Carburettor rebuild

The story begins with some carburettor issues.  Since I got it was not perfect, sometimes it seemed to over-fuel when slowing.  However, the main issue was that the secondaries would get stuck open after going to full throttle.  This meant that the car would idle at 2k rpm after going full throttle.  The only way to get the secondaries to close was to stop the engine and restart.  Really not an ideal situation.

Having spent a long time online reading about other people with similar issues and tying an array of possible solutions nothing really worked.  Searched for vacuum leaks, checking for obstructions etc.  If I lived in the states I’d have looked to buy a replacement carburettor from breakers.  This would have been a quick easy way test if it was carb or something else.  However not really an easy option in the UK.  So decided that the next step was to try a carburettor rebuild.  Ordered a kit from the US with everything in that is needed to complete a rebuild.  Many of the parts in the kit are old stock as they don’t make these all these parts anymore.  But overall a very good kit.

Took lots of pictures from all angles, at different stages of disassembly to ensure it goes back together the same way it came apart.  Also made notes on settings, and positions of the various adjustment screws etc.  Something that seemed odd, during this process, was that one of the idle mixture screws was fully screwed in and the other was out 3 turns.  The base setting for these is meant to be 1.5 turns.

SO many parts 🙂

Many hours later everything was cleaned and reassembled.  Sadly that was the end of the good news.  Set everything up as per the instructions re-installed on the engine.  It did start but it did not run well.  Over the course of several weekends tired different sets of instructions for setting up the carb.  Inhaled far too may exhaust fumes. Had help from family, only just managed to get it to a semi-usable state.  Oddly the mixture screws had to be set as it was when it was taken apart, one all the way in and the other out several turns.  After the rebuild, it ran worse than before.  The secondaries still got stuck open at full throttle. Tried replacing the points with a hall effect Pertronix ignitor & replaced the old coil with a new one (Flame-Thrower also from Pertronix).  Also changed the stock style fuel filter with an external one just in case there were any fuel supply issues.  No luck 🙁

I’m sure that someone with carburettor experience would probably be able to understand what was going on and might be able to fix it.  I get the feeling that there must have been some sort of damage on the carb, either blocked channel or some other kind of damage from my rebuild and/or an earlier rebuild.

Holley Sniper EFI system

After spending way too much time on the carburettor I decided it was time for something more drastic.  I had a plan to install EFI at some future stage.  With all the issues the timeline on this project was moved forward.  So ordered a Holley Sniper EFI system.   I ordered the master kit which comes with fuel filters, fuel pump, hose & fittings.


Mechanical fuel pump removed and the hole left in the side of the engine covered with the supplied cover plate.

Intake manifold removed, damn that’s a heavy lump of iron!  I’m used to plastic or aluminium manifolds.  The coolant temperature sensor for the EFI system was installed in the location of the original factory temperature sensor, this seemed like the optimal location for the best reading for the EFI.  Had to remove the brass adapter in order to fit the new sensor.  It wouldn’t unscrew so it had to removed with a Dremel and tapped out.

The original temperature sensor was installed just behind the thermostat housing.  This placed the sensor on the inside loop of the cooling system so the dash gauge has a good reading.  To install the sensor a new hole had to be drilled and tapped.

O2 sensor installed, the Sniper EFI system comes with a no weld solution which is really practical.  ‘Simply’ (not so simple without removing the exhaust) drill a hole and bold up.

The EFI system requires a return line for the fuel.  I didn’t fancy removing the tank in order to install the fittings.  That left two choices, either return to the filler neck or to the pickup.  The latter was chosen as it is more convenient for connecting the return without having to go into the trunk with a fuel line.  Patrick did a fantastic job of installing the return fittings into the tank.

Fuel lines, fuel pump and filters installed.  Decided to go with hard lines for the majority of the distance.

In order to fit the EFI the original spacer plate was needed.  It lifts the body up high enough so the throttle linkage clears the top of the engine.  The spacer intake holes were polished to remove flash lines and match nicely with the throttle body.

Wiring was planned out to fit on to the engine neatly.  Since I plan to install the Holley Dual Sync distributor all of the wiring & the module for this was prepared in the loom.  As and when this part arrives it should be a simple case of plug an play.  For now, the original vacuum advance distributor will be used.

The display for the EFI was installed in the centre console behind the roll-up storage compartment.  This hides it away keeping a nice stock look.  The display is easily accessible when needed.

All installed, basic setup wizard steps completed! 🙂

The first start it kicked into life right away!  One short blip on the starter and away it went.  Woo 🙂

Second start now with air filter. (Exhaust flaps closed on these first two starts, didn’t want to annoy the neighbours late in the evening, hehe)

It runs really well on the EFI, very smooth, more responsive on the throttle.  Starts right away, no need to worry about cold weather.  Driven a few miles with it so far and the system is in the process of learning, not sure it has much to learn as it runs fine already.  Really happy with this upgrade.

Leave a Reply