Lotus Twin-Cam Camshaft Vernier

The customer supplied camshafts for a Lotus TC engine we are currently building had previously been modified by removal of the single large diameter OEM cam sprocket locating dowel, filling of the dowel hole and then the camshaft flanges were drilled with 15 smaller diameter holes. The engine was supplied to us piecemeal and partially complete. As such, the suitably modified camshaft sprockets that would have been used with the modified camshafts were not supplied to us.

As a result, we synthesised and calculated the required companion vernier holes required in the camshaft sprockets (16 if full circumference) and modified two standard sprockets accordingly. An interesting little exercise.

We ended up having the camshafts freshly reground and during mock build with light checking springs to degree the cams in to specification & assess valve to piston and valve to valve clearance, the IN and EX sprockets were marked at the exact relative index locations required for their respective companion camshaft. The centre vernier hole in each sprocket is the pre-determined master index hole for each camshaft, with the holes either side allowing fine final adjustment when the engine is assembled with the actual valve springs to be used that of course deliver far more force than the light mock build checking springs. As due to prior mock assembly only very fine adjustment if any may be required at final engine assembly, the full circumference set of 16 vernier holes in the sprockets are not required.

Standard Lotus TC Camshaft Flanges from one of our earlier builds

Camshaft with pre-existing previously applied multiple vernier holes (note filled original dowel hole)

Locating hole PCD and circumferential index with fixture in indexing head/rotary table on mill bed

Finished modified sprockets showing small vernier holes and larger OEM holes

L34 Holden Torana Dual Coil Distributor Build

A few details and pictures of old school Holden L34 Torana V8 dual coil distributor we’ve just resurrected. Back in the day, Holden commissioned REPCO (when it was still an engineering company…) to modify a small volume of standard common or garden variety BOSCH Holden V8 8 lobe points cam/single point distributors to an alternate and elegant dual-circuit configuration using two completely electrically independent contact set/condenser/coil circuits. Another US-based company was commissioned to produce the special dual king post cap and companion dual circuit rotor required. This design results in each individual circuit serving only 4 engine cylinders (with the distributor firing order alternating between circuits) so that the dwell behaviour of each circuit is akin to typical 4 cylinder engine dwell levels. This provides superior coil saturation behaviour and de-facto optimised spark intensity at elevated RPM levels. Many of these distributors suffered from rotor to cap interference issues and it is very common for the rotor centre snout to be damaged/cracked/compromised as a result. As the special dual king post cap is NLA, we manufactured a new cap by bonding in a second king post after machining a second post as required from a donor cap. We repaired the damaged rotor by manufacturing a new centre snout from phenolic resin stock and bonding it it place with high temperature aerospace grade epoxy. We also repaired the rotor shank by machining an aluminium support sleeve and epoxying it in place to bolster the rotor’s points cam attach shank hoop strength. With careful final assembly and detail checks and fitting iterations, we ensured a quality rotor to cap fit and interface. The L34 distributor also requires some key specific additional on-going in-service maintenance to ensure reliable performance, but that’s another story…

EH / HD Holden Six Standard BOSCH Distributor Restoration

Recently restored early model U-ZV/PDU6 BOSCH Holden Red engine distributor. This early Holden Red aluminium housing distributor has many detail features carried over from the earlier Holden Grey cast iron distributors and differs from the later Red engine distributors in having screw-on cap attach clips, different LT lead entry detail design and various other detail differences. We have replicated the original chromate finish on the cap attach clips and the distributor has the original period correct ZV P/N prefix brown bakelite cap and rotor. Very nice period piece rebuilt with NOS Australian-made “Lukey” ventilated contact points and NOS genuine BOSCH condenser.

Lotus Twin-cam HART Type Breather Fittings

Now in stock, HART type breather fittings to suit Lotus TC engine. We can also supply in mirror image if required.

Kent Formula Ford Engine

Formula Ford Kent engine that we built, have since dyno tested and that is now back in car and has completed initial track outing.

Kent Formula Ford Large Head Idle Speed Screws

A fresh batch of Kent Formula Ford engine (Weber DGAV) large head idle speed screws finished off today and now headed to San Jose CA. We made one of these large diameter head screw assemblies for a Formula Ford engine build we recently completed and observers of that build progression requested we manufacture some more screws.

The large diameter head allows quick and easy temporary idle speed adjustments to be made by hand for elevating idle speed temporarily (and then returning to the previous setting), during pre-race warm up in the pits, without having to go diving for a screwdriver or someone having to stand (idle…) holding the throttle partially open by hand.

L34 Torana V8 Dual Coil 4 Lobe Points Cam Distributors

VRD recently overhauled/restored/recommissioned two L34 Torana V8 4 Lobe points cam/dual coil distributors for a customer based in Invercargill N.Z.  Two distributors and various customer-supplied spares were selected, restored and overhauled to arrive at two complete distributors by repairing various key rare piece parts in the customer's collection of spare items to enable installation and re-use.

