Technical stuff > Tuning and competition

2 litre uprated engine rebuild

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75coupe:
I am currently in the process of rebuilding my 2 litre engine for more power, as it is currently in a sad state having broken 2 top piston rings and badly scored big ends from the dreaded Beta oil surge problem (despite having a modified sump) and thought I would share the rebuild along the way. Funnily enough the engine did not burn oil and still went well even with the broken rings, but blow by was apparent out of breather....

This is a DIY rebuild, so cost has been a major consideration, but all machining has been done by a local reputable company.

The bottom end spec is:

New 84.8mm Fiat 105TC 1600 cast pistons - approx 10.5:1 CR in 2 litre
Crack tested, polished and balanced crank - std journal size
Crack tested Lightened flywheel, uprated spec clutch all balanced together with crank/front pulley.
Block deck has minimum required machined to ensure flatness
Modified Auxilliary driveshaft - removal of fuel pump cam lobe and plug oil gallery.
Modified sump with windage tray etc, 19 row oil cooler with remote filter, thermostat and 2 quart Accusump to cure oil surge problem and keep oil temp under control

Head:

43mm stainless modified inlet valves, 36 mm std modified exhaust valves
Bronze valve guides
3 angle valve seats
Mild porting around throat area and short side radius only - ports left virtually std size
Isky Uprated valve springs
Cams will be 304 degree 42/82/82/42 with 10.6mm lift which I already have
Vernier cam pulleys - essential for timing cams properly

Carbs:

Weber 45DCOE 152 with 38mm chokes on GC offset inlet manifold, walbro electric fuel pump with holley fuel pressure regulator

Ignition:

Std Beta bosch electronic system

Exhaust:

4:2:1 mild steel header, 2 " single silencer with wide band Air/fuel ratio sensor & gauge.

Will post pictures soon, but if anyone has any ideas that I have not mentioned above, please let me know

75coupe:
Here are some pics:

This is one of the reasons for rebuild and why you need an Accusump or similar for competition work, oil surge wrecks bearings!! Surprisingly crank OK, just needed polish!

Reason no.2 broken top ring on old 1800 piston (only 35 years old LOL!) compared to new cast 105TC piston at 0.8mm oversize.

75coupe:
A few more bottom end pics, showing lightened/balanced flywheel - now 6.4kg vs 8.2kg for original. With Spec uprated clutch fitted it was 2kg lighter overall than std clutch/flywheel assy.
Crank has also been balanced with front pulley/cam gear etc.
Rods were weighed end to end and individually but were a matched set and all fairly close so were untouched.
Aux shaft has been modified so it does not have to be accurately timed. it has an eccentric lobe on the end to drive the mechanical fuel pump, which can hit no.2 con rod if it is not timed exactly. I have seen an engine completely wrecked because of this! I am using an electric fuel pump, so lobe is not required and is cut off and oil gallery tapped/plugged.
Block was rebored +0.80 mm to match new oversize Fiat 1600 Regatta/105TC pistons - available from Vickauto in the USA at a reasonable cost. This will turn the 1995cc block into a 2036cc block, but more importantly a high compression ratio of around 11:1 dependant on combustion chamber volume and head gasket thickness.
Engine was thoroughly cleaned, all core plugs replaced, oil galleries cleaned out with solvent and blown out, aux shaft bearings left alone as no longer available! Block painted black
Everything was assembled using Lucas engine assembly lube, new big ends, mains thrust washers, piston rings gaps were checked but found to be spot on

75coupe:
Before fitting head I  set the TDC mark on front pulley accurately using a dial gauge on top of piston.
Also did a "dry build" to see what piston to valve clearance would be by placing plasticine around top of piston, fitting head with an old compressed head gasket and fitting timing belt (do not use a new gasket!). Cams were accurately timed and engine was turned over by hand a couple of revolutions with plugs out, feeling for any tight spots or locking of engine which would indicate valve to piston contact or chamber to piston contact.
Fortunately all was good so head was fitted properly, but not before cleaning all threads in top of block with a tap and lubricating bolts with oil.

lanciamad:
Brilliant stuff! :)
What about the conrods your using, are they forged items?
I've got a few things lying around the shed/garage so i'd like to compile my wishlist for an engine build and also the reality of how much it's going to cost :-\
I'll be really interested in your sump/accusump setup, very wise, I won't be chucking money at an engine inless I do everything in my power to keep it running sweet for a long time.
Marcus.

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