Roadster swb MGB engine and gearbox help

[sparker1994]

Good morning all,

Please can I place a request to any owners of a marlin roadster that has an mgb engine and gearbox in it?

I'm in the early process of a build where I would like to fit and mgb engine and gearbox in my swb hybrid roadster.

I would highly appreciate it if any owners out there could send me some photos of the engine position, mount position, box tunnel and clearance etc. I'm struggling to imagine how it's going to sit...

Even better if anyone wouldn't mind, I'd love you see one in-person, if anyone would allow me to see theirs I would highly appreciate it! I'm Gloucester based for reference.

Thanks alot!

Sam

[stevejgreen]

Re: Roadster swb MGB engine and gearbox help

Presumably you are confident of passing an ITV, otherwise the additional work may be to no avail.

If you have a Hybrid chassis with the mountings for a B series engine (identical to a Marina) then use them, it’s about as far forward as the engine can go with a mechanical fan in front.
From that point on, the challenge is principally transmission tunnel dimensions, which will impinge on footwell space, and the installation of an MGB clutch master cylinder, and suitable support for the gearbox, for which I have never seen a drawing.

There are other minor considerations like a remote electric fuel pump, which must be considered, especially in the case of an accident, you don’t want the fuel pump running, if you are incapacitated and can’t turn the ignition off, another ITV requirement.

A browse through Tech Tips in the Members Only section should reveal more clues.

Good luck!

I have no definitive pictures so cannot help there, but I would be equally curious to see them too.

[marlin1984]

Re: Roadster swb MGB engine and gearbox help

Good morning all,

Please can I place a request to any owners of a marlin roadster that has an mgb engine and gearbox in it?

I'm in the early process of a build where I would like to fit and mgb engine and gearbox in my swb hybrid roadster.

I would highly appreciate it if any owners out there could send me some photos of the engine position, mount position, box tunnel and clearance etc. I'm struggling to imagine how it's going to sit...

Even better if anyone wouldn't mind, I'd love you see one in-person, if anyone would allow me to see theirs I would highly appreciate it! I'm Gloucester based for reference.

Thanks alot!

Sam

Hi Sam
Gloucestershire is my old stamping ground. I'd be very surprised if there isn't someone with a suitable Marlin in the Stroud & District Motor Club [at their last trial I was told about 12 Marlins were there …] Might be worth joining and asking ?

ATB
(ref. mechanical fans. My Mk2 had a standard-looking B engine with standard mechanical fan. BUT it was so far away from the core as to be useless/just absorbing bhp to drive it/stirring engine bay heat ! [now removed and I will rely on an electric fan in front of rad. - fingers crossed!)

Ideally a mechanical fan without a shroud should be 1/2" to 3/4" from the core [to allow for engine movement under braking. Impossible on Marina-suspended Mk 2 because of the rack].

Reminds me - I must also block the big gaps around the Marlin rad. to ensure all airflow goes through the core.

"ITV" is that a typo for IVA? ITV is a tv station.

[jon_cox]

Re: Roadster swb MGB engine and gearbox help

ITV - Inspecciòn Tècnica de Vehiculos
Spanish MOT test. Steve lives in Spain now so we sometimes get the spanish equivalent in his posts

[Blue Marlin]

Re: Roadster swb MGB engine and gearbox help

My old mates Roadster had a 1.8 Marina engine and he fitted an MGB gearbox with OD. I seem to recall that he had to get a new backplate made but I can't remember what other modifications were done.
It did go to Gloucestershire but I don't think it's there now.

https://www.marlinownersclub.com/forum/showthread.php?5713-Q232-PDS-Where-is-she-now&highlight=Q232

[stevejgreen]

Re: Roadster swb MGB engine and gearbox help

ITV - Inspecciòn Tècnica de Vehiculos
Spanish MOT test. Steve lives in Spain now so we sometimes get the spanish equivalent in his posts

It was a typo, possibly exasperated by my iPad preferring ITV to IVA, which I was careful to check this time.

But yes you are right, the Spanish ITV covers every technical inspection whether IVA or MOT equivalent. The vast majority are operated by contractors, licensed by the government, rarely direct government agency employees.

