What have you done today with your Austin Seven

[DavidB]

Brilliant photos and great to see high visibility rear lights...... A lesson some others could learn! 

David B.

[Zetomagneto]

Possibly over carbed resulting in a lack of torque at low rpm due to low airflow, prob better with a 1 inch SU.
You also have a low comp head, Ruby head would make big difference

[Michael D]

Possibly over carbed resulting in a lack of torque at low rpm due to low airflow, prob better with a 1 inch SU.
You also have a low comp head, Ruby head would make big difference

I've understood a 1.25 inch SU (which is fitted now) should do fine.....so that's disappointing to say the least... And I've got both  Ricardo and  Whatmough Hewitt HC heads lying in waiting..... I'll try fiddling. with advance/retard first... but must consult my friendly mechanic as I'm not versed at that.

[Chris KC]

Michael,

It's hard to comment on your disappointment without knowing how realistic your expectations are... or indeed more about the spec of your car.

Three things I do offer up:
1. Both my cars go OK with 1.25" SU's on. (What needle/ spring do you have?)
2. I once fitted a low comp head, but couldn't get my car to go over 40 mph
3. Most day to day poor running is attributable to points / ignition.

oh yes and 
4. - though I have little experience of them myself - the 3-speed 2nd gear is widely regarded as too low, leaving a precipitous drop to 3rd. This is the 'raison d'etre' of the so-called 'Andes' gear conversion.

[Michael D]

Hi Cris
1. The needle is a. No 6 and the spring is the Blue one (advice once given here by Bearded Wizard Ruairidh)...
2 HC head might contribute (got them lying in waiting as stated) but my friend-mechanic is always quite sceptic about mods I propose and its takes quite some convincing to get him to do what I propose
Plus I'm no real mechanic, have no workshop space, the Missus wants things done professionally for fear of ending up against a hard shoulder in the middle of nowhere, so the more specialist things I have to farm out.
3 I'll take that up prudently with my friendly mechanic as he does have decades of experience with classics and vintage cars and I only drive them since 1985 ......
4 I've. played with the thought of fitting a 4 speed box but Rosengart 4 speed boxes are thin on the ground, costly (the only one. I've found so far is located near Toulouse....and vendor will not ship by courier.....a round trip to collect it would therefore add considerable costs to the already high price asked... ) and would need some modifications to the car (there we go again...) So I'm finding myself between a rock and a hard place ....

[Ruairidh Dunford]

Michael - do note that my 1.25 SU carb is a full downdraft one (see below) - it will perform very differently to your semi downdraft, so the needle and spring that works for mine may not be so for yours.



Purchase a Gunsons Colortune kit (with the correct adaptor to suit your type of plug) and you will learn how the needle is oporating in your engine, from that you can make decisions about how to improve things.

[Terrytuned]

   
Carb size depends on state of engine tune, porting, valve size, cam profile, compression ratio, and to make it reliable the right crank/rods etc:
 I ran a gas flowed 1 1/4" SU for years on my race engine but felt it was gasping for air on acceleration so upgraded to an H4 1 1/2" the change in acceleration is impressive and you don't need to rev it as much to get the same performance, it is also fitted with a blue spring and
 gas flowed throttle spindle still with a 90thou jet and a std RLB needle.
Terry.

[Michael D]

Guys, please....Tell me then why the engine does pick up and rev to the audible max in 1st and 2nd (rev counter to be installed) quite willingly and is it not willing to rev in 3rd?? even taking into consideration the abysmal drop due to the gearing step (or is it a GAP) between 2nd and 3rd there ought to be at least some discernible throttle response and increase in speed....

[Reckless Rat]

Are you sure the carb is operating correctly? Take the ram pipe off and check to see that the damper piston is rising correctly. If the damper and needle are not correctly centred then it can stick and not rise. You can rectify that by loosening the jet mounting and resetting it's relationship with the damper assembly. However, with a standard engine and a LC head I would think that there isn't enough induction vacuum to properly operate a 1 1/4" SU, and as has been said earlier the raised position relative to the tank may be creating some fuel starvation problems. You may need to pump feed it.

You could try removing the spring and see if that makes any difference. The earlier H1 SUs (1 1/8") didn't have a spring.

[AustinWood]

I expect it's just overgeared in 3rd. The standard 2nd ratio is too low to get the speed needed to pull top strongly. I used to find that 25mph was about as fast as was comfortable with 30 max in 2nd. I now have Andes gearing which will take it to 40mph in 2nd and 30 is comfortable.
What speeds can you achieved in 1st & 2nd?