Harry's Roadster rebuild

[Harry]

Re: Dismantling

Hi Harry - give me a pm and i will talk you through the process of uploading if you havent worked it out. Coedpoeth - exactly where I broke down last time i went for a longer run in the roadster! Am 30 mins form you and Derek the Chairman is even closer.

Thanks, I get as far as inserting the photo file in the box, but I cannot get it to upload onto the thread ? Yes, I know where Derek lives I go through there every so often, but never have the time to meet up, one day eh ??

[Harry]

Engine out.

Not done much today, I had a loan of a hoist but it was faulty, so we lifted the engine out the hard way - rope and a scaffold pole, I then removed the clutch, which is in good condition, which surprised me, because almost everything else I've removed is faulty in some way or another, just the gearbox left to remove for tomorrow, will this lot ever go back together again ???

[djj_engineer]

Re: Engine out.

Hi Harry
You could borrow my engine crane. You don't live that far away.
Derek

[Harry]

Re: Engine out.

Hi Harry
You could borrow my engine crane. You don't live that far away.
Derek

Thank's for your kind offer Derek, I'll keep it in mind, I'don't intend sticking it back in the way I got it out, I'm now dithering over what to do with the old lump, there does not seem much to gain by overhauling it myself as the parts cost quite a bit, that added to the machine work that needs farming out, I did want to uprate it a little too.

[Harry]

Not a great Marlin day.

I got home from work had a coffee then set to with my usual enthusiasm, I removed the gearbox, ( I'd forgotten how small the Marina box is ) then sat it alongside it's replacement ( MGB 4 Speed with overdrive ) that's when my enthusiasm nose dived. I had listened to a few people about this set up, I'd also had a bit of a read, and as far as I was aware, this MGB box is compatible with the Marina 1800 - 18v engine as long as one replaces the back plate. Er - no is the answer, you can't beat finding out for yourself eh ? The input shaft spigot is twice the diameter of the Marina box and does not fit the engine, even if the spigot bearing was removed ( any ideas? ) and the MGB box will not fit in the Marlin tunnel, so the tunnel and floor needs removing too ( This job is getting well out of hand ! ) I intended doing the minimum possible to bring the car up to scratch but not there's little left of it, hehehe.
As far as the engine is concerned, after I got prices for all required parts to rebuild it, and paid for machine work on the cylinders and crank etc, it's just as cheap if not cheaper to have the engine rebuilt at a specialists which is a pity. I bought a engine breather box from ebay as the old one had been crushed inwards by over tightening the bolt, then I decided to remove the flywheel ( Another downer ) all six bolts were damaged, I did something I hate doing, I cold chiseled all six of them off, as in turned, not chopped the head off. So, I think I need a new plan, I'm going to take my dog for a walk. Any suggestions are very welcome.

[Mike]

Re: Not a great Marlin day.

Harry

Continue with Plan A - this is how it is with kit cars. When you have done it all, you will be thoroughly chuffed with yourself.........and your Marlin.

Mike

[stevejgreen]

Re: Not a great Marlin day.

I think this is risk that we all take when trying to do the unusual. Often there are workarounds, replacement spigot bushes can be machined to custom diameters. What you didnt mention was that you will end up using the MGB flywheel and clutch assembly, along with an MGB starter motor.
It might be the simpler option to buy a complete MGB engine/gearbox as your starting point.

Something to draw peoples attention to, is that though there is the option to rebuild a standard Marina 1.8 engine (as its mostly MGB parts) take care if you plan is to upgrade the power output. The Marina gearbox, derived from the small Triumph range, has a very limited supply of direct replacement parts. It's probably the single weakest link in the longevity of the Marina Roadster.

MGB however have a great support infrastructure that will probably last another 20 years.

Could it be time to rethink the project and go Zetec with a Type 9 that will just squeeze into the Marlin Roadster tunnel. (It did in mine)

[lil_red_roadster]

Re: Not a great Marlin day.

Some 1.8 Marina's had an insert in the crank which can be removed, facilitating the fitment of an MGB gearbox...most however don't.
If you want lower cruising revs I'd suggest considering a Type 9 instead...as this fits (just) an unmodified tunnel & can be made to fit the Marina bell housing (do a search on the forum or see www.5speedmarina.com).
If you contemplate fitting the B box then yes, the tunnel will require "dressing" to fit & unless you're lucky you'll either need to find an MGB crank or have the Marina crank machined out to fit the MGB input shaft.
Or find a friendly gearbox re-conditioner who can build an overdrive into the Marina box (or find a non-Sprint Dolomite box with O/D and have the Marina input shaft grafted in).

