thspeller
Active Member
This is a long story so bear with me...
I have a series 3 with an 11H 2.25 petrol (branded 2.3) engine from an early 90. It came with a Weber 34 ICH carb and I recently replaced it with a new Weber 34 ICH exactly the same as part of the restoration.
I have struggled for power (especially on long hills) even though my truck is very light (no roof, single occupant, etc.). I assumed this was just a series.
I recently had the chassis changed and new springs fitted which has given it a bit of a lift. I was always running small tyres (215/70r16) which now look silly on vehicle that sits higher. I want to replace tyres to 235/85 or 7.50 size. I am concerned what that new tyre increase will do to the car's performance with only just enough to power to survive my hilly home town.
So, my initial reaction was to get the head gas flowed to compensate for some of the performance but Turner have identified that my big issue by far is the undersized carb for the 2.3 engine which actually came with a 32/34 DMTL which (as the name suggests) has twice the breathing diameter.
So I am now considering converting back to what must have been the original 32/34 DMTL setup. My intake manifold has two ports so I assume that suggests my engine will take the upgrade. I know that I have to play around with the throttle (lever to cable operation), install a fuel return and wire solenoids.
My questions are as follows (if you could try and answer whichever ones you can):
(1) Does anyone know whether the 34ICH to 32/34 DTML have a significant power advantage / enough to offset changes in tyre sizes?
(2) Can anyone confirm that my intake manifold (photo attached) was indeed designed for twin choked carbs originally?
(3) Is there any issue with me having a series stainless exhaust (i.e. would a wider exhaust from a ninety be more efficient)?
(4) My fuel tank doesn't have a return - how important is this? I have hard some people just block off this fuel return or let it drain under the car as it is rarely used?
(5) Any suggestions for the throttle rigging?
Thank everyone.
I have a series 3 with an 11H 2.25 petrol (branded 2.3) engine from an early 90. It came with a Weber 34 ICH carb and I recently replaced it with a new Weber 34 ICH exactly the same as part of the restoration.
I have struggled for power (especially on long hills) even though my truck is very light (no roof, single occupant, etc.). I assumed this was just a series.
I recently had the chassis changed and new springs fitted which has given it a bit of a lift. I was always running small tyres (215/70r16) which now look silly on vehicle that sits higher. I want to replace tyres to 235/85 or 7.50 size. I am concerned what that new tyre increase will do to the car's performance with only just enough to power to survive my hilly home town.
So, my initial reaction was to get the head gas flowed to compensate for some of the performance but Turner have identified that my big issue by far is the undersized carb for the 2.3 engine which actually came with a 32/34 DMTL which (as the name suggests) has twice the breathing diameter.
So I am now considering converting back to what must have been the original 32/34 DMTL setup. My intake manifold has two ports so I assume that suggests my engine will take the upgrade. I know that I have to play around with the throttle (lever to cable operation), install a fuel return and wire solenoids.
My questions are as follows (if you could try and answer whichever ones you can):
(1) Does anyone know whether the 34ICH to 32/34 DTML have a significant power advantage / enough to offset changes in tyre sizes?
(2) Can anyone confirm that my intake manifold (photo attached) was indeed designed for twin choked carbs originally?
(3) Is there any issue with me having a series stainless exhaust (i.e. would a wider exhaust from a ninety be more efficient)?
(4) My fuel tank doesn't have a return - how important is this? I have hard some people just block off this fuel return or let it drain under the car as it is rarely used?
(5) Any suggestions for the throttle rigging?
Thank everyone.
