Roadster LWB Marina 1.8 TC air filters and preventing carbs from over heating

[ggrum]

In order to avoid a bonnet bulge for the side draught carbs on the Alfa engine on my old Roadster I made up a box that just fitted in the space between the carbs and bonnet and ran a large diameter flexible plastic pipe from underneath to the front of the engine bay and fitted a decent air filter. The photo should give a rough idea of the layout. Without a filter some fine dust will enter the engine and eventually cause some internal wear but with the typical mileage that most Marlin owners do It probably wouldn't be a problem as suggested by listerjp2 unless you spend a lot of time driving through deserts.


IMG_4429.jpg

[ggrum]

Dunno why the photos appeared three times!!

[dcunn]

Message sent........please look at top right of your screen for "Notifications"

Thanks DC

[redmonty]

In order to avoid a bonnet bulge for the side draught carbs on the Alfa engine on my old Roadster I made up a box that just fitted in the space between the carbs and bonnet and ran a large diameter flexible plastic pipe from underneath to the front of the engine bay and fitted a decent air filter. .

Thanks for the info and pics. More food for thought. Lovely looking engine BTW.

[listerjp2]

Try this its only 3cm deep, may even fit the left hand carb.

By the way, although it says for Hif44 it will fit the 6.

https://www.somerfordmini.co.uk/ram-pipe-silver-30mm-long-hif44-1-34-su

Adrian

[redmonty]

Try this its only 3cm deep, may even fit the left hand carb.

By the way, although it says for Hif44 it will fit the 6.

Adrian

Wow that looks interesting. Thanks for looking this up.

[john cole77]

You can get low profile stub stacks that will fit inside and air filter
MED STUB STACKS | MED (med-engineering.co.uk)
Should have read to the end of the thread before posting

[listerjp2]

You can get low profile stub stacks that will fit inside and air filter
MED STUB STACKS | MED (med-engineering.co.uk)
Should have read to the end of the thread before posting

You could use these and just have some wire gauze behind them to catch the larger bugs.

Adrian

[Ye Ol Ripper]

With regards to the original post. I also have an 1800TC engine but am still running the original 1&1/2 " Su's.
If you are now running TR7 carbs, the needles within are likely to be incorrect, especially as the engine is nolonger using the original airfilters.

I am using the original Marina steel heatshield with original spacer blocks. I am using airfilters that have foam inserts trapped between an inner & outer wire mesh.

It is a very tight fit to get the front filter on place, so be prepared to have a few stab points on your finger tips .
A useful tip ,If you hold your fingers as far above your head after , the bleeding will stop pretty quickly unless you have a clotting disorder.

When I first used my Roadster after an 1100 hour restoration, it did suffer with vapour lock on my eay around the M25 after attending the Suffolk club meet.
The temp was above 28 degrees. My Marlin was down to 30mph as I managed to keep it going on the inside lane of the M25 with Lorries etc thundering past. It was pretty a scarry experience tbh!

[Ye Ol Ripper]

[Ye Ol Ripper]

I have posted more info in my edited post twice and unfortunately its not displaying?
Perhaps the IT guru can assist with that please?

[listerjp2]

With regards to the original post. I also have an 1800TC engine but am still running the original 1&1/2 " Su's.
If you are now running TR7 carbs, the needles within are likely to be incorrect, especially as the engine is nolonger using the original airfilters.

I am using the original Marina steel heatshield with original spacer blocks. I am using airfilters that have foam inserts trapped between an inner & outer wire mesh.

It is a very tight fit to get the front filter on place, so be prepared to have a few stab points on your finger tips .
A useful tip ,If you hold your fingers as far above your head after , the bleeding will stop pretty quickly unless you have a clotting disorder.

When I first used my Roadster after an 1100 hour restoration, it did suffer with vapour lock on my eay around the M25 after attending the Suffolk club meet.
The temp was above 28 degrees. My Marlin was down to 30mph as I managed to keep it going on the inside lane of the M25 with Lorries etc thundering past. It was pretty a scarry experience tbh!

Hi

I spoke to Burlen personally and got there advice as to the needle requirement. They were spit on first time.

Adrian

[redmonty]

You could use these and just have some wire gauze behind them to catch the larger bugs.

Adrian

Thanks for the update. looks like an interesting option to consider.

[redmonty]

With regards to the original post. I also have an 1800TC engine but am still running the original 1&1/2 " Su's.
If you are now running TR7 carbs, the needles within are likely to be incorrect, especially as the engine is nolonger using the original airfilters.

I am using the original Marina steel heatshield with original spacer blocks. I am using airfilters that have foam inserts trapped between an inner & outer wire mesh.

It is a very tight fit to get the front filter on place, so be prepared to have a few stab points on your finger tips .
A useful tip ,If you hold your fingers as far above your head after , the bleeding will stop pretty quickly unless you have a clotting disorder.

When I first used my Roadster after an 1100 hour restoration, it did suffer with vapour lock on my eay around the M25 after attending the Suffolk club meet.
The temp was above 28 degrees. My Marlin was down to 30mph as I managed to keep it going on the inside lane of the M25 with Lorries etc thundering past. It was pretty a scarry experience tbh!

Thanks for taking the time to share this info, very helpful. I remember the anxiety of the carbs overheating in the past. Very embarrasing especially in a car that attracts attention like a Marlin. Will check with original builder of car if they changed the needles to suit.

[Ye Ol Ripper]

Hi

I spoke to Burlen personally and got there advice as to the needle requirement. They were spit on first time.

Adrian

Hi Adrian

1) Your engine is a 1275cc A series, not a 1798. B series.

2) Your engine is a single carb set up & not a twin carb set up.

The twin TR7 carbs being of larger size , according to Peter Burgess book give less low down torque on a standard 1798 B series engine than the twin 1. 1/2 SU's. It is for that reason they weren't usrd as standard on MGB's.

However if the cylinder head has tripple valve seats, been ported and gas flowed with a long cente branch manifold & a cam such as a piper 270 . Then the TR7 carbs will improve matters.

So my point is it really depends on whether the B series is standard spec or not.

I have rolling road tested many engines. Both the A series & B series engines gave between 2 & 5 hp with water injection.

The key thing here is to get as much cold air into the intake, being drawn from the front of the car, ideally with a large bell ram pipe on the grill end of the hose.

In the future instead of my current pancake filters. I plan to use an area on the offside to mount an airbox with filter, possibly using the cylinder head studs to attach some bespoke brackets. The cold intake from the front enters the airbox , which might be from a puma 1.7. then the large outlet goes to something similar to GGrum's stainless steel fabricated unit on his Alfa engine.

However the air feed to the air filter box (originally from the puma 1.7or Fiesta Mk4),will have to travel either over the engine or at the back of the engine between the cylinder head to bulkhead space and then feed into the carb fabricated air box at the rear or on the top of it. The limiting factor to the routing is that the Puma 1.7 intake hose diameter is very large and it therefore might not fit under the Bonnet/ Rocker cover space , as there needs to be some clearance also there too from the hot engine below it. It is therefore likely to need to have an air entry point into the fabricated carb box at the rear,rather than the top.