Amazon: 1964 Amazon 122S restoration project

[Laird Scooby]

Originally Posted by Juular

Next challenge.

It's doing around 18mpg on decent runs, which isn't right. Measured from taking mileage between brimfuls. I've factored in the 4.1 axle throwing the odometer out by using GPS tracking.

I think I've got the carbs very close, but would being a touch on the rich side account for this? I'm expecting closer to around 25-27 given the diff and OD combo.

If the carbs aren't perfectly balanced (Use a Gunsons Carbalancer or similar) before doing the mixture, this will make the car drink like Oliver Reed on a bender.

Also if you're doing short runs and on choke a lot of the time, that won't help either. Lastly, what fluid are you using in the dashpots?

[Juular]

Fairly long runs. It starts easily and the choke lever goes in by the end of the street so no need for it to be out.

I set it up by disconnecting everything, adjusting the throttle shafts for proper simultaneous engagement, then balancing the carbs using a tube to my ear. I then marked the flats on each adjustment nut and richened them one flat at a turn each until lifting the piston around 1mm using a screwdriver caused a mild increase in revs then back to normal. Finally I set the choke so the first part of the lever lifts the idle, and the final part enriches the mix.

There's absolutely no smoke or fuel smell which makes me think it's not set mega rich.

It idles at around 800rpm and is perfectly smooth. In my findings so far with this, if the carbs aren't balanced exactly the idle is truly abysmal under 1200rpm, so I feel it's extremely close if not spot on.

Ignition timing has been set to around 19BTDC as per the manual.

Dashpots have atf in them.

I've done SUs before and had them just right without any special gear, but haven't dealt with twins before. If it's out, I don't think it's far out.

[Rustinmotion]

Originally Posted by Juular

Fairly long runs. It starts easily and the choke lever goes in by the end of the street so no need for it to be out.

I set it up by disconnecting everything, adjusting the throttle shafts for proper simultaneous engagement, then balancing the carbs using a tube to my ear. I then marked the flats on each adjustment nut and richened them one flat at a turn each until lifting the piston around 1mm using a screwdriver caused a mild increase in revs then back to normal. Finally I set the choke so the first part of the lever lifts the idle, and the final part enriches the mix.

There's absolutely no smoke or fuel smell which makes me think it's not set mega rich.

It idles at around 800rpm and is perfectly smooth. In my findings so far with this, if the carbs aren't balanced exactly the idle is truly abysmal under 1200rpm, so I feel it's extremely close if not spot on.

Ignition timing has been set to around 19BTDC as per the manual.

Dashpots have atf in them.

I've done SUs before and had them just right without any special gear, but haven't dealt with twins before. If it's out, I don't think it's far out.

Do you know what needles are fitted? Just for elimination

[Laird Scooby]

Originally Posted by Juular

Fairly long runs. It starts easily and the choke lever goes in by the end of the street so no need for it to be out.

I set it up by disconnecting everything, adjusting the throttle shafts for proper simultaneous engagement, then balancing the carbs using a tube to my ear. I then marked the flats on each adjustment nut and richened them one flat at a turn each until lifting the piston around 1mm using a screwdriver caused a mild increase in revs then back to normal. Finally I set the choke so the first part of the lever lifts the idle, and the final part enriches the mix.

There's absolutely no smoke or fuel smell which makes me think it's not set mega rich.

It idles at around 800rpm and is perfectly smooth. In my findings so far with this, if the carbs aren't balanced exactly the idle is truly abysmal under 1200rpm, so I feel it's extremely close if not spot on.

Ignition timing has been set to around 19BTDC as per the manual.

Dashpots have atf in them.

I've done SUs before and had them just right without any special gear, but haven't dealt with twins before. If it's out, I don't think it's far out.

With all that in mind, i'd suggest worn jets/needles and possibly throttle shaft seals - all of the above can upset economical running during driving but setting up on idle can still be perfect.

[Juular]

Worn throttle shafts is a possibility. The front carb has a small amount of play in the shaft although it doesn't seem to be having much effect. Carb cleaner / water sprayed around the shaft doesn't alter the rpm at all.

As for the needles, I'll have to look. I'm pretty sure it's got the standard needles for the setup.

[Burdekin]

First place to start is the filters; make sure they aren't dirty, blocked or undersized.

Worn shafts result in a rough idle.

Have you set idle as per Volvo procedure, they should be rich at idle.

Check your needles are correct for engine.

I always fit a O2 wideband and gauge and you can then see how the mixture is when driving.

[Juular]

Right, advanced the timing a touch (21BTDC) and backed off the front carb by two flats, the rear one by one flat, based on the colour of the plugs.

I also fitted the front trim piece that goes above the radiator and seals against the bonnet, as I suspect air rushing into the engine bay isn't helping a huge amount.

Added a few psi to the tyres.

Latest 100 miles of mixed A road and town, then refilling the tank is calculating to 32mpg!


Genuinely surprised at the difference from a tiny bit of adjustment.

[Othen]

Originally Posted by Juular

Next challenge.

It's doing around 18mpg on decent runs, which isn't right. Measured from taking mileage between brimfuls. I've factored in the 4.1 axle throwing the odometer out by using GPS tracking.

I think I've got the carbs very close, but would being a touch on the rich side account for this? I'm expecting closer to around 25-27 given the diff and OD combo.

The consumption does seem too high. GAM does about 25 MPG in everyday running - and has the same set up as your motor car (4.1:1 rear axle, Type D overdrive, B18D motor). On a longer run (over about 50 miles) I might expect 30 MPG.

Alan

[Juular]

Originally Posted by Othen

The consumption does seem too high. GAM does about 25 MPG in everyday running - and has the same set up as your motor car (4.1:1 rear axle, Type D overdrive, B18D motor). On a longer run (over about 50 miles) I might expect 30 MPG.

Alan

That around about what I expected to hear and I'm glad to know it's achievable with that setup.

If I can get 25-30mpg routinely I'll be happy. The rortiness of the twin carb engine with pancake filters is quite addictive!

Can I ask what sort of 0-60 figure you estimate you get with the 4.1 & OD? Is it slouchy or do you feel like it compares reasonably well with modern traffic?

[Othen]

Originally Posted by Juular

That around about what I expected to hear and I'm glad to know it's achievable with that setup.

If I can get 25-30mpg routinely I'll be happy. The rortiness of the twin carb engine with pancake filters is quite addictive!

Can I ask what sort of 0-60 figure you estimate you get with the 4.1 & OD? Is it slouchy or do you feel like it compares reasonably well with modern traffic?

You should be able to achieve 25-30 MPG, I think your twin SU carburettors just need tuning or balancing. The is a good SU set-up page published by Ron Kwas (a contributor to this forum), I'd suggest following it through from scratch.

Balancing the carburettors is a bit tricky, I found the best way was to use my Gunson CO tester, with that I identified that one of the SUs was contributing much more than the other to the CO emissions and so was able to get them the same in just a few minutes, like this:

https://www.volvoforums.org.uk/showp...postcount=1179

Once balanced that made a big difference to GAM's running and fuel consumption.

Alan