[stevejgreen]

Re: Roadster swb MGB engine and gearbox help

My old mates Roadster had a 1.8 Marina engine and he fitted an MGB gearbox with OD. I seem to recall that he had to get a new backplate made but I can't remember what other modifications were done.
It did go to Gloucestershire but I don't think it's there now.
https://www.marlinownersclub.com/for...highlight=Q232

Converting a Marina block to MGB, is a lot more than a backplate. flywheel, starter motor, clutch, spigot bush, fuel pump, spring to mind.

[stevejgreen]

Re: Roadster swb MGB engine and gearbox help

Hi Sam
Gloucestershire is my old stamping ground. I'd be very surprised if there isn't someone with a suitable Marlin in the Stroud & District Motor Club [at their last trial I was told about 12 Marlins were there …] Might be worth joining and asking ?

ATB
(ref. mechanical fans. My Mk2 had a standard-looking B engine with standard mechanical fan. BUT it was so far away from the core as to be useless/just absorbing bhp to drive it/stirring engine bay heat ! [now removed and I will rely on an electric fan in front of rad. - fingers crossed!)

Ideally a mechanical fan without a shroud should be 1/2" to 3/4" from the core [to allow for engine movement under braking. Impossible on Marina-suspended Mk 2 because of the rack].

Reminds me - I must also block the big gaps around the Marlin rad. to ensure all airflow goes through the core.

"ITV" is that a typo for IVA? ITV is a tv station.

My treaties on Overheating Roadsters at Keepandshare covers most of this, but it’s mostly irrelevant to fitting an MGB engine and gearbox in a Roadster.

[Blue Marlin]

Re: Roadster swb MGB engine and gearbox help

Learning loads on overheating / manual fans. I thought the fan on my Alfa engine was doing a great job as I have never had any problems. Now I'm wondering how it can be effective as it has no shroud and sits well behind the radiator.

[marlin1984]

Re: Roadster swb MGB engine and gearbox help

The Alfa engine must be a well-designed and naturally cooled engine. With a mechanical fan too far back then it just stirs engine bay heat and definitely uses a few bhp.

Shame the ACTC will only accept B engines in Class 7 otherwise I'd be quite tempted. The 1750 Alfa engine is much nicer [the 2.0 litre is even better …]

Edited : I happily stand corrected by A K-B. ACTC will accept a few other engines in Class 7 but not the Alfa twin-cam [nor the Rover V8].

[ggrum]

Re: Roadster swb MGB engine and gearbox help

The Alfa engine is all alloy with wet liners so lots of coolant round the cylinders. It also has a large oil capacity (about 6 litres from memory) and a wide alloy sump with cooling fins. I had a thermostatically controlled electric cooling fan which only ever came on once and that was when I was stuck in traffic in the centre of Le Mans on a baking hot June day.

[sparker1994]

Re: Roadster swb MGB engine and gearbox help

Evening all! Sorry for the late response!

Thanks all for commenting, I have just gone for it and ripped the floor and tunnel out the vehicle.

Plan to rebuild the floor and tunnel around the MGB gearbox in hopes that there is still enough space for our legs!

I'll post pictures when on the computer!

Cheers,

Sam

[HairyDave]

Re: Roadster swb MGB engine and gearbox help

Often the best way, that way you have no-one to blame but yourself.

[sparker1994]

Re: Roadster swb MGB engine and gearbox help

So!

I have removed the horrible rotten ply wood floor and transmission tunnel ready to position the engine and gearbox to measure up the mount position etc.

I have rebuilt the SU Carbs, fitted an Acuspark Distributor system (no more points, lovely!) and given it a test fire. 3/4 cylinders have poor compression (valve seat probably need work) but after some fiddling she fired!! there is hope yet!

Engine and gear box are now bolted together for the test fitting.

next steps are to hang the engine and box and figure out where it's going to go!
from there it'll be some thinking and fabricating of new mounts to hold the lump

IMG_20191027_141602.jpg
IMG_20191110_162009.jpg
IMG_20191117_145447.jpg
IMG_20191117_145456.jpg
IMG_20191117_145508.jpg

[wiggiesworld]

Re: Roadster swb MGB engine and gearbox help

Please confirm that you're going to use those caterpillar tracks at the side of the garage to turn it into the first Marlin half-track! Ha ha ha