One distributor is fitted with a new twin coil post cap we provided by inserting an additional coil post to an NORS brown bakelite standard Holden V8 single post cap.

Completed L34 Distributors Ready for Dispatch 

Temporary tags on caps denote distributor (as opposed to engine) firing order.  Provides ease of installation for customer who can reconcile distributor and engine firing orders to ensure correct lead placement.

Twin coil post caps with original on LHS and item on RHS of picture being newly "manufactured" cap

Freshly lubricated and assembled centrifugal advance mechanism and 4 lobe points cam

Broken centre shroud on one dual circuit rotor with secondary crack also visible

Remnants of broken shroud machined away, crack ground out and new black bakelite shroud ready for bonding in place. 

New shroud epoxied in place and crack void potted with epoxy.

The customer supplied 3 caps and rotors and all had signs of rotor to cap interference during previous operation.  The broken rotor shroud pictured would be the end result of rotor to cap interference.  Careful final assembly and clearance checks ensured no interference issues now exist on either of the two finished distributor assemblies.

OEM quality control and tolerance stack-up considerations seemed to be lacking a little with these (low volume) production items.

One cap and rotor amongst the spare parts provided by the customer had clear evidence of electrical arcing/tracking across the bakelite insulating surfaces.  As the offset carbon coil post brush that communicates with the "ring" contact on the dual circuit rotor is some distance from the rotor centreline, this carbon brush has a high rubbing velocity inflicted on it my the  ring contact, whereas the conventional on-centre carbon brush contact experiences very little relative rubbing velocity.  Accordingly, the offset carbon brush experiences a high wear rate and the carbon dust worn from the brush deposits itself on the rotor and cap interior and can lead to cross-firing and arcing in the interior of the cap.  To ensure this does not happen, this design trait needs to be recognised, and the distributor maintained accordingly, with regular cleaning of the cap interior and rotor to remove carbon dust residue and to ensure the required insulation integrity exists.

4 lobe points cam, dual points, dual condensers of the two completely electrically independent ignition circuits.  45 degree distributor firing intervals = 90 degree engine firing intervals.  With each circuit serving only 4 cylinders of the V8 engine and the engine firing order successively  alternating from one circuit to the other, the dwell behaviour of each circuit and coil saturation time is akin to a 4 cylinder engine, so high RPM spark intensity is far superior to a standard 8 lobe cam/single coil V8 distributor.  Due to the independence of the two circuits, careful setting of the 45 degree firing interval between each circuit during final rig testing is crucial to ensure all engine cylinders see the same spark advance during engine operation.

A now well outdated, but still clever and interesting design.

Formula Ford Kent Race Engine Build

Latest engine build in progress is Formula Ford Kent unit for Sydney-based customer.  Some progress shots of bare block with more final assembly pictures to follow.

Yellow highlights @ scrutineer seal wiring sites

Modified Holden Six Distributor

A few pictures of recent Holden Six BOSCH electronic distributor overhauled using customer  supplied core and advance curve modified to compliment customer's other engine modifications.  Vacuum advance deleted and pulse generator stator anchor manufactured + fitted.  Now on its way back to customer based in New Zealand.

Lotus Twin-Cam Engine Build

Some recent pictures of Lotus Twin-Cam engine build underway at present.  Customer arrived with a ute load of sundry English Ford engine parts, a "Fordised" and knife-edged forged steel fully-counterweighted Datsun L18 crank and a well-used bare twin-cam head for VRD to combine into an engine.  Unlike the standard TC engine that is based on the 1500 pre-X-flow block deck height and stroke, this engine will be a "tall deck"/long stroke version based on a 711M Ford Escort block.

Lotus Twin-Cam Cylinder head on VRD Flowbench

Simple (but accurate) template/slave centre made for marking inlet manifolds to increase size to suit 45DCOE Weber carbs

Post modification

Death by Heli-coil...

Rectification of damaged/smeared head bolt washer spot face surfaces as a result of previous use of incorrect washers at these sites.

Increasing depth of LHS engine mount attach threads in freshly bored, decked and line-bored 711M block after removal of 0.450" from LHS engine mount pad to bring transverse block width in to line with that of earlier 120E, 116E, 691M et al pre 711M blocks.

One of several mock assemblies to check various fits and clearances including valve to piston and valve to valve clearance prior to final assembly.  VRD dummy tensioner plunger allows tensioner quadrant to be loaded to set chain tension during mock-up without needing to fit front cover

Clay blobs waiting patiently to be squashed during valve to piston clearance check...

CCing combustion chambers with burette

Fine adjustment to camber volume to equalise CC with slave second-hand valves fitted to protect freshly cut seats

VRD combination drilling/welding jig fitted to sump along with VRD windage tray.

