TVR Chimera 500 | Mustangshire

TVR

CHIMERA 500

TVR

CHIMER500

This car came to me for a service, and to sort out some rough running and strange noises from the engine. I changed the oil, resealed the plenum chamber and it ran reasonably well. However, the noises were diagnosed to be camshaft and followers. This is not unusual for a higher mileage car such as this, and I suggested a rebuild at a later date.

The customer agreed that this was the way to go, and at the same time some performance upgrades to squeeze a few more horses out of it.

When it arrived for the rebuild, the engine was sounding particularly rough, so work began straight away to rebuild it. The engine was removed and stripped down to the block for cleaning and inspection. Various problems were identified, the flywheel had some scoring and uneven wear, one of the pistons was quite badly damaged and four more had damage to the crowns indicating presence of foreign matter in the cylinders at some point. The four pistons were dressed to remove the marks and the damaged one, replaced. The reciprocating assembly was sent away to the machine shop for balancing, and the damaged flywheel refaced. A new friction and pressure plate were obtained, along with ACL main and big end shells, a set of piston rings and a new oil pump gear set.

Hi-tensile ARP cylinder head and main bearing studs were fitted, to help prevent head gasket failure in the future, as the owner intended doing a few track days, which can show up any weaknesses. The advantage of these studs is they screw into the block allowing the heads and main bearing caps to be secured with nuts rather than bolts as per the original. This virtually eliminates the risk of any thread damage to the block, which can sometimes happen when the original bolts are tightened. This may result in having to helicoil the metal in the block to restore the thread.Obviously this needs to be avoided if possible.

All the castings were vapour blasted, and the steel components, shot blasted and stove enamelled. Most of the fasteners were replaced with stainless items, and the exhaust headers shot blasted and painted in a high temperature coating.

The camshaft used was a new profile developed by TVR Power and is know as an 885T. This has the low down torque of the “stump puller” profile, but has a more usable power range peaking out at around 5200 rpm. I think this was the first engine to be built with this cam, and it certainly worked well on the road.

The cylinder heads remained standard, but were cleaned with new valve seals. Competition head gaskets were installed and ARP exhaust header bolts fitted. These have 3/8” AF heads rather than 9/16” AF that they originally have, this means you can get sockets and spanners in to tighten the exhausts much more easily.

A new duplex cam chain was fitted and ARP 12 point inlet manifold bolts to finish the job off. ARP flywheel bolts were also fitted for extra strength, but apart from these modifications, the engine remained fairly standard. New rocker cover badges were fitted and a carbon fibre plenum badge was made with “Chimera 500” engraved into it.

The car was set up on the dyno and produced a healthy 320 bhp and cleanly revved to 6750 rpm.

I was really pleased with the end result of this project, it was a delight to drive, and ran beautifully with the new cam profile. I shall certainly be using the cam in future builds.

The vehicle before any work commenced, a very tired looking engine.

The engine removed from the car, ready to be dismantled.

The engine partially stripped and ready to be removed.

Here is the car with the engine removed. It’s a bit if a mess to say the least, but will clean up with a bit of effort. The wiring was the biggest concern; quite a lot of it will need rewiring or repairing.

The engine being dismantled.

One clean block. The alloy has been acid cleaned, washed and thoroughly degreased with petrol, then cellulose thinners before being dried and blown clean with compressed air. All the oil galleries and water passages have been chemically cleaned to ensure all dirt is removed.

This is the block being cleaned and inspected for wear and damage.

Here the ARP cylinder head studs are being fitted, all the bores are dressed and the block completely spotless.

The ARP main bearing studs fitted, the block is now ready for assembly.

The newly painted engine mounts fitted with stainless bolts.

The 885T camshaft fitted in the block.

The crankshaft in position and the rear crank oil seal fitted waiting for the bearing caps to be installed.

All the bearing caps in place and torqued up. Note the aircraft orange sealant around the rear bearing. This is important to stop any oil leaks from the rear of the engine.

Another view of the installed crankshaft.

Flywheel fitted and a new hi-torque starter motor. Also, the camshaft gear and distributor drive are installed.

Here you can see the freshly ground flywheel, the ARP hi-tensile bolts are yet to be fitted.

Front pulley assembled and temporary fitted to the crankshaft.

Eight spotless pistons, ready for installation.

The ARP flywheel bolts fitted, note the new bronze bush in the end of the crankshaft.

Rocker covers shot blasted and stove enamelled with new “TVR” badges.

Inlet manifold and plenum chamber assembled.

Cylinder head assembled ready to be fitted. Here you can see the ARP exhaust header bolts that make putting the manifolds on so much easier.

Block cleaned ready for head gasket and cylinder head.

All eight pistons installed, cylinder heads to go on next.

The head fitted and torqued to correct tightness.

Things have moved on now, both cylinder heads have been installed, the front alloy castings, the inlet manifold and the idler pulley. The plenum casting and rocker covers are just placed on the engine for now to prevent any dirt getting in.