1966 Mk1 Cortina GT

12 minute(s) of a 210 minute read

The sound deadening has made longer journeys much more bearable but I am looking at changing the gearbox to a Mazda MX5 or RX8 as kits are available and I could go 6 speed - there are a few caveats that I will need to alter the transmission tunnel and figure out how I will run the original odometer as there won't be a cable to drive it (it's not registering correctly anyway!)

Another winter job I have planned is relating to the fuel tank, the tank I have is fine but is from the early Cortina's which has a different sender unit that produces different resistances when full and empty

Another change made between the earlier Mk1 and my 66 Airflow is that the gauzes also use 5v voltage regulated dials and when combined with the earlier sender I essentially get half the resistance I should at the sender so when it's a brimmed tank it registers at half - I basically have to count miles and refill at 200 miles which is playing safe by approximately a gallon left in the tank.

I didn't want to modify the tank I had as welding could have caused more harm than good and new replacements cater for the older style sender and to make things harder the gauge can't be changed for an earlier model too! With all this in mind and that I design industrial tanks to pay the mortgage I decided to design a fuel tank that could take either sender have slightly more capacity and work with fuel injection.

This is a basic block drawing of the original tank

This has 40L capacity which given my 30-35mpg should give me 280 miles if I go steady and use every drop (hence why I play it safe at 200 miles!). The tank base is tapered for the fuel sender pickup and had a single baffle that runs across the width of the tank (not shown).

What I have designed leaves the length and width the same (as this is part of the boot floor). The height has been increased from 168mm to 175mm so it still gives plenty of ground clearance, I have reduced the rear angle to 4 degrees to prevent pooling and levelled the front section with a small sump that fuel can be drawn from along with baffling to prevent starvation on heavy cornering. I will also hinge the rectangular holes next to the pick up to allow fuel flow in 1 direction when cornering too.

The idea with the internal baffling is that it will also play a part of the tanks structure and help align plates whilst being fabricated. All of the plates will be laser cut and motlively be made from stainless steel so negate the need to post process treatments like galvanising etc which makes the cost comparable.

I'll bead roll the top and possibly the bottom for strength and to make it look a little bit factory and angle the filler so I don't have to modify the back panel to tank filler pipe but otherwise the design is about there.

I am planning on learning to TIG weld and I would like to at least jig this one up but will most likely get a responsible adult to help me

11-10-2022

I have let this slip again but I thought I would update this when I had something more to talk about, The last month or so has gone rather quickly partly because Mrs. Jim and I had a week in Anglesey (not in the Cortina) where we caught a lobster and went to a classic car museum/ cafe.

I was tempted to make an offer on the grill as it's better than the ones on eBay!

When arriving at home I received an email from the laser cutters to say that my tank plates were ready to collect so I took the Cortina for a light drive to collect them.

The slots needed a little running over with a needle file as I had kept the tolerances tight between these but the fitment looks great, all I need to do now is sort fasteners for the sender flange and bead roll the top and bottom plates prior to tank welding.

As I bit of fun I thought I would try printing a copy of a Timavo carb trumpet I used to have but stupidly sold. printed from PETG which has worked well under the bonnet and from what I have read it can withstand petrol too

It's louder for one (that wasn't my intention!) Top end 4500 + has a little extra to give but that might be because of the extra noise but it had survived 300 odd miles without any heat issues etc

I would have made a start on the tank after a day out to Bristol for YouTube related shenanigans but my exhaust decided to make an attempt to escape on the motorway - fortunately it was just before junction 26 on the M1 and late at night so it was quiet (apart from my lack of exhaust!) so in a small lay-by I removed the piping hot system, loaded it into the car and carried on up to Junction 27 and home (about 10 miles).

I'll be the first to admit that I am very lucky given what had happened and there was no damage to the floor, exhaust or myself. The clamps took the brunt of the damage as did the flexible joint but nothing that can't be replaced. The manifold however looks like it has been a lot time coming and is an area these manifold tend to let go - fortunately I had a spare manifold years ago that had rusted out at the flanges but the lower part of the manifold was surprisingly good.

I will replace the polyurethane mounts for standard rubber items as I think the exhaust mounts are much firmer than the engine mounts so this should have them balanced, I'll also repair the manifold so I can keep the Cortina going as it is.

My gearbox adaptor plate arrived and I am happy that it went on both the block and the gearbox with little problem, I did have to shave a little material off the bellhouse as the M10 nuts fouled. What I have noted so far is that the exhaust manifold won't fit without modification which I won't do as I'd like to keep it as it is despite the problems I've had so far!

I'm glad I found this out before hacking the transmission tunnel to then stall the project to make an exhaust manifold! What I will do now is get as many ducks in a row before I take the Cortina off the road to get the gearbox in. I would like to have the gearbox in and tested before Le Mans as I have wanted to go in the Cortina for many years now.

I have been spending some time in between jobs tweaking and finessing inlet and exhaust flanges for this very reason and I am just about there now, Printing examples has been incredibly helpful and cost effective.

Having spent some time on the forum I know this is a little council but I have started pallet wood panelling inside the garage, In my defence this is to allow me to hang more tools and free up space rather than look like a hipster coffee shop, I went all in and sanded the wood before treating with tung oil. I'm mid way through this wall and have printed shelf brackets to mount socket rails but it has also taken me much longer than expected!

11-22-2022

I had some off cuts that I figured I'd turn into shelves by making shelf brackets on the printer

All laid out, I like the setup and it's removed a considerable amount of weight (mainly hammers and files!) This isn't all of them but I have planned to have a set in the house. I'm happy with the result and I'll carry it on along the garage - but there's a few more jobs to do before then!

The exhaust is repaired but it's not my finest work and it's given me a few ideas for making improvements when I go with the Mazda gearbox. I meant to take photos but it's nothing exciting!

With these jobs sort I can finally make a start on the fuel tank. the slots are helping locate the plates but I need stability and to ensure they're at 90 degrees to each other so I again I printed some alignment jig things.

Once I have the welding wire I'll make a start in getting it tacked together which is exciting but I'm a little nervous about attempting this but I have friends who can help me out. Having the tank finished in the Cortina will mean I have a fuel gauge that actually works and the extra gallon will be great for longer distance which I'll need when driving to Le Mans next year.