As Mike says, you have to roll with it sometimes...all part of the kit-car scene

It's generally worth a post on the forum if you're considering something, just to flush out any "gotchas" that people have encountered previously.

Good luck

[Harry]

Re: Not a great Marlin day.

Some 1.8 Marina's had an insert in the crank which can be removed, facilitating the fitment of an MGB gearbox...most however don't.
If you want lower cruising revs I'd suggest considering a Type 9 instead...as this fits (just) an unmodified tunnel & can be made to fit the Marina bell housing (do a search on the forum or see www.5speedmarina.com).
If you contemplate fitting the B box then yes, the tunnel will require "dressing" to fit & unless you're lucky you'll either need to find an MGB crank or have the Marina crank machined out to fit the MGB input shaft.
Or find a friendly gearbox re-conditioner who can build an overdrive into the Marina box (or find a non-Sprint Dolomite box with O/D and have the Marina input shaft grafted in).

As Mike says, you have to roll with it sometimes...all part of the kit-car scene

It's generally worth a post on the forum if you're considering something, just to flush out any "gotchas" that people have encountered previously.

Good luck

Thank's Red,Steve and Mike, I have sat on my upturned bucket ( While I was rubbing down the red "Orange peel and run" ) paintwork, and came to the conclusion that if I'm getting the engine rebuilt, I'll have the end of the crank bored out to suit as well. I can buy a mgb engine from the N Wales MGB center near me, but at about £300 - 450 for a used engine of little known condition, I think I'd rather pay more and have mine overhauled.

[stevejgreen]

Re: Not a great Marlin day.

This might help, excerpt from Peter Burgess Book: How to power tune MGB
Power Tune 43.jpgPower Tune 44.jpgPower Tune 45.jpg

[Harry]

Re: Not a great Marlin day.

Thanks Steve, I have read quite a bit of Peter's book, he was brilliant with these old engines ( As long as you have a machine shop and deep pockets eh ) anyhow I checked my crank end and it is the earlier type with the removable sleeve ( One job less ) I did spot a useful bit of info in this article and will keep it in mind for later, I'm off to do a bit more rubbing down now !

[Harry]

Rubbing down

Three more hours on the Marlin, my back tell's me when to stop ! anyhow, it was more rubbing down and a spot of " Cup brushing" best tool out, I love the cup brush! then I started ripping out the tunnel, it seems all the floor must come out too, all waiting for another day, this "bit of a job" has become at least 50% bigger than expected ! but I'm still smiling -------

[Harry]

More rubbing down

It's a bit cooler today after work, so I popped into the garage and had another two hours of rubbing down the body and then the running boards, it's quite therapeutic after a while, I got my new rubbing down tool and wet and dry today from CBS on line, they seem a first class firm to deal with. Anyhow, as I have been stripping this car down, then rubbing down the panels, it occurred to me that this old car was once Navy blue, and that it has spent a long time unused, either left outside or poorly covered, I stripped the engine and found that the bores had signs of corrosion patches in them as well as evidence on the body ( Be nice to know about this period ) Another item that crossed my mind is that the fiberglass back end is distorted inward by as much a 1/4" where the old case rack legs where attached to the body ( In my case, three sets of racks if the number of holes counts) I have filled these depressions in to a degree, they are about 4" square, I think it begs the question whether the body was ever strong enough to take a loaded rack ?? maybe it should have been thicker in this area, but that said the same distortion can be found in the running boards, where they are attached to the body. The running boards were attached to the back arch / wing using two HT 1/2" UNF bolts, if I remember correctly, I think these have a breaking strain of about 2 tonnes, that's 4 tonnes per side, ( to hold fiberglass together ) I think something smaller would have done, I had to get my slitter disc on them to remove them as they were totally solid.

[christopher.bogue2011]

Re: Not a great Marlin day.

Harry, years ago I swapped my marina gearbox with an 1850 Triumph which had the overdrive. The first motion shaft is the same so all that was necessary was to swap the bellhousing and shorten the propshaft as the Triumph box is slightly longer. From what I can remember there was very little modification needed on the tunnel as the Triumph box is much slimmer than the MGB box.

[Harry]

Buying a few parts

Not much done today, but I have bought a few parts ready for the rebuild, I had confirmation that my old Mk 1 rack is repairable and that I will have it back next week £ 113.00 with postage, I bought a stainless steel headlamp bar from ebay £40.00 with postage and two heat resistant braided hydraulic pipes to connect the engine to the oil cooler £40.00 ( Half price! ) I may be picking up a low mileage MGB engine this weekend, including carbs and starter, we will see how this turns out ??