lefthand case half checking it's seated properly, fit new bearings for rods, pre lube, fit rod caps new arp rod bolts torqued to spec (don't forget special grease). Temporarily bolt carrier assembly into left case half to keep things in place

Next time, mating case halfs, fitting pistons 4 thru 6.

GT3 82mm plenum design finalised and should have prototype for checking here next week.





Trying to find a firm that can bend me up some decat pipes, drop me a PM if you know anyone or even have some to hand you don't want





:thumb:
 
Really interesting thread,
if you don't mind me asking are you and eng builder or mechanic by trade?
Great skills, I like to wield the spanners a bit but wouldn't attempt this sort of project.
 
Thanks :thumb:

I'm doing this build myself, mechanical engineer by trade or at least this is what I studied after leaving school when apprenticeships still existed though have spent years working in CAD to the oil & gas industry (sadly now as dead as the animals that gave us fossil fuels thanks to oil price and companies insatiable desire to constantly cut design costs in the last 10 years).

The m96 engine is a mechanical jewel and something like this is entirely within the capabilities of the home mechanic, just take your time.
 
Nice one Harv! Looks like you are doing a very methodical and diligent job, just the way an engine should be built. I'm not sure if you are using a build paste but can recommend Graphogen, have used it for over 30 years. Great to put on shells, cams and followers etc in order to provide total protection whilst cranking for oil pressure. It costs quite a lot but is worth every penny. The only downside is that it makes your oil look black very quickly, but that will be flushed at the running in oil change. We don't use it on piston skirts though.

Good work, keep the forum up to date :thumb:
 
Great work Harv. And inspiring stuff.

I like your idea of not just a rebuild, but an upgrade. And for reasonable money considering the cost of parts and precision machining.

Have you needed to replace the valve guides as well? From a cylinder head flow point of view, is the restriction in the inlet or exhaust side do you think?
I imagine that lovely 3 angle job on the valve seats, together with the increase bore size deshrouding the inlet valve should make a sizable difference to head flow, and hence torque.

Will you change the cams as well? I can imagine this engine will have masses of mid range thump, rather than be a screamer!

Like the others have said, please keep going with the updates. Very interested.

Cheers
 
Cheers,

I couldn't really justify taking this all to bits and then just refreshing it and generally mod my cars a bit when the time comes for something like this.

Regarding the heads no the guides didn't require replacement and had little wear for the mileage, so just the valves, seats and a little porting. I couldn't see anything to be gained in the inlets so only a little bit of clean up and then the exhaust had some smoothing. I don't think there's much on the table with these heads anyway they are not restrictive.

I don't plan on changing the cams either and not looking for all out peak HP just more usable midrange. I'm hoping the car gets is sparkle back, it's always felt lack lustre to me.

:thumb:
 
Wow! Awesome!

Would love to see the 3D printed part your looking to do!
 

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