Windage tray attach brackets manufactured and fitted with floating and self-locking anchor nuts waiting to be welded to sump interior.  Microstop countersink tool in background used to countersink brackets to accept anchor nut attach rivets.

Pre weld

Don't forget the dipstick access hole when making the windage tray....

Oil suction tube skirt

Oil temp sender port and lockwire tab for sump plug and temp sender added to RHS of sump

Bespoke Holden Grey Dual Coil Racing Distributor

Holden Grey six cylinder dual coil distributor development and final rig testing completed this week.  This distributor uses a 3 lobe points cam custom ground for Vintage Racing Developments by Clive Cams in Victoria.  An additional coil lead post resides in the distributor cap to communicate to the secondary circuit on the dual rotor button track.  This design uses 2 completely electrically independent circuits and two ignition coils, such that each coil only serves 3 engine cylinders and accordingly has very desirable dwell/charge soak behaviour for retention of spark energy at higher RPM.

The ultimate points-triggered battery/coil distributor for use in CAMS historic classes that must retain points triggering.  Dwell for each 3 cylinder circuit in this distributor is in the region of 56 degrees (compared to circa 38 degrees for a standard single point/single circuit/single coil/6 lobe cam six cylinder distributor).  Six cylinder analogue to 4 lobe cam L34 Torana dual coil distributor.

Renault GORDINI R1134 Engine Build

Some pictures of recently completed Renault Gordini engine built by Vintage Racing Developments.

Engine Oil Primer

A few pictures of engine oil primer recently completed at Vintage Racing Developments.  Uses standard English Ford "Burman" vane type oil pump and draws from large PVC reservoir.  In-hex drive is fitted to pump shaft where pump drive gear normally resides when pump is fitted to engine.  Male hex drive in hand drill is used to operate pump.

When a new camshaft is fitted to an engine, especially with high load valve springs in a modified/competition engine, it is undesirable to wind the engine over on the starter motor with the spark plugs removed to build engine oil pressure prior to initial start.  For optimum camshaft run-in and subsequent camshaft longevity, it is desirable to immediately bring the engine to 2500 to 3000 RPM as there is then a sufficient supply of "splash" oil released from rotating components to adequately lubricate the camshaft.

Use of the priming pump immediately prior to initial start (along with the usual filling of the oil filter before fitment) provides instant oil pressure upon initial start and allows the requisite camshaft run-in process to be carried out without potential bearing starvation.

Ford 1600 Crossflow Engine Initial Start

Initial start and camshaft run in procedure this week with high ZDDP content oil.  11:1 compression ratio, 45 DCOE carbs, Wade Camshaft, and various Vintage Racing Developments bespoke modifications.

Custom Hybrid BOSCH HEI Distributor (Ford 4 Cyl Pushrod Engine)

Bespoke distributor made using components from 2 different BOSCH V8 electronic distributors, one BOSCH 4 cylinder electronic distributor and original LUCAS points distributor.  Uses 4 of the original 8 plug locations on Holden V8 cap and Holden V8 housing.  Supplied to customer to use on Ford 1500 pre-crossflow engine in Group S historic sportscar.  Uses companion low resistance ignition coil and electronically controlled variable dwell.

Holden V8 housing modification

LUMENITION Electronic Kit to Holden Grey Distributor

Some pictures of recently manufactured small bespoke adaptor plate used to fit English-made "LUMENITION" P/N OS50 eye and chopper to original Holden Grey Motor BOSCH distributor.  LUMENITION make many kits to fit the generic OS50 eye (which is the trigger component of the wider LUMENITION system) to a large range of distributors (but not this one...)

Holden Grey BOSCH Hybrid HEI Electronic Distributor

This distributor is a development that along with modified internals marries the top half of a BOSCH electronic HEI distributor with the lower half of an original cast iron BOSCH Holden Grey Motor points type distributor.  Uses original BOSCH control module (which is usually mounted on the integral "balcony" on the side of the electronic distributor housing) but is now remote mounted for use with the hybrid distributor.  Remote mounting is primarily for packaging reasons, but also has the advantage of removing the module from close proximity to direct engine heat and vibration.  Companion low resistance coil is used and distributor provides variable/active dwell control and high energy spark.

Allows use of 0.060" plug gaps and provides a fully functional true electronic bolt-on HEI system for Grey Holden engines.  Not to be confused with simply fitting an "electronic points" module to a standard distributor which maintains an essentially fixed dwell and points type coil.

Ignition package is for customer in NSW running Holden Grey engined nostalgia drag car.

Vintage Renault Powered Racing Boat

VRD carried out some engine modification work for the owner of this vintage Renault powered racing boat a little while back.  The boat and highly modified engine were built in Melbourne during the 1950s and at that time the builder had bespoke pistons cast for the engine.  The boat set various Australian Water Speed Records in period and the speed record for the 50 cubic inch class that this boat set in 1960 still stands!  The pistons have very large crown intruders and the current owner noticed during routine engine teardown that the edges of the piston intruders were showing evidence of picking up in the bores of the piston sleeves in the direction parallel to the piston pin.  VRD modified the piston intruders to relieve this area with minimal reduction to compression ratio and also measured and selectively matched various pistons and liners the owner had (this is a wet sleeve engine), before "Flexhoning" honing the liners ready for re-assembly.  VRD also manufactured a simple ring lapping tool to allow the owner to lap slightly thicker new piston rings he had obtained to suit the original ring groove widths.

Following the VRD piston modifications and careful engine re-assembly by the skilled current owner, the engine has since performed reliably at various vintage racing boat meetings throughout Australia.

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Modified Holden Grey Distributors

Two more cast iron BOSCH Holden Grey engine distributors off to customers in Western Australia this week.  Both re-curved to suit customers' supplied engine specifications.  Single point unit has typical 6 cylinder 38 degrees dwell and dual point has 48 degrees dwell.  Both retain these dwell readings to beyond 7000 crankshaft RPM under rig test.  Both units have vacuum advance deleted and fixed breaker plate assemblies.

Dual Point Conversion for Group Lb Special

Recently completed dual point conversion and re-curve of BOSCH distributor for use on Group Lb historic MG-based special.  Distributor has advance curve tailored to engine, circa 50 degrees dwell and consistent dwell behaviour beyond 7000 crank RPM.  Some details of the car and pictures of completed distributor below.  Vehicle is based in South Australia. 

1947 MG TC Holden Square Rigger

Background

The car has the following summary technical specification:

1947 MG TC – (original engine number XPAG 3306, chassis number TC2675)

• Registered Number Victoria RZ 685

• Square rigger style T series MG body.

• Cycle front guards.

• Fitted with a modified Holden Grey engine in the 1950’s with triple SU’s and other engine and mechanical modifications (unknown if any competition history).

• Fitted with both 16” and 15” x 5” wheels in the period up to 1965.

• Hydraulic telescopic shock absorbers and axle restraints front and rear.

• Holden grey banjo differential centre and modified axles in TC rear axle housing.

• Cut down Morris Minor rack operating as a steering box across to the original position LHS steering arm (common modification in the era).

• Larger twin leading shoe 10” x 2 ¼” front brakes in one off cast iron finned brake drums.

• Modified finned Monaro Motors 9” MG TC rear brakes.

Competition History

The car was built in the 1950’s as a MG Holden (triple SU’s and modified engine) with modified front brakes, telescopic shock absorbers etc, The car has a confirmed ownership from 1959 and an identified racing history in the period 1963 to 1965:

• Used as a road car from 1959 to 1963 by Vern Barlow in Victoria as a grey Holden engined MG TC special (triple SU’s, modifications, etc).

• Sold to Peter Mahony in 1963 in Victoria (entered under BP Heidelberg).

  • Competed at Lakeland hillclimb, Calder and Templestow hillclimb.

• Sold on then to Rod Cooper, Victoria (entered under SAAS) at some point in late 1964.

  • Competed at Lakeland hillclimb, Calder and Hume Weir.

• The subsequent ownership history is unknown until 2013.  No history of competition has been confirmed before and beyond the dates above, and its competition history appears to have ended in 1965, due to the car quickly becoming uncompetitive. 

• The car was then in storage in a semi disassembled state since 1966.

• The car is currently under restoration to Group Lb specifications in its early 1960’s configuration since 2014.

Engine Specifications:

The following are the key specifications in progress:

•  EJ Block. (early low number block)

• Capacity 2350cc (thin wall sleeved).

• Main bearing straps and girdle.

• Vauxhall E Model crank (stroked to 3 1/8”). – MGB main bearings / modified rear seal arrangement.

• Mitsubishi Starion con rods and bearings.

• Lightweight billet flywheel (8kg), Holden heavy duty 8.5” single plate clutch assembly.

• Ross balancer.

• JE 3 ring domed pistons (21mm gudgeon diameter).

• Modified water pump and head outlets.

• Vintage Racing Developments special twin point distributor.

• Modified camshaft grind – approximately 235 degrees @ 0.050” and 0.3” cam lift.

• Modified head with 1.48” and 1.25”’ valve sizes and relieved chambers – LS1 beehive springs.

• 1.7:1 rocker ratio.

• 10.5:1 compression ratio.

• Triple 30 degree SU 1 ½” (internally modified) on 1960’s Sonic short inlet manifold and common cold air plenum chamber with rolled edge short ram tubes.

• One off exhaust manifold – 1 3/8” primaries, 1 5/8” secondaries into a 2 ¼” system.